mark opa Posted August 3, 2016 Report Share Posted August 3, 2016 1st time member asking a probably stupid question, but can you use an M6 tranny in a 1935 plymouth? Looking to get better top end speed w/o going to a T5 or other tranny. Quote Link to comment Share on other sites More sharing options...
mopar_earl Posted August 3, 2016 Report Share Posted August 3, 2016 (edited) The M6 transmission is underdriven. 4th gear is 1 to 1 same as 3rd gear on a 3spd. Earl Edited August 3, 2016 by mopar_earl 1 Quote Link to comment Share on other sites More sharing options...
William Davey Posted August 3, 2016 Report Share Posted August 3, 2016 If you're trying to reduce engine speed you'll need an overdrive transmission, but you'll probably find it easier to replace the differential gearing with a higher (lower numerical) ratio. 1 Quote Link to comment Share on other sites More sharing options...
mark opa Posted August 4, 2016 Author Report Share Posted August 4, 2016 Thanks for the quick reply and information. Are there any other engines than the L6 that the M6 can mate up to? Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted August 4, 2016 Report Share Posted August 4, 2016 you got to understand the ability of the L6 to generate the torque at the low RPM.....any change about is going to be a bit invasive and labor intensive... Quote Link to comment Share on other sites More sharing options...
dpollo Posted August 4, 2016 Report Share Posted August 4, 2016 I cannot think of a less suitable transmission for a 35 than the M6. My 35 has the stock trans but I have changed the rear end for one with a 3.7 to 1 ratio from a postwar Desoto. Works very well. Quote Link to comment Share on other sites More sharing options...
mark opa Posted August 4, 2016 Author Report Share Posted August 4, 2016 Thanks so much for the info. Sound like the rear axle is the key to achieve lower rpms at higher speed. I have seen that the B-Body rear axles from 1962 to 1970 match the 35 Plymouth well and some have a 2.76 to 1 ratio. That rear axle mated with a standard 3 speed might achieve what I am looking for. Quote Link to comment Share on other sites More sharing options...
dpollo Posted August 4, 2016 Report Share Posted August 4, 2016 2.76 would keep you in second gear all the time. I would not go any taller than 3.54 . I have driven a lot of these cars a lot of miles and I believe 3.7 will do the job. The Business series Plymouth for '35 had this ratio, if you can find one. I used a later housing to get more options. Quote Link to comment Share on other sites More sharing options...
Jerry Roberts Posted August 4, 2016 Report Share Posted August 4, 2016 What size is the engine in your 1935 plymouth , about 196 cubic inches ? I don't think that you would want rear end gears of 2.76 with that engine . I have 2.94 gears with a 218 and I sure wouldn't want anything higher than that . You would need something higher than my gears . Quote Link to comment Share on other sites More sharing options...
mark opa Posted August 4, 2016 Author Report Share Posted August 4, 2016 Looks like a 3.7 is the clear choice. This forum is a great resource for a novice such as myself. Thanks to all that replied! Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted August 4, 2016 Report Share Posted August 4, 2016 There are many speed calculators available on the interweb. Pasted below is an example. Plug in the numbers and you can calculate what differential ratio is correct for the horsepower and torque curves of your engine. What is right for others may not be right for you. http://www.advanced-ev.com/Calculators/TireSize/ Quote Link to comment Share on other sites More sharing options...
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