Cab Isolators

KyleC4

Tech
Dec 30, 2016
449
31
28
Bay Area
Is there any point that a pack reaches where it’s not worth getting re arched? If the steel has just degraded to the point it won’t retain the new arch for very long?

something not frequently talked about (but mentioned in this thread) is torsion bars. What about replacing torsion bars due to sagging? I believe there was different bars even within the same year/model range, let alone different capacity levels. How do you pick the right ones? Or can they easily be re sprung?

i believe there is a code on the torsion bars and that’s what you’ll use to order new ones. I couldn’t imagine what would be involved for fixing torsion bars since they get twisted. Maybe some fancy cryo treatment like crankshafts.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
18,789
1,101
113
Phoenix Az
Well shit haha. It just didn’t seem right to me to sag that much but I guess it is. It does sit an inch higher I noticed too

you want what you are seeing. this is preload on the leaf pack that helps force the tire down into a hole as you drive. there is a happy medium between too much sag (leafs laying too much on the overload) and not enough (no droop travel like you show with the axle hanging in the air). too far each direction hurts ride quality in terms of stock leaf packs. you are in the green zone now.

Yes torsion is front only. I figure the same concept must apply, if the leafs can sag over time and start touching the overload at ride height, the torsions must be suffering from the same.
Only difference is you can adjust the torsion like you said, I don’t know if that “fixes” old worn out bars though.

yes, torsions for sure sag/loose spring rate over time. There is no fixing them just like you cant fix a coilspring this way. i mean, you can try to by taking the temper out of the spring, stretching or rotating the metal back to factory spec and then putting the temper back into the metal but i cant say ive ever seen them last long this way.

leafs get away with this more due to the limited travel they see. if you are constantly loading and unloading the springs from just truck weight to fully loaded weight, they wont last as long as 100% new would. Deaver will continually re-arch leafs in a race pack for race trucks until they break or they notice the spring rate will not hold in their testing. in a race truck, those leafs need to be refreshed and checked every other race but these guys are pulling 20" of travel from a pack too (shit load of flex from leafs)
 

roysbb

New member
May 9, 2021
3
0
1
Hello Guys, James, In an earlier post, it was mentioned that the leaf packs had not changed much between an 01 and 20.
Would a leaf pack from a 20 or 21 be a bolt in for my 2002 2500HD Duramax?

After reading this thread I measured mine and there is only 1 inch of gap between the overloads and the next spring up.
I tow a heavy boat and over the last few years the rear end has dropped quite a bit.

I have added a Timbren "Suspension Enhancement System" which replaced the bump stops on the frame.

I do have a camper shell and quite a bit of "survival gear" in the bed. Truck weight 6000 pounds at what I consider empty.

I have Bilstein shocks and can't complain about the ride though... Roy
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,238
174
63
Texas!!!
Leaf springs changed completely in 2011. They will not work in a 2010 or older frame.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
18,789
1,101
113
Phoenix Az
Hello Guys, James, In an earlier post, it was mentioned that the leaf packs had not changed much between an 01 and 20.
Would a leaf pack from a 20 or 21 be a bolt in for my 2002 2500HD Duramax?

After reading this thread I measured mine and there is only 1 inch of gap between the overloads and the next spring up.
I tow a heavy boat and over the last few years the rear end has dropped quite a bit.

I have added a Timbren "Suspension Enhancement System" which replaced the bump stops on the frame.

I do have a camper shell and quite a bit of "survival gear" in the bed. Truck weight 6000 pounds at what I consider empty.

I have Bilstein shocks and can't complain about the ride though... Roy

what i stated was that the overall design was no different, i then explain as far as how GM uses preload in the pack, distnace between overload and leaf pack and so on. I also then explain that the 01-10 are different from 11-19 and the 20 is different than all those. gotta make sure you read the whole post.

Im not sure what you are wanting if it rides good and hauls the stuff you want.
 

roysbb

New member
May 9, 2021
3
0
1
OK, I just added a helper leaf trying to get rid of the sag in the back. 67 bucks and a little labor, bought me about 3/4 inch in the rear.
I noticed a slight difference when I started driving it, the ride is acceptable, and there is no wheel hop on acceleration.

The Timbrens are adjusted with a slight gap - is this right?
As I figure it, I only have one other option, adding another 1/2 inch rubber spacer, which would mean zero gap, and some compression
as it sits.

I have not tried pulling the boat yet, but expect the added stiffness will be good insurance down the road.

A new leaf pack would be nice, but the price for GM stuff is a bit more than I want to spend right now.
Instead I am looking at a set of GM 20" x 8" alloy take-offs - 1.5 inch wider than my current 16" rims

Thanks again, Roy