[cvc 22349a]

Just wanted to share with those who've been talking about bumpstops and sport (non-c/o) springs lately:
I've wanted to get the BMW PS springs for over a year to go with my koni's. I didn't want the whole 'new' PS kit because of how lousy my oe zsp dampers were and just figured the koni's would have better (and adjustable) damping than whatever BMW provides w/the PS kit. The PS kit dampers were engineered to be used with runflats and I've been off of those for 3 yrs and have <19 lb wheels. The PS springs have been available for over 2 years but you couldn't get the front PS bumpstops seperate from the kit (I've been asking Tischer for over a year). The rear PS bstops have been available. Lot's of folks have added the PS springs to the 'original' or V1 PS kit but that kit was engineered to be used w/zsp springs. Anyway, I didn't want to mismatch springs and bumpstops, so after 1-2 yrs of waiting I contacted Dan@UnitedBMW (1addicts vendor) ; he contacted BMWNA about getting the front PS bstops seperately and voila-1 month later I've got 'em I want to thank a few of you guys that have the new V2 PS kit for answering some questions

I've read a few threads where people are installing PS or aftermarket sport springs and wondering what to do about bstops. I think jwong77 and luckyu have used the E36 M3 front and Z4 rear bstops and are happy with the results (this might be what Dinan uses for their E9X susp kits). But if you're going to install the PS springs, why not use the bstops engineered to work w/those springs? They're used as a secondary spring after all. The p/n is 31 33 6 789 540. For comparison's sake I measured the height of the old v1 and new v2 PS bstops and the zsp bstops. The v1 bstops feel alot firmer than the other 2 and are taller; the front v2 bstops are firmer and shorter than zsp; the rear v2 bstops are shorter than zsp and feel close in firmness. I have no way to measure density or rate with these bstops but here are the measurements:

From left to right are: ZSP F-2 3/4", V1 F-3 1/16", V2 F-2 3/8", ZSP R-2 7/8", V1 R-3 1/8", and V2 R-2 5/8"

[cdgatti]

So just for clarification; your suspension is Koni (yellow?) dampers, BMW PS springs (yellow ones?) and V2 PS bumpstops? Can you provide a performance and ride quality review compared to your old zsp suspension? Thanks.

[cvc 22349a]

Sure, when I get the PS springs installed. Still riding on the zsp springs and koni sports.
'Freelo' has PS springs and koni sports on his car, but I think he still has the zsp bstops which is definately better than riding on the v1 PS bstops.

[mlifxs]

Originally Posted by cvc 22349a

Just wanted to share with those who've been talking about bumpstops and sport (non-c/o) springs lately:
I've wanted to get the BMW PS springs for over a year to go with my koni's. I didn't want the whole 'new' PS kit because of how lousy my oe zsp dampers were and just figured the koni's would have better (and adjustable) damping than whatever BMW provides w/the PS kit. The PS kit dampers were engineered to be used with runflats and I've been off of those for 3 yrs and have <19 lb wheels. The PS springs have been available for over 2 years but you couldn't get the front PS bumpstops seperate from the kit (I've been asking Tischer for over a year). The rear PS bstops have been available. Lot's of folks have added the PS springs to the 'original' or V1 PS kit but that kit was engineered to be used w/zsp springs. Anyway, I didn't want to mismatch springs and bumpstops, so after 1-2 yrs of waiting I contacted Dan@UnitedBMW (1addicts vendor) ; he contacted BMWNA about getting the front PS bstops seperately and voila-1 month later I've got 'em I want to thank a few of you guys that have the new V2 PS kit for answering some questions

I've read a few threads where people are installing PS or aftermarket sport springs and wondering what to do about bstops. I think jwong77 and luckyu have used the E36 M3 front and Z4 rear bstops and are happy with the results (this might be what Dinan uses for their E9X susp kits). But if you're going to install the PS springs, why not use the bstops engineered to work w/those springs? They're used as a secondary spring after all. The p/n is 31 33 6 789 540. For comparison's sake I measured the height of the old v1 and new v2 PS bstops and the zsp bstops. The v1 bstops feel alot firmer than the other 2 and are taller; the front v2 bstops are firmer and shorter than zsp; the rear v2 bstops are shorter than zsp and feel close in firmness. I have no way to measure density or rate with these bstops but here are the measurements:

From left to right are: ZSP F-2 3/4", V1 F-3 1/16", V2 F-2 3/8", ZSP R-2 7/8", V1 R-3 1/8", and V2 R-2 5/8"

Thanks for this!
Regarding your comment about non-rft's and lighter wheels, can you elaborate on why such a set-up would motivate you to avoid the ps dampers?
I'm planning on an v1 PS install and am curious about the effects of less unsprung weight with that setup.

[cvc 22349a]

Originally Posted by mlifxs

Thanks for this!
Regarding your comment about non-rft's and lighter wheels, can you elaborate on why such a set-up would motivate you to avoid the ps dampers?
I'm planning on an v1 PS install and am curious about the effects of less unsprung weight with that setup.

I can't speak to the v1 ps dampers, but with lighter weight wheels/tires oe struts/shocks are very underdamped. It wasn't my intention to make this a PS v. Koni damper thread. My preference is for the Koni's; also I've read some threads where folks using the PS kit said the susp still felt a little underdamped. You got 'em; give 'em a try..

[mlifxs]

thanks, just trying to understand the effect

[luckyu]

Great post, and good job getting BMW to make these available!

[DaanBMW]

Great ! This is one of those must-bookmark threads, as this info is for the 1st time now available. I think I agree these are prob the best fit for the PS yellows, although from the application lists for the p/n's it seems to me like a parts bin approach by BMW. Thanks cvc !

The only other comparo I'd personally be interested in is against the E36 M3 front and Z4 rear bstops set mentioned in the OP, which have been used by some people because the v2 bstops were not avail to order. If someone has them pls post the heights.

[cvc 22349a]

Originally Posted by luckyu

Great post, and good job getting BMW to make these available!

Thx again for those v1 bstpos I'll pass 'em along if I'm happy w/the PS springs

[cvc 22349a]

Originally Posted by DaanBMW

Great ! This is one of those must-bookmark threads, as this info is for the 1st time now available. I think I agree these are prob the best fit for the PS yellows, although from the application lists for the p/n's it seems to me like a parts bin approach by BMW. Thanks cvc !

The only other comparo I'd personally be interested in is against the E36 M3 front and Z4 rear bstops set mentioned in the OP, which have been used by some people because the v2 bstops were not avail to order. If someone has them pls post the heights.

I know. I wish I had those but wasn't going to buy 'em, Maybe 'luckyu' measured them?

[jwong77]

I wish I had measured the bumpstops prior to installing them in my car.

Anyways, good job on getting the PS bumpstops available. If I wasn't so happy with my setup, I would be interested in these bumpstops as well.

[Freelo]

As cvc 22349a pointed out, I have the Koni sports with the BMW performance springs (the newer ones), but I am just using the ZSP bumpstops.

I'm very interested to hear the review on this. As I guessed, there seems to be a bigger difference in the front bumpstops, which makes sense since there is more lowering with the BMW performance springs in the front.

My ride is very good now, but I wonder if it would remove a bit of the bounciness still present in the front if I changed to these PS v2 bumpstops.

Any experts able to chime in on what a difference the switch to the shorter matched PS bumpstops should make?

[luckyu]

Originally Posted by Freelo

My ride is very good now, but I wonder if it would remove a bit of the bounciness still present in the front if I changed to these PS v2 bumpstops.

Any experts able to chime in on what a difference the switch to the shorter matched PS bumpstops should make?

It would be better to change to the v2 bump stops, since right now, with the ZSP bumpers plus performance springs, you have at most 1/4" bump travel before touching the bump stop. If you're experiencing a violent rebound after the car compresses into a bump on the freeway, a shorter bump stop will likely go a long way to reducing or eliminating that. It did in my case. My car used to launch me out of my seat.

I noticed you have Velocity toe arms. Do you feel any difference in everyday driving from those?

[Freelo]

Thanks luckyu for your advice on this. Makes sense to change when I have the next opportunity. I'll contact the vendor that has these parts.

The Velocity toe arms. They are solid looking parts for sure and the OEM toe arms are pretty flimsy. I do not think you'd notice the difference when you are in everyday driving. However, when I am really pushing the car at its limits in turns, I now have dramaticall improved stability. The theory is the rear axle maintains proper camber and minimum deflection. I cannot isolate the toe arms too specifically, however, since I did the subframe bushings and guide arms at the same time.

[luckyu]

Originally Posted by Freelo

Thanks luckyu for your advice on this. Makes sense to change when I have the next opportunity. I'll contact the vendor that has these parts.

The Velocity toe arms. They are solid looking parts for sure and the OEM toe arms are pretty flimsy. I do not think you'd notice the difference when you are in everyday driving. However, when I am really pushing the car at its limits in turns, I now have dramaticall improved stability. The theory is the rear axle maintains proper camber and minimum deflection. I cannot isolate the toe arms too specifically, however, since I did the subframe bushings and guide arms at the same time.

Thanks, I will probably upgrade at some point.

[mike-y]

I reused my stock ones. I just hack-sawed off the lowest nub to make them a little shorter. They looked like either ZSP-R or V1-R

[subieworx]

The problem with hacking off a nub is you change the progression of the stop.

[mike-y]

true, though on a car that isn't lowered much (if at all), I doubt it's anything to worry about. Especially on the longer bumpstops like what I had on my car.

[cvc 22349a]

Originally Posted by Freelo

As cvc 22349a pointed out, I have the Koni sports with the BMW performance springs (the newer ones), but I am just using the ZSP bumpstops.

I'm very interested to hear the review on this. As I guessed, there seems to be a bigger difference in the front bumpstops, which makes sense since there is more lowering with the BMW performance springs in the front.

My ride is very good now, but I wonder if it would remove a bit of the bounciness still present in the front if I changed to these PS v2 bumpstops.

Any experts able to chime in on what a difference the switch to the shorter matched PS bumpstops should make?

I'm no expert... with the ps v2 bstops, you won't contact them as soon as zsp in bump travel. I imagine I'll have more spring rate in front than you do; the bstops are significantly firmer; look at that plastic ring. My rear should be less bouncy w/the shorter ps bstops; I'm also going to use the dinan upper shock mounts I got from luckyu. I'l write up a review when I get these installed, but I'd bet I'll still have some bounce cuz of those lower camber links. If you do the work yourself, I'd say it's worth it to switch; I'm not sure I'd pay the labor to make the switch unless you're due for an alignment.
btw, thx for answering previous pm questions

[cvc 22349a]

Originally Posted by subieworx

The problem with hacking off a nub is you change the progression of the stop.

+100

[cvc 22349a]

Originally Posted by luckyu

Thanks, I will probably upgrade at some point.

I'll let you drive my car again when I get 'em installed but that won't be for a while. Springs first then toe links and alignment.

[hillhucker]

OP, the p/n 31 33 6 789 540 seems to be only for the front or rear...are you able to get the other p/n? Thanks