4x4 Front LeafSpring U-Bolt Question ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

54blackhornet · 01-09-2014, 01:55 PM

I need to remove the front axel from my 71 K-10. What size is the gigantic nut holding the U Bolts on ? And can I reuse them or should you replace all the original hardware when reinstalling the axel ? Thanks

DirtyLarry · 01-09-2014, 02:52 PM

It is always a good practice to replace u-bolts when ever you remove them, especially if they are the originals. Most cities have a driveline shop that can build them for you or you can buy a set through ORD. ORD does have very nice u-bolts whereas some of the u-bolts available from other suppliers are cheesy. Basically you want a u-bolt that has the long nut and hardened washer. Do not accept any u-bolts that use nylon lock nuts. Those nuts are very soft and often strip before you even reach the torque spec.

Oh, if you are asking what size socket to remove the nut, I believe it is a 7/8. The rod thread diameter is probably 1/2" to maybe 9/16" on a half ton.

54blackhornet · 01-09-2014, 03:54 PM

Thanks for the information ! I am going to need a bigger wrench I guess ? I heard from others to use new hardware but an old mechanic friend said that is B&@Sh#T ! Just check for cracks, clean up the threads, repaint with rust oleum and get the torque correct ! I spoke to ATS Spring and they suggest installing all new UBolts and hardware, they stretch during torque procedure.

73chevy95 · 01-09-2014, 04:42 PM

Ruffstuff makes some pretty good u-bolts for cheap, I agree to replace em like dirtylarry said, better safe than sorry!

LONGHAIR · 01-09-2014, 09:02 PM

Cut them off and get new ones, but be aware that there is significant pressure there. It will "pop" when you cut them.....torch or cut-off wheel works great. Put your effort into things that are worthy, unscrewing rusted u-bolts just plain sucks, even with an impact. They just rattle around and the power is wasted.
Like Larry said, you want the "long" nuts and hardened washers....a little lube on the threads is good too.

cableguy0 · 01-09-2014, 09:17 PM

U bolts stretch a ton when they are torqued in the first place. They need to be replaced. Also do not use an impact gun to tighten the new bolts. They will not be tight enough because they are springy the gun will just make them bounce.

54blackhornet · 01-10-2014, 01:21 PM

Thanks for the insight about the U-Bolts, I took a shot at removing one with a wrench and noticed that the threads where all screwed up at the bottom of each bolt. I will use the torch method this weekend. Would it be better to drop the leafs out from the frame first ?

Rubble · 01-10-2014, 08:55 PM

If all your doing is swapping axles,just use a torch or zip wheel & cut the u bolts.Dropping the spring out is a lot of extra work.

**kwmech** · 01-11-2014, 01:01 PM

If they are factory bolts, then they are 5/8 requiring a 15/16 socket. In an ideal world they should be replaced as the bolts are a rolled thread and the nuts are a cut thread, thus when you torque them correctly the threads interfere somewhat locking them in place. On a couple of trucks I have, I used them over without any problems

01-09-2014, 01:55 PM	#1
54blackhornet Registered User Join Date: Jul 2008 Location: Eastern Oregon Posts: 2,291	4x4 Front LeafSpring U-Bolt Question ? I need to remove the front axel from my 71 K-10. What size is the gigantic nut holding the U Bolts on ? And can I reuse them or should you replace all the original hardware when reinstalling the axel ? Thanks __________________ 71 C-20 07 Magnum RT AWD

01-09-2014, 02:52 PM	#2
DirtyLarry Windy Corner of a Dirty Street Join Date: Jun 2003 Location: Pueblo West, Colorado Posts: 2,926	Re: 4x4 Front LeafSpring U-Bolt Question ? It is always a good practice to replace u-bolts when ever you remove them, especially if they are the originals. Most cities have a driveline shop that can build them for you or you can buy a set through ORD. ORD does have very nice u-bolts whereas some of the u-bolts available from other suppliers are cheesy. Basically you want a u-bolt that has the long nut and hardened washer. Do not accept any u-bolts that use nylon lock nuts. Those nuts are very soft and often strip before you even reach the torque spec. Oh, if you are asking what size socket to remove the nut, I believe it is a 7/8. The rod thread diameter is probably 1/2" to maybe 9/16" on a half ton. __________________ Current vehicle collection: 1978 Chevrolet K10, 8.1L, NV4500, NP205 1989 Chevrolet Suburban, 8.1L, NV4500, NP241 1993 Chevrolet C1500 Sportside, TBI 7.4L, 4L60E 2001 Chevrolet K2500HD, Ext Cab, SWB, 8.1L, ZF 6 speed 2014 Chevrolet Impala LTZ 3.6L Vortec 8.1L because life is too short to tolerate underpowered vehicles Instagram

01-09-2014, 03:54 PM	#3
54blackhornet Registered User Join Date: Jul 2008 Location: Eastern Oregon Posts: 2,291	Re: 4x4 Front LeafSpring U-Bolt Question ? Thanks for the information ! I am going to need a bigger wrench I guess ? I heard from others to use new hardware but an old mechanic friend said that is B&@Sh#T ! Just check for cracks, clean up the threads, repaint with rust oleum and get the torque correct ! I spoke to ATS Spring and they suggest installing all new UBolts and hardware, they stretch during torque procedure. __________________ 71 C-20 07 Magnum RT AWD

01-09-2014, 04:42 PM	#4
73chevy95 Registered User Join Date: Jun 2013 Location: Roseville, Ca Posts: 14	Re: 4x4 Front LeafSpring U-Bolt Question ? Ruffstuff makes some pretty good u-bolts for cheap, I agree to replace em like dirtylarry said, better safe than sorry!

01-09-2014, 09:17 PM	#6
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,950	Re: 4x4 Front LeafSpring U-Bolt Question ? U bolts stretch a ton when they are torqued in the first place. They need to be replaced. Also do not use an impact gun to tighten the new bolts. They will not be tight enough because they are springy the gun will just make them bounce. __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

01-10-2014, 01:21 PM	#7
54blackhornet Registered User Join Date: Jul 2008 Location: Eastern Oregon Posts: 2,291	Re: 4x4 Front LeafSpring U-Bolt Question ? Thanks for the insight about the U-Bolts, I took a shot at removing one with a wrench and noticed that the threads where all screwed up at the bottom of each bolt. I will use the torch method this weekend. Would it be better to drop the leafs out from the frame first ? __________________ 71 C-20 07 Magnum RT AWD

01-10-2014, 08:55 PM	#8
Rubble Registered User Join Date: Feb 2012 Location: Big Valley. Alberta Posts: 674	Re: 4x4 Front LeafSpring U-Bolt Question ? If all your doing is swapping axles,just use a torch or zip wheel & cut the u bolts.Dropping the spring out is a lot of extra work. __________________ 1977 Chev C30 454/465/14ff DRW 1974 Chev C20.350/465/14ff " Rock n Roll ain't noise pollution"

01-11-2014, 01:01 PM	#9
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,463	Re: 4x4 Front LeafSpring U-Bolt Question ? If they are factory bolts, then they are 5/8 requiring a 15/16 socket. In an ideal world they should be replaced as the bolts are a rolled thread and the nuts are a cut thread, thus when you torque them correctly the threads interfere somewhat locking them in place. On a couple of trucks I have, I used them over without any problems



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