U-bolt tourqe - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bringit · 07-06-2005, 10:17 AM

I just did a Pro Comp 4" lift and I need to know what to tourqe the U-bolts to on the front springs.The instructions said 60 foot pounds

I know it needs to be alot tighter than that.

ryan68 · 07-06-2005, 10:41 AM

If they are 5/8" u-bolts, they should be torqued to about 110-125 ftlbs.

bringit · 07-06-2005, 11:00 AM

Thats what I thought because I did the rear to that (a month before). But my question now is who is the moron at pro comp that made that mistake? That could be dangrous to those that wouldnt second guess the instructions.

ryan68 · 07-06-2005, 01:11 PM

Yeah, something wasn't right there. Just be sure to re-torque them after 100 miles and flex the suspension a little before you do.

Mudder · 07-06-2005, 02:33 PM

I always tightened them as tight as I could get them. And like they say, retighten after driving a few miles.

4x4Poet · 07-07-2005, 03:23 AM

Exactly how tall are the nuts ProComp provided for the u-bolts? And are they nyloks?

bringit · 07-07-2005, 06:50 AM

They said they were nylocks in the instructions, and Im guessing here but there about 1 1/2" tall.

4x4Poet · 07-08-2005, 06:55 AM

Wow! That's some tall nuts.

Did I just say that?

Most tall u-bolt nuts I've seen are 3/4" tall. 3/4" tall nuts on fine thread 3/8", 1/2", and 5/8" u-bolts can take a lot of torque. Around 80 ft-lbs for the 3/8" bolts and over 100ft-lbs for the larger bolts. With tall nuts, it sounds even dumber that ProComp recommended such a low torque setting. I asked about the nuts' height and if they're nyloks because I've seen some lift kit makers supply 1/2 tall nylok nuts that don't have enough thread to allow for high torque settings. In fact, I think they supply the nyloks in an effort to keep bonehead DIYers from having the u-bolt nuts loosen and cause road failures.

My local spring shop strongly recommends using tall, grade 8 nuts with thick grade 8 washers and no lock washers. Just put a little oil on the threads to stop heat buildup during tightening and to get a sure torque setting.

Can you post a pic of the u-bolt nuts with a frame of reference? One and one half inch tall nuts doesn't sound right, IMO.

07-06-2005, 10:17 AM	#1
bringit Registered User Join Date: Apr 2004 Location: Edmond, Oklahoma Posts: 105	U-bolt tourqe I just did a Pro Comp 4" lift and I need to know what to tourqe the U-bolts to on the front springs.The instructions said 60 foot pounds I know it needs to be alot tighter than that. __________________ 85 chevy K10 350 crate, headman headers, street avenger carb, accel distrib , rebuilt 700r4, on 33" Super Swamper TSL's, 4 inch Pro Comp lift, shocks, and steel braided brake lines.

07-06-2005, 10:41 AM	#2
ryan68 Certified Chevy Man Join Date: Jan 2000 Location: Tucson, Arizona, United States Posts: 2,053	If they are 5/8" u-bolts, they should be torqued to about 110-125 ftlbs. __________________ 68 Chevy CST (327,TH400) 3/5 drop lots of fun stuff 71 Suburban 4x4 (350,TH350) 7" lift 37's, D44/14 bolt and other sorts of goodies, lockers front and rear, flexes 40", 895 RTI score Check out my web site!!! http://www.geocities.com/cst68chevy/

07-06-2005, 11:00 AM	#3
bringit Registered User Join Date: Apr 2004 Location: Edmond, Oklahoma Posts: 105	Thats what I thought because I did the rear to that (a month before). But my question now is who is the moron at pro comp that made that mistake? That could be dangrous to those that wouldnt second guess the instructions. __________________ 85 chevy K10 350 crate, headman headers, street avenger carb, accel distrib , rebuilt 700r4, on 33" Super Swamper TSL's, 4 inch Pro Comp lift, shocks, and steel braided brake lines.

07-06-2005, 01:11 PM	#4
ryan68 Certified Chevy Man Join Date: Jan 2000 Location: Tucson, Arizona, United States Posts: 2,053	Yeah, something wasn't right there. Just be sure to re-torque them after 100 miles and flex the suspension a little before you do. __________________ 68 Chevy CST (327,TH400) 3/5 drop lots of fun stuff 71 Suburban 4x4 (350,TH350) 7" lift 37's, D44/14 bolt and other sorts of goodies, lockers front and rear, flexes 40", 895 RTI score Check out my web site!!! http://www.geocities.com/cst68chevy/

07-07-2005, 03:23 AM	#6
4x4Poet Registered User Join Date: Nov 2004 Location: "Under Montana skies." Posts: 1,836	Exactly how tall are the nuts ProComp provided for the u-bolts? And are they nyloks? __________________ '71 GMC K20 Suburban, '71 GMC K10 Suburban, '72 Chevy C10 CST Suburban, '72 Chevy K20 clunker pickup. Last edited by 4x4Poet; 07-07-2005 at 03:24 AM.

07-06-2005, 02:33 PM	#5
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	I always tightened them as tight as I could get them. And like they say, retighten after driving a few miles.

07-07-2005, 06:50 AM	#7
bringit Registered User Join Date: Apr 2004 Location: Edmond, Oklahoma Posts: 105	They said they were nylocks in the instructions, and Im guessing here but there about 1 1/2" tall. __________________ 85 chevy K10 350 crate, headman headers, street avenger carb, accel distrib , rebuilt 700r4, on 33" Super Swamper TSL's, 4 inch Pro Comp lift, shocks, and steel braided brake lines.

07-08-2005, 06:55 AM	#8
4x4Poet Registered User Join Date: Nov 2004 Location: "Under Montana skies." Posts: 1,836	Wow! That's some tall nuts. Did I just say that? Most tall u-bolt nuts I've seen are 3/4" tall. 3/4" tall nuts on fine thread 3/8", 1/2", and 5/8" u-bolts can take a lot of torque. Around 80 ft-lbs for the 3/8" bolts and over 100ft-lbs for the larger bolts. With tall nuts, it sounds even dumber that ProComp recommended such a low torque setting. I asked about the nuts' height and if they're nyloks because I've seen some lift kit makers supply 1/2 tall nylok nuts that don't have enough thread to allow for high torque settings. In fact, I think they supply the nyloks in an effort to keep bonehead DIYers from having the u-bolt nuts loosen and cause road failures. My local spring shop strongly recommends using tall, grade 8 nuts with thick grade 8 washers and no lock washers. Just put a little oil on the threads to stop heat buildup during tightening and to get a sure torque setting. Can you post a pic of the u-bolt nuts with a frame of reference? One and one half inch tall nuts doesn't sound right, IMO. __________________ '71 GMC K20 Suburban, '71 GMC K10 Suburban, '72 Chevy C10 CST Suburban, '72 Chevy K20 clunker pickup.

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