I've got the green keys installed, which raised the fronts approx. 2.5" from stock. I'd like to upgrade my shocks to either Bilsteins or Rancho 9000X's. I'm aware that the front suspension lost some rebound-travel with the green keys. My question is, is it the shocks that are being maxed out? If so, are there any foreseeable problems with ordering longer shocks? From what I've seen I can either order stock-length shocks, or 4" longer ones. Nothing in between.


Rancho says their stock fitting shocks are good for up to 2" of lift, but the stock ones aren't topped out either until you unload the suspension.

Camstyn I did a little research on this a month ago and here is what I came up with.

OEM Front RS99288 compressed 12.750 extended 15.250 travel 2.500

OEM Rear RS99274 compressed 16.375 extended 26.250 travel 9.875

For anyone running 2” torsion keys up front these shocks should work:

Front RS99283 compressed 13.000 extended 19.250 travel 6.250

As you can see the compressed length is pretty dame close but the extended length would actually allow you to run a 4" lift. The lower bushing on the front shocks are a slightly different size but Rancho should provide a sleve kit to make it fit. Double check with your local shop before ordering.
Edited by: y2kboti

I think you can order longer shocks, but I don't know that there's a point. You are still limited to the factory set limits (jounce bumpers) on upward and downward travel. The factory replacement shocks will still not be your limiting factor, unless you modify your limits, which a true lift will do. Good luck, either way.

y2kboti, how are you measuring shock length? I measured my shocks from the center of the lower hole to the top of the dust cover and got 15.0".


Thanx

I agree with Joe E. You are not going to gain anything by installing longer shocks. There are hard physical upper and lower mechanical stops on the truck suspension. The control arms can only drop a few inches before resting on the lower stops and can only rise a few inches before contacting the upper stops. Within the confines of the upper and lower stops it what is called wheel travel. The stock shock is supposed to support the factory designed wheel travel.


On the stock suspension, if all we ever do is raise and lower the truck via the torsion bars, the total wheel travel remains unchanged. The only thing we're changing is the resting position of the wheel in relation to the wheel travel.


The example I used on a different post was that if our trucks are designed with 14 inches of total wheel travel (just an example, not factual) and the factory setting allows for 9 inches of lower wheel travel and 5 inches of upper wheel travel, if we raise the front of the truck 2 inches, the lower wheel travel has been reduced by 2 inches to 7 inches but the upper wheel has been increased by 2 inches to 7 inches. Again, the total wheel travel is unchanged. The only thing changing is the resting state of the wheel in relation to the total wheel travel.


Dale

Thanks, lots of good info here. I guess what got me wondering is that I remember somebody else posting that they had broken/torn off an upper shock mount from topping out the front end in rough terrain after having the green keys installed. Perhaps it wasn't related, but I thought that longer shocks would keep something like that from happening.

According to the Helms manual, the only downward limiting factor for the front suspension are the shocks. They are what stops the suspension at the lower end. If you go to longer shocks you could damage some suspension components by over-travel.

I'd be shocked (no pun), if the shocks were the limiting factor. That is a horrible design, if it were true, as most shocks are not made to support the weight/impact of the suspension & wheels on droop. Additionally, there have been discussions here on the upper or lower bumpstops (can't recall) which limit the downward travel.

There is a downward travel stop on the upper control arm. Also, on the 03 GMC, there is a sticker on the crossbeam between the torsion bars that offers a warning about adjusting the torsion bars. No one, including myself, has ever mentioned that before.


From what I know about front ends, I don't see the shock being a limiter on this truck. One could prove this by removing the top nut on one of the shocks and then jack up the front end, letting the tires hang down. If the shock is a limiter is would be easy to tell by comparing the two sides.


On some front ends, as on several rear ends of older and new cars, the shocks are a limiter. The Ford Twin I-Beam comes to mind as being one such design.


Dale

Just repeating what the helms manual states. It informs you to be extra careful whenever you replace a front shock that you support the lower arm when the front is raised up to avoid damage. It also states that you should replace the shock with one of equivalent support capability.

y2kboti, how are you measuring shock length?
Jeli I did not do any physical measuring. All of those numbers were obtained off of Rancho’s website. I have recommended those shocks to other HD owners who either cranked their torsion bars or replaced the keys and so far everything has worked out.Edited by: y2kboti

While I tend to agree with what everyone is saying -- that the suspension travel is limited, regardless of the torsion bar keys used -- I have a practical example that contradicts this argument.

At my local 4wd center one of the guys who works there installed the greenies in his 02 2500HD longbed regular cab. Within 2 weeks he had physically damaged his left front shock. He switched to Rancho 9000's and hasn't had a single problem since then.

Long before I installed the keys I swapped to the 9000's -- which I would have done whether or not I installed the new keys -- and haven't had any problems either. Coincidence? Who knows...

Just my 02 cents...