05 TB Front coil spring life?

dla442

Original poster
Member
Mar 31, 2012
249
grand rapids, mi
I have about 120k on the 05TB. I am on the 3rd set of Bilsteins now and they only seems to last about 40k before they loose their perforamnce. I am curious about springs and the lifespan. Truck sits fine but lately going over modrate bumps int he michigna roads, I have noticed it sounds like running over a log and bottoming out. All new ball joints ties rods, links etc. Only thing is springs or perhaps control arms giving way? I am going to replace the bilsteins again(for free) but do not know if the springs have exhausted their life. The steering is tight and performs well on highway, but when the bump comes it is terrible sounding!
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Springs do sag, and you can measure the distance from your fender opening to the ground and compare it to others. But if you're not offroading, most owners find deterioration in the upper shock mounts before they swap their springs. What do yours look like, and have you looked closely at the upper shock mounting nut and the washer on top of the rubber in the mount?
 

dla442

Original poster
Member
Mar 31, 2012
249
grand rapids, mi
Roadie,

I have not inspected shock mounts since 40k ago. I can only guess that with 120k on them they are getting worn out and was going to replace them anyway when I do the Bilstein replacement. The front height seems to be fine....I guess? If the spring settles will this effect the range of motion where a larger bump in road would hit the bump stop?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
The full distance range of motion from compressed to extended is set by the shock. A weak spring will lower the resting height, so there's less distance to go before compression will hit the bump stop, yes. A stiffer spring (available in many - but not all - stiffnesses from GM, and also from Moog and I think other vendors) can bring the resting height up. Offroaders do that all the time to get lift.
 

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