What gears does this 915 have in it?

[Greg_Duncan]

I'm trying to find out what gears are in a 915 trans from a `80 SC.
The only numbers on it are 915303221.1R
Can someone help me find a way to tell what CWP it has?

Thanks,

Greg

[bigchillcar]

only thing i'd be pretty sure about is a 8:31 ring and pinion..
ryan

[Early_S_Man]

Greg,

That is a casting number, not any sort of ID number! What you need to find and post are the serial number [beginning with 7] and Type Number in the form 915/xx ... both are stamped on the bottom rib near the drain plug.

[Greg_Duncan]

OK, I'll have to look again for the correct numbers from this trans.

What kind of Type number would I be looking for to find a 915 with
an Aluminum case and 7:31 CWP? I have not been able to find any
place on the internet yet that lists what the CWP is with the rest of
gear ratios matched with a type number.

Thanks,

Greg

[RallyJon]

Here's one: http://members.rennlist.com/chuxter/901&915ratios.htm

[IROC]

Originally posted by Greg_Duncan
OK, I'll have to look again for the correct numbers from this trans.

What kind of Type number would I be looking for to find a 915 with
an Aluminum case and 7:31 CWP? I have not been able to find any
place on the internet yet that lists what the CWP is with the rest of
gear ratios matched with a type number.

Thanks,

Greg

All of the 7:31 915s were mag-cased, I do believe. 7:31s were only offered as a stock ring and pinion in the '72-'74 915s (all of which were magnesium cased).

Mike

[Greg_Duncan]

Thanks RallyJon,
I had found that one before, but it looks like it may not go new enough and it shows normal vs. option CWP without matching
a type number to a specific CWP gear ratio. Is there such a list
out there? Or do I have to take a chance when purchasing?
Or is disassembly necassary?

Thanks,

Greg

[Greg_Duncan]

Originally posted by IROC
All of the 7:31 915s were mag-cased, I do believe. 7:31s were only offered as a stock ring and pinion in the '72-'74 915s (all of which were magnesium cased).

Mike

So if I want an aluminum case 915 with 7:31 CWP, I'd have to purchase the gear set seperately and install it to get that combination?

Greg

[Bill Verburg]

If it's a stock US '80 SC it's tpe # is 915/63

cwp is 8:31

Ratios are[list=1][*]11/35[*]18/32[*]23/29[*]26/26[*]28/23[/list=1]

electric speedo

[IROC]

Originally posted by Greg_Duncan
So if I want an aluminum case 915 with 7:31 CWP, I'd have to purchase the gear set seperately and install it to get that combination?

Greg

Yeah, most likely - people do it all the time. And keep in mind that all of the original 7:31s were meant to be used with mechanical speedometers and *all* of the aluminum-cased 915s fed electronic speedos. Not the end of the world, but something to consider.

Mike

[Bill Verburg]

The al. case 7:31 cwp set is different from the mg. case one. Heyden explained the difference once but it escapes mw now. May be the e-speedo thing.

Try a search on user name "Wevoid" Haydens screen name