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Old 10-23-2008, 05:03 PM   #1
PetersRedYaris
 
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Bump stop length for drop springs.

Well I did some work today and got a definitive answer. I still donít know what Toyota recommends, but hereís what I did.

I measured from center wheel to the fender and recorded the distance. I then lifted the front of my car until the front wheels came off the ground and measured again. The difference between the two measurements was 3.125 inches, which means the strut is compressed 3.125 inches when the weight of the car is sitting on stock springs. If the car were sitting on lowering springs you would add the drop of the springs, plus 3.125 inches, to get the distance the strut is compressed under the weight of the car.

Next I removed the struts from the car and disassembled them. I then measured from the strut body, up the shaft and marked a line with a permanent marker. I put the line at 4.625 inches, the distance of 3.125 inches, plus a theoretical spring drop of 1.5 inches. This shows me how compressed the strut would be if it were installed on the car with 1.5 inch drop springs.

I next assembled the strut without any spring using a full length factory bump stop. Guess what, it overlapped the line I had drawn on the shaft. This means that if you donít cut your bump stops to a shorter length, you will be sitting on them at a drop of 1.5 inches. Thatís right, your nice drop springs you purchased will be doing NOTHING.

So how much do you cut them? The picture shows the shortest length you want. I tested this by cutting my old bump as shown in the picture. I again assembled the entire strut assembly, this time using the cut bump stop. The distance from the bump stop to the line was about 2 inches. How does this compare with stock suspension travel? It is actually slightly more travel than stock. I tested this by taking measurements using a line at 3.125 inches and using the full length bump stop.



Could your strut bottom out with shortened bump stops? I measured this too. To get the strut shaft to bottom inside the strut, I found that you would have to hit a bump hard enough to compress your shortened bump stop .75 inches, or about 43% of itís 1.75 inch length. So itís possible, but not likely. I say this because the portion of bump stop you are using is the most firm. The softest part has been eliminated when you shorten them. So compressing your very firm shortened bump stop by 43% is unlikely.

In conclusion, by shortening your bump stops you maintain the travel you would otherwise lose when installing drop springs. You donít have to do it, but if you donít the front of your car will just be sitting on some compressed foam, not the springs.

Hope this helps answer any ďDo I cut my bump stopĒ questionsÖ
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Old 10-24-2008, 05:46 AM   #2
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bloody brilliant, i was wondering why i was supposed to do it when i was hacking away at them. My self install was actually better than my friend's who took it to a shop. I asked them if they cut the bump stops and they told me that they cut it in the middle for his car...

I guess he's screwed haha, that and it probably explains the noise we hear when he hits a hard bump or cuts a hard turn.
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Old 10-24-2008, 10:33 AM   #3
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I guess he's screwed haha, that and it probably explains the noise we hear when he hits a hard bump or cuts a hard turn.
I'd say the noise he is hearing is tire rub due to oversized aftermarket wheels with say a 40mm offset maybe?

Not cutting the bumpstops enough only restricts the travel of the suspension, which would actually keep the chassis away from the tire. So the fact that the bump stop was only cut in half is a good thing for your buddy because otherwise the rub would be worse.
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Old 10-24-2008, 05:46 PM   #4
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Quote:
Originally Posted by Smokey159 View Post
I'd say the noise he is hearing is tire rub due to oversized aftermarket wheels with say a 40mm offset maybe?

Not cutting the bumpstops enough only restricts the travel of the suspension, which would actually keep the chassis away from the tire. So the fact that the bump stop was only cut in half is a good thing for your buddy because otherwise the rub would be worse.
40 is nearly stock. If you're at 38, then you'll have to worry about rubbing the fender lining. I rub with a ET of 38, and thats on hard cornering. With my 230lbs fat ass.
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Old 10-25-2008, 11:18 AM   #5
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My wheels are +40 and had a slight fender rub due to the 205 50 16 tires.

With the Tokico struts in installed, I rarely rub anymore.

I just cut my bumpstop to the plastic piece for insurance. I have only hit the bumpstop a couple times ever, and I'm lowered 1.8 inches.
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Old 10-26-2008, 07:04 PM   #6
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Originally Posted by largeorangefont View Post
My wheels are +40 and had a slight fender rub due to the 205 50 16 tires.

With the Tokico struts in installed, I rarely rub anymore.

I just cut my bumpstop to the plastic piece for insurance. I have only hit the bumpstop a couple times ever, and I'm lowered 1.8 inches.
Must be the stiffer struts... Did you have the lowering springs installed on the stock struts, and if so did you hit the bump stops considerably more with them?

I ask because based on my measurements, you don't have much travel left. I'm guessing 1/2 to 1 inch...
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Old 10-26-2008, 11:42 PM   #7
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Originally Posted by PetersRedYaris View Post
Must be the stiffer struts... Did you have the lowering springs installed on the stock struts, and if so did you hit the bump stops considerably more with them?

I ask because based on my measurements, you don't have much travel left. I'm guessing 1/2 to 1 inch...

Yea, I ran for 20K miles with the same lowering springs on the stock struts.

The only time I ever hit the bumpstops, was over potholes at speed. I drive the car pretty fast into turns. and with the new struts I get less tire rub on the fender liner, but never ride the bumpstops through turns.

I have more than 1 inch of up travel.
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Old 10-27-2008, 03:38 PM   #8
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Check it out!

http://fatcatmotorsports.com/FCMstops_Yaris.htm
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Old 10-27-2008, 05:20 PM   #9
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Thats a ripoff, and you don't need bumpstops for the shocks.
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Old 10-27-2008, 05:27 PM   #10
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Don't cut ..........period
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Old 10-27-2008, 05:50 PM   #11
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Don't cut ..........period
You like the feeling of compressed foam between your a-arm and strut tower? Why not just take your springs out and sit on the bumpstops? It wouldn't ride any different...

Or are you saying get the fatcats?

I also see you have the TRD Sportivo struts/shocks, this doe's not apply to them...
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Old 10-27-2008, 06:28 PM   #12
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Yes I have the TRD shocks with the Tein springs . They work VERY well , even on dirt . From my past experiences with other shock/spring combos ,I found that if you are not lowering more than 2" cutting the bumps will shorten the lifespan of your shocks . If you cut the bumps the energy transfered will be greater . Keep in mind the idea behind bumps is to dampen .

If I were to switch bumps it would probably be with energy suspension bumps .
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Old 10-29-2008, 12:23 PM   #13
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Thats a ripoff, and you don't need bumpstops for the shocks.
Hmmmm I wonder why the factory installs them then???
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Old 10-29-2008, 04:14 PM   #14
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BTW, how do you guys bottom out? i mean... my echo had the eibach pro kit 1.3" drop (looked more like 1.5" but anyways), i had the stock shocks and i never bottomed out. I never took a look at the bump stops, i just put back the struts straight back in with the new springs...
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Old 10-29-2008, 09:15 PM   #15
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Hmmmm I wonder why the factory installs them then???
Maybe you should read my post again and go have a look at your SHOCKS. The front struts need bumpstops, rear shocks do not. The rear springs will coil bind before the shocks bottom out. Buying bumpstops for the shocks is a waste of money. Buying new bumpstops for the struts is a waste as well, the OEM units work fine.
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Old 10-29-2008, 11:36 PM   #16
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Do you mean the rear drop springs, because they have a tighter coil, will bind first? I ask because the OEM rear springs have far less coils than drop springs and the rear shocks do have rubber bump stops inside the plastic boot. I assume the OEM coils wouldn't bind first, otherwise Toyota wouldn't have bothered putting bump stops in the rear at all.
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Old 02-11-2010, 04:21 AM   #17
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Hey guys, I'm new to the forum and "bump"ing this thread back to life since I have a question about my installation. I got the H&R coil over kit and performed the install on my 2007 Yaris sedan. Everything went beautifully except the only thing left in question was the bump stop. I looked at it and looked again and there was no way even a 1 inch sliver would fit in there without the sub-tower resting on the stop. So guess what. I left the dang thing out! No bump stop at all. I took it out for a test drive pushing all limits and man this thing dances. I have several speed bumps in my apartment complex and tried bottoming out, no problems.

Anyone else do an H&R coil over install and leave the bump stops out?

edit - BTW the rear I used the stock bump stop cover thing, no problems there.

Last edited by jonnydwolf; 02-11-2010 at 04:25 AM. Reason: Addititional comment
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Old 02-11-2010, 02:42 PM   #18
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OK, just got off phone with H&R technician, for the Yaris kit their bump stop is internal for the front set.

So discard the bump stop.
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