Me & My '59 Apache - The Story Begins

[dsraven]

speedo drive ratio adatper
https://mrspeedometer.com/products/r...ceat3BG5EC-SAI

speedo drive adapter for turbo 350, removed from trans
https://classictransmissionsolutions...GRyU-w9O20UxCe

https://classictransmissionsolutions...RRt86x7mPVfJGa

speedo drive gear calculator
https://www.tciauto.com/speedometer-...=AfmBOorfY4fqd

[Blackie]

Originally Posted by B52bobardier1

Hello,



I have a new "bullet gear" inside this transmission that did correct the speedometer error a little but only by 2-3 MPH. That drive gear that is deeper inside the tailshaft will require the removal of drive shaft and the tail shaft cover and I guess that is what I'm up against at this point. I have no idea which plastic gear is actually installed and I need to find these before I start this job. Its a TH350 transmission with a 3.08 set of differential gears and about 26 inches for a tire height.

Great advice above and I thank you.

Rick

I use this guide here for speedo gear calculations - but you will need the info above plus your drive gear ratio - they are colour coded so you should be able to yank the cable out and look inside the hole to figure out how many teeth on the drive gear ? https://www.tciauto.com/speedometer-gear-calculator

[dsraven]

good idea to look inside the adapter hole. just know that trans fluid sometimes discolors the plastic. you should be able to see if the gear is flat on top aross the teeth or rounded from wear. if the new gear that was installed was a bunch different than the internal gear was made for then quick wear on the inside gear may have occured since it is a pretty fine tooth set. either way, you should be able to get some idea as to what you have.
dropping the driveshaft and the tailshaft housing is pretty easy. I recommend to have the truck at a good rake angle so trans fluid runs forward and there is less mess from fluid spilling out when you pull the housing off. a big chunk of cardbard on the floor is a good catcher if you don't have a large drain pan.
it's a good idea to check the output bushing for wear and replace that output seal while the housing is off. clean up the driveshaft yoke past the area where the seal normally rides and shine it up with some emery cloth, then run a straightedge across the length of it to check for wear, then check it inside the bushing to see if it is a nice fit or if it's pretty sloppy.
removing the seal is fairly easy with the housing off the trans cuz there is no shaft in the way, then clean the housing well and use something flat and larger than the seal to knock a new seal in
if the rear bushing is worn out take the clean housing to a trans shop and have them replace the bushing and the seal. it's always good to take your driveshaft with you so they can make sure the new bushing fits the shaft yoke properly as well as ensure they get the proper seal. some seals have a raised edge on them that will bottom out on the housing when the seal is in to the hilt. others will require a little more finesse to ensure they don't get pushed too far. thats the reason for using the flat driver thats larger than the seal when doing this yourself, the driver will bottom on the housing when the seal is inserted to the end of the housing. then check the seal to ensure the little spring that goes around the inside of the seal lips is still intact and didn't fly out of the seal with the impact of drivng the seal in with a hammer. some seals are single lip ans some better ones are dual lip

[dsraven]

I don't know what the underside of your truck looks like but a good rinse before starting this makes it a little better from the perspective of dirt and dust dropping into the open trans when the tail housing is off. also keep the shopdoors closed so airborne stuff stays out. if it's gonna be done outside then you don't have much control over it. drape a clean rag over the area when the housing is off.
when you take the driveshaft off use some electrical tape wrapped around the U joint so the bearing caps don't fall off and lose needle bearings.

[dsraven]

not sure of your experience so thats why the long write up, lol

[dsraven]

not sure of your experience so thats why the long write up, lol