I am toying with the idea of taking out my 700r4 and going with the t-5. I saw in a post where the VSS and the speedo drive and driven gears were not the same. I looked in the technical info post about this subject and found a list of different gears, but how do I know witch ones to get for a t-5? Rearend is a 3.45 BW.

 

You want a 7 tooth purple drive gear and a 19 tooth white driven gear. You should be able to use the search feature and find the GM part numbers.

Yes the T5 and 700R4 use different speedo gears.

 

diff speedo gears. same VSS though.


the gear is just slip fit on the VSS.. it slides right off and the proper gear slides on and you're set.

 

The VSS in a 700r4 WILL NOT it in a T5. The one on a 700r4 is about 3x the diameter as a T5 where it enters the transmission!

 

i was told the VSS given to me thats in my car now came from a T5?

looks like this:



what does the T5 one look like?

 

the one that you have can not have come from a t5.

Below is a picture of a vss from a mid 80's bird. Where it goes in to the trany is considerably smaller. I am at work so I dont have a picture of mine. Looks similar to the one you posted (plug wise) however, the diameter where it goes thru the trany is the same as the one I posted.

 

The 7/19 gear combo worked out perfect for me but I had 3.27 gears and and stock size 245/50 tires. I tested it with a gps unit and was dead on at 60 mph, you might want to try a higher speedo gear like 20 teeth if you have 245/50 tires.

 

thanks. If I can find a doner car to get all tha parts off of Ill try to get the correct speedo gears part #s.

 

U can use this calculator to figure out the speedo gear combo

http://www.hanlonmotorsports.com/t5speedo.asp

7/19 would be the best combo.

Some of the combos are not available for the GM t5 only the ford t5 in the calculator.

 

Here is a pic of my t5 VSS, newer style vs my first pic. You can see how much smaller it is where it enters trany.

 

After looking over this thread as well as other info out there, I can't find which gears are used with a 3.45/3.42 rear. The purple/white - 7/19 or the purple/blue - 7/20 is the correct set? I have seen people mention both. This thread mentions the Hanlon calc. spitting out 7/19. I picked up a T-5 that was to have come out of a 3.45 car that has the 7/20 set. Others have mentioned this is correct. Is there a mathematical formula or something to use for this? What a chase!

 

Does anyone know which gears GM used with this rear ratio?

 

i have t-5 1992 version VSS gears setup for 3.42 rear axle, if you need then lemme know, i am parting out a 92 t-5 tranny

 

The "correct" gears depend on your tire diameter; which can easily be different from the factory tire diameter, even if the "trade" size (245/50 or whatever) is the same.

You'll never ever get a speedo gear that's dead on *****, except by pure dumb luck. The best you can get is the closest approximation. For example, you might use that calculator, and doscover that you need 19.4 teeth to make your speedo come out right. Obviously you can't get a fractional number of teeth; you have to use a whole number. So if you use a 19 tooth gear, your speedo will be about 1.5 mph high at 60; and if you use a 20-tooth, it will be about 1.7 mph low at 60. So, which gear is "right"? Then, you buy a new set of tires, with 11/32" of tread or whatever; you drive them for a while; presently they're down to 5/32" of tread. That change right there, by itself, is almost one whole speedo gear tooth. Are you going to get out and change your speedo gear as your tires wear? I doubt it.

I can tell you from having had LOTS of cars over the years with LOTS of different gears: for 3.42 or 3.45, 7 & 20 will be plenty close enough with tires near the stock diameter. Again, you'll introduce a greater error just from one brand of tires to another or in your tire inflation, than the difference in the speedo gears.