Front suspension bump stops

[2fast2]

Newbie here.
I was under the truck changing the transmission filter yesterday (dealer said it didn't need changing until 25K -- idiot) and I noticed the front lower control arms are apparently in contact with the yellow bump stops with the truck flat on the ground. Is this how they designed this thing? It seems to ride OK, although I'm considering the Bilsteins for better ride control.
Thanks,
Jim
2003 Silverado 2500HD D/A CC, 5900 miles.

[ 11-23-2003, 04:40 AM: Message edited by: 2fast2 ]

[10851]

2Fast2, I have an 03 GMC 4X4 2500. My yellow bumpers are touching (on level ground). I have a friend with a crew cab 03 4X4 that adjusted the torsion bars. After he made this adjustment the bumpers are not touching. You will love the Bilsteins!! The ride will be slightly firmer, however the over all handeling (loaded and unloaded) will be a vast improvement! Good luck! smile.gif

[chipper]

On my 2001 GMC Ext cab, when I adjusted the torsion bars to factory specs, I have about 1/4" clearance now.

[Turbo Al]

One of the guys at work just bought a 2003 gas pot and his bump stops are touching as well, so it's not the weight of the diesel engine doing it.

[2fast2]

Guess that is the way GM intended it. Very strange that an integral part of the suspension would be a rubber bumper. Since this is at the inner end of the lower control arm, there'd actually be a fair amount of wheel movement to produce a small compression at the bump stop, but still, it makes me wonder.
Jim

[8.1PWR]

My truck rides on the bump stops also. asked the dealer about it, they said it was normal. I looked at half a dozen 2500HD's and they all sat on the stops.
Does turning the torsion bars up so it does not ride on the bumpers give you a harsher ride? I know it limits your downward wheel travel. I would like to turn my bars up about 1 inch so the truck will sit level with my camper on it.

[VFRRider]

I turned my bars up to add clearance for my H2's. Yes it is a firmer ride. I'm not picky tho, it doesn't bother me a bit.

[Kennedy]

These aren't rubber jounce bumpers like the old days, rather a cushion that is apparently an integral part of the suspension.

Air lift has a cellular type of bumper like this for helping the eraly IFS trucks hold up a snow plow...

[Buck]

Originally posted by kennedy:
Air lift has a cellular type of bumper like this for helping the eraly IFS trucks hold up a snow plow... Ya, what gives, I called air lift and they told me they are NOT :( working on a product for the front of the HD trucks. Kind of funny cuz they have them for the 1500 series. Looked like a nice product
smile.gif air cell (http://www.airliftcompany.com/aircell.htm)

[JimWilson]

Those aren't bump stops at all, they're dampers.

Torsion bar suspensions can't be programmed to have progressive rates of compression, like coil and leaf spring suspensions can. Progressive damping is a very good thing for ride quality, but since torsion bars can't be made that way GM added those dampers.

Basically, they help "smooth out" initially suspension deflection and make it so the front end has what seems to be the same type of progressive rate of travel that a coil/leaf suspension in the front would have.

If your truck is not riding on them your ride is affected, as is the case when you crank your torsion bar keys. Some/all of the progressive rate affect (depending upon how far you've cranked your tbars) is mitigated if the dampers are not in contact with the lower control arms.

When looking for shocks make sure the Rancho 9000x is on your list. These are an excellent shock, which comes with a 9 way adjuster as standard. This is a tremendous advantage that affords you the ability to custom tailor the ride/handling to your exact specifications.

[jobbie]

another newbie here.
i work for gm truck here in warren and have and am worked on the light duty truck suspensions.
i also hate to say it but the 3500 trucks are considered light duty.
the "bump stops" as you guy's are calling them are called by the gm engineers as auxiliary springs. the front aux. springs were designed to
aid the torsion bars or coil springs depending on suspension design and NOT as a last stop limiter to the suspension travel. also regarding the green keys(15592573 pn.) that everybody is talking about. gm has another one that MAY possibly raise the truck higher but MAY cause a severe bind at the front cv joint? they have a white paint dot on them and carry the part number of 15592574 they may also raise the truck an extra inch over the green keys but be aware that going that far MAY DAMAGE the front drive shafts.
p.s. this is a great site.

[Kennedy]

Good info jobbie!

Personally, I see no need to go beyond what the stock keys will allow as once you are up that high, the bump steer is TERRIBLE! Just watch as you pick one up how they toe in just like the trucks do at the pulling track or here:

http://www.kennedydiesel.com/photogal/images/John%20Kennady%20copy2.jpg

[Buck]

That a lot of toe in :eek: :eek: Didn't you get realigned JK. Sure made a difference when I got realigned ;)

[Kennedy]

I had it alingned after cranking it up. When I get off the power, it will relax, but until then, it stays "humped up" as I used 4wd for launch, and it will not disengage until pedal is relaxed...

That and the front end (idler & pitman?) is pretty much shot...