About to put 4.10's in my 2008 F150. I plan on using a solid spacer since thats what I've always used on my rear end builds for GM 7.5 and 8.5 rears. Need to know the pinion nut torque using a spacer, and pinion bearing preload when installing new pinion head/tail bearings and races. Always shot for 20 - 25 in lbs on my camaro using new bearings and 125 - 150 ft lbs for the pinion nut, but again I have no idea about the 8.8 rear in my truck. Don't see anything on it in the stickies on the forum so I posted. Thanks in advance!!

 

Seems to me the bearing preload won't change whether a spacer or crush sleeve is used. And it seems to me that the pinion nut torque will have to be based on what it takes to get the correct bearing preload. The one crush sleeve that I used way back when, took a tremendous amount of torque to start the crushing. I'd guess something on the order of 400 ft. lbs. But, I ain't no expert!

 

Yes the pinion bearing preload will be the same whether a spacer or crush sleeve is used, I just need to know what it is lol. Once the desired preload is found using a spacer w/shims the pinion nut torque will not affect the preload. I prefer spacers in mine and have used them for over 15 years and never had a pinion bearing fail.

If no one knows or I can’t find it, I’ll just shoot for 25-32 in lbs and see what happens. Surely someone on here has set up gears in the these trucks, either with a spacer or crush sleeve.

 

So after further research the pinion bearing preload on the 8.8 rears in our trucks, when using new bearings/races is 20 - 28 in lbs. I still don't know the pinion nut torque when using a solid spacer but i'm sure 150 ft lbs will be just fine, or just tighten the **** out it with a breakover bar. I'll be going with 4.30's most likely, so ill have a brand new set of 4.10's to sell. The 4.6L needs all the help it can get and gears seem to be the most cost effective way to give more power out of these trucks. Figured I would update so others can have the info, I'll update again once I'm actually done with the swap.

 

I think you need to ask an expert about that pinion nut. I don't think there are experts in diff gears setup on this site. I just watched this video and it explained a lot to me.


this guy used 130 ft lbs for the final pinion nut torque for a GM 8.5" .

 

I've used 125 ft lbs for gm 7.5 rears ive setup in the past, so that's pretty close on his 8.5 inch setup. Contrary to what people might say setting up these types of rear diffs isn't that difficult with the right tools and some patience. What sucks about a crush sleeve is if your not careful and over crush the sleeve you have to start all over with a brand new crush sleeve...can't un-crush the sleeve for less preload. And by that time you've already installed the pinion seal too so now you have to buy another crush sleeve and another pinion seal. All part of the learning process though, and still way cheaper than paying a shop.

 

The right tools and enough knowledge on how to do it. Today though, with the youtube videos you can do almost anything you want if you study them enough. I tried my hand at setting up a couple of diffs back in the 70's and they seemed okay afterwards but some of these videos would have been a huge help.

One trick I came up with that I was proud of was how to insert the two plates with the compressed 4 springs back into the eaton posi diff. The manual I had showed the use of C-clamps but that didn't work. So, I clamped the two plates together and ran multiple loops of fishing line through the plates and springs and tied the lines to keep the springs compressed. After inserting them into place I cut the fishing lines and pulled them out. Worked great on my 12 bolt Chevy eaton posi-traction.

 

Well this ended up turning in to multiple jobs. I replaced to front lower ball joints, outer tie rod ends, stabilizer bar links, and installed a 2 inch leveling kit on the front springs. Almost didn't have the energy to start the rear but I managed. Ended up just using a crush sleeve, which saved alot of time. Adjusted my shift points and speedo, and man I love the 4.10 gears, really woke the truck up. Been looking at cams but don't see hardly any options for these trucks. Looking for more low end and mid range, but seems like the overall consensus is to just leave the 4.6 alone.