Is 3" enough for air bumps?

loki_racer

NAXJA Forum User
Location
Pittsburgh, PA
I don't compete in JeepSpeed, but do compete in a different racing league that is similar to JeepSpeed.

I recently did a WJ knuckle conversion, TNT Customs trackbar and HySteer axle bracket. After the first race with this set, it quickly became apparent that I need some type of air bump.

How do I know if a 3" air bump will be enough to stop the track bar from contacting the oil pan? As a side note, what are some suggestions for nice "go fast" shocks that aren't adjustable?
 
When you say "3 inch air bump" do you mean 3" of travel? Just curious because most air bumps are either 4" travel or 2" travel however you can add a spacer to them to get them at anything inbetween. What brand air bump are you looking at?

As far as clearance, the only way to be sure is to take out your coils and discharge the bumps down to very little presure and cycle your suspension.

Chris
 
What's the best method for testing if the 3" will be enough? I guess if it's too short I can buy some of that white plastic stuff (can't remember the acryonom for it) and stack it on the axle spring perch to shorten the travel distance.
 
on a short travel suspension like the cherokee's, many prefer a shorter bumpstop travel.
If you have 4" of bumpstop travel, on a 10" shock, on a 50/50 setup, your tire goes up 1 inch, and youre shock's compression valving goes out the window. let the bumpstop do it's job, handling the last chapter of your suspension.

full bump is full bump, install them to sit where you need them to, you can allways add on spacers.

i have a thread on installing airbumbs, feel free to go check it out, it's not that difficult.
 
What's the best method for testing if the 3" will be enough? I guess if it's too short I can buy some of that white plastic stuff (can't remember the acryonom for it) and stack it on the axle spring perch to shorten the travel distance.

Jim, I think there is a bit of confusion here. Do you have the link to when we set up your bumps?
 
The thing I'm worried about with the can mounts like those (other companies have the same style mounts) is getting them mounted inside the spring. The Light Racing mounts are designed to be welded inside the spring.

I haven't been able to find any photos online of air bumps mounted on XJ's anywhere but inside the spring.
 
Anyone have any suggestions in dialing in the air bumps?

I bought the Barnett air bump mount kit and a set of Fox 4" air bumps. I understand how to mount the kit and bumps, but am unsure about how to ensure the bumps will stop my trackbar from striking my oilpan.

I don't want to lose functionality of the air bumps, but have to ensure they always stop my suspension from traveling up too much. Any suggestions?
 
discharge your shocks and your airbumps (let out all the nitrogen), remove the coil springs, and compress the suspension to where you want it to stop. Mount your airbumps where they will be at full compression just before you reach that point.
 
You, sir, are a gentleman. Next question. How should I go about deciding how much nitrogen to run in the bumps? What type of "store" sells nitrogen? I know some tire dealers have nitrogen filling stations, but doubt they can get up to 150psi or so.
 
A tire shop should have plenty of PSI, they are filling off a large bottle of nitrogen not compressing it themselves. Just don't put standard air in them, it will contain moisture and corrode them from the inside out.

I would contact whoever made your shocks and bumps and ask their advice on pressures. Different companies have different reccomendations.
 
Good point. Thanks.

Another question. Do I need to have a strike plate or is allowing the air bump teflon tip to strike the spring perk acceptable?

Sorry for all the questions, but I'm out on a limb with this stuff and haven't been able to google-fu any write-ups about it.
 
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