I have a 68 MAlibu Convt. with a non posi 3.08 ratio 10 bolt. The rear end has never been worked on and it seems to get really hot while driving and was wondering if this was normal? By hot I mean after a 15 mile drive it's really hot to the touch. After a 90 mile drive you can only hold your hand on it for about 1-2 seconds without burning. THe heat seems to be located twords the front where the driveshaft hooks in but the whole thing gets hot. There is plenty of fluid in it and I change it regularly. I pulled the plug after a 90 mile drive yesterday and the fludi came rushing out (sems like it expanded) but did not burn my hand. Any Ideas? Is this normal or should I have it rebuilt? Would it be ok to drive another 5k miles or so to get me through the summer?

If I rebuild it I was thinking of going to a Auburn Posi with Richmond 3.23 gears. Any Comments/sugestions would be much appretiated.

Temperature increases in an axle are pretty normal. The heat results from the gears churning the oil. I once worked in a test lab for axles and they had a water spray to cool the center portion of the axle when it was on a dyno.

If the heat is located ner the front where the u-joint hooks up, I would ask you if you recently had the pinion yoke off, and what procedure you used when it was put back on. If it was removed and not done correctly, it could have been overtightened which would crush the sleeve and put too much preload on the bearings, which could result in high operating temps.

At my shop, we charge $185 labor to replace bearings, and the bearing kit runs about $125. Axle seals are usually replaced at the same time, & they cost about $7 for the two, no extra labor cost. The bearing kit comes with a new crush sleeve, all the bearings, pinion seal & nut - axle bearings are extra and if the axle is worn, it would be time to put in an axle saver bearing & seal combination, or to replace the stock type axle bearings, you will need new axles if they are bad.

Do you hear any growling coming from the rear? If so this may be your problem. If not, it may be normal. Rear diffs do get hot, but in your case it sounds a bit excessive.

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70 & 1/2 RS Camaro
SB406 & M20 4spd
9" Rear
70 Malibu
SB350 & TH400

Gold Member # 103



[This message has been edited by Scooter (edited 07-12-99).]

Since we're on the subject of 10 bolts, I'm going to try to find a ring and pinion set at the next swap meet. (3:23s or 3:31s) I've seen gears for 8.2 and 8.5 inch rear ends sold in Jegs and Summit. How do you tell the difference between the two, which one came stock in a 71 Chevelle, and what do I need to look for to identify the right one for my car? Scooter pretty much hit the nail on the head for your problem, Cortese. I would suspect pinion bearings. Any noises?

It's funny becouse there is no noise at all and everything feels smooth. I never seem to remeber it getting that hot but it may be normal and me just being paranoid. I take it for 100 mile trips every weekend in the summer so I dont want to be dead in the middle of the trip.

I have never had the pinion off but have had the rear cover off and rebuilt the driveshaft and things look good inside. Scooter, You mentioned that the axle bearings (at the wheels?) are extra? Should I have these replaced also. I am of the thinking to replace eveything.

On another note we have a 93 chevy truck with a 10bolt rear and after a 100 mile trip it feels about the same temperature. I think the 68 may be a little warmer but not much...

Skunkynuggets, scooter and I went around a bit on the topic of how to tell an 8.2 from an 8.5. Didn't we agree on counting pinion splines? I forget. BTW, for my $.02, scooter is usualy right in the money with his advice.

As I mentioned, if the axle bearings are bad, you will have score marks on the axle. You can go with axle saver bearings, at about $35 each, or you can buy new axles, and use the stock style bearings. These bearings are pressed into the tube, and the axle rides on it.

How to tell the 8.2 from the 8.5?

Pull the cover.
Look at the bolt that holds the spider gear pin in the carrier.
If it needs a 1/2" wrench to remove it, it's an 8.2, or if it needs a 5/16" wrench to remove it, it's an 8.5.

Most likely a 71 came with the 8.2.

Ddoler, thanks for the compliment, it means a lot.

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70 & 1/2 RS Camaro
SB406 & M20 4spd
9" Rear
70 Malibu
SB350 & TH400

Gold Member # 103



[This message has been edited by Scooter (edited 07-20-99).]

If in doubt, check the heat on another car. That may make you feel better.

(I sure hope you know somebody else with a GM)

Wes.