TopGunM2k

Good afternoon everyone, I saw a few threads where people recommend cutting or installing smaller bump stops when putting in lowering springs. It was mainly recommended when running an aggressive spring that lowers the vehicle -1.5 inches or more. I bought new KYB gas-a-shocks and installed them on Tein H tech springs(front -1/ Rear .3). I also bought new bearings, rubber bushings, and bump stops for this install (all KYB brand). I decided not to cut the bump stops as I didn't think it was necessary with the drop not being too aggressive. The car handles and drives great since the rear shocks were blown and the front were a bit weak. I have not noticed any harsh issues when going over speed bumps as some people described when not cutting the bump stops. Has anyone with this setup cut the bump stops or just left them to factory spec?

_JB_

I cut the rear bumpstops on my Koni+Tein H tech springs and they bottom out at times.

TeamRX8

iTrader: (25)

the OE bump stops are intended to bottom out under particular circumstances. And they’re also designed such that just cutting them is not a good idea. They also should be replaced along with when the shocks are replaced, but most people never do out of a lack of understanding. The overall issue is that most lowering springs are under-rated (too soft) in not accounting for the changes they require resulting from modifying the original factory design basis.

https://www.rx8club.com/series-i-whe...g-rates-33424/
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TopGunM2k

Thanks for the input guys; it's greatly appreciated. So it sounds like it was a good idea leaving the brand new bump stops alone. It honestly didn't feel right to cut or hack up the brand new material as my concern was also that it could affect the structural integrity of it with it being made of the foam/rubber composite.

_JB_

​​​​​​I have Tein S and H techs on three cars in my fleet and all the instructons said to cut the bumpstops but I've never hit them. For whatever reason my RX8 will hit the rears but never the front. It wouldn't surprise me if you tap the rears sometimes.

TeamRX8

iTrader: (25)

i can’t find an installation pdf for the Mazdaspeed lowering springs, but according to various threads they don’t state to cut the factory bump stops despite them lowering between 0.8 - 1.0” as reported by multiple users. The people who didn’t cut them said as far as they can tell the uncut bump stops were not hitting.

however the factory bump stops are a progressive rate type to add spring rate as they make contact with the shock body and begin to compress. If you cut the shock contact side of the bump stop off then the progressive end is being removed. That may be part of why you feel them contact. In reality they will contact when full length and again are designed to do that, but gently to start and then stiffen more and more as they squeeze down fully, but gently.

So Mazda didn’t cut them, but that Tein etc said to doesn’t make them correct imo.
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TopGunM2k

Totally agree with just leaving them alone - no problems so far. I would recommend that anyone changing shocks also change out the stuff i did. I did notice the rubber bushings for the top mount of the shock and also the bump stops were worn and had cracks.