The 700R4 in my 89 Formula does not use the standard speedometer driven gears. I don't know the formal terminology but I call it a hybrid electromechanical setup. The drive gear on the tranny output shaft drives a plastic gear in the tailhousing like earlier 700R4s. The difference is that the driven gear has a half moon slot in place of the plastic shaft used on earlier gears. The gear fits on a metal shaft that drives an encoder inside the tailshaft. There's a weatherpack style electrical connector that plugs into the encoder to provide a signal to the speedometer (no mechanical cable).

The problem I've run into is that the GM parts books only seem to list 41 and 45 tooth driven gears for this setup. I need a 42 or 43 tooth gear. Are these available? If so, I'd greatly appreciate part numbers.

Failing this, could I use a Cyberdyne recalibration box like that listed in the Jegs catalog?

 

The FAQ on this site lists the part numbers you're looking for. Yes you can also use a Cyberdyne unit.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

I'm 99% sure that the part #s in the FAQ work with the earlier style speedometer but are not correct for my setup. I had the local GM dealer check this for me before posting. I also had him cross reference parts #s in a speedo recal article in the March 2000 issue of CHP. Dana at Probuilt couldn't confirm existance of gears other than 41 or 45 tooth in this style.

I'm sure that someone with a late 80s Firebird has already solved this problem. I'd like to know if it can be done with GM parts.

 

Hmm, the p/n's the the FAQ should be for the elect speedos, which sounds like what you have. I got the lt blue and it has the half moon, or D slot you speak of. As far as i know, 38-45 tooth gears are still avail.

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-Justin-
T-Top '86 5.0L LG4 700R4 WS6 Now Bilstein equipped!
T-Top '92 5.0L TBI 700R4
My '86 Firebird Homepage
The F-body Model Kit Pictoral Archive (updated 9/18/00)

There can be only one!!

[This message has been edited by Justins86bird (edited January 11, 2001).]

 

Mark, I'm leaving for England in a couple of hours so I'm a bit rushed.

I looked at my GM list for 89, and the teethnear that count avail for your year are:
just the 41 & 45. So looking at the 92 I see 42, p/n 25513049, Green.

From the 90 chart, 44 is p/n 25513051 DK Gray.
I don't see a 43 but if the p/n stay seq, then it should be 25513050.

Kevin


Sorry I don't have time to look at FAQ chart

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KevinP92Z
92 Z28 383 SLP cam,SLP headers,SLP 2ontheLeft,Trick Flow TW heads & pistons,Edelbrock base,Accel SuperRam,52mmTB,Scat Crank & forged ConnRods,MSD 6AL,SLP convertor,Baer 13/12" Track,Moser axles,Hotchkis,Genuine GM 3.42s,SLP HD Torsen,17x9" chrome SS rims
96T/A w/SLP Ram Air,SLP 2ontheLeft, Bilsteins, Baer, Hotchkis, Genuine GM, Torsen
76 4X4 Blazer 400TPI project

 

KevinP, the PN's you list are the same as those in the FAQ, validating what Kevin and Justin are saying. I'll try another counter man at the local dealer. I believe I also have an aftermarket source should there be no joy through GM the second time around. Thanks to all for the replies.