Rear differential

[grousehunter 61]

My new center carrier came and it is for the 373 gears, working on it today and have a problem, gee, that's unusual, OK here it is, the center pin in the carrier sticks out and hits the pinion, I introduced it to the grinder and it no longer contacts the pinion, but what is the clearance between the carrier and the pinion. I am sure that the pinion is spaced out to far and that is the problem, BUT, the pinion bearing was heated to go on the pinion, cutting it off and buying a new bearing is out of the question at this time. I guess I just answered my question. take it all apart pull the pinion remove the bearing remove some of the spacers and start over again. Anybody know the distance between the face of the pinion and the center of the axle shaft???

[Accelo]

Not enough information to diagnose over the internet.
However, you are far enough along now to get a pattern and post a picture.
Cheers.

[grousehunter 61]

ACCELO it an 12 bolt diff in a 71 chevy 4x4, with 3:73 gears. don't know what more I can say about it.

[grousehunter 61]

got it back together , haven't buttoned it up yet, drive shaft needs hooked up and it will be done. turning it over by hand, I feel a rough spot, not bad just a soft drag, I think I got it too tight, not bad just a little. I am hoping it will wear in and of course it still dry so that my change things.

[indymachinist]

I have never seen the pin stick out and touch the pinion when correctly installed.

I hope you set up the gears correctly and didn't just throw it all together.

https://www.racingjunk.com/news/how-...ear-correctly/

This may help.

[grousehunter 61]

Your right, neither had I but, found I had two many shims on the pinion shaft, I headed up to the golf course that I worked at for 13 years due to the fact I remembered they have a hyd press. The new mech said I was welcome to use what ever I wanted, pressed the bearing off the pinion removed 3 shims reinstalled the bearing and put it back in the housing, no more problems. I don't have all the gages that is normally use when setting up a diff, so it was set by feel, I have about 10 thousands play between the ring gear and the pinion gear, could be 8 or could be 12 as I said all by feel. The center carrier is firm in its location. No oil in the housing yet as I used gasket maker and want it to set up before running it. If its bad shame on me.....this is what happens when you get old.

[grousehunter 61]

OK, if you took the tires off my truck to rebuild the diff what would you have done with the lug nuts, I can't find them, not in the tool box, not in the tray I use for parts, not under the truck, not in the stands used to hold the truck up, not inside the truck or in the bed of the truck, maybe the squirrels got them......

[jessemthompson]

So you set your rear end up without measuring backlash or the pinion preload? Maybe it’s good you can’t find your lug nuts. I would not run a rear end without measuring.

[grousehunter 61]

some have all the tools and some don't, wait till you get on social security and can't afford to pay somebody to fix things and you don't have the tools but need the truck. when you reach 80 give me a call.

[jessemthompson]

Originally Posted by grousehunter 61

some have all the tools and some don't, wait till you get on social security and can't afford to pay somebody to fix things and you don't have the tools but need the truck. when you reach 80 give me a call.

Well definitely not meant as an insult. I would borrow some tools so this doesn’t leave you stranded somewhere.

[burnin oil]

I have set them up by feel and done well. I couldn't find my adapters to put a 1/2" socket on the inch pound torque wrench. Pinion drag was set by the "yup feels good method". That front axle has been used daily with a trac rite and no issues. Painfull as it would be I can see setting up a rear-end that doesn't have side bearing preload without any measurement tool if you have alot of experience. Alot of crush seals are setup by professionals every day by the feels good method. We all struggle for that perfect pattern but probably near as many said that is close enough. Alot of set up is based on experience. I know that I can run a solid cams valves as this point and probably be within spec before ever breaking out the feeler gauges. Same way that I know how loose to leave the valve before locking down the poly locks and ending up at the correct lash. We have all been there and made something work whether it was from breaking a tool or not having one available. Especially think of road side repairs to get us home! Ideal, no, but it does work most of the time.

[BigBird05]

Did you run a gear pattern? If you did show us it and we can tell if the back lash and pinion deep are OK.

[grousehunter 61]

I don't think I have ever explained my situation here. I live in the bottom of a canyon, it's 12 miles to the closest town of 400 and nobody repairs vehicles there, the next town is 34 miles. The Napa store there does not loan tools. I could go the other way and it's 55 miles but again nobody loans tools, these miles are all one way so double it for round trip. I have been a mechanic most of my life, starting at the age of 13 I rebuilt a 1936 Chevy In the air force I was a mechanic and worked on B 47 bombers, I was a 7 level line mech, and have letters from the Air Force commending me for my abilities. One night a B47 came in with a hole in the right aileron, myself and one other stayed all night replacing it, come morning it was done and the test flight showed no added trim needed. I have rebuilt 283,s 327,s 350s, and ford flat heads, 318 dodges, 454 Chevys. Now to my 71 chevy 4x4 pickup, I bought it new in 1971 it has over 500,000.00 miles on it, it came with higher gears that I didn't like so I changed them to 3:73's and a posi unit, in 83 or 84 the posi unit went out and I replaced it with a new set of gears, but still 3:73's, the reason was becouse the disk's in the posi unit wore out, nothing last for ever. The problem I have today is I am 80 years old and the old brain doesn't work like it did when I was younger and sometime I can't remember what I do with things, like the lug nuts on my truck, you hide things so you know where things are but after a couple of months you don't remember where, only to never be seen again. It took over 9 weeks for the differential to show up from Summit, to long between tear down and rebuild. The first center carrier they sent was the wrong one, it was for 3:43 gear's and not knowing I worked for 3 or 4 days trying to make it fit, one of the guys on here explained that the carrier is made for a certain gear ratio, some thing I was not aware of, I called Summit and they said to send to unit back and they would send me right one, in 9 weeks as they had been back ordered. Why the ring gear isn't just made thicker or thinner is beyond me, except for the 4:11 that don't fit my housing. OK this is long enough, not mad at anybody, life is to short to be mad.....

[grousehunter 61]

Sorry big bird, I didn't answer your question, yes I did a reading on the pinion depth on the ring gear and it is as far as I can tell right on, 2/3's down the ring and centered on the teeth. I would show you the pattern but it is buttoned up and the only thing holding me up is where are the damn lug nuts.

[BigBird05]

If the pattern looks good then run with it. Less back lash with be a little quiter, more backlash will add some noise. Since you have a good pattern you should be good to go.

[grousehunter 61]

If it's not one thing it's another, it's buttoned up 80-90 oil installed and still on the jack stands. fired it up and ran for 20 min in reverse, stopped and ran it 20 min in drive, no noise or clunks, no wine ( not the drinking kind ) no leaks found the lug nuts, they were in a plastic bag in the traveling tool box. Got it down from the jack stands, forward no problem, reverse nothing, drive shaft is not turning so it's not the rear end. Low on trans fluid, ? maybe, two quarts, still nothing, it wants to go but nothing seems to be connected in reverse. Before the rear end went out I had both forward and reverse, it never was a problem. I don't see how anything could go wrong just sitting on jack stands for a couple of months and as I said , with the wheels off the ground they turned both ways. I will fill it until the transmission fluid runs out the dip stick hole. I have a dirt driveway so no telling how much trans fluid leaked out and that's where it was sitting but it never leaked before, so why now.

[Louisvillekytruck]

Thank u for your service. Do u have any pics of your truck

[pjmoreland]

This is mysterious, so I'm just thinking out loud here. I took a look at a photo of a pinion gear from one of our trucks, and it appears that when it is twisted in the direction for reverse, the helix of the gear teeth will push the pinion gear toward the rear of the vehicle. Is there any chance your pinion gear is loose allowing it to slide back and contact the diff carrier when in reverse?

[grousehunter 61]

No, everything is lined up and working as was showing when it was up on jack stands with the wheels on the ground and in forward it moved no problem but when in reverse the drive shaft doesn't turn so it has to be something in the transmission. The truck sat for a couple of months with the back end jacked up a foot or so higher then the front end, but you would think that if the fluid ran out it would do it while driving and it never has. What would happen if most of the fluid ran into the torque converter and the reverse clutches were left dry for a couple of months. Knowing the reverse clutches are at the tail of the trans is that possible ?

[pjmoreland]

If you've got a leaky dipstick tube seal, then I could see you losing some fluid that way with the rear end up high for a long time.

Is your truck parked on level ground? What is your transmission fluid level according to the dipstick when the engine is running? Maybe try shifting slowly through all the gears several times with the engine running.

[grousehunter 61]

PJ, no my driveway is sloped slightly down so that compounded the angle the trans was sitting at. I am going to head into town and pick up a couple of more quarts of trans oil and see if that helps. As I said, it was working fine when I parked it and while I had it in the air the trans worked ok in reverse and it ran about 20 min then I shifted to forward and it also worked good. I applied the brakes and stopped the rotation before shifting into drive. I hope this is just a fluid thing.....I may try it again this morning as it has sat over night with the trans somewhat level.

[grousehunter 61]

Low trans fluid is the problem, I crawled under the truck and found a large area of wet ground about where the the front of the trans was sitting, so I have a leak somewhere up front most likely the filler tube. without putting any more fluid in it and with it sitting level all night, enough fluid came to the back and old yella backed up, not great but it moved. With all the rain we have had the wet spot did not show until I got under the truck.

[pjmoreland]

That sounds promising.

[grousehunter 61]

Two quarts of fluid and it backs up like always. a very slight click between forward and reverse. Sure wish I could remember all the things I have forgotten, I wouldn't feel so dumb.....I sure appreciate this sight, lots of good info on here. You young guys keep and old man going, thanks.

[grousehunter 61]

I am fairly sure I have found the trans leak, its the fill tube, but its so messy around there its hard to tell. I know its not anything around the torque converter as there is not any fluid in that area. I need to clean the trans and then see exactly where its coming from, but from the fill tube back its very wet with trans fluid. Time will tell...