Urethane trailing arm bushing experiences?

[Beej '86 325es]

Crap...now you've got me questioning where the bumpstops are, I never saw them. I guess I thought there were some in the middle of the springs. As for the one that should be around the shock's shaft, I don't think there is one there, or else I wouldn't have completely ruined my old 450 lb. springs.

edit: I'd also like to add that 600lbs/in is overkill for bilstein sports... 450 is overkill for the stock bil sport valving

I assumed you were talking about Bilstein Sports. The Bilstein HD's shafts are too long to use with Ground-Control. With those shocks, I definitely would have bottomed out the shock before the spring! :)

[Bill 84 318i]

I assumed you were talking about Bilstein Sports. The Bilstein HD's shafts are too long to use with Ground-Control. With those shocks, I definitely would have bottomed out the shock before the spring! :)

That's the way it should be!

AFAIK, the rear bumpstops were built into the upper spring pad. The movement will be stopped by that nub thing.

[Charlie]

300 lb springs are too much for an OTS bilstein sport.

Out of curiousity, what are you planning to do with this car, autox, track? If this is just mostly a street ride, I can't fathom why you're going with anything near that stiff. 600 lb is way too stiff for any sort of track usage, and your setup doesn't sound ideal for an autox car.

-Charlie

[Beej '86 325es]

300 lb springs are too much for an OTS bilstein sport.

Out of curiousity, what are you planning to do with this car, autox, track? If this is just mostly a street ride, I can't fathom why you're going with anything near that stiff. 600 lb is way too stiff for any sort of track usage, and your setup doesn't sound ideal for an autox car.

We're talking about the rear springs, not the front. 300 lb. 2.25" x 5" springs probably would not support the rear of the car. Even my 600 lb. springs compress about 2" under load. You should see how bad of shape my 450 lb. springs were in, their free length sagged about 1/2" from binding so much. In the rear, the spring rates have to be much higher given their location. Most people with Ground-Control run about 450-500 in front and 600 is average for the rear. I'll eventually just be using the car for autocross and track, but for now it's street/autocross. I can't remember if it was the Group A or N M3's, but they ran 1200 - 1300 lb. spring rates.

[Beej '86 325es]

That's the way it should be!

AFAIK, the rear bumpstops were built into the upper spring pad. The movement will be stopped by that nub thing.

The problem with using Bilstein HD's with the car so low is that the car would bottom out the shock way too soon and would not be damping properly since the shock is not in a good working range.

Hmm, my spring pads now don't have any bumpstop built into them, it just fits around the nub...and hitting the nub would be very bad! I no longer have a nub on the trailing arm on one side from the binding. The coilover sleve sits in a dent! :shock: Been that way for about a year an a half, but I should finally be fixing it soon.

[Bill 84 318i]

That's the way it should be!

AFAIK, the rear bumpstops were built into the upper spring pad. The movement will be stopped by that nub thing.

The problem with using Bilstein HD's with the car so low is that the car would bottom out the shock way too soon and would not be damping properly since the shock is not in a good working range.

Hmm, my spring pads now don't have any bumpstop built into them, it just fits around the nub...and hitting the nub would be very bad! I no longer have a nub on the trailing arm on one side from the binding. The coilover sleve sits in a dent! :shock: Been that way for about a year an a half, but I should finally be fixing it soon.

Oh, I know that the HD's are probably too long (although I'd still like to see an HD next to a Sport in person). However, the suspension should hit the bumpstop before the spring binds in any situation. Ideally, you'd have neither though.

At full low (I have 600lb barrel springs), the spring will never bind. I've had 7 people in my car at full low before, and coulda swore I heard some banging (can't tell for sure, everyone was drunk :P). I'd like to know if it was the shock bottoming out (since AFAIK, rear Bilsteins don't have built in bumpstops) or the nubs hitting each other.

Pics:



They were taken with the car parked on a hill, at this ride height:

[trent]

300 lb springs are too much for an OTS bilstein sport.

Out of curiousity, what are you planning to do with this car, autox, track? If this is just mostly a street ride, I can't fathom why you're going with anything near that stiff. 600 lb is way too stiff for any sort of track usage, and your setup doesn't sound ideal for an autox car.

We're talking about the rear springs, not the front. 300 lb. 2.25" x 5" springs probably would not support the rear of the car. Even my 600 lb. springs compress about 2" under load. You should see how bad of shape my 450 lb. springs were in, their free length sagged about 1/2" from binding so much. In the rear, the spring rates have to be much higher given their location. Most people with Ground-Control run about 450-500 in front and 600 is average for the rear. I'll eventually just be using the car for autocross and track, but for now it's street/autocross. I can't remember if it was the Group A or N M3's, but they ran 1200 - 1300 lb. spring rates.

I can't stop laughing. Do you have any idea WHY they ran 1200-1300 lb springs?

[Beej '86 325es]

Looks like you have the newer urethane spring pad, I have a rubber one that doesn't come down as far. I actually have mine adjusted to the highest position and it's still super low. Maybe it's just the way your spring is designed, but looking at it, it seems like yours holds the car higher then mine. I'll have to get a picture of the spring under load.

Your car looks rusty underneath like mine...well the flash on a camera always makes it look much worse than it is normally. Here's some axles I'm in the middle of refinishing that I'm going to put in when I redo the suspension...the look just a little bit better than the ones in there now. :)


I'd say you would have had to have been bottoming out. I don't even allow people in my back seat unless it's a girl. How the hell did you fit 7 people in your car!? Were they Oompa Loompas?

[E30-323ti]

Since you have the axles sitting there could you please take a few measurements for me.
The diameter of the spline, number of splines, length of spline and length of shaft to the end of the thread.

Thanks Heaps

Bill: It doesn't look like you have much suspension travel left between the white bumpstop thing and the top of the threaded sleeve!?!?! (in the 2nd pic of your post)
Does it hit much!?!?! Looks like about 1" or so!?!?!

[Digitalwave]

I think Bill and I have even less travel in the front :)

[Bill 84 318i]

The car 'normally' sits a good 3/4" higher than that, but you're right - there isn't much travel. I think ideally, you'd want to screw the trailing arm mounted spring, cut off the nubs and have true coilovers (although I can't imagine you wanting to go too much lower than the height I was at in that picture).

As for the front...shortened housings/inserts are the only way to go.



As for seven people...2 shottie, 5 in the back, and me. I can't imagine a much slower car.

[Beej '86 325es]

Here's a shot of the rear 600 lb. spring with the sleve at the highest position...

Since you have the axles sitting there could you please take a few measurements for me.
The diameter of the spline, number of splines, length of spline and length of shaft to the end of the thread.

What are you trying to do with all those numbers? I'll try and get some measurements tonight before I leave town.

[Bill 84 318i]

Here's a shot of the rear 600 lb. spring with the sleve at the highest position...

Whoa. What's the unloaded length of those springs? Mine are about 5" and don't compress nearly as much as yours.

[E30-323ti]

I have a Supra LSD and axles to go with my engine and gearbox and was wondering how much different the splines were.

I'm a little worried about blowing the backend so I'm being real gentle.
Just got my E36 compact parts today for the 5lug conversion and some even bigger brakes :)

[derek w]

I'm running IE urethane trailing arm bushings
Poly filled rear subframe mounts (stock)
M coupe diff mount (stiffer)
konis
H&R

It's a sweet setup and I have no regrets.

But I have something to say about ireland. Never order from them. It took them 2+ months to get the bushings to me. It prevented me from getting a lot of work done. Bastards.
There was one excuse after another. NEVER EVER ORDER FROM IRELAND!!!