What is available?
How many splines on the 55 axle?
55 limited slip or positraction
Moderator: Joe Johnston
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55blacktie
- Posts: 1157
- Joined: Sat Sep 05, 2020 2:43 pm
Re: 55 limited slip or positraction
The 1955 Dana 44 rear axle has 19-spline axles.
I had an Auburn limited-slip differential installed, at the same time the stock 3.31 gears were swapped for 2.72 for the highway. I'm still working on the restoration, so I can't provide the results. One person suggested that I wouldn't like limited-slip, but the same person also told me the 2.72 gears wouldn't fit. My 88 Mustang, which I mentioned earlier, came equipped with Ford's Traction-Loc/w 2.73 gears. That's probably one of the reasons I opted to have it installed in the Tbird. Considering most new cars come equipped with electronic traction control, I can't come up with a valid argument against it.
There are 2 different Dana 44 carriers. The small carrier is good for up to 3.73. Numerically higher ratios require the large carrier.
It does little/no good to have a lot of horsepower, if it doesn't reach the ground. If you lack the right tires, suspension, and gears, it's wasted.
You might ask a profession builder's opinion about upgrading to 30-spline axles. I didn't, but made I should have. If your tires go up in smoke, due to lack of traction, 19-spline axles are probably ok. If you hook up with enough power, you might wish you had 30-spline axles.
I had an Auburn limited-slip differential installed, at the same time the stock 3.31 gears were swapped for 2.72 for the highway. I'm still working on the restoration, so I can't provide the results. One person suggested that I wouldn't like limited-slip, but the same person also told me the 2.72 gears wouldn't fit. My 88 Mustang, which I mentioned earlier, came equipped with Ford's Traction-Loc/w 2.73 gears. That's probably one of the reasons I opted to have it installed in the Tbird. Considering most new cars come equipped with electronic traction control, I can't come up with a valid argument against it.
There are 2 different Dana 44 carriers. The small carrier is good for up to 3.73. Numerically higher ratios require the large carrier.
It does little/no good to have a lot of horsepower, if it doesn't reach the ground. If you lack the right tires, suspension, and gears, it's wasted.
You might ask a profession builder's opinion about upgrading to 30-spline axles. I didn't, but made I should have. If your tires go up in smoke, due to lack of traction, 19-spline axles are probably ok. If you hook up with enough power, you might wish you had 30-spline axles.
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55blacktie
- Posts: 1157
- Joined: Sat Sep 05, 2020 2:43 pm
Re: 55 limited slip or positraction
P.S. Automatics aren't as hard on the drivetrain. Sidestepping the clutch pedal of a manual transmission during a hard launch is a recipe for disaster.
Re: 55 limited slip or positraction
I'm not interested in putting a lot of horsepower on the ground - I'm interested in one wheel on a solid surface, and the other on mud or ice.
As an aside, the clutch doesn't have to be hard on the transmission. I've got a couple of Dodge trucks with eight forward gears and most unsynchronised, and I don't use the clutch at all. You just match rpm by ear as you shift. Unclutched, they handle the power from a big block Chevy with no trouble at all.
However, you can use the clutch if you prefer.
As an aside, the clutch doesn't have to be hard on the transmission. I've got a couple of Dodge trucks with eight forward gears and most unsynchronised, and I don't use the clutch at all. You just match rpm by ear as you shift. Unclutched, they handle the power from a big block Chevy with no trouble at all.
However, you can use the clutch if you prefer.
Last edited by JimCunn on Tue Nov 24, 2020 8:41 am, edited 1 time in total.
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55blacktie
- Posts: 1157
- Joined: Sat Sep 05, 2020 2:43 pm
Re: 55 limited slip or positraction
You're welcome.
Re: 55 limited slip or positraction
Info is much appreciated.
Thanks
Thanks
Re: 55 limited slip or positraction
Blacktie, the Auburn looks good, and reasonably priced.
Where did you source the 2.72 ring and pinion, and how many splines did the pinion have - or did you replace the flange yoke too?
Where did you source the 2.72 ring and pinion, and how many splines did the pinion have - or did you replace the flange yoke too?