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PostPosted: Wed Sep 26, 2012 3:58 am 
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I wrote this article on Redline but have now finished so will post it here, hopefully the Mods might remove one or two of the very old
sticky threads with broken links.

First up I have to say that I have the same love hate relationship with koni's that a lot of other people have, great shocks but it REALLY
pisses me off that I can't buy spares and service koni's myself.

Koni make 3 different main types of Shocks.

Twin tube Hydraulic
Twin tube hydraulic low pressure
Mono tube high pressure

Each type has it's pro's and con's, Mono tubes have good heat transfer properties and with high internal pressure are good for raising
static ride heights, however most can't be adjusted easily unless they have external oil reservoirs, Rally guys tend to use Mono tubes
because the Nitrogen charge stops the oil from cavitating, Bilsteins are a rally favourite.
Monotubes can also be mounted at any angle so can be used on inboard suspension designs unlike twin tube Hydraulic which require
gravity to keep the oil near the foot valve.

Twin tube hydraulic designs can easily have external adjustment, the pressurised versions have a small amount of Nitrogen to control
cavitation, generally adds about 8lb/in to your spring rate, sometimes you will hear the term 'degassed' that just means they have taken
the gas out of a low pressure shock, usually done on control or OEM dampers to lower the car slightly, not the best idea really.


Most Koni dampers are twin tube hydraulic with or without low pressure gas, they are what we are mostly concerned with, construction
is pretty similar regardless of how they are packaged, main flavours are,

Sealed strut ie, Mk2/3 Rear Koni sport
Cut a Strut ie, Mk2/3 Front Koni sport
Dry Cartridge/insert , ie 8611-1257RACE
Wet kit- the same internals from dry cartridge built directly into your old strut housings.
Attachment:
Koni x 3.jpg
Koni x 3.jpg [ 76.13 KIB | Viewed 12478 times ]

Photo shows left to right, sealed strut, some models will come with the spring seat welded to the body.
Next is the 'cut a strut' easily spotted by the retaining post on the bottom, cut and gut your OEM strut and install the insert in.
3rd photo is the dry insert, many older cars have struts that have inserts from the factory, vw golfs, corollas etc, this insert shown is the
double adjustable race one with the bump(compression) adjuster at the bottom.

The 'Wet' inserts are exactly the same internals as the others but are installed directly into the strut, essentially a collection of parts adapted
to fit into a strut housing, pretty much any existing strut can be modifed to be a Koni double adjustable.


Last edited by Dattman on Wed Sep 26, 2012 4:13 am, edited 2 times in total.

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PostPosted: Wed Sep 26, 2012 3:58 am 
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Should probably clairify rebound and compression damping before I go too much further.

To plagiarise the koni website :D
"Compression or bump damping controls the unsprung weight of the vehicle (wheels, axles, etc.). It controls the upward
movement of the suspension such as hitting a bump in the track. It should not be used to control the downward movement
of the vehicle when it encounters dips, also, it should not be used to control roll or bottoming."
Basically it affects the interaction of the tyre with the track, getting it right maximises the grip.

"The rebound damping controls the sprung mass of the car, it controls transitional roll (lean) as when entering a turn.
It does not limit the total amount of roll; it does limit how fast this total roll angle is achieved.
How much the vehicle actually leans is determined by other things such as spring rate, sway bars, roll center heights, etc.

The reality is rebound is the most important part of the damping, not enough and the weight transfer will play havoc, too
much at one end and you'll lose response and cause undue loss of car balance and too much in total can cause 'jacking down'
where the shock gets compressed under bumps and never extends back up, hit enough bumps in a short time and the shock
will be compressed onto the bump stops.
"Contact with the bump stops causes a drastic increase in roll stiffness. If this condition occurs on the front, the car will understeer;
if it occurs on the rear, the car will oversteer."

On a road car the bump settings are optimised for the road which has all sorts of bumps, potholes, manhole covers, different types
of surfaces etc, the race track however is generally very smooth so you can run much more compression damping.

Here's a quick photo of the internals of a twin tube shock.
Attachment:
Koni bits.jpg
Koni bits.jpg [ 169.95 KIB | Viewed 12477 times ]


On the end of the inner tube is the foot/compression valve and on the end of the piston rod is the piston, imagine the shock is fully
extended, the inner tube is full of oil, when the piston rod is pushed in, some oil flows without resistance from below the piston to above
and the rest thru the non return bump valve at the end of the inner tube and into the outer tube which is effectively just a reservoir, this
valve controls the oil flow and therefore compression damping.

On the rebound stroke, the piston rod is pulled out and the oil above the piston which is pressurized is forced to flow through the piston
this generates the rebound damping, at the same time some oil flows back, without resistance, from the outer tube through the footvalve
to the lower part of the inner tube to compensate for the volume of the piston rod emerging from the cylinder, basically under vacuum.

So looking at the two piston rods the most obvious thing is the rebound stop (black arrows) is in a different place, this stop determines
how much of the piston rod is left inside the shock when fully extended, so shock travel is basically the length of the inner tube/shock body
minus how much piston rod is left inside.
So if you ask your koni agent to shorten the shock they will usually add some nylon rebound rings (yellow arrow) which prevents the piston
rod from extending out of the shock as far.

So why does the subaru piston rod extend so far out of the shock at full travel? well the shock has a very long stroke ratio to the over all length
of the shock and the problem is at full extension the shock is very weak, ie not much piston rod left inside, since it's a macpherson strut it's
subjected to side loading, the top bronze bush and the piston are what stops the shock from bending in half, the further the shock is compressed
the stronger it is in terms of side loading as there is a greater distance between the top bush and the piston.

OK, back to the suby shock, droop is the answer, they use progressive rate springs and huge droop, the actual ride height will put the piston back
in the middle of the stroke where it's stronger but the advantage is over bumpy stuff the shock has extra travel to control the wheels, with 190+mm
of travel they probably run about 90mms of droop, pretty hard to lift one wheel off the ground when there is so much travel in reserve.

For a race car the higher spring rates mean for a linear spring you won't get much droop, on my car with 280lb front springs I get 33mms of droop
and for the rear I get 27mms of droop, a rough guide is to run at least 1/4 travel for droop, so 33 x 4 gives me 132mm of travel, not much point
having any more travel than that, standard swift strut has 155mm of travel, basically I would have 23mm extra travel which adds to the ride height,
only way to add droop to lower that ride height is to use keeper, tender or progressive rate springs.


Last edited by Dattman on Wed Sep 26, 2012 4:07 am, edited 1 time in total.

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PostPosted: Wed Sep 26, 2012 3:58 am 
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So what are our options???

We'll start with the obvious choice, the swift Koni sports front and rear, part numbers 86-2588sport and 87-2429sport respectively, great value for money and excellent for a road car.

The issues with them are
Same length as standard shocks.
Improved valving over OEM shocks but is struggling to control 270-300lb spring/wheel rates.
No external rebound adjustment.

I'll discuss the rear shocks first as there is only two options, off the shelf 87-2429 and custom made.
The problem is Suzuki came up with a bizarre rear hub clamp which no one else uses hence no interchangible shocks from other cars, fit though is straight forward as it's a complete
shock, again no external adjustment, to get around the length issue you can either make a new strut top with a bearing really high up or mount the shock lower in the clamp, no idea
about waranty issues so modify at your own risk.

First you need to knock the retaining lug off, a cold chisel and a hammer usually does the trick, it's not actually needed but makes lining up the groove in the shock much easier when
trying to install the clamp bolt in the rear hubs.
Secondly you'll need to make a new groove, 25-30 mm further up is about the right amount, the wall thickness of the shock is 2mm so you can press and or file a groove relatively easily,
below is a photo of a 15 yr old Grp N short double adjustable rear koni with 2 extra grooves added lower down, the owner must of needed more ride height at some stage...
Attachment:
Aug-25th- 007s.jpg
Aug-25th- 007s.jpg [ 100.39 KIB | Viewed 12475 times ]


Remember though that lowering the shock 25mm will not lower the car by the same amount unless you shorten your springs, it will increase preload making them slightly stiffer though,
a 25mm reduction in shock length might result in a 15mm car height reduction, all depends on the length, spring rate and weight.
Don't forget the suzuki oem rear spring location has a 2-1 ratio, so a 600lb spring is actually the same as a 300lb coil over spring, really important to point it out to your koni agent if
you ever get the rear shocks revalved because he will ask what rates you are running and the valving for a 600lb spring is quite different from a 300lb spring!


Front shocks

Plenty of threads around on installing the 'cut a strut' sport insert into the oem suzuki struts, again the same issues of length, no external rebound adjustment and bump
adjustment only suited to mid 200lb spring rates exist, there are several things you can do to make them shorter, a decent set of fixed alloy strut tops with the bearing mounted
high actually lowers the car in respect to the shock.

You can shorten the over all length of the shock but if you have standard springs then you are only adding preload so you will be lowering the car slightly by reducing droop.
However if you have super low springs which are stiffer and shorter then you will see a bigger result, if you have adjustable spring seats then you can really benefit from shortening
the shock.
Easiest way to shorten these inserts is to actually seat them lower into your old strut housings, you can drill out the bottom and weld a new bottom on, you can trim down the retaining
post as well and seat the insert at least 30mm lower.
Attachment:
Insert.jpg
Insert.jpg [ 59.9 KIB | Viewed 12475 times ]


Remember if you trim down the retaining post then you will need a press to push the insert in all the way, I have shown a pan head philips bolt in the end on the insert and would only be
used to ensure insert retention not for actually pulling insert into strut housing, also you don't actually need to weld the washer or plate onto the end of the strut, the large domed
washer would be fine once it's all torqued up.
The main limitation in lowering the insert is the retaining bolt rubbing on the CV boot, you could also tack weld the shortened retaining post into position instead of using a bolt, you
could also cut a groove in the retaining post and use a circlip over the outside, or machine up alloy cups to fit into the bottom of the struts.

Here is an example I turned up very rapidly as a demo, excuse the finish, blunt tools and no bench grinder... anyhow you get the idea, I pressed it into the bottom of the strut and it fits
nicely, again the limiting factor is the retaining bolt rubbing on the CV but this one has plenty of clearance so you could make them deeper if you wanted to.
Attachment:
Suk strut cap.jpg
Suk strut cap.jpg [ 44.36 KIB | Viewed 12475 times ]


Last edited by Dattman on Wed Sep 26, 2012 4:34 am, edited 1 time in total.

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PostPosted: Wed Sep 26, 2012 3:59 am 
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Before I get to other cut a strut inserts I should mention that if you are stuck in a racing class that prohibits adjustable spring seats/perchs then using a mk1 swift housing is a good
option as 65mm id racing springs actually fit really well, I used them on my old mk1 years ago and the ability to buy springs of all different rates makes fine tuning your car much faster,
easier and cheaper, I can buy and sell a set of race springs and usually get 90-100% of my money back if I don't need them.

Below is a comparison between mk1 and mk2 struts, body diameter is the same at 40mm ID and 44mm OD, if you are a mk1 owner then installing the mk2 koni sport into your housing
will result in a decent length reduction, you'll lose 20-30mm off the body length and 10mm stroke reduction, you'll need to drill out your strut tops as the mk2 shock shaft doesn't have
the flat part and you'll need a spacer tube to accomodate the extra shoulder length sticking out.
Attachment:
Mk1vsmk2.jpg
Mk1vsmk2.jpg [ 62.49 KIB | Viewed 12475 times ]

I've seated a spring to show the length and a suspected stoke range, haven't done the mod yet so can only guesstimate, depends in part as to how low you can get the insert.
Attachment:
Aug27 005.jpg
Aug27 005.jpg [ 46.85 KIB | Viewed 12475 times ]


The spring is 250mm long, 300mm gives far to much preload so you will need to play around with thicker top spring seats to get the preload right.
The example below was on a standard mk1 kyb, I think it was either standard height or 20mm taken off the shock shoulder, with the shorter koni insert I think that a 250mm long spring
will be getting close to being captive.
Attachment:
Mk1strut.jpg
Mk1strut.jpg [ 63.33 KIB | Viewed 12475 times ]

Other Cut a Strut inserts

I have mentioned before about people using EP82 Toyota Starlet inserts, GtiJedi bought a set and measured them up for me, same 40mm OD means it will fit into a swift housing, in fact
a lot of small cars appear to have 44mmOD / 40mm ID struts so there is a large range of small cars with similar front struts, the lengths are similar but the main difference is the top of
the shock shaft and therefore the type of strut top being used.
If you are converting to a pillowball/camber plate with spherical bearing then the end of the shock shaft is not much of an issue, personally you must be crazy if you are still using the
rubber oem strut tops, not only do they flex badly robbing you of your negative camber when cornering they also don't allow enough articulation through the suspension stroke and the
forces try to bend the piston rod/shock shaft resulting in less smooth travel and more wear on the brass bush at the top of the shock body.

Whats so great about the EP82 Starlet cut a strut insert? well it does have external rebound adjustment and it's also one of the few that is low pressure gas charged, because of this
they are slightly more expensive than the swift koni cut a strut inserts but well worth the extra money.
My Koni agent gave me the open and closed measurements of EP82 insert as 524mm and 369mm respectively and that compares to the swift at 523mm and 384mm, I also found the
BG Mazda 323 as having 501mm and 349mm, potentially a shorter insert, not sure if they still make them though.

EP 82 Starlet 8641-1214 Sport Ext adj + gas
BG Mazda 323 86-2447
Diahatsu Charade (G200 I think) 86-2400

I also think the Nissan March 86-1319 would be worth looking at as it also has external rebound adjustment, not sure what the difference with the EP91 Starlet is over the EP82 but the
front shocks have a different part number, the part number for the EP91 is 8641-1353, again cut a strut, Ext Adj and gas.

A lot of the other cars I have looked at have dry cartridge inserts, mk1,2,3 golfs and fwd corollas for example, most of them are too long as they are much bigger cars but the housings
can be adapted to run other shorter inserts including the Koni twin tube 'Race series' cartridge's.


Last edited by Dattman on Wed Sep 26, 2012 4:56 am, edited 1 time in total.

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PostPosted: Wed Sep 26, 2012 3:59 am 
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Dry Cartridge Inserts

To quote Koni again
"The 8611 series double adjustable strut insert is a universal strut insert that can be used in many different applications. Originally designed for European touring car classes utilizing
strut suspensions, the 8611 has become an affordable double adjustable option for club racers and auto crossers in North America"
Here is the Koni NA website, the inserts that apply to us are the ones I've arrowed
http://www.koniracing.com/8611.cfm
Dry Cartridge Inserts
Attachment:
cartridge1.jpg
cartridge1.jpg [ 33.11 KIB | Viewed 12473 times ]



Ok, now the interesting part, these inserts need a 44mm ID shock body, I know alot of the Corolla fwd models had front suspension with cartridge shocks, here is a photo of some AE101 (edited for accuracy)strut housings that have been shortened, not pretty but will do the business, http://www.locostusa.com/forums/viewtop ... 1&start=15
Attachment:
IMG_2261.JPG
IMG_2261.JPG [ 110.31 KIB | Viewed 12473 times ]



Here is a pic of the bump valves, on the right is the standard foot valve, oil flow is controlled by the stack of shims and washers.

The adjustable foot valve has a small hole in the top and oil flows through and around the shims, the tension on the shims is applied through the adjuster which is on a ramp type arrangement.
Attachment:
Aug31 001.jpg
Aug31 001.jpg [ 75.5 KIB | Viewed 12473 times ]

I should probably mention that the 8610 rebound only race cartridge has crazy hard bump damping in it, really designed for Hondas and the like running really stiff springs and would be
way over damped out of the box if used on our cars.

Here's an ad for Truechoice, Koni agents in the states, circa 2005
Attachment:
wet.JPG
wet.JPG [ 78.3 KIB | Viewed 12473 times ]



Here is a photo of a double adjustable rear shock showing you the length difference to the stock shock, notice the collar, your koni agent has access to blank collars, it's internal diameter
suits their small top rod guide, you machine it to fit what ever strut housing you want, also at the bottom is a machined up 'double adjuster housing end plug', both are fitted and welded in place.
Attachment:
Koni03a.jpg
Koni03a.jpg [ 50.97 KIB | Viewed 12473 times ]



The OD of the collar is the perfect size to slide a threaded sleeve over the top, a small sleeve is required at the base of the threaded sleeve.
Attachment:
Attachment:
Koni6.jpg
Koni6.jpg [ 77.64 KIB | Viewed 12473 times ]


Last photo is of my front double adjustable, have included a rule for length reference.
Attachment:
Koni11.jpg
Koni11.jpg [ 56.86 KIB | Viewed 12473 times ]


Hopefully that will give people a few ideas rather than just off the shelf (vanilla) koni sports.


Last edited by Dattman on Sun Jan 25, 2015 3:05 am, edited 1 time in total.

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PostPosted: Wed Sep 26, 2012 1:30 pm 
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Nice write-up, Thanks for putting all this in one place.........


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PostPosted: Sun Oct 14, 2012 11:09 pm 
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Dattman:

We've got a nice dialog going on my autocross thread, but I've got some questions that I'll ask here because I think they are relevant and will help me (and others at a similar stage of the journey) make use of the info.

1. So I am reading that the 8611-1257 cartridge insert will work with our cars as far as travel, but not with our existing struts because the ID is too large (44mm). I also read that VW Golfs, fwd Corollas, and MR2's have struts that are 44mm ID and come from the factory assembled as an insert, so they can be modified so that the 8611-1257 Koni insert will fit them after the stock cartridge is removed and the donor strut is cut shorter to fit. You show a picture of MR2 strut modified to fit a race cartridge, and of the double adjustable you are using on your car. What car did the strut you actually used come from? Nothing like starting with a known quantity, if possible. What about the back--is it from the same car? Did the bracket that fits the knuckle have to be welded on or were you able to use the one on the donor?

2. This may well be covered in another area, both on this forum and outside (some of the information I was looking for was on the Far North Racing site, but I still have some questions:

The other half of building the suspension to use better shocks like this would be getting the correct springs, coil over sleeves, perches and top hats. All the kits I can find seem to be minimal and do not include Torrington bearings. Further, it's hard to shop by dimension rather than application. I know that race springs are sold in a few standardized diameters, and can infer that coil overs bits should be somewhat similarly universal in sizing, but I don't know what I am looking for--a guide for how to properly get these pieces together for a Swift would also be welcome if you or anyone reading this is inspired.

At minimum could you share with me the part numbers or basic dimensions of the pieces you would recommend as far as sleeves, perches, bearings and top hats to work with the solid mounts? Any advice on getting this part of the equation correct would be appreciated, even if it is simply pointing me to another site--are the dimensions we need for bearings and sleeves similar to those described here for DSMs?

http://farnorthracing.com/autocross/konis.html

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PostPosted: Mon Oct 15, 2012 5:34 am 
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I was at pick a part the other day and I spotted dozens of drab medium sized cars with 50mm OD struts with cartridge inserts that would of been suitable donors, just measure the outside and check it has a top nut, preserve that top nut when taking the insert out, you'll need to reuse it with koni cartridges, Koni america website has the dimensions you need to shorten the strut to.
My front shocks are koni blank housings with a 'wet' kit, they weld the tabs on to match the thickness of the hub mounting, the advantage of mine is they are only single walled so a little lighter and maybe a little more oil, they are basically identical to the double adjustable cartridge, the advantage of cartridge is you can do it yourself without the labour costs from truchoice or other agents.

Haven't yet seen a kit with torrington bearings, only know of a few guys running them, less of a problem with longer springs.
2.5' Id springs are what you are after for the front, 9'-10' is the free length required.


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PostPosted: Thu Jan 08, 2015 11:13 pm 
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I am currently in the process of trying to find and modify some junkyard strut assemblies to work with the 8611-1257 cartridges.

I am not sure where I read it, as it isn't in this thread (which should probably be a sticky, by the way) but I pulled some Mk1 VW Golf strut assemblies to use as donors to put the cartridges in because I thought they would need the least fabrication to fit (based on some faulty research somewhere, apparently).

The ones I pulled have the top nut threading onto the outside of the strut, and my research leads me to believe that some Mk1 VW struts are built like this and others have the top nut threads on the inside. Maybe the inside-thread assemblies will work, but the ones I got definitely will NOT :cry: They are 44mm ID at the top, but pinch down to slightly less partway down inside.

It's also worth noting that Mk1 VW struts exactly match the bolt size and spacing of the Swift, but the VW knuckles are skinnier so the tabs are too close together. If the inserts had fit, I would have removed some material in the inside of the tabs and reinforced the outside, but now I've got to go get something else.

Kinch and Van used later model VW struts for the same inserts on their Mk1 Turbo Spring build (I saw many more of them at the yard and passed them by :thwack: ). They do need to be redrilled as the bolt spacing is off, but that's easier than welding new tabs. So that's probably what I'll pick up.

:(

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PostPosted: Thu Jan 08, 2015 11:25 pm 
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Thanks for adding, Murr used the VW struts for the race inserts and when I asked him about these about 9 years ago he was pretty vague about what sort of golf struts, he thought they were Mk1 but maybe they were mk2???


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PostPosted: Sat Jan 10, 2015 3:31 pm 
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Teeth wrote:
should probably be a sticky


Agreed and stickied :)

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PostPosted: Sat Jan 24, 2015 11:56 pm 
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Some additional notes for those that need to get something to put the double-adjustable race inserts in that will fit on a GT.

Donor struts that will not work:

Mk1 VW Golf

I bought a set of these, but failed to notice that they get narrower partway down the tube--the inserts won't fit. Also, the bolt spacing on the tabs is correct, but they are too narrow to fit the GT knuckles.

Mk1 MR2 rear struts (1985-1986)

I also bought a set of these--I won't go into excuses I could come up with for why I didn't measure the ID properly, but now I have two sets of struts that won't work. Also too skinny. It is worth noting, however, that the tabs match the GT tabs almost exactly.

Did I mention that visiting the junkyard where I live is an all day event :thwack:

I did some more web research and found the original source of Dattman's photos:

http://www.locostusa.com/forums/viewtopic.php?f=36&t=3241&start=15

So those are actually AE101 struts. Because the rest of the suspension in that thread is based off MR2 bits, I got all excited that the AE101 struts might have tabs similar to the MR2, but have a large enough ID to fit the race inserts.

Nope. I went to the junkyard today, and for one, most Toyotas of that vintage no longer have their original struts, so it's almost impossible to find a set that aren't sealed aftermarket replacements without a top nut. It doesn't matter though, because, while the spacing of the holes in the tabs is pretty close to the MR2, the Corolla bolts are huge in comparison, so I'm not sure how to fix them to fit the GT knuckles correctly. Also, the AE101 struts are almost identical to Camry struts of similar vintage, so that's a more common source for a tube that fits.

If it's just a question of finding a tube that fits the Koni insert, then I might as well get some Volvo struts, which have no tabs at all, cut them to length and have somebody weld on tabs and something on the bottom to keep them in. This would work, but it's easier to find somebody to simply shorten the body than to weld on tabs (I will not be doing this welding myself :roll: )

If my research is correct, apparently Mk1 MR2 struts from 87-89 have a larger strut body but the same tabs. My next course of action is to source those on car-part.com and have them shipped after confirming the dimensions with the seller. They'll still need to be shortened and have a hole drilled in the bottom, but that's all they should need.

Easy as pie right :blackeye:

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PostPosted: Thu Feb 12, 2015 1:52 am 
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Getting warmer...

Image

I'm not sure how much detail I need to share about the expensive mistakes I've made getting these started, but I have hope that eventually I'll have double adjustable dampers actually bolted to my car :roll:

To follow up the previous thread, the "Mk1b" MR2 struts are no magic bullet, and have the same large bolt pattern as the Camry struts, which are way more common. As these were the third set of struts I'd purchased, however, I decided I'd have to make them do at this point. Thankfully I found a local fabricator that was willing to cut them up. He removed the Toyota tab assembly entirely and cut them to length, rather than sectioning them in the middle, which I think was a better plan. He then welded some Swift tabs from some old struts I had lying around onto the Toyota tubes. He also welded a washer to the bottom of the tube to retain the inserts and machined some material off the insides of the gland nuts so the inserts would fit snugly inside them. I don't know if he welded the tabs upside down on purpose, but they will just clear the CV boots, so I don't think I'll complain.

I am glad I found this guy--he's got a late model stock car in the garage, and a Chevy Sprint on his lot =)

Now that I've got what he did back in my garage, I found that the ebay sleeves I got for $2 each, the rusty #250 Hotbits springs and upper perches are all 60mm and not 2.5". I never bothered to measure them, so now if I want to use the new #375 springs I bought for $70, I'll either need to buy 4 x 60mm to 2.5" adapters for $80 or some combination of those and new solutions for one or both perches :oops:

I think I'll probably just get the adapters and drill the plastic bushing, thrust washers and so on that I've already got on the upper spring perch out to fit on the 14mm Koni shaft. The setup works well with my existing camber plates, and I'd probably need to replace both the upper perch and the camber plates at enormous expense to get something that works as smoothly without rotating the spherical bearing.

I'm still trying to figure out where the support to set the sleeve on needs to go, but not far from the tabs would be my guess--I've still got a ways to go before they are on the car :(

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PostPosted: Thu Feb 12, 2015 2:27 am 
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Crikey you're making hard work out of that :lol: struts are better the way you've done it compared to a join in the middle though :thumbsup:
The best sleeves are actually the fine pitch steel ones, you only need two small tacks at the bottom to hold them in place, simple task to grind them off and reweld them if you find they are not in the right place.
Have you checked both ends of your springs, usually one end is a bit smaller than the other, if one end is loose fit in the spring seat then the other end needs to be a good fit so the spring doesn't move around too much, I don't have a lot of clearance between the tire and the spring, maybe little finger width, you'll have more room due to your lack of offset on your wheels, I have run with less clearance but soft sidewall slicks flex a lot and I'd often get tell tale rubber marks on my springs.

Keep up the good work.


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PostPosted: Thu Feb 12, 2015 11:49 am 
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The best sleeves are actually the fine pitch steel ones


Well, that makes sense, and it would be easier than figuring out how best to immobilize the cheap aluminum sleeves I've got, and maybe not much more $$ than the spring perch adapter--that's one of the reasons I posted now, while I'm still getting it all together. I'm less stubborn about using what I've already got if the parts only cost me $2 :D

One thing though: Where on earth does one find these steel sleeves???

In addition to the fact that no vendor I can find lists the ID of these parts (it's always, Penske, AFCO, Bilstein, Koni, etc... I don't know why they don't have any for 1988 MR2 :lol: ), the parts I can find are also all aluminum, no matter who makes them.

Perhaps it would be worth it to get better quality aluminum sleeves, as I see I can get Koni-branded sleeves and perches for a little over $20 (if they are the right ID) but I'm not sure if it makes that much difference.

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PostPosted: Wed Mar 25, 2015 10:20 pm 
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Well, I've finally got the new dampers on the car:

Image

If I were going for a rally setup, I believe I'd be in good shape--maybe I'll start a new trend called hellagap :roll:

:thwack:

I've since cut down the stops that the sleeves are resting on and I believe I am now pretty close to where I used to be or a smidgen lower. I say "believe" because I wasn't smart enough to measure the ride height before I started taking the old setup apart :oops:

Whether that's where I should be is another question--having gotten this far, I wouldn't mind some advice on what the sweet spot for ride height might be before issues with raising the roll center offset the benefits of lowering the center of gravity--and yes, I know it depends on the tire and where you measure, so, what tire do you run and where do you measure?? I am at about 177mm from the center of the front control arm bolt in the front and 212mm from the center of the big round eccentric adjuster on the toe bar in the back, for now, when the car has the 185/60 r13's on it.

So far I've been working around the unibody nature of the fenders in the rear, and I still won't cut them but I believe I can get some more space to work with if I can get someone with a good fender rolling machine to mash them up as hard as possible, so I'd like to start working towards "ideal" rather than "just low enough that the rear tires don't rub like hell" if anyone has an opinion about what this might be.

Here's the stack I put together for the top of the strut:

Image

I used the tops of the broken coilover setup I got from Airwerks that uses the OEM thrust bearing and had them bored out to fit the 14mm Koni shafts. I'm still not happy with how I've centered the plastic bushing in the center of the bearing, as I used a piece cut out of the plastic bits packed with the Konis to protect the adjusters to do it. Because it's plastic, I suspect that the spacer will squish when tightened and preload the bearing too much, then allow the nut at the top holding it all together to loosen :( I can and will get a proper steel piece made, but I'm pretty tired of pulling these on and off the car right now...

Here they are assembled with the other insert for scale:

Image

And installed on the car:

Image

I didn't neglect the rear, as I am now running #375 springs up front. I still don't know how I feel about building an adjustable perch, and cutting the wheel well for coilovers back there is neither SCCA legal nor a good idea, so I cut some heavier junkyard springs instead. The math says this should work, but we'll see. I also nabbed some Mk4 control arms for additional camber--I thought I'd be all "stanced" but now I think I might have to slot them a bit further than the original location to get what I need.

I had read that the Mk4 arms were longer, but nowhere did I read of anybody actually bolting them up to a Mk2/3 to see how that works--it does, and here's what the setup looks like:

Image

TeamSwift member DTM_GTi gave me some clapped out koni sports for the rear, which I had revalved and converted to external adjustment. The heavier springs (I don't know the source because I pulled them out of a pile) needed a thinner top rubber to fit right on the upper seat, so I cut that out of flat stock:

Image

Image

So far I've only been able to get the car out and cruise around some on public roads--the big surprise is that this setup rides far more comfortably than the "phonis" that I was running before, at least when adjusted to full soft or wherever they are set from the factory. :alien:

I will update as I work out adjustment and see how these actually work in competition =)

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PostPosted: Thu Mar 26, 2015 2:43 am 
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Definitely getting closer... do you have any preload on the front springs? I run zero preload so I have maximum sag which with my 280lb springs gives me 38mm droop, I should point out I got the stroke reduced even further down to 118mm, I'm at the point now where at static rideheight the LCA mount is lower than hub, ie lower arm has gone past the horizontal, bumpsteer is becoming an issue, I may raise it back up 5 or 6mm, I will do this by using shims between the shock shaft and strut top, winding up the spring wlli reduce my droop.

I looked all thru my race book and cant find height measurements anywhere, I can't exactly measure it on the car either at the moment.
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PostPosted: Sat Mar 28, 2015 10:24 am 
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I have zero preload, and in fact, I'll have to come up with a strategy for what to do to keep the springs captive. I made poor decisions about where to weld the stop for the sleeve thinking that I would need some preload to achieve a reasonable ride height. Now, even after trimming another 40mm off the perch for the sleeve I am still at the bottom of my adjustment when the hub is parallel with the pivot.

Given that TeamSwift went down right after I posted :cry: I had to do some outside research on ride height and I gather that other cars with macstrut suspensions are often faster when run as low as possible for autocross, geometry be damned, though they also generally need to be set up ridiculously stiff. While I am making fewer compromises with this car all the time, I am still loathe to make it worthless for anything else, however, so I'll start with the pivots horizontal and see how that works first.

As far as droop goes, I don't know if it's really an acceptable solution, but I may just drill the upper seat and zip tie the springs to it. That way if I do catch some air, the sleeves will keep the springs from hanging up on anything on their way back down to where they belong. I'm too cheap for helper springs, I think, though I suppose that would really be the best plan.

Right now the biggest things I still need to sort out are in the back. I'm working on getting more fender clearance without cutting--I think I'll try some ghetto "phonebooking" first, but if that is not satisfactory I see that I can get an actuall fender rolling tool on ebay for less than $100. Once I can get the fenders out of the way, I'll need to figure out how I'll keep the shorter, stiffer rear springs captive--they are already loose and the car is still too high. Yes, the ideal solution is to knock the tab off the damper body and move the indentation for the keeper bolt upwards, but the Koni sports actually get slightly larger in OD right where the tab is attached to the whole body would actually need to be turned down to get it right :( I meant to have this done when I had them converted to external adjustable and I shudder to think what Proparts will charge me to do this :( :( :( So maybe I will rig a strap...

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