3.54 rear axle ratio

Finally got my 1948 Traveler and am getting it in shape for a trip to Hershey from Chicago as I do every yr. Found my diff has a lot of play in the ring and pinion and can turn the driveshaft back and forth quite a ways. I was going to pull the diff unit and adjust the R & P back to correct clearences. But the ratio is 3.9 and I would like to put in something higher for the highway. I know this was covered before but I need to know what unit would slip in and from what car. I used to shim a lot of racing car diffs so know how to do it but would rather not. My workshop manual lists a 3.54 offered with the hydraulic trans,??? Any info on this, many thanks.

Calling JON ROBINSON----he knows the right stuff you will need---and there is a 3:54 ratio for this unit---may have to get a whole pumpkin from a bone yard---then swap---check with Jon he`s a walking Chrysler manual-------Good Luck.....

Calling Jon Robinson

The 3.54 was the standard ring & pinion for the Chrysler Royals and Windsors that had the "Hydraulically-operated transmission" ( semi-automatic).

You might even find a complete rear axle fairly "easily"...

I think Jon Robinson swapped a 3.36 from a later '50s Dodge into his '50 De Soto Coupe, and is very happy with the result...

Frank, thanks, I would like to know which ratio would work better.

Well, it's a trade-off... the "taller" you go with rear-end ratio ( smaller number), the less revs your engine will turn per mile ( ie: will theoretically increase the top-end of your cruising capability)... the trade-off is in terms of the mechanical advantage: the taller your rear gears, the less pulling power your car will have... it will take off slower from a stop, climb hills slower, etc.

The Chrysler engineers worked all this stuff out pretty carefully when they designed your car... and found a rear-end ratio that was about the most practical compromise between pulling power and cruising speed; so for a regular Windsor, the 3.54 is probably about as tall as you'd want to go, unless you live in really flat country.

I have a '48 New Yorker with 3.36 gears, and that would cruise at 70-75mph all day with no castasrophe... but that had another 20 HP on the six cylinder Chrysler...

I also have a '41 De Soto that has 4.1 gears, and at 60 MPH, my engine is turning about 3,000-3,100 RPM, still a few hundred rev's below the factory test red-line of 3,600 RPM... it sounds busy, but shouldn't be destructive for an engine in decent shape ( mine is exceedingly tired).

Jon's '50 De Soto coupe is a bit lighter than your Traveller, but he's really happy with his 3.30-ish rear, and he lives out near the Mojave Desert, and climbs all sorts of hills in his driving... I'll try to swing his attention this way...

Hope this is some help...

Frank, ty, I am confused as to what ratio my Traveler has. Book says C38 with Hydrulic shift has 3.54, when I had it on a lift and counted the turns of drive shaft it looked liked 3.9 to me. Perhaps I already have a 3.54 and dont need to change.

If I remember correctly from my '41-'48 Chrysler shop manual, the only sixes that did NOT have the 3.54 rear would've been the 7-passenger sedans and the Town & Country sedans: these would've had the 3.9 rear, to help compensate for the additional weight of the heavier models...

Of course, a customer could've ordered the car with a differnt rear...

I believe on the outside of the differential carrier, on the passenger side, facing the ground, there is a flat boss that has the rear-end ratio ( or number of ring teeth, followed by the number of pinion teeth) stamped in it... I think it's near one of the webs on the pinion housing nose...

If you can get under the car with a wire brush and some brake-kleen, you might be able to reveal that number and see what your car actually has inside the punkin...

Frank, thanks, saves pulling the diff, Ill have the C38 up on the lift next week sometime for brake work and Ill ck it out and report back.