I have a 91 RS with the electronic transmission. I changed the rear end gear ratio from 2.73 to 3.73 and I can't figure out how to make the speedometer read right. I can't change the speedo gear becuase its electronic, and It has the speed limiter on it also so when I'm going 85 the car thinks I'm going 115 and kills the motor. I've talked to 3 or 4 transmission specialist in my town and noone knows what to do.

 

cant help ya bo, but just reaffirms my beliefs in carbs engine doesnt give a damn whats going on w/the tranny, rear end, whatever. likewise for other parts of the car. but yea, ill have to agree, a tpi engine does feel much better driving. i'd never driven one before, and i got into a rather beat up 89 iroc, and just reving the engine nearly sent me into ecstasy. yea, i'd love to have a TPI, but im still working up the gonads to go with the installation

 

it has something to do with the drak unit or some **** like that, you need to reprogram it I think....... I just lost the speedo

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91 RS W/carbed 350, Vortec heads, performer rpm, Comp cams Xtreme energy 280 grind. BFG Drag radials. 3.42 posi,Corvette servoed 700r4, ****ty stock converter
13.24@104

 

Wait a minnit; I thought that the VSS in the tailshaft was spun by normal, replacable gears? Am I wrong? How did GM account for different rear gear ratios, then? Did they have different VSS units?

At any rate, if you're sure there's no gears under that VSS cover, then you might want to check out "The Recalibrator". It's an electronic device you hook in between your VSS and speedometer. You flip switches on it to account for your tire size or gear ratio change.

AutoTransInc makes it, their website's at: http://www.autotransinc.com/index2.htm

Scroll down the page until you can click on "The Recalibrator". You can even see a quick movie on how it was installed on The Shadetree Mechanic.

Good luck, let us know what you do!


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

TomP is right. The 4L60/700R-4 in ALL 3rd Gens just have VSS. They do not have an electronic transmission like 4th Gens. They are controlled manually internally.

The later transmissions in 3rd Gens DO have VSS and you can replace the gears just as TomP said. For 3.73s you need the Dark Grey Driven gear (44 tooth) that spins the VSS sensor (easy to replace) and and the Grey Drive gear (15 tooth) that goes on the output shaft of the transmission (requires removal of the driveshaft and tail piece on the transmission).

That works for 25.65"-26.00" tall tires like 245/50/16s.

[This message has been edited by Glenn91L98GTA (edited November 14, 2000).]

 

I agree with the above post, maybe Im wrong but it sounds to me like you need to change that spedo gear in trans, just my 2 cents..

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(Kill the headlights, and put it in neutral)

--George
92 RS 25th Aniv.
350 Goodwrench (NEW LO5)
700R4 Raptor: high performance intermediate billet servo,Mega Valve,13 vane high performance pump,1800 heavy-duty stall converter and a 29 element heavy-duty forward input sprag

 

I hear 700r4 's make good boat anchors.............LMAO ( iguess for a daily driver they may be ok, but I cant wait to get rid of my 700Rjunk.......