8.8 U bolt size

[chad551]

Anyone know what size the stock u blts are for the 8.8 rearend? I am doing my SOA this weekend and want to go and pick up some new u bolts and nuts.

 

[Scott B.]

A 31-spline axle works best with 3 1/8" u-bolts. 3" will fit, but you have to "encourage" them onto the axle.

 

[chad551]

What is the stock u bolt diameter though?

 

[Carguy3J]

Dorman Catalog

What is the stock u bolt diameter though?

3-1/4" inside diameter is the correct size. The thread size, to fit the stock shock mount plate is 9/16-18. (weird thread pitch-forget Home Depot for nuts) Dorman/Motormite has them in different lengths. Forget about Autozone or Advance getting them though. You'll need to find a part# on in the Dorman catalog first, then search Rock Auto by that part# to find them. They won't be listed by application.

https://www.dormanproducts.com/upload/banner2/HELP.pdf

Pg 152 (of the catalog) pg 162 in Adobe Viewer

I used # 35625 These are a little longer than stock, since I'm going to be lowering my truck. If you're willing to drill out the holes in the plate, and use 5/8 diameter bolts, you'll get a few more choices in length. I would think that if you're lifting it, you shouldn't need longer bolts, unless you're really going big.

 

[Scott B.]

You can get some custom-made u-bolts from Michigan Truck Spring. I ordered a set from them, had them in 2 days.

I got grade 8, 5/8" x 10 1/2" long (to accommodate my 12 leaf spring packs and lift block.) They bent the 3 1/8" radius for me. As Carguy3J said, you can use 3 1/4" radius also.

 

[snapp central]

A 31-spline axle works best with 3 1/8" u-bolts. 3" will fit, but you have to "encourage" them onto the axle.

Hey Scott,

I'm new to this site and excited to see your posting. Unfortunately I have over torqued a U bolt after an add a leaf on my 97 explorer and I want to replace both u bolts on that side. I tried 3 1/8" u bolts and had to really work at it to get them on - in the end I took them off and decided against them because there was too much stress.. Should I have to really force them on like that and will it be okay over time etc?..

was wondering what you thought. Thx for your time .

Steve

 

[Scott B.]

Hey Scott,

I'm new to this site and excited to see your posting. Unfortunately I have over torqued a U bolt after an add a leaf on my 97 explorer and I want to replace both u bolts on that side. I tried 3 1/8" u bolts and had to really work at it to get them on - in the end I took them off and decided against them because there was too much stress.. Should I have to really force them on like that and will it be okay over time etc?..

was wondering what you thought. Thx for your time .

Steve

Steve,

When you install a u-bolt, and tighten it, you reform/stress it. If the u-bolt doesn't exactly fit the axle, by the time it is tightened, it will have conformed to the curve of the axle (more or less) - which is a good thing.

As such, u-bolts are a one time use part.

To answer your question, forcing them on shouldn't really hurt anything - it's just a pain to do. You might want to order a new set of u-bolts with a 3 1/4" diameter bend, for peace of mind.