I was reading a page on Z car modifications.Eventually they got to a section about changing the rear end ratio and correcting the speedometer.I know old subaru's and old datsun's shared alot of parts, so it is possible that speedometer gears for a datsun might work in a subaru to correct for different sized tires.For instance according to the website the WHITE gear is 19 tooth for 3.90.I took apart an old 4 speed DR and IIRC it had a white speedometer drive gear.Anybody know how many teeth the speedometer drive gear has for our subies?If its the same than re-gearing the speedometer might be possible.

 

just as a point of reference here are the datsun colors and teeth counts:

 

YELLOW is the 16 tooth for the 3.36

BLACK is the 17 tooth for the 3.54

BLUE is the 18 tooth for the 3.70

WHITE is the 19 tooth for the 3.90

RED is the 20 tooth for the 4.11

PURPLE is the 21 tooth for the 4.38

Good post not many of these around.

You have to replace the "drive gear" and the "driven gear" as a set.

 

My most recent replacement i used part numbers for a turbo 3.9, and they were white with black on the small gear i believe

 

The old set coming out was green with white i believe.

 

Anyhow, the old big gear was smaller, than the new replacement set big gear. On the new small gear, it was bigger, so they match correctly.....

 

I think my speedo is still about right, I changed to 15" from a 14" anyhow, and went a size taller due to snow tires..

 

 

good thread.

Interesting.

 

The drive gear on the 5MT's is part of the pinion and cannot be changed. No provision for different driven gears was provided by Subaru because the final drive is part of the pinion shaft of the front diff. Unlike a Datsun where there is no final drive in the transmission but you still need a way to change the speedo ratio correspondingly when different final drive rear diffs are used.

 

So this doesn't really apply to the Subaru MT's.

 

GD

I thought it might be worth sharing but I guess it won't work for us.

Holy Cow, I Liked this Thread because since I went from 13" to 15" Tires on my BumbleBeast, the Speedometer reads way too low.

 

Then I Read this:

 

...The drive gear on the 5MT's is part of the pinion and cannot be changed. No provision for different driven gears was provided by Subaru because the final drive is part of the pinion shaft of the front diff. Unlike a Datsun where there is no final drive in the transmission...

 

And as Usual, GD is Right; so there's no way to do that on my 5MT BumbleBeast, but there are aftermarket Rate Changin' Boxes, such like This:

 

 

http://www.transmissioncenter.net/speedometer_calibration_______va.htm

 

Little in-Line Speedometer fix, known as "Ratio Adapter":

 

 

There's a Thread about that:

 

http://ultimatesubaru.org/forum/showthread.php?t=128049

 

 

Kind Regards.