LUVTruck.com

My daughter said the truck is making weird sounds. I took it for a ride. I think the diff is going out. Will be needing a good rebuild shop or other ideas for a replacement. It's a 79 4X4.

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OK, I'm over it. Where's the beer?

Ron, I have the stock rear from my 72 laying around still. It has pretty fresh brakes and I had put a 3:42 carrier in it when I first bought my truck. The pinion seal is leaking but other than that it is good to go. Let me know.

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Three Amigos

Mine is a 4X4. I believe, (haven't gotten the book out yet), 4X4 have 4:10's and front and rear need to match. But thank you, and I will keep that in mind if I need it. Thanks.
My son reminded me of a drive line shop close by that did my other son's Bronco front diff. I'll be getting a quote from them, when I get on this. It might be a week or 2 before I do. I have other weekend plans. It will have to wait. She can drive my totally cool mini van. Or she can get a job and buy her own vehicle. What does she expect for free?

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OK, I'm over it. Where's the beer?

I thought the same thing, but he's offering you his "stock" rear end--the one he took out. Is it possible it's the same as yours?

Jack

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'83 Isuzu P'up Diesel LS - Original Owner
JoeIsuzu@IsuzuPup.com
IsuzuPup.com

Take the driveshaft loose at the rear, see if the pinion nut has backed off a bit. Most common symptom when they loosen is more noise on coast, not much under power. Sometimes you can re-tighten the nut and salvage the rear, just don't overtighten or you will collapse the crush sleeve too much & the rear must for sure be rebuilt or replaced. Try about 100ft-lbs, test drive, see if the noise is less. You may have to sneak up on the right degree of tightness over several steps. If you get the noise to go away make sure to stake the nut threads to the shaft threads or it will quickly loosen up again.

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'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, rough body, bought new 12/4/78.
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch,more to come.

Stock '72 rear is likely 4.56 ratio. Count pinion teeth to be sure, 4.56 has 9, 4.10 has 10, both have 41 ring gear teeth.

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'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, rough body, bought new 12/4/78.
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch,more to come.

Thanks for the info guys. I'll look into it. I will check my factory shop manual for the ratio questions. I think '72 was much lower geared than the later years. I know my '80 was taller than my '79 4X4 and my '78, and they were the same with 4:10's. I will look at the pinon nut before I start pulling it out from under the truck.
And yes, it is making noise on coast and not on acceleration. but has a hell of a vibration around 45mph. The drive shaft and u joints are good, I already gave that a shake, plus I replace them about a year ago.

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OK, I'm over it. Where's the beer?

My 72 diff has a 3:42 carrier I installed just after I bought my truck. The 4:56 was junk so I tossed it.

If the nut is loose the pinion bearings aren't pre-loaded, which can cause the whole pinion gear shaft & yoke to wobble. Put a socket on the nut, see if you can turn it easily just a bit by hand, if so it's definitely loose. The nuts are supposed to be staked to the threads, this deformation can give you a false reading on a torque wrench just about the time it gets tight enough, so that's why you may have to sneak up on the correct tightness. You can also take the nut completely off, run a tap through it and a thread chase on the shaft to clean the thread burrs, then you'll get a clean torque reading. If you have the nut completely off whether you're cleaning the threads or not this is a good time to replace the seal- which starts leaking quickly with a wobbly shaft- (drain the lube first or park with the nose uphill), seal is Timken #474133.
I have fixed one rear with a loose nut & replaced a pinion seal in another by doing the thread clean method on both the shaft & nut, then torqueing the nut to 100 ft-lbs (tighten until the noise goes away, then stop, 100 ft-lbs worked for me- twice), then staking the nut in about three places (I had to re-do one because I didn't stake it sufficiently, the nut didn't stay tight) and both rears have been doing fine for a good while.
Be aware this method may not work- if the nut has backed off despite the staking & you catch it quickly enough it has the best chance. A failed pinion bearing can also cause slack in the nut, but re-tightening will make it worse, not cure the problem. As with over-compressing the crush sleeve the only cure for a bad bearing is a complete rebuild or replacement.

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'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, rough body, bought new 12/4/78.
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch,more to come.

Rondog....I had the same thing on my '77 stocker a few years ago and the rear trans carrier bushing had failed and was allowing the 'wobble'. The wobble shook the heck out of the truck. Cost me a few hundred to fix it---I couldn't diagnose the problem then-- and the rear tranny yoke was scored a little. I tried to get another within the LUV group but couldn't. Anyway, the old scored one is still working fine and there is no leak from the rear of the transmission.

72 was stock with 4.56. I have mine still, you know I switched to 3.73

car-part.com helped me find my 3.73 3rd member locally, it was a shop near Santa Fe Dam, I want to say Truck Parts Company. Just went over there and picked it up. They had a 4.10 at the time (long ago), but I bet you can locate one if you don't want to repair the one you have.

Well lucky me!! It was just the rear u joint. I bet it doesn't have 10k miles on it yet, surprised to find it bad. A local 4X4 shop is pressing in new u joints at both ends for me.
I'm so happy I pulled the front shaft out also. I will drop it off when I pick up the rear shaft. The front has been all wobbly at higher speeds when in 4X4 for a long long time. I very, very rarely use 4X4, so I hadn't bothered with it until now. It might be going for a romp up at Gorman, CA next weekend, so.......

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OK, I'm over it. Where's the beer?

2 new u joints and a balance, $122. Back in the truck and it drives great. He put the zirt fitting in the end of one cap. Never seen that before, but it's easy to get to, and it doesn't get hit by the yokes.

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OK, I'm over it. Where's the beer?