Mitchell transmission or overdrive
 

I would like to improve the drivability of my 31 closed cab pickup. Originally I was thinking about a Mitchell overdrive but now I’m wondering if I would be better off with the Mitchell synchromesh transmission. The truck has a strong engine and 3.56 rear end and 19 inch wheels. Most of our touring is at 45 to 50 we seldom run much higher. Our terrain is flat to rolling hills. My thinking is that the 3.56 rear end gets us going fast enough, seems like it would be great to have the easy up and down shifting from a synchronized transmission. I know this transmission is only synchronized in 2nd and 3rd gears that’s what I’m used to with my 40’s vintage cars. I wonder about your experience with either the transmission or overdrive and what other factors I might be overlooking. I have read as many past threads as I could find and am still pondering.

Thanks
Bill

Re: Mitchell transmission or overdrive
 

Buy the overdrive..actually its a splitter box,the first time your wring out second low and shift to second high you'll be sold.

Re: Mitchell transmission or overdrive
 

I have one car with both the MItchell transmission and O/D. We do lots of miles towing a camper behind that one. I have another 3 cars and all of those have the original cog house and a Mitchell O/D (gear splitter). One of those also has a 3.54 rear end (1928 Tudor) with a B engine fitted with a downdraught carby. That car doesn't handle hills all that well but I can sit on 60 mph easily enough in it on the flat. I think I prefer the standard rear end with O/D. The original gearbox is fine.
In your case, I'd go the O/D

Re: Mitchell transmission or overdrive
 

I think you mean 2nd and 3rd.

Re: Mitchell transmission or overdrive
 

I have the F150 OD with 3.78 rear. This gives me Synchronized gears plus OD. Does very well on the flat or hills.

Re: Mitchell transmission or overdrive
 

We have a 31 Tudor with a strong engine, Mitchell overdrive 26% and Mitchell gearbox with 15% higher 1st and second. Diff is 3.78 and tyres are 16 inch on V8 rims.
This is a nice car to drive, but every now and then on really steep 180 degree uphill bends needs first gear to avoid straining. On the other hand on long uphill pulls in the hills where top gear is too high, overdrive second really speeds things up.
Our Roadster with a very strong engine cannot go as fast up these hills where second gear is needed without going over my 2600 rev limit. But it pulls the very tight uphill bends in second gear ok. It has 19 inch wheels with Excelsior sport radials 155X19. Gearbox is standard Model A, overdrive is 26% Mitchell and rear end 3.78.
Both are a delight to drive and impossible to say which is best.
Reading this to myself I think the message is stay with 3.78, put in 26% Mitchell o/d and if your gearbox needs any kind of attention put in the Mitchell synchro internals. For a strong engine ( higher compression, better camshaft, larger carb.) go for higher first and second gear ratios. For a standard engine I am not sure on this last point. One can up the ratio on either or none of first and second gears.
I put a plus 15% first and second in a friends cabriolet with standard diff and tyres. His only comment is "it goes very fast in reverse now, especially in backing out of my shed". He is 85 and a rather slow driver.
SAJ in NZ

Re: Mitchell transmission or overdrive
 

I have the 3.54 rear with the Mitchell synchro tranny, was going to get the overdrive, but don't think its needed since I just cruise at 60mph.

Re: Mitchell transmission or overdrive
 

I ordered a 26% Mitchell two weeks ago for our Tudor with stock 3.78 rear end gearing. . I've had an old Borg Warner overdrive in the car since the late 1980's. Last fall the Borg Warner made a terrible clunk and then nothing. Permanent neutral. Tow truck ride back home. No more Borgs for us. Thanks for the great info guys! Makes me feel good about ordering a Mitchell.

Re: Mitchell transmission or overdrive
 

Have a 36% Mitchel for the cabriolet but also have a cut down Columbia in the '28 pickup with 3.78's and REALLY like being able to split the gears.

Re: Mitchell transmission or overdrive
 

Did you opt for th 15% higher 1st and 2nd gear?
Thanks

Re: Mitchell transmission or overdrive
 

I'm sure I wouldn't be driving at that speed even with the higher ratio diff and without an O/D.

Re: Mitchell transmission or overdrive
 

A Model A has so much torque (125 ft lbs) relative to its weight that I can't see how splitting gears would be an advantage. The owner's manual wants you to get into high gear at 12 MPH.

I also agree that being able to cruise at 60 and better is not something that I would do without a modern brake and tire upgrade.

These are great cars, but they have their limits.:)

Re: Mitchell transmission or overdrive
 

I don't remember, it was 4 years ago, I just did what the Mitchells recommended. The receipt says ratio #3.

Re: Mitchell transmission or overdrive
 

Iam under 3000rpms at 60

Re: Mitchell transmission or overdrive
 

Dick, my 16s stop on the dime, with all new brakes and good thick shoes from Randy.

Re: Mitchell transmission or overdrive
 

If you do go with just the tranny, consider instead of a higher 1st and second, go with just the second. First is pretty high, especially for parades etc. Then there is a big jump to third. We opted to keep 1st as it is then a 15 percent higher second. Initial test drive, we liked it but winter hit before we could test it much.

Re: Mitchell transmission or overdrive
 

Bill, Is this with your Roadster or Town Sedan?

Re: Mitchell transmission or overdrive
 

Can we assume your engine is not stock? 3000 rpm is pretty high for a Model A engine.

Re: Mitchell transmission or overdrive
 

That is in the roadster.

Re: Mitchell transmission or overdrive
 

Inserts, 6-1 Head, Ross forged pistons,counterbalanced crankshaft,lightened flywheel, etc.