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ivanz62

I have been asked about the availability of 3.5:1 ratio gears for Hudson and Terraplanes of the '30s. I do have these that fit the earlier differential carrier

that has six bolts holding the ring gear. I am not certain when Hudson changed to an eight bolt ring gear. The man asking has a '39. Can anyone tell when the change occurred and how to identify the rear axle as an eight bolt model without x-ray vision? The gears I have in stock were made in England for Railtons and are of excellent quality as Richard Esparza's experience this year shows.

Ivan

Geoff C., N.Z.

The gear set was changed for the 1939 model year except for the 112 models, which used up all the old gears, until car # 90356. I don't know that there is any identifying mark on the later units. You could probably re-drill the carrier for 8 bolts, but I'm not sure on this. The parts book states only interchangebale with earlier models as complete units.

Geoff.

Jon B

Ivan, I may be dreaming but didn't Pat say he was considering making the 8-bolt model of the gear at some point? I believe it's the same gear, just has more bolt holes.

ivanz62

Pat McDonald says that he needs a good sample of the later 8 bolt style to copy and has never been able to get his hands on the parts. The ring gear mounting bolts are the only difference in dimension. Re-drilling the mounting holes in an already hardened part would be a job possibly done--can't say if the eight hole pattern would overlap the six hole pattern. I would also question the demand for this later gear set. They would only be useful where an overdrive is not an option as in 1939 to 1941. I would think overdrive is relatively available for post war cars and don't know if the Hudson built rear end assemblies built through 1951 use the same gears.

Can someone advise on the possibility of putting '51 ring and pinion on a '39 differential carrier? Geoff? Walt?

Someone would have to invest to make a short run of '39 spec parts and lend a sample to be copied to keep the unit cost down. And who's going to put up the money?

Ivan

ivanz62

I should add that I have four gear sets here in California on hand at $850 for anyone interested in fitting one.

I have two fitted to my own cars and can't praise them highly enough.

Ivan

Richard E.

Amen Ivan, I sure like cruising with traffic with these gears. My main consideration was my desire to restore my electric hand unit. If you don't care about keeping the electric hand you can just put in a '40 OD, assuming you can find one. The beauty of the gear sets made for Railton is that it allows you use the stock transmission with all of EH hardware.

If you go this route there are some tricks to getting it installed which Ivan can advise on. It isn't a big deal but you need to know what the fix is. I am not qualified to explain it. I had my set expertly installed by our local Hudson guru.

Geoff C., N.Z.

I wasn't advotcting drillling the ring gear, just the carrier that it mounts on, this is not hardened. However, I don't know whether this would affect it's structural integrity, without studying one, but I doubt it.

Geoff.

Ken U-Tx

As for re-drilling the carrier or ring gear for 8 holes from 6 holes, only one diametrically opposite pair of the 6 hole setup can be used. In the six hole set up, the holes are spaced 60 degrees apart, and the 8 hole setup will need to be 45 degrees apart.

6 hole : 0--60

120--180--240

300

8 hole : 0--45--90--135--180--225--270--315

Assuming the ring gear is about 8-1/2 to 9" diameter and the bolt circle is about 5", then the 4 sets of holes that are spaced only 15 degrees apart will overlap each other, and probably that would not be desirable. Would be a simple matter to modify the sand casting pattern to make an eight hole center, or to leave the holes out of the casting and have them drilled before the heat treating/ case hardening of the ring gear. As for drilling holes in hardened/ heat treated parts, the simplest thing is to have the holes put in by a hole popper EDM using copper or brass tube electrodes and thru flushing. Another possibility might be to carefully MIG weld 4 of the 6 holes up taking care not to let the teeth portion of the ring gear get hot, and then EDM the 6 other holes for the 8 hole setup. Just thought I'd share my thoughts on this. Kenneth

Ken U-Tx

Upon further careful reading of Ivan's post , I see he is inquiring of using a higher ratio ring gear on the 39-47 Hudson rear axles (except the 39 112 series). I think that the ring gear or the entire pumpkin, or carrier set from a '51 or early '52 Hydramatic equipped car can be fitted to the 39-47 rear axles. This would give you a 3.55:1 ratio. This would greatly simplify matters! Kenneth

ivanz62

Is the spline on the axles and spider gears of the '39 the same as the later cars?

Could one then swap the entire assembly from a Hydramatic stepdown into the '39 housing? That would be a great option. Is the ratio for the early auto trans cars 3.55 or 3.08 like the later cars?

Ivan

Ken U-Tx

Ivan, the early Hydramtic (single range) hudson axle ratio is 3:55 to 1. PS, i have another '54 Power steering setup for sale, know of any one that wants one? Regards, Kenneth

walts garage-53 · walts garage-53 March 2009 Posts: 1,470Platinum Member

Ken U-Tx wrote:

Ivan, the early Hydramtic (single range) hudson axle ratio is 3:55 to 1. PS, i have another '54 Power steering setup for sale, know of any one that wants one? Regards, Kenneth

Ken, Walt here, I asked you awhile back what are you asking for that set up. I have a friend that just bought a 53 and wants P S. I can have him e-mail you if you want.

Uncle Josh

Watch the width. The stepdown axles are 5 inches narrower than the earlier ones.

Huddy42

I have two (2) new old stock Case & Stud assemblies part number 199160, and possibly gears to suit. These are the eight (

stud pattern assemblies..

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