[nad427]

This will take a minute so please bear with me...

I have an 88 Chevy long bed 1/2 ton parts runner pickup with a problem. The truck has been mostly trouble free for many, many miles but lately the rearend has been complaining and showing signs of being in it's death throes. Throwing 90w everywhere and clunking, howling, and vibrating something fierce. After doing a ton of research I've found that it's a five lug, 8.5 inch, ten bolt cover rear with 3.42 gears and has never been out of the truck in over 300,000 miles (same with engine and tranny).

I found that since it's a first year of that bodystyle model, that true to normal GM form they used some of the remaining 87 rearend style to use up stock on the early 88's, then came out with a new one for late 88 and 89 up to late 99 or so. The 87-88 had 28 spline axles while the 88-89 on up had 30 spline.

My options...
1. Buy a 'takeout' from a junk yard and just swap em.
2. Pay a local guy 1500 bucks to rebuild mine.
3. Buy the specialized tools I don't have yet and parts and rebuild it myself for half that price.

1a. I found an outfit on ebay that sells complete takeouts for really good prices and free shipping (don't know how they can do that). The price is so reasonable that it'd be cheaper to get one than to go to a local place and go through the hassle to pull one out myself. Condition unknown though and could be near as bad as my present one.
2a. The local guy rebuilds them right in the truck so it's just a matter of dropping it off, paying and driving off with it when finished. New guts.
3a. New guts, plus a learning curve since I've never tackled one before, but half the price, and saying that I did it myself. I think I can handle it, and would be good knowledge to have.

My delima,
I really don't want to buy new parts, then have to send them back to get correct ones should I choose to go that route.
So,
How in the heck do I figure out which of the two rears I have without having to pull an axle to count splines?? Any body here know if it can be identified from external view?

 

[lonewolf85]

This will take a minute so please bear with me...

I have an 88 Chevy long bed 1/2 ton parts runner pickup with a problem. The truck has been mostly trouble free for many, many miles but lately the rearend has been complaining and showing signs of being in it's death throes. Throwing 90w everywhere and clunking, howling, and vibrating something fierce. After doing a ton of research I've found that it's a five lug, 8.5 inch, ten bolt cover rear with 3.42 gears and has never been out of the truck in over 300,000 miles (same with engine and tranny).

I found that since it's a first year of that bodystyle model, that true to normal GM form they used some of the remaining 87 rearend style to use up stock on the early 88's, then came out with a new one for late 88 and 89 up to late 99 or so. The 87-88 had 28 spline axles while the 88-89 on up had 30 spline.

My options...
1. Buy a 'takeout' from a junk yard and just swap em.
2. Pay a local guy 1500 bucks to rebuild mine.
3. Buy the specialized tools I don't have yet and parts and rebuild it myself for half that price.

1a. I found an outfit on ebay that sells complete takeouts for really good prices and free shipping (don't know how they can do that). The price is so reasonable that it'd be cheaper to get one than to go to a local place and go through the hassle to pull one out myself. Condition unknown though and could be near as bad as my present one.
2a. The local guy rebuilds them right in the truck so it's just a matter of dropping it off, paying and driving off with it when finished. New guts.
3a. New guts, plus a learning curve since I've never tackled one before, but half the price, and saying that I did it myself. I think I can handle it, and would be good knowledge to have.

My delima,
I really don't want to buy new parts, then have to send them back to get correct ones should I choose to go that route.
So,
How in the heck do I figure out which of the two rears I have without having to pull an axle to count splines?? Any body here know if it can be identified from external view?

Its going to have to come apart any way. just tear it down. The rearend is pretty simple if you set the backlash and tooth contact properly they wont make noise. I wouldn't be afraid to use used parts.

 

[Rick_L]

Does it have a gov-lock type posi? They are a POS. I wouldn't mess with a bad gov-lock, I would put another used bullet in it before I'd do that.

 

[nad427]

Does it have a gov-lock type posi? They are a POS. I wouldn't mess with a bad gov-lock, I would put another used bullet in it before I'd do that.

No it's open. I've heard the same thing about those Eaton 'guv-locks' and plan to avoid them. But, no matter what I do the new or new used rear is going to have a posi of some sort. You heard any good or bad on Auburn units? Any others to investigate?

 

[jmg283]

The whole housing in an 88 is wider than an 87. The axles are 28 spline in both, but won't interchange because the 88's are longer. They changed to beefier 30 spline axles in 89.

I know this because I put a 28 sp posi unit from a 75 Malibu in my 89 1/2 ton. The ring gear fit the carrier and all was well until I went to put the 28 sp axles from our broken 87 Suburban diff. I had to really push to get them in far enough to install the c clips. After installing the cover and filling with gear lube I stuck the brake drum on. :redface: The drums hit the backing plates about an inch before bottoming on the axle. Only about 1/4" of the wheel studs were through the brake drum.

About 6 months later I bought a 91 caprice and swapped the 30 sp auburn type posi with the open diff in my pickup. I have since found an 88 rear end with 28 splined axles, I may put the 75 Malibu S spring type or a 72 caprice clutch type Eaton posi in sometime, but haven't been motivated enough yet. The Caprice unit isn't acting real posi ish in snow/ice, but is quiet running.

You should be able to find a 3.42 pretty easily, it seems that they are a common ratio around here. Take the cover off and look for broken chipped gears, glitter in the oil, smooth rotation and backlash in the ring and pinion. If all is well, pull the axles and look at the bearing surfaces. The wheel bearings are known to wear into the axles if ran low on lube or high miles. I'd change the wheel (axle)bearings or at least the seals while you already have the axles out.

To answer your question the only reason you'd have to know your spline count is if you were replacing just the axle shafts in your 88 rear end. They're a rare bird because they are 28 spline like the 82?-87 but longer like the 89-98. A one year part. If you buy a complete 89-98 rear end it will have 30 sp spiders and axles, but that's stronger and easier to find.

I hope this helps!

 

[nad427]

To answer your question the only reason you'd have to know your spline count is if you were replacing just the axle shafts in your 88 rear end. They're a rare bird because they are 28 spline like the 82?-87 but longer like the 89-98. A one year part. If you buy a complete 89-98 rear end it will have 30 sp spiders and axles, but that's stronger and easier to find.

I hope this helps! I have an 87 and a 88 laying side by side if you want measurements, let me know.

I've heard that about the measurement differences. I even had a passing thought about getting the shorter one and adapting it to fit my truck so I could maybe get some 10 inch wheels on it. But came to my senses since I already have one project car thats just sitting here. Do you know if the much later 98 type rear is a bolt-in, including parking brake stuff etc?

 

[jmg283]

I've heard that about the measurement differences. I even had a passing thought about getting the shorter one and adapting it to fit my truck so I could maybe get some 10 inch wheels on it. But came to my senses since I already have one project car thats just sitting here. Do you know if the much later 98 type rear is a bolt-in, including parking brake stuff etc?

I don't know how late you can go for exact parking brake fit etc., but when I called about a complete rear end for our 99 GMC Yukon, they said there was a waiting list. I knew they had scores of 88 up trucks in their yard because I had been there for a seat belt for my 89. When I asked they said something about the sway bar on the 99 SUV. What else is different, I don't know.

It seems like a lot of parts are the same 88-94, but I'd be guessing with the later ones. I have a 90 3.42 open (or gov-lock) I'd sell you, but it's a long way from my house to yours.

 

[hotrodg726]

I find it hard to believe that it would cost 1500 to rebuild your rear end.
400 for a posi
125 for a bearing kit
300 for axles if needed
250 to assemble.
I doubt you need a gear set. but that would be another 175
if you skip the posi you could do this really cheap.

 

[jmg283]

I find it hard to believe that it would cost 1500 to rebuild your rear end.
400 for a posi
125 for a bearing kit
300 for axles if needed
250 to assemble.
I doubt you need a gear set. but that would be another 175
if you skip the posi you could do this really cheap.

When a carrier bearing in our 99 Yukon failed (85k miles)and the confetti went through all the other bearings, the junkyards had waiting lists because of GM using light weight synthetic starting about 99. (their words, not mine). My brother got all the bearings and seals at his business cost for about $225/250. The maligned gov lock, axles, ring and pinion was fine. It has about 55k since and no problems. I ran 80w90 in it since the rebuild.

 

[nad427]

Wish I could call the guy and dictate my own made up prices, but I doubt that'd work. This guy works out of his own barn with no lift and quoted me 1487.00. That's close enough to 15 to call it 1500.00 in my book. Other 'official' shops with with main street addresses and business licenses were north of 1900.00, so I'll just say 1900. This is why the thought came to my mind to buy my own tools and do it myself.

JG283, thanx for the info you provided. This is why I love this site so much. I'll be getting ahold of you via pm as I progress, Dan

 

[Chevyragtop57]

Sorry for the problems. I never heard of using lightweight gear oil in a rear end. I always use 80w90. Mike

 

[TheHotrodHandyman]

Try looking here, They are all over my area from $135 up already out of the vehicle.

http://www.car-part.com/

 

[hotrodg726]

Wish I could call the guy and dictate my own made up prices, but I doubt that'd work. This guy works out of his own barn with no lift and quoted me 1487.00. That's close enough to 15 to call it 1500.00 in my book. Other 'official' shops with with main street addresses and business licenses were north of 1900.00, so I'll just say 1900. This is why the thought came to my mind to buy my own tools and do it myself.


the point here Dan was if you source and buy the parts your self, you could save some coin. the only thing you need special to do the job is a dial indicator and beam type inch lb. torque wrench. if it is just bearings and no other parts needed you could do the job yourself and save the labor for under 300 and be on the road. I am kind of cheap that way. if I cant do a job my self I will source the parts myself then only pay what I have to for labor. also it is much easier to do the rear end on a bench vs. in the truck.

 

[nad427]

Try looking here, They are all over my area from $135 up already out of the vehicle.

http://www.car-part.com/

That's a really cool site Bruce, I bookmarked it. Thanx for turning me on to that.

the point here Dan was if you source and buy the parts your self, you could save some coin. the only thing you need special to do the job is a dial indicator and beam type inch lb. torque wrench. if it is just bearings and no other parts needed you could do the job yourself and save the labor for under 300 and be on the road. I am kind of cheap that way. if I cant do a job my self I will source the parts myself then only pay what I have to for labor. also it is much easier to do the rear end on a bench vs. in the truck.

If I do it myself the parts I will source myself.
Tools I need that I don't have..
shop press
brass drift punches
inch pound torque
depth gauge
really bigass pipe wrench (or some other means to hold the pinion during crush sleeve operation)
long pipe for axle bearing removal
bearing separator and tooling for it
Etc

I really do want to do this myself, if nothing else just for the knowledge and experience, but Bruce spun my head out with his site. The prices just can't be beat so far. Plus, unbolt and bolt back with nothing in-between means use of truck in just one Saturday's work is kinda appealing. As usual for me, decisions get complicated.

 

[maddogs1965]

Dan

Probable a stupid question, but since it is throwing gear oil every were, have you checked the pinon nut to make sure it has not just backed out? It sounds like the bearing behind the in-put shaft has taken a dump, and a new bearing, crush sleeve and pinion seal would most likely fix the issue if it hasn't already let the pinion suck back in enough the start scoring the ring gear. It is pretty hard to damage a open rear end.

 

[hotrodg726]

I don't have half of the things on your list. If you are not replacing the ring and pinion you don't even need a depth gauge. as far as bearing separators I gut the inner races 90% of the way thru then split with a chisel. they almost fall of that way. as far as a press I have a cheap one but you could get the 3 bearings that need to be pressed on done at any local shop for 1/2 hr labor.

 

[nad427]

Dan

Probable a stupid question, but since it is throwing gear oil every were, have you checked the pinon nut to make sure it has not just backed out? It sounds like the bearing behind the in-put shaft has taken a dump, and a new bearing, crush sleeve and pinion seal would most likely fix the issue if it hasn't already let the pinion suck back in enough the start scoring the ring gear. It is pretty hard to damage a open rear end.

Hi Rick!
Pinion nut tight. Hard to tell though because of the crush sleeve.
Pinion bearing trash. Yoke moves all around sideways and up-down and is puking 90w plus metal. Not good symptoms to the eye.

The more I think of this the more getting a whole working rear assembly seems the smarter thing to do. Who knows the damage I might find in mine, which equals a waste of work, tools, and parts if that's the case. Over 300,000 miles with part of it with broken parts should be a clue.

 

[maddogs1965]

Hi Rick!
Pinion nut tight. Hard to tell though because of the crush sleeve.
Pinion bearing trash. Yoke moves all around sideways and up-down and is puking 90w plus metal. Not good symptoms to the eye.

The more I think of this the more getting a whole working rear assembly seems the smarter thing to do. Who knows the damage I might find in mine, which equals a waste of work, tools, and parts if that's the case. Over 300,000 miles with part of it with broken parts should be a clue.

I hear ya having 300,000 miles on the truck....It sure sounds like the pinion bearing just took a crap.

The metal shaving's are most likely from the bearing itself or it is eating the race that the bearing rides on. Up and down movement is ok, that tells ya the bearing is history, but if the pinon can be moved in or out, that is when it starts eating the pinion and ring gear and chipping or breaking teeth off, i bet if you pop the rear diff cover, you will not find any damage (minus the 300,000 miles of normal wear and tear) to the ring and pinion.

If it as me, I would pop the rear diff cover and see if the ring & pinion or the spider gears have any damage to them, if not i would buy a new pinion bearing with a new race included, crush sleeve, and pinion seal and slap it back together. If there is scoring to the ring & pinion or the spider gears, then ya up grade to the newer style complete rear end housing.

I guess it all comes down to how much money you want to put into a truck with 300,000 miles on it.:sign0020:

 

[nad427]

I hear ya having 300,000 miles on the truck....It sure sounds like the pinion bearing just took a crap.

The metal shaving's are most likely from the bearing itself or it is eating the race that the bearing rides on. Up and down movement is ok, that tells ya the bearing is history, but if the pinon can be moved in or out, that is when it starts eating the pinion and ring gear and chipping or breaking teeth off, i bet if you pop the rear diff cover, you will not find any damage (minus the 300,000 miles of normal wear and tear) to the ring and pinion.

If it as me, I would pop the rear diff cover and see if the ring & pinion or the spider gears have any damage to them, if not i would buy a new pinion bearing with a new race included, crush sleeve, and pinion seal and slap it back together. If there is scoring to the ring & pinion or the spider gears, then ya up grade to the newer style complete rear end housing.

I guess it all comes down to how much money you want to put into a truck with 300,000 miles on it.:sign0020:

Most of the time whenever Chevy changed to a new bodystyle I seem to always like the first year of it best. 68 Corvette, 68&70 Chevelle, 70 Camaro, 88 Chevy pickup, etc.

I like my truck. It's a POS in others opinions and that's ok, but I like it. I don't have to be 10 feet tall or have to use a ladder just to get things in and out, it has FI but not so overcomplicated that I can't understand it, plus I really like the bodystyling. This truck has a lot of miles but has been THE absolute most dependable car I've ever owned. Even with all those miles it gets me back and forth no matter how far away without much trouble, til now anyway.

My plan is new rear, motor, tranny, paint, interior and on and on just cuz I like it so much. Ever had a car like that yourself?

Right now I don't drive it cuz of the rear prob, but after that's fixed it'll get me back and forth to your house without a worry, for now anyway.

I hear your points above about checking out the existing rear. But I'm also seriously thinking now about getting another known working complete 89-90 rear (for the better axles), bolting it in and using the truck. Meanwhile I'll gather tools and parts if the 88 rear is rebuild-able, and get my jollies setting it up and either keep it for later or sell it to someone who needs it.

 

[maddogs1965]

Most of the time whenever Chevy changed to a new bodystyle I seem to always like the first year of it best. 68 Corvette, 68&70 Chevelle, 70 Camaro, 88 Chevy pickup, etc.

I like my truck. It's a POS in others opinions and that's ok, but I like it. I don't have to be 10 feet tall or have to use a ladder just to get things in and out, it has FI but not so overcomplicated that I can't understand it, plus I really like the bodystyling. This truck has a lot of miles but has been THE absolute most dependable car I've ever owned. Even with all those miles it gets me back and forth no matter how far away without much trouble, til now anyway.

My plan is new rear, motor, tranny, paint, interior and on and on just cuz I like it so much. Ever had a car like that yourself?

Right now I don't drive it cuz of the rear prob, but after that's fixed it'll get me back and forth to your house without a worry, for now anyway.

I hear your points above about checking out the existing rear. But I'm also seriously thinking now about getting another known working complete 89-90 rear (for the better axles), bolting it in and using the truck. Meanwhile I'll gather tools and parts if the 88 rear is rebuild-able, and get my jollies setting it up and either keep it for later or sell it to someone who needs it.

I am no pro at setting up rear ends, and have never purchased the correct tools to measure the back lash & pinion pre-load, but Persian Blue has treated me pretty good since i have gone threw at least 8 broken pinion's in my 65 L.C. Needles to say the pinion is the weak link on all stock L.C. rear end's. All of there stock running gear is rated to the equivalent of a Dana 60, then they went and wimped out on the pinion thickens, it is about the thickness of a size two pencil :sign0020:
And thank god no stupid crush sleave to mess with every time.


And yes the Throttle Body Injection fuel injection is a very easy and reliable style to use and work on, if it only produced a little more H.P. like the multi port F.I. does....