vince vette 2

Ready to have the Dana 44 rebuilt and would like to switch the 3.07 to 3.31. Rebuilder advises me that the next jump on the Dana 44 for an 80 is 3.54. Is this correct? I see a posting in Tom's Rear Ends (which is closing) for a 3.31 specifically for 80 vette Dana 44. Also, the rebuilder told me that people swapping out to a different ratio "could never get the speedometer gearing correct". There again, when I go to TCI and check out their drive and driven gear calculator there seems to be combinations which work for a TH350. Technically my tranny is a TH350c, but TCI informed me the gears are the same. I guess the simple question would be has anyone swapped a 3.31 gear set (or close to that) into a 80-82 and if so, what was the source of the gears and also, was there any trouble getting the speedometer set up reasonably close.

lakerider57

I have a 1980 corvette. Tracdogg2 is rebuilding my diff from 3.08 gears to 3.31 gears. He is using a c4 carrier and gets the whole kit from Tom's differentials. He says that Tom's is still in business in terms of shipping out orders. When I had my TH350c rebuilt, I told them I was going to 3.31 gears and tire size and they changed out the gears in the tranny so the speedo would be correct.


Richard

jim-81

You are correct that the next step up from 3.31 is 3.54 because that is what I have. Got my gears from Tom's a couple years ago. At the time I had a Super T10 and was not able to get the speedo correct. I purchased a gear (brown?) for the trans but it didn't correct the speed enough. I was told I needed to change the gear INSIDE the trans, which I didn't want to do, so I lived with it. I don't remember where I got the gear from but they had a lot of info, sorry.

Here are a couple links that may help:
http://tri-5.chevyrides.com/speedo.php

http://chevellestuff.net/tech/speedo.htm

Jim

Street Rat

I have a 3:54 in my '81. For a time I was using a th350. Constantly dicking with speedo gears. I got it close at 55 but still it was off by approximately 2 mph. The good things are that the gears are easily accessed with the transmission in the car and that there are gears available.

When I went to an overdrive transmission I purchased a cable to gps adapter. Now I have gps accurate mph and no more gear changing.

Gale Banks 80'

The 3:54 and 3:73 ratio's are common and probably the only ones made today. Other ratio's are listed in everybody's catalog but can be challenging to find. Tracdogg2 has also done mine and is recommended. Lots of Corvettes rolled off the production line with 3:36 Gears ( Not 80-82 Dana 44's) so the speedo gear should be a no brainer.

Grumpy 427

I went with 3.55 gears in my 80, and changed to the grey speedo gear my speedo is ok. with 255/60/15 rubber all around. The jump from 3.08-3.55 was 500 rpm, and now the car accelerates and drives way better. Would not go with anything less than a 3.55 in these cars, way to sluggish otherwise. Besides i didnt buy this car for MPG. lol I went with Motive gear, Gear set.

Grumpy 427

https://www.motivegear.com/auto-part...=corvette+base

calwldlife

2 gears drive speedo.
color coded.
should be an easy find.

HeadsU.P.

Another option would be one of those in-line cable adaptors sold by Speedometer World for $88. They claim it will match up any axle ratio to your speedometer. All though its a small custom made unit, there is still no room next to the tranny to mount the adaptor and no room behind the dash. The unit would normally mount onto the cruise control transducer on the fender well. If you don't have cruise, then you would have to run two short speedometer cables with the adaptor in the middle.

vince vette 2

Now, I have no idea about this particular unit, but here's the story of one I used back in 1983. There was advertised an inline unit which would reduce the rotation rate of the speedometer cable an appropriate amount so that the kilometer scale would actually indicate mph. Nice trick for those in the era of 85 mph max speedo's. Cost was $100 - that's 1983 $. I was young, single, and flush with oil field money, so I bought it. Turns out this was a standard device form Stewart Warner that retailed normally for about $25. But no internet back then so you were limited in knowledge to the magazines you read. Anyway, I installed the unit and had two issues. First, it stuck so far out that the cable exited close to the floorboard and had to do a nose dive putting a heck of strain on it. Second, in the process of turning some stuck bolt, the wrench slipped running my thumb against the cat heat shield. Got 4 stitches, adding as I recall about $50 to the tab. The scar is still easy to see.

But it was in and did what they said. It was a little jittery, probably from the sharp bend in the cable. But I had to get going as I'd quit my job in TX and was heading to FL to meet up with my parents who were camped down there for the winter. I believe it worked all the way there. But as it warmed up we headed back to NY. Someway along the way my cruise control transducer quit. But I didn't really need that. So I kept going for a while. Then the speedo died. I pulled the cable and found it had snapped back close to the tranny. So I bought a new one and didn't worry about the cruise control again. In '84 I got a job down in PA, so moved down there. After a few trips between there and NY I decided I needed to get my cruise back, So I bought a new transducer and per in. A few months later, that one cratered. It was about this time I figured out the unit was transmitting a load onto the cruise transducer as its socket for the end of the speedo cable was too short. So I drove without cruise again.

Then some months later my speedo quit again. I had now had it. I decided to go back to stock but not worry about the cruise control anymore. I got under the car to pull the inline unit off. Turns out it had bailed out by itself. It was no longer on the car. I guess my $100 unit was out on the interstate somewhere. And personally I was OK with that. Probably saved me from slicing open my thumb again to get it off. C'est la vi