Ring Gear Part Number

[Chuck G.]

Need some help. Went to look at a supposed 62 Corvette 4.11 posi rear today.

Well, it's not a Corvette rear. It's dated K 28 61, and has a few "T's" cast on the case, so it's a Tonawanda casting. The casting # of the case is 3789812. Has the big "P". It's definitely a posi rear.

Couldn't find anything stamped on the case indicating ratio, but it was awfully greasy.

I was dressed in my "dental togs" as I went at lunchtime, and couldn't get TOO dirty, as I had patients in the afternoon.

The number on the ring gear is 3830270. Couldn't see the number on the pinion.

Can anyone check this number? Is it a 4.11 ring gear?

This isn't for any Corvette....it's for my 56 Chevy, so I don't care about matching numbers, I just want to know the ratio.

TIA.

Chuck

[Joe L.]

Re: Ring Gear Part Number

Need some help. Went to look at a supposed 62 Corvette 4.11 posi rear today.

Well, it's not a Corvette rear. It's dated K 28 61, and has a few "T's" cast on the case, so it's a Tonawanda casting. The casting # of the case is 3789812. Has the big "P". It's definitely a posi rear.

Couldn't find anything stamped on the case indicating ratio, but it was awfully greasy.

I was dressed in my "dental togs" as I went at lunchtime, and couldn't get TOO dirty, as I had patients in the afternoon.

The number on the ring gear is 3830270. Couldn't see the number on the pinion.

Can anyone check this number? Is it a 4.11 ring gear?

This isn't for any Corvette....it's for my 56 Chevy, so I don't care about matching numbers, I just want to know the ratio.

TIA.

Chuck

Chuck-----


I can't find that number. However, it looks to me like it's from a series of part numbers used to convert numerically low R&P gearsets to numerically high gearsets. My GUESS would be that this ring gear is part of either a 5.13:1 or 5.38:1 gearset. A tooth count on the ring gear might help confirm this.

[Chuck G.]

Re: Ring Gear Part Number

Chuck-----


I can't find that number. However, it looks to me like it's from a series of part numbers used to convert numerically low R&P gearsets to numerically high gearsets. My GUESS would be that this ring gear is part of either a 5.13:1 or 5.38:1 gearset. A tooth count on the ring gear might help confirm this.

Thanks, Joe.

I'm going to go back up on Wednesday, my day off, when I can get "down and dirty" and look it over better.

This rear has been sitting in this fellow's shop for over 30 years. Needs a total rebuild, so it's certainly no "barn find". Also, NO idea how much $$$ he wants for it.

5.13's, 5.38's? WAY too high (or low depending on your point of view) for me.

Someone gave me a 200R4 overdrive automatic trans. It's sitting in my garage in Florida. 4.11's or 3.70's would work REAL well with the OD trans.

Right now, I'm running a Muncie 4 speed with a 3.36 open rear.

Chuck

[Dick W.]

Re: Ring Gear Part Number

Look on the end of the pinion, sometimes the tooth count will be stamped there such as 9-37 etc

[Chuck G.]

Re: Ring Gear Part Number

I looked, Dick, but it was so greasy that I couldn't "dig" into it.

Didn't bring any rubber gloves. I'll get a better look tomorrow.

Chuck

[Joe L.]

Re: Ring Gear Part Number

I looked, Dick, but it was so greasy that I couldn't "dig" into it.

Didn't bring any rubber gloves. I'll get a better look tomorrow.

Chuck

Chuck----


If you can't see a pinion stamping, just count the teeth on the ring gear.

41 teeth= 5.13:1 ratio

43 teeth= 5.38:1 ratio

Very few other R&P sets used the 41 and 43 tooth ring gears and those that did would be extremely unlikely in this case. So, if you find either of the above ring gear tooth counts, it's a virtual certainty that you have the ratios listed above.

I believe the pinion gear will be 8 teeth.

Let us all know what you find.

[Chuck G.]

Re: Ring Gear Part Number

Here's a little follow-up. Joe was spot on, as usual.

Went back today, in my "street clothes".

There are 41 teeth on the ring.....8 on the pinion 5.13 ratio.

Also, armed with my rubber gloves, I could see 41/8 stamped on the ring gear.

The ring gear is dated 11 65, so it's not original to that case.

WAY too high (numerically) for me.

Anybody want to go drag racing with a high winding small block can give me a call.

Chuck