Kurt Bob

One question. Why did you feel the need to modify your bump stops?

Silverarrow

i too want to know about the bumpstop modification, i didn't have the instructions, therefore i did not know to cut them (doh) but, i wonder is it worth it to take everything apart again, merely to do that? What is the purpose? Am i missing something without modifying them?

thanks

TheDosDog

Trimming the bump stop is specified in the RB instructions. During hard driving on stock springs I would frequently hit the bump stop,sometime upsetting the car significantly (not good). Trimming the stop yields a little extra travel. With this combination of bars, springs, and trimmed stops the suspension no longer bottoms out. It's perfect for "spirited" drives on windy roads.

GeorgeH

iTrader: (2)

To further clarify, when you install lowering springs on stock shocks, you reduce the clearance between the bump stop and the shock body, effectivly reducing suspension travel. Trimming the bumpstops stops restores travel, with the potential downside of effectively stiffening the bumpstops. Cut too little, and you don't have sufficient travel. Cut too much and the bumpstops become too stiff.

Jim is the real expert here on his setup, and I defer to his judgement, but my experiences with Miatas says that you should heed the installation instructions and cut the stops, even if that means disassembling the suspension one more time.

Racing Beat Inc

It sounds like you guys have this one covered!!! Who wants a job manning the phones on the Racing Beat tech desk???

All of the above comments are valid, but cutting any stop is really just a "band aid" remedy. The stop is really just a small "spring" and cutting not only changes the length, but the rate. If the budget allowed, the correct approach would be to design and manufacture a correct stop for EACH exact spring/shock combination. But since these are normally produced in manufacturing runs in the tens of thousands, the cost for a small run would push the per unit price out the roof! Ah, the ugly business side of things always spoils the fun.

Jim Langer
Racing Beat, Inc.

GeorgeH

iTrader: (2)

Thanks for the complement Jim. I’m going to rethink my answer, just a bit, because I’d hate to have somebody tear their suspension apart again unless it’s really necessary.

As Jim points out, bump stop selection is an integral part of the suspension setup, and it’s a bit of a black art. The collective experience in the Miata community (a car which has limited suspension travel to begin with), states that if you lower the car without either shortening or softening the bumpstops, (or using some other technique to restore lost travel) you will get a stiff, uncomfortable ride, and the car will tend to “pogo” off deep suspension hits, which can dangerously unload the suspension in mid corner.

Now, the RX-8 has more travel than a Miata, and it’s conceivable that the RB springs with OEM bumps is a workable solution. We will find, over time, that we will gain experience with this car and the “correct” answers will eventually surface. Right now we are still learning. But, if you already have the springs installed, but did not cut the stops, the questions you should ask are:

Does the car ride to rough?
Does it tend to loose grip during cornering over rougher roads, where once it had grip?
If you hit a transverse dip on the freeway, such that both wheels enter the same time, does it tend to pogo out of the dip?

If you answer “no” to all these questions, then perhaps you can leave the un-cut bumpstops in place. If any of these characteristics surface (and sometimes they surface after the newness wears off and you are able to be more honest with yourself) then I would recommend cutting the bumps. And, I’d recommend anybody who is installing for the first time to follow RB’s recommendations.

Hope this helps, sorry for the length.

George

cgrx

I had springs installed on my 2000 Celica and bump stops were not cut, I know they are different cars, but I've heard it is only a recommendation and is not completely mandatory for performance.

murix

I should add to this post that I did solve my noise problem and it was the swaybar clamps not being torqued down correctly. I set them to 36lbs-ft and all is good.

I also find the car spends less time on the bumpstops then before with the new suspension.

Racing Beat has been more than helpful with my troubles.

Great service and products!

cgrx

I'm getting mine soon.
I thought you weren't going to drop your ride DOSDOG ?

Any pics up?

murix

Me at the track with my Racing Beat suspension if that helps.

The RB suspension is less about lowering and more about handling.

cgrx

I'm definitely going with the WHOLE package..............eventually

TheDosDog

CGRX - The ride height does not change much. About .50" in the front .75" in the rear. When your ready to install yours give me a yell.

MURIX - Those are great pics. The suspension looks pretty loaded on that hard right. You had to be on the stop on that one. Did the RB suspension do anything for your lap times?

cgrx

Will do !
Thanks

murix

I am not keeping track of lap times right now so I am not really sure. The extreme difference in temps and different tires changes things as well. What I can say is the car feels much flatter with a lot less roll and better turn in and higher limits before it starts to push which is easy to counter with some throttle control.

Essentially the same as stock but better if that makes sense.

Kurt Bob

Thanks for the info on the bump stops! Racing Beat didn't supply any instructions with their springs, so I relied on the shop manual for the instructions. However, common sense would tell me that since I was installing a set of springs that only lowered the car 1/2 inch and provided a spring rate increase of 20%, I wouldn't necessarily need to trim bump stops. In addition, I installed the sway bar set, which would provide even more assurance against bottoming in cornering maneuvers.

Jim Langer, can you please send me a file with the instructions for the springs?

Thanks!

Ophitoxaemia

a spring rate change of only 20% shouldnt require any changes to the shock/struts.

i use a double adjustable shock on my race car, and swap springs and sway bars for different sites- there is a decent range where different combos will work.

i find my rx8 will bottom out driving fast on bumpy/windy roads, causing it to jounce sideways terrifyingly. also, it is very easy even on street tires to get on the bump stops in the front under heavy trailbraking. more spring needed.

it was my understanding that we have monotube shocks standard... sweet.

im planning to get the RB springs...

james

ScudRunner

Kurt Bob: As for install instructions, if you email Jim Langer using the address on the Racing Beat Contact page, he should be able to send you a .pdf or .doc file with the spring install instructions. He was pretty quick about sending me the documentation for their flywheel when I asked for it.

I've had the RB Springs installed for some time now, and just put the sways on yesterday. As for the springs, I trimmed the bump stops when I put them in, per the instructions from RB. I certainly would not complain about the ride being harsh at all. And, I could probably count the number of times I have felt myself hitting the bump stops on one hand. As for the sway bars, no words yet about the new feel, but I'm autocrossing my baby tomorrow, so hopefully I'll have a good feel for them then. Unfortunately, it's been a while since my last autocross when I had the stock sways (due to a little stint in Iraq), so my memory might not be good enough to tell the difference right away. On a side note, when installing the rear sway bar, don't forget to adjust your torque wrench when moving from the end link nuts to the bushing bracket nuts. 40 ft-lbs of torque applied to the nuts on the bracket (versus the 13-19 that is called for) will shear the bolt right in half :o . And the bolt is tack welded to the car, and the dealership didn't have a part number for an exact replacement. So not an easy fix.

RojoOcho

For the record, I had the clunking in the front sway bar (Drivers' side), had it re-torqued, and everything is fine now. Torque it towards the high end of the recommended spectrum.