So, I'm wrapping up a build of a 1950 Ford shoebox right now after doing a 289/C4 swap. Got a new driveshaft in and just replaced the ancient/leaking pinion and axle tube seals on the original rear end. I took the entire third member out and had to remove the pinion to punch the seal out from the inside. Surprisingly all of the bearings and race cups look and feel great. I even had some NOS replacements that I'm just going to keep on the shelf. Before removing the pinion nut I marked on the nut and pinion where it was to get close to the original preload, but since this is one of the last things I need to wrap up, I just want to make sure I get it right. I'm setting the preload to 18 inch pounds tonight when I get out to the garage since they are used bearings, but a thought occurred to me just now, and I want some input. Do people generally set the pinion bearing preload with the wheels/drum brakes on? I went through the entire brake system during this process and the rear drums have a slight bit of drag since I want them to seat correctly on the first drive. Should I just take the drums off and set the preload or put the wheels/tires on and set it that way? It might sound like a strange question, but the more I thought about it, the wheels/drums would create a certain resistance that would show up on the pinion preload bar gauge. I'm most likely overthinking this, but I'm probably going to remove the drums so the preload it set to the actual pinion bearing and differential resistance, as opposed to the additional force required to move everything else. Let's hear it.
Is this ford 9in or gm rear? You have a crush sleeve or a sleeve eliminator and shims? It doesnt really matter as both should be done with only the pinion in then rear. On a ford you can actually set the preload with the pinion out of the rear end on a bench, thanks to the bearing support being removable. On GM style you have the pinion in and nothing else....tighten it down and check it..tighten..check it and once you have the preload you want your done. Also if you are reusing the same bearings on a ford 9in and a new crush sleeve (must use new sleeve every time) your target is about 15in lbs...not the normal 25in lbs for new bearings. Edit...lots of videos on the you tubes on this for every type of rear end. easy to blow one up real quick if done wrong. Easy to set up but definitely watch some videos.
It's a Ford, but not the 9inch. It's the predecessor found in the 49-54? cars. Frontload 3rd member. For the life of me I haven't been able to confirm if it is a Spicer variant or Dana variant. They made millions of these cars but the info on those rear ends is pretty vague in my research. Here is a link to the best info I have found to date, which is just excerpts from the original shop manual : https://shoeboxford.wordpress.com/resources/the-green-bible/rear-axle-and-drive-lines/ I have been going off of this for everything so far. With that being said, I'll come back to the original question. Wheels/drums on or off for the bearing preload? I would think off since that is likely how they were setup in the factory prior to being installed into the vehicle.
Every diff I have ever seen...granted I am no diff expert....there is nothing in the housing for pinion preload. The preload is so little...in lbs...any thing would over power that reading...the diff, axles, etc. They all have too much resistance, drag, inertia, etc. If the pinion bearing support is removable (ford 9in type) then you set preload with the pinion and support out of the housing. for the non removable type (gm, ford 8.8, etc) the housing is empty, you install pinion, sleeve, seal, etc and torque and read, torque and read until its good. Then assemble and your done. Worst case is you set in the third member and find out the pinion depth is way off and have to shim it, new sleeve and re do it.
All of the pinions I have preloaded in the past, and like you I don't consider myself a diff guy either, I have done installed in the housing attached to the diff gearing. In the past I would do it with the wheels off, but they were all disc brake rears with basically no drag at the rotor, or even the rotors removed. My thought there is I imagine you would want the preload set when the resistance is what would be seen during rotational operation. Again, the more I thought about it this morning, the more I really couldn't seem to come up with a clear answer, which is why I brought it hear. I know plenty of guys who set it with the complete rear end together, wheels/tires on and they don't run into any issues. At least that they know about.
Here is a really bad image of the pinion cropped out of a large photo, but it gives you an idea of the spacer. To me it appears to look like a crush spacer, but I can't for the life of me find anything on it. The service manual simply refers to it as a bearing spacer. Maybe this is an original that wasn't crushed: https://www.ebay.com/itm/3751295718...7F80jE7EB_S34trIfw-s9aQKgKEjXPmMWwokKudcXBVyY Genuinely no idea lol. Guys on the different shoebox forums haven't been much help other than asking me if I have a copy of the service manual.
I guess too much pre load is better than none...because that's what would happen with all that stuff on there. Although I guess its as dig a deal as getting a good wear pattern. As to that spacer...that looks like a spacer. A crush sleeve usually has some indents and bend in it. I cant tell if yours in the pic does. that one you linked sure doesnt. When I looked at that manual a little closer it looks like they didnt use crush sleeves then. They used the solid spacer and shims to set depth and preload. So if you are re-using all the original stuff you "should" be OK. Although they do say to use anew spacer as they may squish slightly. You will have to re-assemble the Pinion with new seals and spacer, keep the shims in the correct spot that you took off. Torque it down to ~15in lbs and then assemble the diff into the housing....that's what the manual says as well. Set preload with only the pinion in. If you re-assemble and your wear pattern is off you may have to take it all apart, re shim it, re pre-load, re-assemble, re-check and keep doing it until you get a good wear pattern. But if the pinion depth was good before it should be OK now. Usually its when you make bearing changes, new 3rd member, etc that everything goes to hell. I put a new LSD in my Camaro I am building....well sitting mostly lately lol...and I made check bearings for the pinion. I bought 2 sets of bearings...exact same ones. Ground out the inside of one some so it would slide off the pinion. Then I went back and forth about 3-4 times installing and re-shimming the pinion and diff until I liked the pattern. Then I pressed on the real bearings and did final assembly. Pattern was the same. This was with a crush sleeve eliminator...basically a solid spacer like yours so the shims had to be just right since there was no crush sleeve to squish to take up slop.
Chem Guy is right, set the pre-load with the ring off. If you don't want to do that, then line it up with your mark. Sure you can check afterwards and it should read more, definitely not less from seal/bearing/axle/carrier but theres no way to calculate how much. Do you have a backlash number you can shoot for? .008"-.012"? I'd rather kill bearings than kill gears. You aren't dealing with a lot of power, a lot of speed, or a lot of miles, so if it doesn't make noise after... meh, I'd run it.
Gentlemen, I knew I'd be in good hands. Thanks Chem and Cooter, I'll set it with just the pinion in and go from there.
