Speedo Gear Question
Thread Starter
Safety Car
Joined: Jun 2000
Posts: 4,870
Likes: 25
From: Long Island, NY
Speedo Gear Question
I am going from 3.07's to 3.73's, does anyone know what Speedo gear I need ?
Also, What does the Speedo gear control besides the speedometer ?
If I don't swap it right now, is it an issue ? This is on my 89 Vette.
Vic
Also, What does the Speedo gear control besides the speedometer ?
If I don't swap it right now, is it an issue ? This is on my 89 Vette.
Vic
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
You need the grey drive gear, and the 45 tooth driven gear.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
The grey, 15 tooth, drive gear, part number 8642620 , and the light blue, 45 tooth, driven gear, part number 25513052. There will be no need to mess with the VSS.
I don't think the speedo controls anything directly, but it does feed info to the ECM. On an '89, I don't think it affects anything critical.
RACE ON!!!
Thread Starter
Safety Car
Joined: Jun 2000
Posts: 4,870
Likes: 25
From: Long Island, NY
The grey, 15 tooth, drive gear, part number 8642620 , and the light blue, 45 tooth, driven gear, part number 25513052. There will be no need to mess with the VSS.
I don't think the speedo controls anything directly, but it does feed info to the ECM. On an '89, I don't think it affects anything critical.
RACE ON!!!
Thanks for the info guys, should I get these parts from a GM dealer or will a local Tranny place have them ?
Vic
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
The part numbers are GM part numbers. I would think that if a transmission shop had them, either they would have come from GM (and be marked up) or be used and maybe be a bargain. There would be nothing wrong with using used. The gears you've been using for years are "used". They aren't too, awfully, expensive, but by all means do some shopping.
RACE ON!!!
RACE ON!!!
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
It's not "an issue" but the drive gear on the output shaft is way easier to replace when you have the rear end out, You need to remove the support beam from the trans to remove the extension housing, you will kick yourself if you install the rear end then go back to do the drive gear.
Thread Starter
Safety Car
Joined: Jun 2000
Posts: 4,870
Likes: 25
From: Long Island, NY
It's not "an issue" but the drive gear on the output shaft is way easier to replace when you have the rear end out, You need to remove the support beam from the trans to remove the extension housing, you will kick yourself if you install the rear end then go back to do the drive gear.
I though this speedo gear install was an easy job, but now I realize that the tail from the Tranny has to come off.
Now I have to pull the C beam and complete this job. Like you stated, it would have been much easier with the Rear already out.
Vic
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
Guess what ? I completed the rear installation yesterday and took it out for a spin. Obviously the speedometer is way off.
I though this speedo gear install was an easy job, but now I realize that the tail from the Tranny has to come off.
Now I have to pull the C beam and complete this job. Like you stated, it would have been much easier with the Rear already out.
Vic
I though this speedo gear install was an easy job, but now I realize that the tail from the Tranny has to come off.
Now I have to pull the C beam and complete this job. Like you stated, it would have been much easier with the Rear already out.
Vic
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Pro
Joined: Dec 2002
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From: 84 383 XFire Chandler, AZ
When I swapped my gear in the tail shaft it was a pain to get off. It was as if it was welded to the shaft. I ended up scribing it with a dremel tool and breaking it in half. Pay attention to the orientation of the metal clip in the gear as well.
Team Owner
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