Bump Stop Advice

1950StangJump$

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Hey guys . . . I think this should be in Tech?

I have a full rear BMR setup, including adjustable LCAs, 2011+ UCA, panhard, panhard brace, relocation brackets, sway bar, and upper axle bushing. I also have Pedders adjustable coilover setup. I ended up liking and keeping the standard height that Pedders suggested, which is roughly 1-1.5" lower than stock. I'm on 20" rims.

At the same time, I replaced the bump stops out of an abundance of caution. I just noticed that the car sits low enough that the bump stops are touching, though not really depressing, all the time. Should I cut them down?

IMG_1038.jpg

IMG_1039.jpg
 

07 Boss

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Well you want your car to ride on the springs. Riding on the bump stop has got to get kinda harsh sometimes and you'll end up busting a rim if the suspension can't articulate when that pothole comes out of nowhere. I cut the two nubs off mine.
 

1950StangJump$

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Thanks.

To clarify, when I put new bump stops on, they were the FRPP that are supposed to be soft enough to allow for the lowering springs:

https://www.americanmuscle.com/frpp-jounce-stops-0513.

So, I'm unclear if they are okay to touch like you see in my pics cause they are softer, or if they need cut because my setup is even lower than what they are designed for.
 

07 Boss

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And that's all fine but you want to ride on your springs. The stops are only there for extreme cases when your suspension gets bottomed out and you don't lose the fillings in your teeth.If you're riding on the bump stops you are not allowing the springs to do their job properly. You're suspension needs to articulate for proper handling. You want to ride on more than just the air in your tires to absorb the road.
 

1950StangJump$

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Okay. I just took 10 mins and cut off the first nub.

I see lots out there on this - some do the second section also, and some don't. I guess I'll see how it goes with just one section off before deciding
 

1950StangJump$

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And that's all fine but you want to ride on your springs. The stops are only there for extreme cases when your suspension gets bottomed out and you don't lose the fillings in your teeth.If you're riding on the bump stops you are not allowing the springs to do their job properly. You're suspension needs to articulate for proper handling. You want to ride on more than just the air in your tires to absorb the road.

You were right.

I had complained that I needed to literally steering the car around turns with the throttle. I guess the bump stops were preventing an articulation/squatting -- just cutting off that first section made the rear stick much better.

I think I will cut off the second section. Worst case, it costs me $30 to buy more and go back to just the first section cut.
 

oldVOR

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I agree with 07 Boss, take them down to just the base cylinder which gives your springs roughly 1.5" of additional travel before the bump stop touches. You can also shift the location so it's under the flat portion of the frame and not the angled portion for even more room.
 

1950StangJump$

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I agree with 07 Boss, take them down to just the base cylinder which gives your springs roughly 1.5" of additional travel before the bump stop touches. You can also shift the location so it's under the flat portion of the frame and not the angled portion for even more room.

Perhaps this is a naive question .... if I take it down to that base cylinder, thus cutting off about 1.5" ....

I'm low enough now that I barely have 1.5" of free wheel well to give. Assuming the bump stop compresses some, won't 1.5" less plus the compression mean my rear wheels end up rubbing?
 

07 Boss

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Post up a pic of your wheel well. Take it down the side like this.




You can see where my tire is and I have never rubbed. There is actually a lot more room than it looks and the fender is rolled from the factory. Unless you have some funky wheels with some odd backspacing you should be OK. And if it does rub go get another set and not cut them down as far.
 

06StangGT

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Do you cut the bump stops down only with certain suspension set-ups? I've replaced the entire rear setup but haven't touched the bump stops.
 

bujeezus

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I only cut the top nub off with my H&R Super Sports. After my springs settled, I realize I need to take 1 more nub off.
 

1950StangJump$

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Post up a pic of your wheel well. Take it down the side like this.




You can see where my tire is and I have never rubbed. There is actually a lot more room than it looks and the fender is rolled from the factory. Unless you have some funky wheels with some odd backspacing you should be OK. And if it does rub go get another set and not cut them down as far.

The car has settled a little since I took this picture. It is closer to yours now. With the first nub removed, it no longer sets on the bump stops, but I still can't get a finger in between the stop and the frame.

I suppose I can try to take it down to the main cylinder section, as everyone here seems to recommend, and just buy new ones if its a problem. Also, since I'm on the adjustable Pedders, I have the option of firming up the rear . . . I'm assuming that would allow me to stop any wheel rub.

View attachment 71847

file4-46a.jpg
 
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1950StangJump$

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Here is the Eibach bumpstop for lowered cars vs the FRPP one.

View attachment 71850

Funny, cause I thought about buying it . . . except it doesn't look as though they sell them anymore . . . at least not with the part number on these forums.

And, interestingly enough, it looks even with FRPP with only the top section cut off -- not both sections like is a frequent recommendation.
 

RED09GT

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I cut both sections off mine. My 60 ft times sucked and my car would unload the tires a couple feet out, even on drag radials when my car was still N/A. It was all because the car would hit the bumpstops and bounce back up. Cut them down in the pits at the track with an Olfa box cutter and went from a few 2.2 60 fts to a 1.84 on the last run of the night.
 

06StangGT

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And, interestingly enough, it looks even with FRPP with only the top section cut off -- not both sections like is a frequent recommendation.

This is the first thing I noticed as well.

RED09GT - was it blatantly obvious that the bump-stops were problematic on those runs before cutting them?
 
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RED09GT

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It did feel like something was abruptly stopping the suspension from compressing, not as harsh as an actual bottom out but a noticable thunk and a bounce. We went looking for the source and noticed that there was barely any space between the bumpstop and the frame.
This was the first time at the track after switching to steeda springs and tokico d-specs so my first instinct was that I did something wrong during install.
It wasn't obvious that it was a problem until having issues at the track. The car felt fine on the street for the most part but there was a bit of an abrupt hit over speed bumps, kind of a pogo-stick type feeling. That went away after cutting them down.
 

1950StangJump$

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So, I realize that the answer to this question will be "it depends" on things like spring/shock package stiffness.

But, as a general rule, how far do you guys think is enough space between the top of the bumpstop and the frame when the car is at a rest?
 

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