Need bumpstop advice after lift: '20 JTR, 4.5" 38s

[Rubiko]

Hey all,

Looking for some advice on how much bump stops I really need, and more generally what the point of bumpstops are.

2020 JT Rubicon
4.5" Teraflex lift and 38" Toyo MTs.
high clearance steel fenders (roughly 5 more inches of clearance all around).

For the rear, the instructions recommend about 4 inches of bumpstops. I slapped on 2.5", and still have plenty of space at full tuck using a forklift.

For the front I'm also running less than the required bumpstops (about 1" if I recall correctly). Also no rubbing even at full tuck.


My questions are:

Do I just remove as much bumpstops as I can without any rubbing or is there a secondary reason for them?

In the front, I've got TF Speedbumps, which are meant to compress, yet they only touch the lower bumpstop on full tuck. Do I need to adjust my front bumpstops?


Any tips appreciated!

Attached some pics to illustrate:


Rear bumpstops at ride height:

Not full tuck, only lifted only rear bumpstops are touching:

Front bumpstops at ride height:

Front at full tuck

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[Rubiko]

Front at full tuck:

 

[kevman65]

The bump stops are to keep your shocks from slamming all the way compressed and damaging them.

Has nothing to do with tuck and rubbing, although that is a side affect.

The people who put together the lift kits have done the math and engineering and list the bump stop height to prevent damage.

 

[CrazyCooter]

Shock travel, coil bind, and any other clearance issues are what you are bumping for.

You might not need anything in the rear depending on coil bind and remaining shock travel.

 

[Escape.idiocracy]

Front at full tuck:

I have never seen anyone measure ground to top of tire when flexing…. Usually it’s ground to bottom of the tire. ??

Op- there are a lot of variables when setting bump stops. Tires- wheels- suspension- to include variations with springs, and shocks.

At a minimum- pull the springs on the front axle. Re-attach your shocks no springs…. You will want to droop one side and stuff the opposing side and check for clearances. Then stuff the entire axle up.

You do not want your shocks either together or one side to be the stopping factor for how far the axle can be stuffed up.
Usually leave 1/4” shock shaft if you are using hydro bump stops.
If you are using factory bump stops (or similar) personally I pull them off! (For clearance checking…) when the metal of the joust mount touches your bump stop pad this simulates full max compression of the factory jousts…. (With a little safety factor). Again leave 1/4” shock shaft minimum showing if the rest of your clearances are fine.

Once you have checked everything, you can determine the height of your bump stops.
I like to use hokey pucks while I’m monkeying with setting everything….. then once it’s finally blessed and not getting touched I order 3” diameter aluminum and make my final pump stop height with that.
(This was pre economic crash- so I haven’t looked to see what aluminums at. Usually I can get 12” for around $50…. Today it might be close to $300… )
Over compressing springs is another issue- each manufacturer is going to have a full extended and full compressed coil length- so you are going to have to reach out.

some times the coils will bend when compressed to a certain point. This can cause the spring to catch on what could be several things…..- sometimes this can be helped with spring wedges….. sometimes bump needs to be increased.


bump stops are important…. A lot of folks over look this and are either missing out on a couple inches of “would be nice” up travel…. Or worse! Push an axle/truss into the oil pan.

 

[CrazyCooter]

Another trick I use when forklift testing flex is to leave the front bar connected while testing to force more rear stuff. Then disconnect for front testing.

 

[Escape.idiocracy]

The people who put together the lift kits have done the math and engineering and list the bump stop height to prevent damage.

This isn’t true at all. A lot of lifts are sold without shocks- or several shock options. Most manufacturers will offer “recommendations” based on tire size. But 90+% of the time this is way on the precautionary side to keep them from being liable.

if an individual isn’t informed or capable enough to check for proper bump height that’s fine. Lean on the manufacturers recommendation. OR find a reputable dedicated off road shop. (NOT necessarily a big box chain- no offense just their mechanics understanding and knowledge is a little bit like Russian roulette…)
Find a small shop and have them checks your clearance.


quite honestly…. This is a HUGE step that should be done before any significant shock purchase is made….. (again which is why some companies do not offer shocks with all of their kits…)



My last Jeep- “2.5”” lift kit…. I was running shocks that were for 4.5” lift kits… synergy shock brackets were awesome- could help dial in how much I wanted the shock to hang down and still get away with as little bump stop pads as possible. 37” tires, cut fenders and really long shocks…. Allowed for more than 40” under any given tire while still keeping a low center of gravity. May or may not have been like driving a boat home when it’s windy out…… but was badass on the rocks.

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