TeamSwift
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Suspension: Shock Therapy (Tuning the OEM Struts)
http://www.teamswift.net/viewtopic.php?f=10&t=25593
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Author:  Swift73 [ Sun Jul 16, 2006 3:51 am ]
Post subject:  Suspension: Shock Therapy (Tuning the OEM Struts)

As many of you may already know and others may be pleased to know, there exists on this forum many threads about the process of, as N1tr0 states, making a set of "phonis".

This mod is done using the old stock/OEM struts, which are non-pressurized (non-gas). Typically the strut will be carefully drilled using a sharp drill bit, as sharper bits have the characteristic of leaving the user with long, ribbon-type shavings (as opposed to smaller particles). The latter is undesireable as it may aid in contaminating the strut oil reservoir with tiny metal shavings, and thus work to damage the shock in the future.

The purpose of the hole is for draining the oil from the spring dampener, or strut, and then refilling with a suitable replacement oil. There are many names by which one can search to obtain a suitable replacement fluid:

1) Fork Oil / Fork Fluid
2) Shock Oil / Shock Fluid
3) Suspension Oil / Suspension Fluid

NOTE: In my research, I have found that some call it OIL and others term it FLUID. Keep this in mind when you search. Also, all web searches were conducted using Google.

As stated in the beginning, there are already many threads that talk about what setup may be best for the purpose that you are driving your Swift for. Obviously, strictly street requirements are going to be different than strictly track, but most likely you will seek to find a satisfactory compromise that suits your driving style/needs.

This is where the process of choosing the oil viscosity (or thickness) comes into play. A suspension/fork/shock fluid/oil of a relatively-lower viscosity than another is going to affect a given strut differently than one of a higher viscosity. This is because of the valving in the interior of the strut, the means by which compression and rebound characteristics are generated.

You will need to carefully measure the amount of oil removed from the strut (so that you will know exactly how much fluid to replace). IMPORTANT: Overfilling the strut must be avoided, so take note of how much is removed from each strut. Replace the fluid in that strut with no more than came out of that very same strut to begin with.

I am in the process of modifying my struts as I write this post. However, my Swift is used strictly on the track, so I will be doing so with a setup inclined towards that end. I tell you this so that you'll interpret my findings with this in mind.

I will be adding to this post information, as it becomes available to me regarding sources of the needed lubricants, brands, and viscosities of each.

This sounds like a kewl mod :D , and I want to share the results with you. I will keep you updated.

Author:  Swift73 [ Sun Jul 16, 2006 4:30 am ]
Post subject: 

I just read a thread about a guy who insists that gear oil is okay to use as a replacement: WRONG!

All suspension fluids are fortified with anti-foaming chemicals. This is important! Don't use gear lube, which is not made for use in a dampener (shock/strut/fork).

********************
UPDATE:
I have found that the many higher-numbered viscosities may be difficult to locate, especially locally. In a cross-town search of four motorcycle shops, I only found one that had anything thicker than 5W or 10W. It was 20w and was found at the local Suzuki dealer (it was in an old-school steel can, and it looked like it had been there on the shelf for 10-15 years).

Anyhow, there is a lot of discussion in threads relating to this topic of choosing an oil like 30W for the rear and 20W for the front. While there are sources available online, I have yet to find one locally. In stock, that is. The local Yamaha dealer said they could order other viscosities, including 30w.

The going price seemed to be about $5-8 per pint (16 oz) container. I bought the one pint of 20w that I mentioned and the one pint bottle of 10w that was also found (also the last one). After I bought these two bottles, every general cycle shop and japanese cycle dealer in town did not have anything left in stock except for 5w pints and 10w liters (I am telling you this for information, not to dissuade you from attempting this mod. Just prepare to plan ahead. You may find that you will have to special order what you need).

However, that was before I stopped in at Harley Davidson on the way home. At the Harley Davidson dealer I found that they deal with four (4) types of Fork Oil:

1) Harley Davidson Type B Fork Oil (#99880-73) --> 10W, or as another website termed, "medium light";
2) Harley Davidson Type E Fork Oil (#99884-80) --> 20W, or as another website termed, "medium";
3) Harley Davidson Screamin' Eagle Heavy Fork Oil - Performance (#99881-87) ---> indentified via website cross-reference as 40w;
4) Harley Davidson Screamin' Eagle Extra Heavy Fork Oil - Racing (#99909-93R) ---> simply undisclosed/yet-to-be determined... still searching http://www... I haven't got a viscosity index no. for you yet (but the "bottle shake" test at the local Harley dealer let me know that it was definitly thicker than any other suspension fluid yet. It had more of a 'plop' sound when shaken than 'slosh', almost like gear lube).

Not only did I find the Harley Davidson products available over the counter, but available online as well. The cost online was the same as in the H.D. dealership, $ 4.95 US.

If you're looking for a stiffer strut to match the needs of your stiff spring and you've found with 30W to be unsuitable, then you may want to consider trying the above-mentioned product(s) numbered #3 and/or #4.

Author:  Swift73 [ Sun Jul 16, 2006 5:10 am ]
Post subject: 

Here's a thread (one of many) about the shock oil modification. This link will help show you where to drill the hole in your strut:
http://www.teamswift.net/viewtopic.php? ... w=previous

One important item of interest here is the instructions to do not fill when the piston rod is out:
http://www.teamswift.net/viewtopic.php?p=10460

Here's another one with even more info:
http://teamswift.net/viewtopic.php?t=11561

And some more discussion on the topic:
http://www.teamswift.net/viewtopic.php?p=12735
http://www.teamswift.net/viewtopic.php?t=11158
http://www.teamswift.net/viewtopic.php?p=169139
http://www.teamswift.net/viewtopic.php?p=36956
http://www.teamswift.net/viewtopic.php?t=8133
http://www.teamswift.net/viewtopic.php?p=12616
http://www.teamswift.net/viewtopic.php?t=1128
http://www.teamswift.net/viewtopic.php?p=10758
http://www.teamswift.net/viewtopic.php?p=10383

In all of these threads, there is also lots of discussion regarding the desirability of viscosities (or weights/thicknesses, simply expressed as "W"; eg, 30W).

Anyone considering this modification would be well advised to absorb the information and the experiences of other members before just jumping in head-first & blindfolded. A lot of the leg work in searching has been done with the inclusion of the links above in the hope that it may become a "sticky" topic as well.

:thumb2: (Thanks to N1tr0 for enlightening me to this killer mod!) :thumbsup:

Good luck, and feel free to report on your experiences here. Also, if you round up any other links then let us know & post it.

Author:  suprf1y [ Sun Jul 16, 2006 7:59 am ]
Post subject: 

I used 20w Belray (I think its synthetic) fork oil, and it worked fine for me. I don't think the amount of oil refilled is critical, as long as you're close.
You may have to work the piston up, and down a number of times in order to get the oil in the reservoir.
Mixing of the oils is OK, in order to get the viscosity you are after, but I would only mix the same brand of oils together.
When I raced bikes, we used to use auto trans fluid in the forks, and you could probably use it here, but as far as I know, you can't get different viscosities any longer.

Author:  Metropwr [ Sun Jul 16, 2006 10:22 am ]
Post subject: 

I used 30W Belray. It was a special order.

It is an OK mod to do. The stock strut still has very little compression dampening(almost none it seems).

Author:  HiTempguy [ Sun Jul 16, 2006 11:09 am ]
Post subject: 

I also picked up 30w belray synthetic fork oil from Poor Boyz Choppers (on the outskirts of town). Cost me $15 for a litre. From the info that I gathered, for racing purposes you WILL want to go with the 30w unless driving on extremely rough conditions (then 20w-25w), otherwise (as has been stated) there will not be enough compression damping.

Author:  Swift73 [ Mon Jul 17, 2006 1:47 am ]
Post subject: 

Metropwr wrote:
I used 30W Belray. It was a special order.

It is an OK mod to do. The stock strut still has very little compression dampening(almost none it seems).

Hey Metropwr... I was just going to go with putting 20w in the front struts and 30w in the back, but in light with what you've said here would you say that a higher viscosity than 20 or 30 is needed?

I've been having a problem with excessive dive & roll in my '93 Swift GT circle track racecar. Here's a thread on that topic w/pics here (below):
http://www.teamswift.net/viewtopic.php?t=25444
Due to rules I am limited to run "stock" parts (eg, no Koni's or racing/lowering springs). I can make modifications only with "stock-appearing" parts.

If you look at the pics in the above-mentioned post, I think that it's fair to say that a little shock therapy would be in order. I'm thinking, and someone please correct me if I'm wrong, that I need to be a little stiffer in the front and a lot stiffer in the rear. With that in mind I have cut the stock springs on the front and am planning to increase the dampening in the front struts with this mod (as a stiffer spring needs a stiffer strut).

However, if you're telling me that the performance of compression dampening was less than optimal after you did this "OK mod" using 30w, then that's got me thinking that I should try a higher viscosity suspension fluid in the front struts (since it's apparent that they're having to combat this tendency of the car to dive forward extremely, which is on the compression stroke in the front, right?).

Author:  Swift73 [ Mon Jul 17, 2006 2:29 am ]
Post subject: 

HiTempguy wrote:
From the info that I gathered, for racing purposes you WILL want to go with the 30w unless driving on extremely rough conditions (then 20w-25w), otherwise (as has been stated) there will not be enough compression damping.

If I opt for a higher-viscosity fork oil so as to optimize compression dampening, is this increase going to have an adverse effect on the rebound characteristics?

In other words, am I then going to find that it's gonna' take, like, forever for the suspension to return to it's normal point after compression? (I've made an assumption here. With all the pointers about the lack of compression dampening with the lower-viscosity shock oil, I've assumed that rebound dampening is okay. And, if it's satisfactory with a relatively-thinner suspension fluid, will the rebound suffer with the thicker oil?) I hope that this mod is not a "Catch-22" because it seems pretty cool and promising!!

Am I worrying about nothing? Is it okay to have the rebound stronger than the compression? Maybe I'm completly wrong with my whole analysis. I don't know, but I'm sure that I'll be corrected if so.

(Swift73 is keeping his fingers crossed ...hoping for good news)

Thanks. -Greg

Author:  Metropwr [ Tue Jul 18, 2006 1:46 am ]
Post subject: 

Cut some MKIV springs for your car, put some 30W in the front and rears (maybe a little more in the rear, like the Hardley HW oil).

Can you change to urethane swaybar bushings?

Do you have a rear sway bar? If no, get one and try it to see how it works. If still too much understeer remove the front sway bar.

Don't worry so much about the lean when turning. Worry about making your car oversteer at will. You need a better suspension balance.

My car used to run so had in the turns that I could smell the tires cooking from the turning force, but yet the car was very controllable and stable.

Author:  Swift73 [ Tue Jul 18, 2006 6:43 am ]
Post subject: 

Metropwr wrote:
Can you change to urethane swaybar bushings?
Perhaps, but I need something that looks like the stock rubber ones (they need to be black, not some flashy color that shouts "I've been pimped!")

Metropwr wrote:
Do you have a rear sway bar? If no, get one and try it to see how it works. If still too much understeer remove the front sway bar.
Yes, I have both, but I have removed the front one as per the advice of N1tr0. The rear bar is stock for the '93 GT. I am interested in finding the rear bar from a mk4 ('95+) as I understand that it is thicker, and the front bar from a mk2 ('89-'91) as it is thinner.

Also looking for mk4 springs (give me a SHOUT if anyone has some extras).

Author:  Swift73 [ Tue Jul 18, 2006 4:07 pm ]
Post subject:  Gas/Nitrogen Charged Strut

By the way, does anyone know what the typical pressure of a gas-charged strut is? I believe it's nitrogen gas, but at what psi?

Author:  Metropwr [ Tue Jul 18, 2006 10:39 pm ]
Post subject: 

Maybe if you really need the springs I can get them from the junks.

Author:  n1tr0 [ Wed Jul 19, 2006 12:19 am ]
Post subject: 

Swift73 wrote:
Yes, I have both, but I have removed the front one as per the advice of N1tr0. The rear bar is stock for the '93 GT. I am interested in finding the rear bar from a mk4 ('95+) as I understand that it is thicker, and the front bar from a mk2 ('89-'91) as it is thinner.

the mk3 gt bars are the same as the mk4-5 non-gt cars. no sense in wasting money.

Author:  Swift73 [ Wed Jul 19, 2006 2:24 am ]
Post subject: 

Hi there Metropwr! Do they have many Swifts in the junks there? Whenever I go to a junkyard their usual response is, "For a what? No, I don't think we have any of those, but you can take a look if you want."
Metropwr wrote:
Maybe if you really need the springs I can get them from the junks.
I may just take you up on your offer. Let me check some more yards first. I'll let you know. Thanks.
-Greg

Author:  Swift73 [ Wed Jul 19, 2006 2:27 am ]
Post subject: 

n1tr0 wrote:
the mk3 gt bars are the same as the mk4-5 non-gt cars. no sense in wasting money.
Thanks for the heads up on that, n1tr0.

Author:  Metropwr [ Thu Jul 20, 2006 12:18 am ]
Post subject: 

I can usually find them around here.

Author:  Swift73 [ Thu Jul 20, 2006 9:49 pm ]
Post subject: 

I measured the wire diameter on some springs from a '95 Metro today. I had thought that the wire diameter would be larger, but it looked to be the exact same size as my '93 Swift GT.

Aren't the springs from the '95+ Metros supposed to be larger & stiffer, or is that only on the Swifts?

I have been unable to find any Swifts, let alone a '95+ Swift, in the junkyards here (SW FLA). That's why I started looking at Metros.

Author:  Metropwr [ Sat Jul 22, 2006 3:13 pm ]
Post subject: 

I have put them side to side with standard Metro springs and they looked to be 2-3MM larger also around 1 1/2" longer.

Author:  GTi_boy [ Thu Jul 27, 2006 2:44 am ]
Post subject: 

will using thicker oil in the stocks help stop my axial tramping???

Author:  Larry S. Oxenham [ Fri Aug 04, 2006 5:16 pm ]
Post subject:  SHOCK OIL:

A long long long long time ago, I heard about a guy that used Mazzola Corn Oil to re-fill the struts in a 240Z. So I thought that I would try it on my 240Z. I cut 2 links out of the stock springs and filled the struts with the required amount of Mazzola Corn Oil. Your not going to believe this but it worked fantasic. My "Z" sat down 2.5" on the front and 2.0" on the rear, road firm but not like a buckboard. So....how do you think it will work on my "Vert?" That's what I am about to find out in a few weeks when I do it to the stock struts and cut 1.5 out of a pair of GTi springs.

*The reason for the Corn Oil I was told was so that the seals would not become rigid or rot.

Author:  Gasoline Fumes [ Sat Aug 05, 2006 6:21 am ]
Post subject:  Re: SHOCK OIL:

Larry S. Oxenham wrote:
A long long long long time ago, I heard about a guy that used Mazzola Corn Oil to re-fill the struts in a 240Z. So I thought that I would try it on my 240Z. I cut 2 links out of the stock springs and filled the struts with the required amount of Mazzola Corn Oil. Your not going to believe this but it worked fantasic. My "Z" sat down 2.5" on the front and 2.0" on the rear, road firm but not like a buckboard. So....how do you think it will work on my "Vert?" That's what I am about to find out in a few weeks when I do it to the stock struts and cut 1.5 out of a pair of GTi springs.

*The reason for the Corn Oil I was told was so that the seals would not become rigid or rot.

Does it have to be Mazzola, or do other brands work too? :D

Author:  zukman79 [ Sun Aug 06, 2006 11:12 pm ]
Post subject:  Strut mod

So what cars had non-pressureized struts vs gas-charged? I have '91 metro vert that needs some ride upgrade (way too soft).

Author:  Gasoline Fumes [ Mon Aug 07, 2006 4:17 am ]
Post subject:  Re: Strut mod

zukman79 wrote:
So what cars had non-pressureized struts vs gas-charged? I have '91 metro vert that needs some ride upgrade (way too soft).

Take the strut out and compress it by hand. If it extends by itself, it's gas-charged. If it stays compressed, it's either not gas-charged or was and the gas leaked out.

Obviously you'd have to remove the front springs to do this test. :D

Author:  zukman79 [ Tue Aug 08, 2006 4:10 pm ]
Post subject:  strut oil

So I went to a local bike shop, pick up some Fork Oil , Belray 30w
$10.00

Author:  zukman79 [ Tue Aug 08, 2006 4:13 pm ]
Post subject:  strut oil

$10.00 for a Liter. hope I can do all four struts.

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