Number of axle splines on the Z11 cars?

Blk61409

Well Known Member
Supporting Member 7
#6
Tenxal above has a point.

My Z car has its original axles, both are the same as any other car I have.
I have heard for years about the possibility of different side gears and axles that were over the counter or shipped to guys like Bill Jenkins, etc. I never encountered them and I doubt they would have stood up.

In that day running either a 409 or Z-11 the Chevy rear end was ok when having to roll out and then stand on it with 7” slicks.

In all reality it was easier to just put a ‘57 Pontiac under it, I ran one with a 4:88.

Just a little cutting old brackets off and welding the new Chevy ones on.

If you didn’t change and you campaigned the typical Chevy rear end you had to have lots of spare parts. If and when you began to use wider tires the Chevy was sure to come apart.

I stuffed some 9.5” under my 61 Flattop. With a .060 over 409 and Frank Sanders’ Z top half I launched about 5-6 times. Finally I launched hard, hit 3rd gear and all hell broke loose.
The Chevy rear end exploded, sheared the side bearings off the posi case, cleaned the ring gear, twisted both axles, one completely in half, torqued the entire rear end tube from backing plate to backing plate, and driveshaft destroyed.

Fortunately a friend owned a wrecker:)

I’m sure changing side gears and Mopar axles made a difference. I remember you were legal if it was a GM product, but if you had the Mopar axle nut sticking out, nooo, you were in some modified class!

Lots of rambling, but that’s what I remember.:):):)
 

oldskydog

Well Known Member
Supporting Member 9
#8
How many splines on the Pontiac rear?
When I bought my 61 block off a flatbed truck loaded with blocks and race parts from SoCal, there was a big box of posi parts. They looked very much like the standard GM posi but the side gears were 19 spline.
 

benchseat4speed

Well Known Member
Supporting Member 3
#9
I have a couple 57-64 Olds/Pontiac rears under my cars, even the ol’ 63 bracket car has one in it. Currently building two more for the 61 and the other 55. They are not cheap, but with Mark Williams billet caps and 35 spline axles they’ll take a hell of a beating. Broke an axle in the 55 last summer, 31 spline master line. Had a Trophy Track posi in it at the time, and that dang posi works so good, I DROVE it back to the pits from the starting line on one axle. Anyway....

57-58 olds/pontiac rears are all 29 spline with 2-rib case, 59-64 are all 31 spline with a 3-rib case. Everything else is interchangeable.

Well, almost everything. I think the pinion seal is different on 63-64 cases. Dave or Brad at Fabcraft can verify.
 
Last edited:

Fathead Racing

Well Known Member
Supporting Member 7
#10
Tenxal above has a point.

My Z car has its original axles, both are the same as any other car I have.
I have heard for years about the possibility of different side gears and axles that were over the counter or shipped to guys like Bill Jenkins, etc. I never encountered them and I doubt they would have stood up.

In that day running either a 409 or Z-11 the Chevy rear end was ok when having to roll out and then stand on it with 7” slicks.

In all reality it was easier to just put a ‘57 Pontiac under it, I ran one with a 4:88.

Just a little cutting old brackets off and welding the new Chevy ones on.

If you didn’t change and you campaigned the typical Chevy rear end you had to have lots of spare parts. If and when you began to use wider tires the Chevy was sure to come apart.

I stuffed some 9.5” under my 61 Flattop. With a .060 over 409 and Frank Sanders’ Z top half I launched about 5-6 times. Finally I launched hard, hit 3rd gear and all hell broke loose.
The Chevy rear end exploded, sheared the side bearings off the posi case, cleaned the ring gear, twisted both axles, one completely in half, torqued the entire rear end tube from backing plate to backing plate, and driveshaft destroyed.

Fortunately a friend owned a wrecker:)

I’m sure changing side gears and Mopar axles made a difference. I remember you were legal if it was a GM product, but if you had the Mopar axle nut sticking out, nooo, you were in some modified class!

Lots of rambling, but that’s what I remember.:):):)
Rambling the man says,,,,,,its history to me.
 
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