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What are the guidlines for adding bump stops? Picture.

mako my day

mako my day

NAXJA Forum User
Location
Aliso Viejo
6.5", Curries UCA, RE fixed lowers. Stock bump stops.The tires just get stuffed.
Are there any guidelines or rules for adding bump stops? Does this look fine?
I think it's ok, but I'm new, and I hope nothing breaks.



Uploaded with ImageShack.us
 
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The standard way of checking front end clearance is too remove the front coils, and, leaving the wheels on, cycling the suspension in every possible direction, including turning the wheel from side to side, while checking for interference.
Use small zip-ties, on the shaft of each shock, to show how much up travel is being used. I like to have 1/4"-1/2" of unused travel to be left, after a few very hard hits, so the shocks never bottom out.
I use Prothanes on the front and some tall 4-1/2" stops in the rear.
http://www.flickr.com/photos/lwade/sets/72157623386411798/
http://www.jegs.com/i/Prothane/311/19-1704/10002/-1
http://www.polyperformance.com/shop...Bump-Stop-with-Slotted-Mount-Plate-p-208.html
 
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Bump stops are for 2 good reasons.
To keep your tire from hitting your fenders or flares.
To not let your shocks act as your bump stops. Like it says above, have it hit the bump stops with 1/2" remaining on shock travel
 
Dumb question... Why isn't this predictable? I'm in the process of finishing up my lift. I should end up with 4 - 4.5" with OME shocks, leafs and coils. I picking up a set of 32x11.50x15's tomorrow. Why isn't it as simple as saying you have this much lift with this sized tires, you need to bump stop this much? Be gentle. :)
 
Sounds like your are volunteering to build a spreadsheet with all of the variables factored in......
 
I would if I knew the variables. I could create a very nice spreadsheet with all sorts of crazy formulas. :)

I know computers. I'm what you call expert. I don't know Jeep suspensions. I'm what you call rookie. LOL
 
Well my rig pictured above has Curries adjustable uppers, fixed re lowers, hd trackbar with double shear, stock bumps, 33" dooshtech shocks with 11" travel, and the tires are 32x1150x15.
Here is the same pic, opposite side showing rear stuffing.
flexin.jpg
 
cipher said:
I would if I knew the variables. I could create a very nice spreadsheet with all sorts of crazy formulas. :)

I know computers. I'm what you call expert. I don't know Jeep suspensions. I'm what you call rookie. LOL
Click to expand...

Trimmed or untrimmed fenders?
Flares or no?
Backspacing
Which arms ( JJ flex better than bushings)?
Short arms, DB, or LA?
Which shocks?

In short, there are too many variables to give a good answer.
 
The basic rundown, add 1" of bump for every inch lifted. That just factors in the suspension. Add larger tires, your clearance changes in your fenderwells. Then there's trimming, etc etc like others have stated.
 
Add more bumpstop than what you figure you need and use the zip-ties to see actual shock travel. Reduced the amount of bumpstops until you get full shock travel, minus 1/2" of uptravel, plus not hitting anywhere.
Moving the shock mounts can be of great help when trying to achieve maximum suspension travel.

Every XJ is set up a little different, your bumps will be unique to your rig.
 
lazyxj said:
The standard way of checking front end clearance is too remove the front coils, and, leaving the wheels on, cycling the suspension in every possible direction, including turning the wheel from side to side, while checking for interference.
Use small zip-ties, on the shaft of each shock, to show how much up travel is being used. I like to have 1/4"-1/2" of unused travel to be left, after a few very hard hits, so the shocks never bottom out.
I use Prothanes on the front and some tall 4-1/2" stops in the rear.
http://www.flickr.com/photos/lwade/sets/72157623386411798/
http://www.jegs.com/i/Prothane/311/19-1704/10002/-1
http://www.polyperformance.com/shop...Bump-Stop-with-Slotted-Mount-Plate-p-208.html
Click to expand...


These flickr photos helped a lot. I have a much better understanding of what you guys are saying now. Question... How do you safely figure out the shocks full travel? What about disconnecting the lower shock mount and manually compressing to find bottom?

Also... did you make the 2 inch stack of plastic spacers in the rear?
 
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cipher said:
How do you safely figure out the shocks full travel? What about disconnecting the lower shock mount and manually compressing to find bottom?
Also... did you make the 2 inch stack of plastic spacers in the rear?
Click to expand...

In the front end,I remove the coil springs and then cycle the suspension and steering, at all angles, to find if and where things hit. Adjust the bumpstops so there is around an inch of extra shaft remaining for up-travel.
The rear is more difficult since the springs cannot be removed and still cycle the suspension. Disconnecting the shackle help some. I measure the remaining shaft up-travel and compare it to the gap between the axle and rear bumpstops, subtracting an inch or so for compression of the rubber.
Using the zip-ties, to see the actual shock travel allow fine tuning. I have a few local hard dips and bumps, when hit at speed, to test the settings, making sure to have a minimum of 1/2" left after very hard hits.
This extra 1/2" will get used in case of extremly hard hits (like driving through an unseen washout) where everything in the rig flexes.
Steel, no matter how thick, can and will flex when hit hard enough.
I just want to make sure the shocks are not subjected to any bottoming.

The rear spacers are cut from a plastic cutting board, a readily available, cheap source of spacers. Using a hole saw, I cut front spacers from the same material.
 
cipher said:
Question... How do you safely figure out the shocks full travel? What about disconnecting the lower shock mount and manually compressing to find bottom?

Also... did you make the 2 inch stack of plastic spacers in the rear?
Click to expand...

There ya go. Definitely better than abusing via forklift, and you can do top and bottom.

Oh lazyxj already answered hehe
 
when i built my front end i just took the spring out on one side and let it down slowly and jacked up the other side of the body. remember that the droop on the opposite side will put the tire even farther into the wheel well on the stuffed side even after you hit the bump stops.
As Souske mentioned, everything makes a difference. if you have very offset wheels or wheel spacers, you can trim your fenders and get a little more uptravel. with my wider axle which is pushed forward a little and 3.25 backspacing, i could hit the stock bumpstops with 5" of lift and 35's, assuming i still had them.
 
Just to get a rough figure, couldn't you just measure the total distance between the two bump stop surfaces, the total travel on the shock at that height, and find the difference?

For example:
8" gap between bumpstops
6" uptravel on the shock at that height
=====================
Need 2.5" thicker bumpstop (add extra .5 for insurance)

I realize that doesn't account for the weird things that happen when the axle is fully drooped on one side and compressed on the other, but i'd bet it gets you close enough since the shock and spring are pretty much inline....

No?
 
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