I will be replacing the pinion flange seal and the crush sleeve/collapsible spacer for the original 6 3/4" rear end from my 78. I am wondering about how I should go about torquing down the flash nut when I finish up the reassembly, as tightening down that nut collapses the crush sleeve/space, which gives the pinion the correct depth to mesh up with ring gear correctly.
The axle is out of the car, so I think it will be easier to do.
Can I lock one of the axles with a pipe across two wheel lugs, and then tighten the bolt to the correct rating? The picture below visually explains how I'm thinking of doing this.
The manual says the minimum torque required to tighten pinion flange nut to obtain correct pinion bearing preload is 140 foot pounds. That's a lot of torque! Would the lugs on the axle shaft be able to hold up to this?
How else could I lock everything in place to turn the nut with 140 ft. lbs to reach pinion bearing pre-load?
I think the lugs would take it, but also think you might have to secure the rear end down so it doesnt try to walk away or jump on ya.
Yeah, securing it wouldn't be to hard to do, I think....I can come up with something.
Any ideas how shops do this?
Typically they do it in the car (at least the shop I know). I have done it both ways, and I prefer in the car. Nothing moves that way.
If this not a show car, you could hold the universal flange with a pipe wrench with an appropriate pipe on the handle for additonal leverage. This way you would be pulling the torque wrench against the pipe extension (one in each hand or two hands on the torque wrench and a knee on the pipe wrench extension). This avoids the torque multiplcation of the differential when immobilizing the axles.
The crush sleeve sets the pinion bearing preload and not the pinion depth (mesh pattern). Shims are used between the pinion gear and the first bearing to set the pinion depth. To set the bearing preload, I believe the ring gear needs to be removed from the housing. This will allow enough pinion rotational travel to get a good inch-pound reading. In practical terms, just torquing the nut to the minimum 140 ft-lb may work.
Have fun with project.
I would take the rear end to a shop at does that it`s a complicated job done with dial indicators and blue die to mesh the gears right and set up is important for gear wear and noise .if you try this yourself and the carrier is in the rearend you can use a clean rag to lock it up stuff it under the carrier and turn it till it jams between the carrier and the housing......
As was stated the crush sleeve is just for setting the bearing preload. It was also correctly stated that to do this requires either the ring be out of the housing or you have a removable pinion carrier a'la 8 or 9 inch. also 140 ft lbs is just a torque it tights spec. realistically it takes 180-200 lbs to start and continue to crush the sleeve.
if you are not changing bearings or ring / pinion i would recommend you replace the seal and leave the original crush sleeve in place. rattle the u joint flange back on with a 1/2 inch air impact that doesn't make more than 150 ft lbs torque and call it a day. this will snug the bearings up to the crush sleeve and 99 times out of 100 put the right preload on for a used set of bearings.
a new crush sleeve is a whole mess of hassles. you have to have an inch lbs wrench with a flex arm on it as opposed to just a regular break type so you can get the reading while the pinion is spinning. it has to be freewheeling so the ring has to be out. etc etc etc.
OhSix'
I don't mind removing the ring to do this, I need to reset the backlash on it anyhow.
I am not replacing the bearings or anything, just the crush sleeve and the flange seal.
The reason I am doing this is because I never had an issue with the original rear end until I replaced the flange seal the first time, then it started to make a thunking sound upon acceleration when the clutch would first grab. I'm only guessing that the flange nut was overtightened the first time, causing the crush sleeve to collapse to much and screwing up the bearing preload. Other than the thunking sound, there wern't any other problems with it.
The 3.40 axle I have in the car now runs like a champ, it's tight, no odd sounds or thunks, the gear ratio is just to low for me. I would prefer a 5 speed transmission with the 3.40 gears, as driving around in fourth gear just to do 35-40 mph tops is annoying, even more so on the freeway!
hahahaha
Dave I know exactly how you feel. was out cruising the '69 tonight. its got a 3 spd auto and 3.73's in it. snaps off 2 shifts by the time you have crossed the intersection. 60 mph is a 4000rpm proposition
OhSix'
OhSix you know exactly what I mean! :lol: :fastcar:
Put the axle back in with a new crush sleeve. I torqued the nut down to 140 ft/lbs with a new crush sleeve and now the rear end whines, and whines LOUD. Overloaded bearings?
I'm going to pull the nut off and reinstall it just tightening it as much as I can with the impact wrench and call it good. I think it's to tight right now and there's to much pressure on pinion bearings.
Could it be the ring gear and pinion mesh, or would that be more of a groan/grinding sound?
EDIT: Upon further thought, I want to do this RIGHT. I will go down to the pawn shop soon and get the inch pound dial torque wrench they have on the shelf. It's not expensive, and it sounds like the best way to make sure this is done RIGHT. I'll keep you all updated.
Man am I bummed out about all of this. :(
if its loud then they are underloaded. the pinion is walking around. its is it louder under decel than under accel? 140lbs won't crush that sleeve. you can try and set them after getting a dial but there is a good chance you will have to do bearings as you have likely trashed 'em. an overtight set will be quiet but heat up and pile up on ya.
remember if you go to tight on a crush you cant just back it off and run the nut tight again. you will have to get another crush and do it again. i would suspect that its not crushed though. pull it and check it against the original with a micrometer. if its shorter it is def over crushed. other option is put the original crush back in and see what it sounds like
check all the bearing caps in your u joints as the possible source of the original clunk
It is louder on decel than it is on accel. We'll see how the bearings look when I pull it apart again, it's going to sit parked until I can pull it apart again.
I pulled the flange and the seal tonight to check the crush sleeve and the bearings. The bearings are in great shape, no odd wear or scoring, no damage from what I could see! That was a relief!
The crush sleeve was, as you mentioned, not even collapsed! In fact, it didn't look like it even had any wear from spinning on the ends or inside of it! That was a SURPRISE!
I put the original spacer back in and spun the nut for the flange on with the air impact wrench. The flange doesn't pull in and out like it did before with this crush sleeve, that was the original source of the clunking. It a little bit of excessive backlash, but nothing so far that I'm terribly worried about, maybe at the max allowed backlash.
It's quiet again now, sounds like it did when I had the axle in the car before I installed the 3.40 axle. It whines a little on decel but not NEARLY as bad as it did when the new sleeve was installed.
I've decided to find the bearings, races/cups and seals, then take it to the reputable drive train shop here in Boise (Jim's Drivetrain). They do custom drive trains and stuff, and the owner said he would be more than happy to rebuild the axle if I can locate the parts, as he cannot. For a price of $150.00 he could rebuild it and set everything to specs for me! I have two good new crush sleeves for him to use and set bearing preload correctly, and an original Ford shop manual for the 6.75" rear end he could use for reference. I'll get this sorted out! :)