Speedo adapater TSB change

[Steve L.]

My new 73 always chewed up the plastic gear on the speedo cable at teh tranny. I kept putting in a new gear. But 35 yrs later, I noticed that the adaptor was changed due to this problem. I still have the original adapter which will keep chewing the gear.

Anyone know what the change was made to the service replacement adapter and can this change be made to the original adapter to fix this problem.

[Robert S.]

Re: Speedo adapater TSB change

I cannot comment on the TSB change but I had an experience on my 74' which might explain why you are chewing up the plastic speedo gear. In my case I was not chewing up gears but rather would lose the speed indication altogether. After a lot of troubleshooting I finally found that the groove in the aluminum speedo adapter which mates with the flat plate that holds the adapter to the gearbox was worn. This allowed the gears inside the gearbox to disengage. I could see that this wear could also allow the gears to come apart enough to let the plastic gear to get chewed up. I resolved the problem by making up a new flat plate out of thicker steel so that it was a tight fit in the adapter groove. This was done about 8 years ago and the speedo is still working. Best part is that the fix cost me about a dollar.

[Steve L.]

Re: Speedo adapater TSB change

Thanks Robert,
Maybe this is what they changed on the service part

[Edward J.]

Re: Speedo adapater TSB change

Steve,
You May Also Want To Check The Tailshaft Housing Bushing On Trans. For Excessive Play Causing The Driveshaft Yoke To Move Around More Than It Should.