Teraflex 1.5" Kit Bump Stop Extensions?

[SoK66]

Right after I got my new '23 Willys I installed the TF 1.5" leveling kit. (The poor thing sat so nose down it looked like a female cat in heat.) At the same time I added TF's 2" shock extension kit and the Mopar 2" lift kit's longer control arms. I bumped the tire size to 285/70s (33s), set the tire size change with JSCAN and that's going to be it for this rig. It rides & handles very well, and since I have a (money pit) built JKUR for the trails, the JT is just going to be my daily driver.

HOWEVER, when I was installing the spacer kit something seemed screwy to me regarding the bump stop extensions they included with it. Once the leveling spacer is installed the length and travel of the front springs remains stock. With the spacer installed the only thing changed with respect to suspension travel is the shock upper mounting point, and the upper bump stop, which are raised 1.5" and 1.5” travel gets subtracted from extension. If you didn't install the bump stops the compression travel would still be the same as stock, no risk of over-compression, in fact you'd likely be leaving 1.5" of compression travel unused. All the spacer does is raise the frame, and effectively takes away 1.5" of shock extension. It has no effect on compression which would still be limited by the stock bump stop.

So, it looks like I raised the frame, lost 1.5" of shock extension, and with the bump stop I lost 1.5" of shock compression as well. The only reason I can think they added the bump stops was to prevent rub in case you installed 35s or 37s. Where am I going wrong?

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[chorky]

Post a picture.

By any chance does the bump stops included in your kit say 'progressive' on them anywhere, or does it say 'progressive' bump stops in the kit?

 

[dayusmc]

I believe the bump stops are in case you put bigger tires on it so rhey don't hit. I saw a list somewhere that said what size bump stop extensions for lift and tire combo.
You also do not want to bottom out the shocks. So you have to figure out max compression for the spring and make sure your shicks have a collapsed length less than that.

 

[jac04]

If shock extensions are added to stock shocks, you need to add the same amount of bump stop spacer to prevent the shocks from bottoming out. It's as simple as that.

 

[SoK66]

I believe the bump stops are in case you put bigger tires on it so rhey don't hit. I saw a list somewhere that said what size bump stop extensions for lift and tire combo.
You also do not want to bottom out the shocks. So you have to figure out max compression for the spring and make sure your shicks have a collapsed length less than that.

I scratched my head on this and concluded there is no effect whatsoever on the total stock suspension travel when the spacer kit is installed. The spacer raises the frame 1.5", which means it also raises the upper bump stop and the upper shock mount. That mean it has extended the shock rod, at the expense of full suspension extension (droop).

 

[jac04]

... That mean it has extended the shock rod, at the expense of full suspension extension (droop).

Not sure what you mean by "at the expense of". Adding a shock extension will increase full droop by the amount of the shock extension. The shocks control full droop. You need to add bump stop spacers to prevent the shocks from bottoming-out at full suspension compression (up travel).

 

[SoK66]

Not sure what you mean by "at the expense of". Adding a shock extension will increase full droop by the amount of the shock extension. The shocks control full droop. You need to add bump stop spacers to prevent the shocks from bottoming-out at full suspension compression (up travel).

Core t, that’s why I added the shock extension. My question was why add the bump stop extension to a spacer lift, where like on this one the shock isn’t changed and the total travel remains as is, but with a loss of droop created by the thickness of the spacer. The spacer raises the upper spring bucket/frame which takes with it the upper bump stop and the upper shock mount. I added the shock extension to restore the drop that was taken away by the spacer.

 

[Escape.idiocracy]

I vote you flex it out and really see what’s what…. I went with 1.5” springs up front, Bilstein 5100’s for a 2.5” and 37’s and landed with 1/2” bump pad extension (on the axle- with the bump joust removed, to clear…) left me with 3/4” shock remaining. This is for a Diesel… which does have 1-3/8” longer bump joust tubes…

my point is, when you start piecing/frankenstining the variables are all over. Just flex and check clearances. ?

 

[jac04]

Core t, that’s why I added the shock extension. My question was why add the bump stop extension to a spacer lift, where like on this one the shock isn’t changed and the total travel remains as is, but with a loss of droop created by the thickness of the spacer. The spacer raises the upper spring bucket/frame which takes with it the upper bump stop and the upper shock mount. I added the shock extension to restore the drop that was taken away by the spacer.

When you add spring spacers by themselves, it does not change full droop or full compression locations of the suspension. Those 2 points are still in exactly the same place, you have simply raised the ride height of the vehicle. Full droop is still controlled by maximum shock length (which you have not changed) and full compression (uptravel) is still controlled by the bump stops (which are still in the same location on the frame).

Now, if you then add shock extensions, full droop is changed by the amount of the shock extension because it lengthens the total extended length of the shock. The problem is full compression. The shock extensions also increase the collapsed length of the shocks, which will typically cause the shocks to be fully collapsed before the bump stops limit uptravel. You never want the shocks to be fully collapsed and limit uptravel because this will damage the shocks.

So, in order to keep the shocks from bottoming out before the bump stops hit, you add bump stop spacers that are the same thickness as the shock extensions.

 

[SoK66]

I got all that. But the kit didn't come with shock extensions (that's why I added them), it came with bump stop extensions that don't appear to be needed for any reason other than perhaps you're going to add too large a tire for the available clearance. If Jeep designed the suspension correctly at full compression the shocks wouldn't be bottomed out. Adding spacers would have no effect on the suspension's compression, it would still compress fully and the shocks wouldn't bottom out. The shock would simply be starting its compression cycle from a point 1.5" lower than it would have without the spacer. But that 1.5" has to come from somewhere on the shock travel, so it has to come at the expense of droop.

Say a shock has 8" of total travel and at rest sits at the middle of the stroke, 4". It can compress 4" and it can extend 4". Add a 1" spacer and the shocks upper mounting point is raised 1', leaving 5" of the rod exposed for compression, and only 3" left for extension. Add a 1" bump stop extension to the mix, the suspension can only compress 4" again, leaving 1" of the shock's compression travel unused, and it again can only extend 3" from rest. The only fix is to add a 1" shock extension, which didn't come with the kit.

 

[Zachanadandy]

I got all that. But the kit didn't come with shock extensions (that's why I added them), it came with bump stop extensions that don't appear to be needed for any reason other than perhaps you're going to add too large a tire for the available clearance. If Jeep designed the suspension correctly at full compression the shocks wouldn't be bottomed out. Adding spacers would have no effect on the suspension's compression, it would still compress fully and the shocks wouldn't bottom out. The shock would simply be starting its compression cycle from a point 1.5" lower than it would have without the spacer. But that 1.5" has to come from somewhere on the shock travel, so it has to come at the expense of droop.

Say a shock has 8" of total travel and at rest sits at the middle of the stroke, 4". It can compress 4" and it can extend 4". Add a 1" spacer and the shocks upper mounting point is raised 1', leaving 5" of the rod exposed for compression, and only 3" left for extension. Add a 1" bump stop extension to the mix, the suspension can only compress 4" again, leaving 1" of the shock's compression travel unused, and it again can only extend 3" from rest. The only fix is to add a 1" shock extension, which didn't come with the kit.

Obviously these cheap leveling kits are incomplete. You are correct in your conclusion that you are losing suspension up travel by adding bump stops and not increasing shock length. Most people want the cheap leveling kit to run bigger tires and thus the included bump stops. It's the same reason the JLs with xr package get longer bump stops. If you were trying to get the most out of your Jeep, you'd set your bump stops to keep whatever tire size you run from rubbing and from there measure the maximum compressed length shock you could run. Buy the longest shock that you can fit in that space and you get maximum suspension up and down travel. Most won't go anywhere near this level of detail and just run whatever off the shelf shock says "for 1-3 inch lift" never knowing that they probably could have fit a larger shock with their bump stops. The JL sport/Sahara models only have 5" of shock travel, running extensions to save such a limiting shock is a waste of time. Even the rubicon shocks only have 7.5" of travel. With the bump stop extensions you can easily fit a shock with 10+" of travel. The only stock shocks worth trying to save are the mojave bypass shocks in my opinion.

 

[jac04]

Ahhhh, now I see how you are looking at this. To me, "loss of droop" means the a change in the point of full suspension droop, but to you it is a change in shock downtravel from normal ride height to full shock extension.

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