GTR1999 - Rear Axle Parts Questions For You.

[SVO]

I have seen reference to a “Type A”(big block) rear axle and a “Type B” (small block) rear axle. My understanding is the difference between the two is the big block model had gears sets made of high nickel alloy for impact resistence, 400 pound pre-load springs, and the cap type stub axles. Were there other differences between the big block and the small block rear axles? I ask, because I would like to up-grade a small block rear axle for moderate street use with a big block car. Gear set will be from Tom’s.

I purchased a batch/bunch of rear axle parts out of an estate sale (bought a car also as part of the deal). Included were a pair of the reproduction cap type stub axles. Do you have an opinion on the quality of the repo axles?

Also included was a new in the box Eaton differential. Box indicated the diff has carbon fiber clutches. Any opinion on the quality of the carbon fiber clutches compared to the old style clutches?

Quality of SKF bearings compared to Timkin bearings?

Would you know of a source for the 400 pound pre-load springs?

Would appreciate your opinion so as to figure out what to keep and what to swap meet.

Thanks,
Bob

 

[GTR1999]

Hi Bob
I have heard the BB vs SB diff comparisons for years and have rebuilt a ton of them. I never saw a difference between the BB & SB diff's other then the axles and stampings. I have not seen an axle break at the yoke so while the "HD" term for the cap axles has been tossed around for years the std U-bolt axles are still pretty good.

I have seen axles twist splines, wear down the faces past the snap rings and grind into the housing. The "new" stock 17 spline axles I have seen are all imported and again the ones I had were JUNK. I found the snap ring groove in the wrong place( guess the Chinese copied a worn out axle), the axle faces were soft- just like the junk GM used from 73-79. I confronted the supplier about this at Carlisle about 8 years ago and he coldly told me he knew what he was selling was soft faced. I never bought another "NEW" axle again. If you have a 63-72 axle check the dimension from the face to the snap ring and check the hardness of the face. I have found most of these to be in like new condition, mostly with the 63-69's but the 70 into 73 are good a lot of the time.

Eaton sells various rated springs for the posi's as well. I never use springs in my posi builds. I polish and tune every posi I build and machine fit them for -0- lash and endplay. Then I run them in on a machine I built. You can see Tom do this on YouTube as well. I have used some of the new loaded Eaton posi's, but only for the cases. I don't like the spiders, huge springs, or the fiber coated clutches. They smudged off in my hand without much pressure. They will work but will be wearing off every corner you make. I use only solid steels and tune them as mentioned.

SKF made good bearings some still in the USA. I have not used them in a diff or trailing arm. I use only Timkens and still can get USA made, although for how long who knows.

Tom's ring and pinion are the best and some rebox and sell them. Get them while you still can. Use ARP Ring Gear bolts over kit bolts or reusing originals.

Toss out the idea about BB vs SB now you know much better and leave the hype to those trying to sell over priced parts on auction or forum sites. Build the diff to your application, if you can do it yourself all the better. Expecting to find someone in the vette business to build one like I do- I doubt it. You will get stamped out common rebuilds from all of them but look at them and ask how they are built. Then check my threads on DC or I can send you the links. One of my blueprinted diffs is good into the 400hp range but a lot depends on power, trans, traction and your right foot. I will be glad to go over any questions you have, just email or call me.

 

[toobroketoretire]

My '82 still has it's original side yokes after almost 300,000 miles and they still look like new.

 

[GTR1999]

My '82 still has it's original side yokes after almost 300,000 miles and they still look like new.

That is impressive. Last year I rebuilt Jack Panzica's 66 diff ( actually it was a 68 diff in his 66) that had 300k on it before the posi imploded. This was an iron unit with Eaton posi. These are much stronger diff's then the 80-82 DANA's so that is a lot of miles on the diff but I bet they weren't abusive miles. The DANA diff's use aluminum bearing caps, have issues with the clutch retainers getting chewed up and many have had issues with them, while others like yourself have not. I personally do not like them so I won't take them in. I gave away all the DANA parts I had including a supposedly rebuilt complete DANA diff I took in trade that turned out to be junk. The axles do wear on these too but they are not the same as the 63-79's.

 

[SVO]

Well crud, Gary, I was afraid you might say something like this. Tossing the differential and stub axles into the swap meet pile leaves me with a empty case and a gear set. The car currently has a 2:75-ish rear end. The previous owner fubar'd the original 3:08. According to his wife and son, he turned a corner and punched it, the stub axle exited the case and then made a new hole in the side of the case. Supposely, the whole differential was destroyed, and the PO started gathering parts to build another rear for it. I was hoping to put the pile of parts together and then spent a weekend changing out the rears. I don't want the car down for a long period of time, so I guess I need to find myself another good differential and rebuild that.

When you say "your threads on DC", what is "DC". That abbreviation escapes me.

Thanks again for the advice, I'm sure I'll be back with more questions.

Best regards,

Bob

 

[GTR1999]

Hey Bob,
Well I didn't want to sugar coat anything. Now there will be guys out there that will tell you they abuse the heck out of their 80-82 DANA diff and it's fine. That may or may not be true but I won't change my stance on them. Yes you should be able to find complete 80-82 online, how good they are is another question. It comes down to time and money, like any project. I have converted the 80-82's to the irons and those were pushed pretty good and held up. Yours can be rebuilt and a steel cap and c4 posi added but it's not worth the cost in my opinion, yours may differ.

DC= digitalcorvettes.com another forum. I can post links here if allowed otherwise email me at gtrvette1999@gmail.com and I'll get you the info. A fellow on there did go through one of these last year and posted pictures of the build. Unfortunately the last DANA diff I had I shipped to him to use and he found the housing was warped.

If you want to look around locally for a 71-79 parts car, take the diff, brackets, driveshaft, 1/2 shafts, and outer axle inner flanges for conversion to iron. It will add about 30-40 lbs to IRS.

 

[SVO]

LOL Gary, you have confused me with Twobroke. I was asking questions pertaining to my '69. Of the two us, I would like to think I'm prettier than Twobroke. :L

Again, thanks for the opinion, as you told me what I needed & wanted to know. I'll look up your posts on DC.

Bob

 

[GTR1999]

Ah, a 69 diff is a bit different.

Some things to know about a 69.

1. Has the wider carrier ( housing ) which is better then the 63-66's had
2. First year for the better Eaton posi, but some early 69's had left over 1st design Eatons
3. Posi used 10-18 spiders, not as good as the 71-79 10-17 spiders
4. Posi used solid steel clutches, the best. The 71-79 used the "snowflakes" Aftermarket used fiber coated, stay with solid steels
5. GM gears are date coded so you can see if you have original or replacements. Look on the side of the Ring Gear for the stamping information.
6. Many of the axles are still in good shape, if original. Measure from the axle face to the snap ring = if .200" to .190" I bet you will find the hardness in the 50-55 Rc scale.

 

[GTR1999]

PS- the 71-79 308 complete diff's are your best bet to build up. They are usually out of low powered automatics and worth about $300.

 

[SVO]

Zombie thread back from the dead.

Have picked up a complete rear suspension and 4 sp transmission out of a 69 small block car according to codes on the housing. Guy I got it from says that he has had it 40 or so years. I trust his word from previous dealings with him. Only downside is a torch was used to remove the trailing arms and the diff cross member. It's a 3:36 posi, and when I removed the rear cover, it all looks pretty good inside. Have it soaking to clean out the old gear oil. My plan is to clean it up, replace the seals and use it as it to temporary replace the 2:73 currently in my '69. I'll dig into the 2:73 and rebuild it with a 3:36 gear.

My pile of parts I was asking Gary about have been disposed of on Craigslist. Now to start the fun.

 

[GTR1999]

Zombie thread back from the dead.

Have picked up a complete rear suspension and 4 sp transmission out of a 69 small block car according to codes on the housing. Guy I got it from says that he has had it 40 or so years. I trust his word from previous dealings with him. Only downside is a torch was used to remove the trailing arms and the diff cross member. It's a 3:36 posi, and when I removed the rear cover, it all looks pretty good inside. Have it soaking to clean out the old gear oil. My plan is to clean it up, replace the seals and use it as it to temporary replace the 2:73 currently in my '69. I'll dig into the 2:73 and rebuild it with a 3:36 gear.

My pile of parts I was asking Gary about have been disposed of on Craigslist. Now to start the fun.

69's will have the later tear drop posi case with the 10-18 spiders. The Ring Gear will be dated coded on the side.
If it was sitting for 40 years I would check those bearings too. The bearing caps should not have the tabs cast into them.