PetersRedYaris
10-23-2008, 06:03 PM
Well I did some work today and got a definitive answer. I still don’t know what Toyota recommends, but here’s 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 don’t cut your bump stops to a shorter length, you will be sitting on them at a drop of 1.5 inches. That’s 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.
http://i227.photobucket.com/albums/dd181/peter0022/DSC01713.jpg
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 it’s 1.75 inch length. So it’s 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 don’t have to do it, but if you don’t the front of your car will just be sitting on some compressed foam, not the springs.
Hope this helps answer any “Do I cut my bump stop” questions…
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 don’t cut your bump stops to a shorter length, you will be sitting on them at a drop of 1.5 inches. That’s 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.
http://i227.photobucket.com/albums/dd181/peter0022/DSC01713.jpg
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 it’s 1.75 inch length. So it’s 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 don’t have to do it, but if you don’t the front of your car will just be sitting on some compressed foam, not the springs.
Hope this helps answer any “Do I cut my bump stop” questions…