BW T10 Followup

[Bob Scott]

Now that we know it's a 59 to 61 T10 can you tell me what speed gear (ie how many teeth) I need for 3.36 gears and stock tires (ie 6.70x15).
As usual, thanks again. Bob

[Joe L.]

Re: BW T10 Followup

Bob------

Assuming that you have the correct DRIVE gear installed in the transmission, which is likely, then you require a BLUE, 20 tooth DRIVEN gear of GM #3987920. If the DRIVEN gear that you remove is of 18-21 tooth count (or, a SILVER gear of 22 tooth count), then you have the correct DRIVE gear which will be compatible with the 20 tooth DRIVEN gear.

[Bob Scott]

Re: BW T10 Followup *NM*

[Bob Scott]

BW T10 Followup - Joe Lucias

Thanks Joe: But what if the nylon gear I took out is 24 teeth? - It also has an S and a 3 stamped on the gear. I believe this gear was for a 4.56 rear end, but someone told me that gear should be metal. I would just like to get it close for the 3.36 rear end w/o having to change the drive gear. Your the best.
Thanks, Bob

[Joe L.]

Re: BW T10 Followup - Joe Lucias

Bob-----

If the gear that you took out is a 24 tooth (and, assuming that it's not "chewed up" as it would be if it was installed against an incorrect DRIVE gear), then you will have to change the DRIVE gear in the transmission to use the 20 tooth gear necessary for a 3.36:1 ratio. The DRIVE gear that the 24 tooth DRIVEN gear is compatible with is the GM #3708145. The DRIVE gear that you need for the 20 tooth DRIVEN gear is GM #3708144. Both are discontinued, but available aftermarket or used.

Your 24 tooth DRIVEN gear should be YELLOW and was used with 4.11:1 ratios.

Another option for you if you don't want to change the DRIVE gear, which is very understandable as NO ONE wants to have to change a DRIVE gear, is to use a speedometer adapter. This is a device which mounts onto the transmission speedo fitting and to which the speedo cable then attaches. It changes the output speed of the installed speedo gears by a specified ratio. Doing this is not a task that you can really accomplish yourself since it may require changing the DRIVEN gear (still to a 22-25 tooth compatible with your DRIVE gear, of course) PLUS the possible custom calibration of a speedo adapter to achieve an accurate speedo reading. So, you really need to take the car to a speedometer shop which has the experience, capability and parts to perform this work.

STRICTLY AS A "GUESSTIMATE", I'm going to offer that if you were to install a 22 tooth GREEN DRIVEN gear of GM #3860345 PLUS speedometer adapter GM #15635469 (which has a 1:1.1111 ratio), that would get you very close. BUT, IT'S JUST A GUESSTIMATE. First off, I don't know if this adapter would be compatible with your existing speedometer cable length PLUS these adpaters are expensive (this one is $57.82 GM list) PLUS you may need other parts (called keys) to make it work.