Bilstein strut info...

[bwh13]

Just got off the phone with Bilstein regarding the HD struts I have on the car. These struts have 3.75" of travel and the difference between them and the Sport struts is the length of the internal bumpstops. Between the shorter ProKit springs and the heavier S52 engine, I'm probably riding on the bumpstops now.

The bumpstops can be changed pretty easily by dis-assembling the strut, so I'll do that when I change the springs to the H&R's. This should give me the ride quality I'm looking for...If not then I might have Bilstein revalve them for me.

Rear HD shocks should be fine even with lowered cars as they have a lot more travel...

[lifeiskaos]

good info

[E30_fiend]

Rear HD shocks should be fine even with lowered cars for less than 1000 miles as they have a lot more travel...

fixed.

HD's will blow. Especially with Eibach Pro Kit. The guy from Bilstein probably assumed that the Eibach kit lowers 1.25-1.5" according to their website, rather than the 2.0+ inches it ACTUALLY drops the car. The Sport shocks are only a little bit more than the HD's. I dont see why people spend the money on HD's when sports will work with both applications. Lowered or stock height cars.

[bwh13]

I did tell the Bilstein tech the car was down approx the 2" the Prokit actually drops the car. He agreed it was probably on the bumpstops now.

I think by switching to the H&R sports with the 1.3" drop and changing the bumpstops I should be OK. At least I'll gain about an inch more travel. I'm pretty sure the rears will be fine, they have at least 5" of travel now...

EDIT: I just figured out I do have the Sport version, based upon the part numbers on the rear shocks.

Now I'm wondering why the front is so stiff. with almost no compliance...

[E30_fiend]

ok well that makes sense. Yeah if you modify the bump stops then it could work

[Stephen]

Can you post pics of the bumpstop process? I want to shorten mine

[E30_fiend]

Can you post pics of the bumpstop process? I want to shorten mine

what he said

[bwh13]

As soon as I get the info from Bilstein on the part numbers I'll post it. They did send me a diagram of the bumpstops, the HD versions are 50mm tall, the Sports are 35mm tall, so you gain approx 15mm (1.38") of travel.

Interestingly the shorter stops are larger in diameter, not just a shortened version.

I remember when we just shortened the bump stops when installing shorter springs and different struts in my 240z or the Hondas...but then again those were on the outside of the strut on the top...

[E30_fiend]

As soon as I get the info from Bilstein on the part numbers I'll post it. They did send me a diagram of the bumpstops, the HD versions are 50mm tall, the Sports are 35mm tall, so you gain approx 15mm (1.38") of travel.

Interestingly the shorter stops are larger in diameter, not just a shortened version.

I remember when we just shortened the bump stops when installing shorter springs and different struts in my 240z or the Hondas...but then again those were on the outside of the strut on the top...

it makes you wonder if you can just shorten the bump stop rather than the shorten the strut bodies for more travel. You could put an extra long adjuster and spin the coils all the way down! If I can gain 1" from the bump stop shortening then thats 1" I dont have to shorten from the strut body.

I REALLY hope this works

[bwh13]

I don't think the strut bodies are different lengths, I think it's just the internals that they change. Also I noticed that the M-Tecnic struts used a different upper bump stop than the standard struts. Shortening the upper bump stop might gain some more travel as well...may not have to open up the strut after all.

Anyway I just looked at my struts and it looks to me like there is only about 1" of travel before the springs start binding. I don't know why they are like that, maybe the S52 weighs more than I thought and they are just being compressed farther down. Or the springs have weakened and allowed themselves to be compressed more. Either way that may be the culprit for my harsh ride; 1" of travel before spring bind certainly won't cut it...

I'm thinking with the extra weight up front I should be using a taller spring that has the right spring rate.

I just spoke to Eibach and found the front spring rate of the Pro kit is only 114 lbs/inch. That is way less than I thought it would be, I was thinking it should be somewhere around 135-145 lbs/inch, similar to other performance springs. The rears are progressive; 280 to 325 lbs/inch, which seems way high but until I talk to the engineers I'll just have to wait and see.

I just checked the conversion from newton meters to inch pounds that the Eibach rep gave me and they appear to be different. They told me 20 newtons which is 177 inch/lbs not 114 like they said...177 is more like it...

[E30_fiend]

binding, explain your binding issue.

The s52 weighs more than the M20 but my buddy had eibachs with billy sports and it was soft but it was in no way a harsh ride.


I'll be waiting for your answer. There may be another culprit here that ISNT your springs.






Taylor

[bwh13]

If you look at the springs, there is only about 1" between the coils. If the suspension compresses 1" then the coils will contact each other and the spring rate now goes to infinity (or close), effectively making the strut a solid piece.

It's called coil bind.

I can't explain why it only has that much space between the coils, unless they have sagged.

I had another car that happed to with Eibachs, and they sent me out a set of replacement springs. They had a tempering issue at the plant so the steel the springs were made from was not as hard as it was supposed to be.

I'll have to check the free length when I take them off (spec is 295mm).

[Jean]

Did you ask Bilstein how much travel Sports have?

[E30_fiend]

I understand what coil binding is but other people have talked about binding because they hear a pop when they turn their steering wheel.

Eibachs have a lower spring rate than the stock springs on the car. the best thing to do would be to sell the eibachs and look for a spring with a higher rate or possible just a progressive spring rate.

Sounds like its one of two things. Either you got a bad batch of eibachs or your motor weighs too much. It very well may also be a combination of the two.

[bwh13]

Didn't ask about the Sport travel, although if the strut is shorter then the shorter bump stop would indicate the travel would be the same...I'll have to ask them.