OK, I have a 92 Z and am going from 3.08 to a 3.42 next week. Do I need a new speedo gear and speed sensor, just one, or neither. I need to order my parts before hand so any help would be great.
Thanks
Jeremy

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92 Z conv
5-spd B&M
alston SFC, few mods, some free, some not

 

You'll just need the new speedo gears. A dealer should be able to help you with choosing the right ones. I forget if it's drive divided by driven or the other way around, but nonetheless you want to to get the same ratio as your new rear end.

Hope this helps,

Jason

 

thanks Jason, I will order this today.

Jeremy

 

You need a purple 7 tooth, and a white 19 tooth. Good luck.

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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=-

 

kevin---
thanks for the info, how bad are they to change?

Jeremy

 

Hey Kevin, I'm still learning about all this, but it was to my understand that the speedo drive gear ratio was supposed to be the same as the rear end ratio. 19 and 7 is not a 3.42 ratio. Just wondering

Jason

 

Jason, I dunno about that, but a 7 tooth and a 19 tooth is what came stock from the factory for a T5 with 3.42 rear gears.

 

The speedo gear ratios aren't quite that simplistic. They're affected by other things, like tire size for example.

7 and 21 IIRC was what my 83 (3.73) came with. The 91 model T-5 I have now came from a 3.42 car, and arrived to me with 7 blue and 19 white as described above, so I'm farily sure that's the ones you'll need.

Every V-8 T-5 I've ever seen had the 7-tooth blue drive gear. I'm not sure what cars with 2.73 or 2.77 gears came with, if there are any such things though; all the ones I've worked with have come out of performance-optioned cars. So if your car has the blue drive gear in the trans, the driven gear is a piece of cake; just popo the VSS out of the trans (one 10mm screw) and swap the gear. It takes longer to raise the car than it does to do the swap.

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"So many Mustangs, so little time..."

[This message has been edited by RB83L69 (edited December 14, 2000).]

 

RB, the T5 cars I know about, the lowest ratio I've seen is 3.08. They have a red 9 tooth drive gear, and I forget which driven gear. I think its 22.

Thanks for posting about the 7/21 combo coming stock. Now I know for sure what to get for my 9-bolt 3.70 swap.

 

Correct about replacing the drive and driven gears. As for replacing them in a 5 speed, it is a pretty big job. Tail shaft has to come out among other things. I got my friend who is a 25 yr GM tech veteran to do it and it took him several hours with all the right tools and lift.It was worth it though.......bob

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91 camaro RS L03 convert,
t-5, ultimate TBI mods,TBI spacer,SLP 1 5/8 headers,
3"cat back, 3.42 torsen posi,alston SFC's,Global West LCA relocation brackets

 

Right rsilver, the drive gear is a witch with a capital B. The driven gear is a slam dunk, as long as he already haas the right drive gear, which he probably does. Let's hope he already has the 7-tooth blue, otherwise, he needs to seek professional help.

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"So many Mustangs, so little time..."

 

I should add (now that I am learning how to burn a PROM), that while you do not have as much to be concerned about the PROM with a standard as you do with an automatic (TCC locking, unlocking), you do have to consider the fuel and spark tables as you will be at a higher RPM at any given speed. This will get your engine to perform optimally with the new gears.

 

Now you all are scaring me. I am praying I have the right gear, but with my luck I probably don't. I will find out soon enough though.
Thanks alot for all the responses, this is great
Jeremy



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92 Z conv
5-spd B&M
alston SFC, few mods, some free, some not