Pinto Car Club of America

What are the teeth on the worm and plastic pinion speedometer gears for a 3.08 rear? What would they be for a 2.79 rear to read correctly?

A speedo gear reference would probably be a good idea for a FAQ entry.

Maybe I should restate this question and make it more simple. What speedometer gear was used on a '79 Pinto with an automatic transmission and a 2.79 rear end? Can somebody with a Pinto parts book help me out, please? Thanks!

I looked in the Ford 1979 car shop manuals and could not find a listing for the number of teeth.  The manual even says rear gear ratios are 2.73 and 3.08 in two locations (typos?).

What I have done in the past is to check the speedo accuracy and do a ratio to determine what number of teeth are needed on the speedo cable.  In your case if the speedo is accurate with 3.08 gear, the number of teeth you need for a 2.73 rear is 2.73/3.08 times the number of teeth on your existing speedo gear.  Of course you have to round off to the nearest whole number of teeth.  I usually round down so that the speedo reads a little high (speed ticket avoidance).  I have never had to change the worm gear, only the plastic portion on the speedo cable (an easy change).

I found out that you can't change the worm in these things. It's machined into the tail shaft. I was justing thinking back to a '58 Chebbie pick-up that I had in back the '80s that started out as a three on the tree and then became truck four-speed and finally a $90 T-5 supposedly out of a dead Firebird. Swapping the worms and pinions around to make the speed read right was almost a bigger pain than the tranny swaps. Did improve my algebra figuring it out.

Next time I'm up at the farm so that I can work on the Pinto, I'm going to drop the speedo gear and actually count those gear teeth and go from there.

Just think, back in the '80s I had a late model Pinto for a daily driver and a pick-up for a beater-resto-rod sort of thingie. Now I have a late model pick-up for a daily driver and a Pinto for a beater-resto-rod sort of thingie.

That's pretty cool Doug. I bought and drove new Pinto's in the '70's as daily drivers. They took me all over the country. I shudder today to think of the trips I have made in Pinto's. Didn't have them for 20 years, now back into them. It is a fun hobby. Becoming a lifestyle!

Dave

79 Pinto auto with 2.79 rear used 18 tooth gray gear.
NOS Part# C7SZ17271B

Thanks for the information. Just bought one off from eBay.

My first Pinto was a MPG Pony gotten new back in 1980. Got rid of it in 1992 and 120000 miles later. Probably the best car-car (not a pick-up) that I ever had. A lot more reliable than the oxidation and leak prone 1984 "Thunderbucket" and 1990 "Sinkin' Lincoln" that followed. I think that the Pinto's bad rep is mostly undeserved.