Nine Inch Rear Question (rather off topic, I apologize)

Gentlemen, I was doing about 85 mph on the interstate on Sat. in my 1969 XL convertible, when suddenly my pinion shaft snapped. This was an OEM Ford piece 3.25 nine inch, limited slip set up. I do have a shorter drive shaft and a Gear Vendors overdrive unit behind the 429 / C6 combo.

It made some scary noises until I could pull over and shut off the engine.

My question: I left my pinion yoke, nut, and part of the pinion shaft somewhere on I-25 along with what I can only describe as an elastomer counter weight looking piece that sort of covered the U-bolts.

I could turn this piece to expose the nuts on the u bolts for disassembly, but it did not turn easily. The piece also had drill marks in it, which is what led me to the conclusion it was some sort of balancer.

That said, do I need to find a new one for my rebuild?

I figure that it's an old Ford part, which I could only find in a junkyard on another nine inch.

If I don't need it, then great, I'll just call Summit and get that Detroit Locker that I'd been considering anyway, along with a new drive shaft, yoke, and ring/pinion combo.

Oh, this car came OEM with a nodular case rear end and 31 spline axels.

I know this matters when specifying the differential, but how about the pinion yoke? Summit lists 28 and 35 splines for the pinion yoke.

Are they referring to the splines on the pinion gear? How do I know what I had / have, as the pinion gear was sheared off a little inside the oil seal.

Thanks so much.

I've done engine work, but never messed with the rear end other than fluids.

Jim

28 and 35 would be for the pinion yoke...normally 35 splines are for the softer Pro-racing gears, etc.

Jim
You have a 28 spline pinion. The 35 is for the big pinion pro series gears and takes a special pinion support.
Rich

I have seen those elastomer things on stock driveshafts before but never one that moved or turned on the shaft???

I'm thinking yours was faulty anyway.

Either way not a required part.

My suggestion would be to order your new center section with a 1350 series yoke and then have a new driveshaft built to suit. If you are buying a new one anyway's the difference in cost is minor and the piece of mind is great.

dkp

Thank you all so much for your help.

Bosshoss, I believe that you are correct in your observation.


I think that the elastomer thing was faulty (it should not have moved) just like a really old harmonic balancer, and simply came apart. The fact that it sheared off the pinion gear just at the seal ( a clean 90 degree break just where the balancer was located) seems to support this theory.

I called Randy's Ring and Pinion, and they said that although they had seen all manner of funny balancers on old Ford nine inches, they were not necessary. I figure that I'll just rebulid it without one, so that it can't explode my rear end again on me.

Thank you Quickford1. Just after I posted this I went to Summit and realized that the it was the number of the splines that are on the pinion and go into the pinion yoke.

I'll get a new one with 28.

Thanks again for the help.

Jim