What limits suspension down travel??

[mckee1710]

3” RC suspension lift on my 97 K1500 that just doesn’t quite ride right in my opinion. Feels like there’s not enough downtravel in the front end suspension linkage. I’ve removed the bump stops beneath the upper control arms, as I first assumed that was the issue. Helped, but didn’t completely fix the bottoming out/binding feeling when the front of the truck comes up after hitting any sizeable bump at speed. Also tried longer sway bar links but turns out the stock ones aren’t limiting the travel. I don’t believe it’s the CV axles or tie rods. Shocks are new and have plenty of travel.

So what the hell limits front end suspension down travel on these trucks other than the upper bump stops??

 

[jdla140]

Did you install the shock extensions? Maybe lower ball joint or control arm bushings or something, those 3" "lifts" are pretty much glorified torsion bar cranks, there are a lot of variables involved. Maybe post some pics of your suspension angles?

 

[mckee1710]

Did you install the shock extensions? Maybe lower ball joint or control arm bushings or something, those 3" "lifts" are pretty much glorified torsion bar cranks, there are a lot of variables involved. Maybe post some pics of your suspension angles?

The shock extension brackets are installed. With the wheels off and the truck on jack stands I’ve been trying to determine what prevents the whole assembly from traveling father down, but I can’t figure it out. I’ll post some pics of angles.

 

[454cid]

On my truck, with no lift, it's the upper control arms hitting frame, and the shocks. I think the anti-sway bar eventually matches the torsion bar at some point and prevents further movement down. The bushings themselves provide resistance to movement, too. When the control arms move, the rubber twists, it's not like a bushing in a motor or a door hinge, where the rotating part is free. The upper arm even when disconnected from the rest of the suspension will stick straight out. It doesn't flop down. I think the lower would do the same, but am not positive as I always have the torsion bar in.

 

[Schurkey]

I’ve removed the bump stops beneath the upper control arms,

Very bad idea.

I bought an ancient El Camino that someone lifted for no good reason I could think of. They pulled the bump stops out. Truck looked like a 4-wheel drive.

Now the upper control arms hit the frame when the wheels droop.

I had to replace both upper control arms--they were badly bent from slamming into the frame every time the wheels dropped into a pothole or other obstruction.

Of course, I scrapped the crazy-tall front and rear springs, so the ride height is more normal now.

Bump stops can be considered to be part of the suspension--properly done, they make for a rising-rate "spring" that only engages when the rest of the suspension is at the limit of it's travel.

As said, the bonded rubber bushings will also have "some" effect on the movement of the control arms. Excess movement--like a lifted vehicle--can tear the rubber. If you have rubber bushings (a) they're probably rotted and should be replaced, and (b) you should loosen the through-bolts with the vehicle at it's new "normal ride height" so the bushing can relax.

This is yet another benefit of Polyurethane bushings--they're not bonded, so they aren't stressed by excess movement of the control arm.

 

[mckee1710]

Now the upper control arms hit the frame when the wheels droop.

I had to replace both upper control arms--they were badly bent from slamming into the frame every time the wheels dropped into a pothole or other obstruction.

The “bump stops” I removed were bare frame just a rolled extension of the frame below the control arm mount, and the underside of the upper control arms were making contact on suspension down travel. Probably not enough to bend them over time, but enough to make the ride rough over any sizeable bump in the road.

 

[Chuck_13]

On my 98 K1500 Z71 the upper control arms hit the frame;makes for a very unpleasant ride.Cranked the torsion bars down,and that helped,but it still feels kinda 'pogo-ish' on rough roads.If there is an upper bump stop,I don't know where it is.