Gear Change & Speedo

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Feb 12, 2007 | 09:18 PM

severe-1

Thread Starter

Racer

Joined: Jun 2002

Posts: 411

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From: Palm City FL

Gear Change & Speedo

I am in the process of switching from a d36 3.07 rear to a d44 3.54 gear.

What do I have to do to correct my speedo? New gear of some sort in the 700r4 or maybe burn something in the chip?

tia

Feb 12, 2007 | 09:31 PM

Pete K

Race Director

Joined: Feb 2004

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A simple speedo gear swap is all that is nescessary.

Feb 12, 2007 | 10:26 PM

severe-1

Thread Starter

Racer

Joined: Jun 2002

Posts: 411

Likes: 0

From: Palm City FL

Okay, I went searching, but found nothing...
Anyone got a link?
(I love these online stores that you type in "speedometer" in their search engine and you get t-shirts)

Feb 12, 2007 | 10:47 PM

severe-1

Thread Starter

Racer

Joined: Jun 2002

Posts: 411

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From: Palm City FL

I searched the forum and found more info..
Still need a part #for the gear (3.54)
Also not really clear on how to change it...
Pull the tailshaft from the tranny?

Feb 12, 2007 | 11:00 PM

johnnyevans

Drifting

Joined: Mar 2002

Posts: 1,251

Likes: 2

From: Thomson Georgia

Here's some part #s for the 3.54 Gear, they may still be good. The driven gear was around $7, discount from GM.
The drive gear was the same on my 700R4, 15T 3.07 vs 3.54, seems like the driven gear was 39T on my auto. When I went to 3.73s, I went to a 45T driven gear.

43T 25513050
15T 25007308

'85-'96 Speed Sensor P/N 25007308
Drive Driven
3.54 15T 43T +3@100 speedo error

Feb 13, 2007 | 06:21 AM

rodj

Le Mans Master

Joined: Aug 2000

Posts: 8,838

Likes: 31

From: Australia

http://www.bowtieoverdrives.com/catalog/catalog.php?
Action=GETSUBCAT&CATID=DA2

$6.80 DRIVE GEAR
$8.60 DRIVEN GEAR

Feb 13, 2007 | 07:32 AM

Desert1957

Racer

Joined: Sep 2005

Posts: 271

Likes: 0

From: New Freedom PA

Speedometer Gears

Quote:

Originally Posted by rodj

http://www.bowtieoverdrives.com/catalog/catalog.php?
Action=GETSUBCAT&CATID=DA2

$6.80 DRIVE GEAR
$8.60 DRIVEN GEAR

Thanks ,

Any one know where us 1992 ZF-6 Speed guys can get tranny gears? I cannot do a PCM flash on a 92.
I would rather change the gears then Hack into my speedo-sensor and wiring...

Desert

Last edited by Desert1957; Feb 13, 2007 at 07:33 AM. Reason: additional info

Feb 13, 2007 | 11:29 AM

C4Techie

Racer

Joined: May 2006

Posts: 293

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Quote:

Originally Posted by severe-1

I am in the process of switching from a d36 3.07 rear to a d44 3.54 gear.

What do I have to do to correct my speedo?

Change the red, 17 tooth, drive gear for a grey, 15 tooth, 8642620, drive gear. You can keep your current, green, 42 tooth, driven gear and VSS. The transmission tailshaft housing has to come off.

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Feb 13, 2007 | 11:37 AM

C4Techie

Racer

Joined: May 2006

Posts: 293

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Quote:

Originally Posted by Desert1957

Any one know where us 1992 ZF-6 Speed guys can get tranny gears? I cannot do a PCM flash on a 92.

From GM and the other suppliers mentioned above. In most cases the 6 speed speedo gears are the same as the auto and 4+3 speedo gears.

Feb 13, 2007 | 09:52 PM

#10

Desert1957

Racer

Joined: Sep 2005

Posts: 271

Likes: 0

From: New Freedom PA

cannot find any speedo gears?

Quote:

Originally Posted by C4Techie

From GM and the other suppliers mentioned above. In most cases the 6 speed speedo gears are the same as the auto and 4+3 speedo gears.

thanks,
Still seaching for speedo gears for 4:10 ratio , with a black tag ZF 6 Speed trans anyone HELP!!!

Desert

Feb 13, 2007 | 10:25 PM

#11

Pete K

Race Director

Joined: Feb 2004

Posts: 12,518

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Quote:

Originally Posted by Desert1957

thanks,
Still seaching for speedo gears for 4:10 ratio , with a black tag ZF 6 Speed trans anyone HELP!!!

Desert

To my knowledge, there is no aftermarket gearset that would work for the 4:10 ratio.

Feb 13, 2007 | 10:29 PM

#12

Desert1957

Racer

Joined: Sep 2005

Posts: 271

Likes: 0

From: New Freedom PA

any other options?

Feb 14, 2007 | 02:29 PM

#13

C4Techie

Racer

Joined: May 2006

Posts: 293

Likes: 0

Quote:

Originally Posted by Desert1957

thanks,
Still seaching for speedo gears for 4:10 ratio , with a black tag ZF 6 Speed trans anyone HELP!!!

Desert

GM never used gears as low as 4.10 with a tire as small as 26". The closest you can get using stock GM gears is to swap out your driven gear for a light blue, 45 tooth, 25513052, driven gear. It is an easy operation. The driven gear will come out when you remove, the VSS. You will keep your old drive gear, the more difficult to change, and your VSS.

Also, you can do a search. I have seen some very expensive, replacement, specialty, speedo gear sets listed on the forum that will probably get you very close. *I* would try the 45 tooth driven gear first and see if that will do it for you. The 45 tooth gear gives you a speedo gear ratio of 3.00:1. You need closer to 3.15 to 3.20:1. The 45 tooth gear will read about 3 MPH fast at 50 MPH, about 6% off.