Extending Bump Stops - Unsure of Length

[Koko4]

Before I put my lift on, I was dumb and did not take any measurements. I have no idea of how much actual lift I gained.

I installed the Bilstein 5100's for the Tundra in the rear, which have a:

Collapsed length: 13.84"
Extended length: 22.4"
Part #: BIL 24-100144

I measured my hub-to-fender and it is 23"
From the ground to the fender is 38"

I am running 265/75/16's.

I'm trying to figure out how much to lower my bump-stops, to ensure that I will not "bottom out" my shocks. The last thing I want to do is blow my shocks, especially since getting those top mount bolts off SUCKS.

I have a piece of stock, which is 2" or 3", depending on how you orient it. Here are some pictures:

Horizontal: 2" (fits well with the bump-stop)

Vertical: 3" (is not as wide as the bump stop, does not fit as well)

Sorry to be obsessing about this, but I honestly don't know how to determine what I need to do in this situation. All of the factors (height due to oversized tires, shock length due to different extended / collapsed lengths of shocks) really confuse me when thrown together like this.

 

[fourfive]

When I installed my 890s on my 02, I gained ~2.75 inches from the stock set up:
stock rear: ~20"
lifted rear: ~22.75"
I also have 285/75/16s. I never changed out my stock bump stops but you may want to check with toytec or SS to see what they recommend.

 

[Koko4]

When I installed my 890s on my 02, I gained ~2.75 inches from the stock set up:
stock rear: ~20"
lifted rear: ~22.75"
I also have 285/75/16s. I never changed out my stock bump stops but you may want to check with toytec or SS to see what they recommend.

Sorry, I meant 265, not 285. Glad to know you got 2.75" of lift, though. I think ToyTec and SS both recommend their extended bump stops, HOWEVER they never actually specify how much it lowers them, exactly.

I can get 2" out of the horizontal piece of stock, and then a further .75" from two pieces of rubber that I have laying around. Is that too ghetto?

 

[D Farms]

flex your truck and take measurements. it would be dumb to just extend them the same amount that you lifted. the bump stops should be set up specifically for a tire size. for example i have stock tires, i only rub at full flex on the plastic cover for the filler, so i did not need to extend my bump stops much, if at all. for a 35 or 33 its a good idea to extend the bump stops to prevent rubbing at full flex, or at full compression if your tires dont tuck into the fenders.

 

[KidVermicious]

This is easy to determine. Stuff your suspension with the shock removed until the bump stop is completely depressed, this is easier if you put the opposite corner on a ramp. Now measure hub to fender. Lower the truck, replace the shock, stuff it again until the shock bottoms out. Measure hub to fender. Take the difference and add a 1/2inch or so and that's how far you need to extend your bumpstop.

 

[ARC]

flex your truck and take measurements. it would be dumb to just extend them the same amount that you lifted. the bump stops should be set up specifically for a tire size. for example i have stock tires, i only rub at full flex on the plastic cover for the filler, so i did not need to extend my bump stops much, if at all. for a 35 or 33 its a good idea to extend the bump stops to prevent rubbing at full flex, or at full compression if your tires dont tuck into the fenders.

You're forgetting the real reason, which the OP stated is to keep from over compressing shocks that have a longer compressed length than stock.

 

[JayRolla]

flex your truck and take measurements. it would be dumb to just extend them the same amount that you lifted. the bump stops should be set up specifically for a tire size. for example i have stock tires, i only rub at full flex on the plastic cover for the filler, so i did not need to extend my bump stops much, if at all. for a 35 or 33 its a good idea to extend the bump stops to prevent rubbing at full flex, or at full compression if your tires dont tuck into the fenders.

That is not completely true. Yes lower bump stops will help larger tires from over compressing but the main issue is over compressing your shocks and blowing them out. Huge reason people sometimes complain about there new tokicos or billys being bouncy with there 8 wrap coils.

You think toyota installed the stock bump stops to stop your little tires from rubbing? No they where installed to stop over compression of the shock. Also if it was for a softer bottom out than they would not have installed solid rock stoppers.

The normal rule is lower the same amount you have lifted so they work again. Mine are 3 3/4" lowered for my 4" rear lift.

 

[hounddogman]

This is easy to determine. Stuff your suspension with the shock removed until the bump stop is completely depressed, this is easier if you put the opposite corner on a ramp. Now measure hub to fender. Lower the truck, replace the shock, stuff it again until the shock bottoms out. Measure hub to fender. Take the difference and add a 1/2inch or so and that's how far you need to extend your bumpstop.

This is probable the most accurate and best way to do this but if you want to be lazy, than it seems you could take your Collapsed length of 13.84" and subtract the collapsed length of the OEM shock .

 

[D Farms]

hmm wierd my shocks only get close to bottoming out in a flex situation, and not at any other time.

 

[Koko4]

Thanks for the replies. I'm not going to remove the shock, though, and purposely bottom out the tire into the wheel-well to see what the limit is.

I would rather add a little too long of a bump-stop, rather than too little. I should have just measured what my stock height was and what it was after lifting, to begin with :doh:

I've heard numbers thrown out anywhere from 2.75" - 3.75", and really need to figure out what would work in my particular case. I have 285/65/16's with OME 890's in the rear (and Tundra / TRD coils in front, if that even matters).

 

[mountainbiker42]

I'm brining this one back from the dead, maybe I can help any future readers. I've installed the OME 1.5 inch suspension lift which comes with the longer 3" lift shocks. I used the fork lift we have at work to pick up one rear tire (rear sway bar removed) and flex the suspension until the tire being lifted no longer compresses upwards. This position I assume is where the shock has bottomed out, preventing any further compression. I measured the gap between my bump stop and axle which tells me how much I need to extend my bump stop to prevent damage to the shocks.

I then went around the other side where the tire was in full drop to figure out how far down it can travel before my rear spring started to come loose, this measurement gives me an idea for how long my limit straps need to be (remember, 3" lift shocks, OME 906 springs which are only 1.5")

I don't do hard rock crawling, but being a mechanic by trade I like things to be working properly, ready for any situation. You never know what you'll come across on some of the Colorado forest roads.

 

[SilvFx]

I'm brining this one back from the dead, maybe I can help any future readers. I've installed the OME 1.5 inch suspension lift which comes with the longer 3" lift shocks. I used the fork lift we have at work to pick up one rear tire (rear sway bar removed) and flex the suspension until the tire being lifted no longer compresses upwards. This position I assume is where the shock has bottomed out, preventing any further compression. I measured the gap between my bump stop and axle which tells me how much I need to extend my bump stop to prevent damage to the shocks.

I then went around the other side where the tire was in full drop to figure out how far down it can travel before my rear spring started to come loose, this measurement gives me an idea for how long my limit straps need to be (remember, 3" lift shocks, OME 906 springs which are only 1.5")

I don't do hard rock crawling, but being a mechanic by trade I like things to be working properly, ready for any situation. You never know what you'll come across on some of the Colorado forest roads.

I dont claim any expertise on this at all, but what I have seen multiple times on the Jeep forums is that you have to remove the rear coil and shock, sway bar etc while leaving on the wheel/tiresand measure the distance from the Centerline of the lower shock mount to the upper shock mount and ensure that is not smaller than the compressed length of the shock and ensure you are not hitting the inner fender with wheel/tire. To the extent it is smaller or hitting the wheel/tire you need to come up with a bump stock that will not compress any smaller than the difference between the compressed length of the shock and the centerlines of the shock mounts.

The only criticism I have of your method is that when you raise it with the forklift and have both shock and spring in place, you dont know what is keeping it from compressing further - the rear coil or the shock. If its the rear coil no longer compressing simply from the weight of the vehicle and you still have more travel in the shock you could potentially go further as you are likely to do when hitting bumps at speed.

 

[mountainbiker42]

I dont claim any expertise on this at all, but what I have seen multiple times on the Jeep forums is that you have to remove the rear coil and shock, sway bar etc while leaving on the wheel/tiresand measure the distance from the Centerline of the lower shock mount to the upper shock mount and ensure that is not smaller than the compressed length of the shock and ensure you are not hitting the inner fender with wheel/tire. To the extent it is smaller or hitting the wheel/tire you need to come up with a bump stock that will not compress any smaller than the difference between the compressed length of the shock and the centerlines of the shock mounts.

The only criticism I have of your method is that when you raise it with the forklift and have both shock and spring in place, you dont know what is keeping it from compressing further - the rear coil or the shock. If its the rear coil no longer compressing simply from the weight of the vehicle and you still have more travel in the shock you could potentially go further as you are likely to do when hitting bumps at speed.

Your raise a valid point and I don't disagree with what you said. While a co-worker was operating the fork lift I could watch the shock compress and hit a definite stop. While I don't have x-ray vision to see inside the shock, I assume this was point where it bottomed out. Maybe I could get a fully compressed measurement from OME and compare that to the rear shock when fully compressed to see if it really is bottomed out.