refilling stock struts?

[rc423423r]

anyone did this or have any info on what to replace the strut oil with? i've heard that is Dextron III in the stock struts, i would like an oil with a little more dampening for the upcoming autox season to match my 200lb springs on the car, any help would be great thanks

[ProDarwin]

I'd refill with ATF, or use some 10W fork oil. You can buy fork oil anywhere from 5w to 30w. Mix the ratios right to get whatever you want. ATF should be approx. 7.5

[rc423423r]

okay sounds good well see how this goes...

[ZombieSatty]

Wasn't really aware they were rebuildable without destroying things?

[punkboySL2]

I was thinking about doing this for my coupe. Would you just want to drill them out (though the bottom?), drain, refill and install a schrader valve?

[HStockSolo]

anyone did this or have any info on what to replace the strut oil with? i've heard that is Dextron III in the stock struts, i would like an oil with a little more dampening for the upcoming autox season to match my 200lb springs on the car, any help would be great thanks

How do you know that you need more damping?

I really wish I had kept my stock struts. A 200lb/in spring would not require much of a change, maybe just a bit more rebound. Adding more compression would likely be a mistake, so changing the oil is probably a mistake. The KYB GR-2s are overdamped with the H&R Race springs, so I am not recommending those either. Maybe take your chances with something else (Sachs or AC Delco?)

[rc423423r]

I was thinking about doing this for my coupe. Would you just want to drill them out (though the bottom?), drain, refill and install a schrader valve?

yeah thats what i was thinking but probably just thread a hole and put a plug there.

[rc423423r]

How do you know that you need more damping?

I really wish I had kept my stock struts. A 200lb/in spring would not require much of a change, maybe just a bit more rebound. Adding more compression would likely be a mistake, so changing the oil is probably a mistake. The KYB GR-2s are overdamped with the H&R Race springs, so I am not recommending those either. Maybe take your chances with something else (Sachs or AC Delco?)

i was thinking about the kyb's because im not looking for coilovers. just want to give the suspension a refresh to go along with the with all the other parts replaced on the car. a slightly higher weight oil would be all i would do.

[HStockSolo]

Let me dissuade you from doing either. Overdamped feels better, but it is slower. Driver feel is very misleading. I've made the mistake with Konis of running high rear rebound to try to tune out understeer on my 325i. It causes so many other problems that even that is not worth doing, and it rides horrible. You really want very little damping and it mostly needs to be in the low speed range.



"When I moved to a 65% critically damped setup, the car felt way less planted; way less tied down. It was actually a little bit scary, because it moved. At turn in, the car would make a definite movement in roll to the peak roll angle, and even though that roll angle was actually pretty small, all that moving around was a little bit disconcerting. The perceived loss of grip was also completely illusionary, as the data proved over and over again that the car not only had better peak grip, but it also didn't get upset over bumps anymore. The day I crashed through one of the big Peru dips at full throttle and nearly full roll, and the car didn't even notice... wow.

Once I got used to it, the car was faster, it was easier to drive, and it eliminated a ton of bad habits from both the car and myself. As a system, we got way faster, more often, more consistently. That's a good thing!" - Dennis Grant

For comparison I kept good condition stock struts on the rear of my SW2 with KYBs in front. That car had faster autocross times than my all KYB SC2. The KYBs do slow down body roll, but that isn't what dampers should be doing, and if they are doing that, they are not doing their job of keeping the wheels on the ground as well.

So, I'd recommend keeping your stock struts and doing nothing to them. The slight increase in spring rate requires no valving change.

[ProDarwin]

The above is linked in the stickies. It is good reading.

H-Stock is on solid ground. Then again, if your spring rate is locked sometimes you have no choice but to either Overdamp, or run crazy rebound and jack the car onto the bumpstops (See ES Miatas)

Lemons guys are known to refill struts, but they are generally running either completely worn-to-shit 20 year old dampers, or spring rates grossly higher than stock (like 3X or more), or both.

If you have worn out stock shit, go for it. If you don't, it may not be worth it. If you are going to do it, Bilstein sells good weld-in schrader valves for like $2 each. When you are done replacing the fluid with the correct amount, keep the strut upside down and pump it a ton to bleed the air out, then install the valve into its housing. Take it to your local decent tire shop and slip the guy $10 to charge them with nitrogen.

Be prepared to trash the first one you drill into.

[HStockSolo]

Does anyone even know who makes the OE dampers?

Rockauto has Sachs Supertouring struts for our cars. Supertouring is their base damper, but I know Dennis recommend Sachs as one of the few recommended brands.

[ZombieSatty]

Not to refute you or anything of that nature Hstock, just a question.

If the stock struts and or KYBs are technically overdamped for even H&R race springs, has the common suggestion been to stay away from them for fear of blowing the struts? Is it because wth stock springs, the struts are used as a 2nd spring as described? I ask because I loved my H&R sports/kyb combo and feel that I could be much faster with them than my AMRs (untill I get the AMRs tuned to 65%).

[HStockSolo]

If the stock struts and or KYBs are technically overdamped for even H&R race springs, has the common suggestion been to stay away from them for fear of blowing the struts? Is it because wth stock springs, the struts are used as a 2nd spring as described? I ask because I loved my H&R sports/kyb combo and feel that I could be much faster with them than my AMRs (untill I get the AMRs tuned to 65%).

I don't have any stock struts right now, but they seemed to be valved quite well for the stock springs at least. I remember thinking that when I first got them for my SC2, but I stupidly kept the GR-2s. I then bought Eibachs for my SW2 and only got KYBs on the front, and sold the Eibach after a few months and went back to stock springs. That combination worked better than the all KYB setup. I haven't tried anything else except all stock on my former SL1.

If you have good stock struts recommend trying them with the H&R Sports. I really don't think the Saturn GR-2s are probably good for anything--they seem better with the H&R Race springs, so maybe going with even higher rates might be okay with them (i.e., coilover conversion collars).

It seems like most adjustable dampers are quite bad regardless of adjustment. Often they are very progressively rebound valved at full soft. And while the rebound become digressive at the full stiff setting, then the compression valving is way too high. Right now I am trying to decide if AST and KW coilovers are okay or complete junk because I have seen dyno plots of both which have these characteristics. The ASTs are pretty well respected in national autcrossing, but that might not mean much. Tokico, Tein, mostly garbage. Though KYB's AGX actually seem decent. It really seems like Koni Sports, while still pretty junky, are the only decent, cheap adjustable stuff out there. And really on the Konis only the softest part of the big rebound range adjustment should be used.

[ZombieSatty]

I still have my 4-5 year old (been that long?), Kyb/H&R sport combo and a few pairs of used KYBs sitting on a shelf in the garage, but no 'stock' struts.

When I find a shock place around here this summer, I would like to have them at least dyno the kybs (front and rear) so we could see some numbers. Then we might be able to better determine the best springs, by numbers rather than feel I mean.

[rc423423r]

points taken HStocksolo, from what ive learned the kybs are over dampened for most aftermarket springs, and if i were to actually change the oil to a slightly higher weight oil and recharge the struts no one really knows how it would affect things, so if i do anything ill go get an extra set of stockers and experiment.