ok my speedometer says i am goin 10 mph faster than what i am. I have a rebuilt 700R4 in my car right now. I have been told that all i have to do is put the gear from my other tranny in the tranny i have now. what all do i have to do? I have the gear from the nose peice from other tranny and that cast alum. peice also. Do i just pull the one out and put the other in or do i have to do something else. thanks in advanced

 

Try http://www.700r4.com/speedoCalc/speedocalc.shtml and/or
http://www.tciauto.com/tech_info/speedo_gears.htm

Use to calculate the gears you need and compare to what you have. You have to remove the speedometer sending unit (on tail shaft) and remove the drive shaft and tail shaft to get to the gear on the output shaft. You remove a clip and slide the gear off. The other gear is on the speedometer sending unit.


-Barry brl90Iroc

 

my brother thinks the tranny was out of a truck(i got the car off him) i have the gear and the removeable housing from the orignal tranny. can i still use the gear inside the tranny and just put the other gear and removeable house in the new tranny or do i have to change the other gear also.

 

can anyone help me out on this

 

Reuse the two original gears that were on your old tranny. You will have to pull the tail shaft housing to get the one off of the output shaft, and use the original that was on your cable or sender unit.

 

so there is no way i just can use the one on the tranny now and just replace gear on the sending unit?

 

i just tried to take the gear out of the old tranny but i can't get it off. i got the metal clip off but i can't get the gear off. do i have to do anything special to get it off or doesn't it come off?

 

compare the gear on the shaft of the new trans (count the teeth and check color) to the gear on the old trans. If they happen to be the same, you don't have to change the gear on the shaft. A chance, slim. To get the correct ratio, several drive gears mate to several driven gears.

Barry

 

Typically that gear is a slight press fit on the shaft...especially after being attached for years... Anyway I just carefully use a crescent wrench slightly larger than the shaft and TAp the wrench gently with a hammer.... If you hold the wrench so the face of it rides on the face of the gear and gently tap it will slide right off...


Personally FWIW If it were me...GM sells the gears for almost nothing... Get the color of the gear and go buy some new ones... that way you dont have to mess with the old tranny... Mine were under 12 bucks for both from GM...

 

why dont u just use your other tail shaft 4 bolts and u are done... simple as that and u wont have to switch any gears out at all... thats what id do if i had the other tail shaft with the right gearsi it all ready... do ur self a favor and save ur selfsoem time and just switch the tail shaft man it not hard at all.

 

When I rebuilt my tranny, I had to pull all the guts out to get at the snapring to pull the tailshaft.

I would agree with Kenwood, just buy a new gear like the old one on your original tranny.

red, 17 teeth GM Part Number 8640517
gray, 15 teeth GM Part Number 8642620

EDIT: I don't know if these are the only two colors available, I just found them in the F.A.Q. section. My 87 T/A originally w/2:73's had the red one.