Bump stop question (pic's added)

screamin reel · Oct 5, 2010

With my new 3.5" lift I have 11.6" of travel from the frame to the axle. My shocks have 6.6" of travel. The tallest bump stop sold by vendors is 4.6" which would mean my shocks would bottom out 2" before the stops would contact the axle. This does not make sense to me. I understand the whole articulation thing but on a straight up bump, my shocks will make contact before the stops do.

Do most people just weld in some square tubing to make up the difference ?

Pic 1 - Total travel on rear 11 1/2"
Pic 2 - Downward travel remaining on shock 6 1/2"
Pic 3 - Length of shock cylinder rear 12"
Pic 4 - Downward travel remaining front shock 6"
Pic 5 - Length of shock cylinder front 12"
Pic 6 - Total travel on front axle 10 1/2"

As it sits now I would need a minimum 5" bumpstop before contact which does not leave any room for compression.

On the front I would need minimum of 4 1/2" again not leaving anything for compression of the stop.

All shock mounts are in the stock locations.

Action · Oct 5, 2010

Bumpstops

Sometimes you just have to do what it takes!
Jack

broncnaz · Oct 5, 2010

Sounds like you have the wrong shocks. I believe stock shocks have 7in of travel so shocks for a 3.5in lift should have at least 10in of travel. Might want to check into that because your more likely to drop a tire into a hole and have the shock be limiting your downward flex.
Also your shocks may not be centered in there travel at ride height. take it out and get one tire in a deep hole so the suspension flexes see how much shock travel you have left?
You'd have to hit a very big bump very hard to bottom the suspension straight up. Are you planning on jumping it?
but yes otherwise a lot of people just use square tubing to extend there bumpstops the needed amount.

screamin reel · Oct 5, 2010

I would hope that when someone orders a complete suspension from one of the vendors on this site they would send the proper shocks to go with the amount of lift.

broncnaz, I understand what you are saying and I will snap a few pics in the morning.

Thanks

DirtDonk · Oct 6, 2010

Isn't the accepted stock distance between the front axle and the frame 7"? If so, and this is the front you meant, then you've actually achieved 4.6" of lift as it sits now.
That doesn't necessarily help your too-long of a shock issue, but it's one more aspect to look into while you're figuring things out.

I say the shocks are "too long" because, if I'm reading you correctly, you're saying that, as they sit now, you have that 6.6 inches of downward travel available. Meaning that, if they're mid-way into their travel, the shocks have roughly 13 to 14 inches of overall travel.
Is that correct? Or did I mis-read what you were saying?

Are you running aftermarket shock mounts, or stock still?

The suspension you got may put more emphasis on droop, rather than compression. If so, then that might explain the longer-than-expected shock size. Which might just be too much shock for stock type mounts. If they're non-stock mounts, then it sounds like they're just plain too long.
Still though, you'd think they'd mention that, if you wanted to make sure your bumpstops hit first, that you would either have to modify the mounts to get the available bumpstops to work, or supply shorter shocks.
Most vendors probably don't think much about the stops, but BC, being the racing persuasion, like they are, would have some experience in this department.
Let us know what they say.

Paul

fabster54 · Oct 6, 2010

i dont think with the bind you would encounter when flexing that this is to far off.. i say call the vendor and see why they sent you these shocks.. they could probably explain it better as they put the package together this way for a reason... or they didnt and sent you the wrong shocks

bronko69er · Oct 6, 2010

Are we also forgetting that 11.6" (- bump stop height) of vertical axle travel doesn't equate to shock compression due to the angle? For the sake of argument lets say total travel with a bump stop is 8", the shock will not compress 8" if the axle does. I say its time to dust off that trig hat and throw an angle finder on the shock. Also during compression, the axle rotates rearward further decreasing the compression of the shock. It's quite posible that your current shock is pretty close to adequate. But this only accounts for the rear.

screamin reel · Oct 6, 2010

bronko69er said:
Are we also forgetting that 11.6" (- bump stop height) of vertical axle travel doesn't equate to shock compression due to the angle? For the sake of argument lets say total travel with a bump stop is 8", the shock will not compress 8" if the axle does. I say its time to dust off that trig hat and throw an angle finder on the shock. Also during compression, the axle rotates rearward further decreasing the compression of the shock. It's quite posible that your current shock is pretty close to adequate. But this only accounts for the rear.

bronko69er.

Makes sense to me although my trig hat is all but empty ! Should have paid more attention in school I guess.

So if I take the dummy approach, I could compress the rear suspension to see how far it travels before the shock bottoms out. This should give me a measurement for the bump stop height correct ?
As you say though, this method would work for the rear but not for the front.

Thanks:-[

bronko69er · Oct 6, 2010

If you can get an angle measurement of the shock I can do it for you.

screamin reel · Oct 6, 2010

Rear shock is 24 degrees.

Thanks again

Broncobowsher · Oct 6, 2010

The angle will change as the suspension cycles. Makes the math a bit harder.
I take the shocks off, cross it up, crawl under and measure the distance. That will be the compressed length.

bronko69er · Oct 6, 2010

If i did the math right:

If the shock shrinks by 6.6" the the vertical travel is 7.25". 11.6" travel minus 4.6" bump stops = 7". So I'd say your shocks are darn close. This is why most people that have lifts and plan on squeeking out the full range of travel opt for new shock mounts allowing for longer schocks.

bronko69er · Oct 6, 2010

It doesnt appear that the angle will change a sizeable amount. If you draw a line from the front spring bolt to the lower shock mount, the shock is virtually perpendicular to this line. So as the spring follows is arc the shock will stay relatively linear. as the spring flattens out it will roll the axle rearward, decreasing the shock's compressed length.

Bronchole · Oct 6, 2010

I think you missied a step in your lift installation. The step befor you go out and buy shocks should have been to install bump stops. I didn't see any on your rear suspension. YOU NEED BUMP STOPS on your rear suspension. Leaf springs (at least the ones in the back of lifted EB's) do not like to be reverse arced. They don't even really like being made to go 100% of the way flat. They will sag allot faster if the bump stops are set to flat or reverse arc on full compression. In my experience it doesn't take long to break them if they are allowed to go to reverse arc either.

Once you have the rear bump stops set (my guess is that the bump stops will need to drop the stock bump stops about the same distance you lifted the rig) you will notice that you have signifcantly reduced the available up travel.

You should also jack the rear end up off the ground and see if the shock are topping out, or how close they are to topping out. You may need limiting straps to keep them from topping out.

The front coils may be self limiting (coil bind) and since the shocks are back a bit from the axle centerline that actual wheel travel is a bit longer than the shock travel. Again figure out what you are going to do for upper travel limit, stretch it out and see how close to topping out the shock you are and go from there.

I know it is a common issue on 5.5" lifts that the stock shock mountings will not allow for full travel even with the bump stops adjusted down. I am unfamilliar with less that 5.5" lifts and their issues though.

screamin reel · Oct 6, 2010

Bronchole said:
I think you missied a step in your lift installation. The step befor you go out and buy shocks should have been to install bump stops. I didn't see any on your rear suspension. YOU NEED BUMP STOPS on your rear suspension.

Explained in post #1

Bump stop question (pic's added)

screamin reel

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