'30 Dodge differential.

I am using a '30 Dodge DC spiral bevel diff on my current project with a 4.6 to 1 gear ratio. Any way to change the gears in it to lower my ratio, short of having new gears made at a machine shop? Does anyone know much on the subject who can help me out? I don't know how many of you use Dodge parts for their hot rods, but I'll bet there aren't too many... lol

 

Closest swap I ever heard of was...a 32 Plymouth rear that were converted to use a late 40s to early 50s Mopar center section.

The bolt pattern was different where the later center section fit to the 32 rear housing, so that needs either redrill or making a new flange to weld in.

That 30 DC is/was an 8 cylinder car, so I'd bet it has a different rear than the 32 4 cyl Ply.

Just wonder why you want to keep that rear?.. is it because you want to run stock wire wheels?

 

Not too many of those rears used, ( for just your reason), so, ya' answered your own question

Taller wheels and tires, ( drastic for a noticeable change), and an O/D transmission.................................Or upgrade, iffn' ya' want to be able to depend on it..................

 

machine up a box to take quickchange gears between the drive shaft and diff, some of the old local racers were running setups like that on ford rears if they were too cheap to get a real QC

 

Contact noboD here on the HAMB- he would have the info or could find it.

 

Thanks for the help and the comments!
I am already getting ready to send off my engine off to the machine shop, I suppose I could talk to them about about QC gears, that idea definitely sounds good to me. So thanks for the idea Shaggy.

It'd be a waste of an axle really NOT to use it. It has about 14000miles on it, and is in perfect working order with no wear at all. Makes for an original vintage custom.

F&J, according to my books the 32 Plymouth also had a spiral bevel differential, but with a 4.33 to 1 ratio. Those are the oddest gear ratios I have ever seen on a passenger car of that age. I imagine as of 28 or 30, all of the Chrysler associated makes used this type of rear end up to '37 then switching to a hypoid rear end which is used today in RWD vehicles. Same as they used the same basic design in all their L head engines from '30 up until the 50's. Ok, I rambled there, but I just thought this was interesting and worth sharing.

Anyways, YES is the answer to your question. I am using EVERYTHING off of my DC, except the Detroit lubricator joint. That thing makes me angry just looking at it. HOW DOES IT NOT BREAK???

Long story short, Thank you for the advice and responses. I know how I'm going to deal with it now.

 

Hey i support anyone that wants to use non traditional old parts to make a hot rod. Truthfully the type of quickchange setup i was discribing is pretty unorthadox and would require dropping the driveshaft to change gears. But an old racer talked about a bunch of the cheaper local guys were running them at the track in the late 50's. I wouldnt assume it would be too hard to fab one up, but then again with labor costs what they are today who knows

 

I think Outlaw sprint cars use the same sort of quick change gears I'm thinking of, and that's exactly what you're thinking about. The neck on my diff is offset kinda like the 80's ones, but centered, anyways if I flip it over and put a box on it, the drive shaft will link in the same place, so it would work out well. Not that I'll be changing gears constantly, but I have a visit to Bonneville on my bucket list. Would be cool to hit some high speeds on a dry lake bed with my home built hot rod. Thinking of trading in my coupe body for a roadster to have a lighter body, then maybe it'll be possible.

With the amount of work I'll be sending to Millar Auto Machine, maybe I'll get a bulk discount. lol

 

Even though you indicated that you knew what path you were going to take, I thought I'd throw this out there for any other '30s Mopar fans. Maybe some of you have done this swap already. If so, let me know if I've got this right-
An older gentleman that I knew had a nicely restored stock '36 Dodge (with 4:10 gears). He wanted to be able to drive it to Hershey annually, as well as other meets, both near and far. In order to drive it at freeway speeds without the engine being wound tight, he installed a complete '49 Dodge rear axle. The only thing that he said he had to do was chisel the spring pads off of the '36 rear axel and substitute them for the ones which came on the '49. Apparently there was a difference in the spring widths. The later rear axle had 9" inch brakes instead of the 8" which came on the '36. Because of this difference in brake sizes, he also switch the front drums and backing plates. I don't recall if said he had to modify anything anything in order to swap the front brakes. It almost sounds a little too easy, so if you guys have any thoughts, please share.

 

Awesome info to know, thanks for posting.




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I'd believe it.

 

You know, I just ran across this today, but a friend of mine has a motorhome on what I believe to be a '75 ish Dodge Chassis, and I out of curiosity I snuck a peek at the front end, and the bolt pattern for the brake plate onto the spindle is literally the exact same as my '30 parts (The parts are much beefier of course). After seeing that I can say it's safe to assume that this was a standard design up until IFS.

 

Burnin8, That's interesting. I guess that a person might think that nothing was ever changed that didn't actually require being changed!