M5R2 or ZF?

[SDFarmKid]

ok thats what i figured...well ill add it to the list ill either swap the tailshaft case or figure something else out. Thanks for the info, truck been on the back burner the past few days because of the last week of school for the semester Im ready for break!

[Wilma-Colorado]

SD Farm Kid,

Please do post photos of your M5R2 install. We're wanting to do the same thing and frankly, it's intimidating when we've never done anything like this before. Our truck is a '70 F100 LWB with a 302 and three speed column shift. It has a 3.50 axle and we wonder if it will be about right for highway driving with the M5R2 overdrive 5th gear.

Good luck on your project - sounds like you're capable and have a plan.

Wilma / Colorado

[eggman918]

I have a M5R2 in my F-250 4x4 with the cummins 4BT and it runs about 1900 rpm @ 65 mph with 31.5" tires which might be a bit low for a 302 but with smaller tires you will get more rpm's.
here is a link to a good gear calculator http://www.grimmjeeper.com/gears.html you can run any combo with it,hope this helps
Steve.

[9t3svt]

Any m5r2 factory equipped truck I have checked the rear axle tag on has had 3.55 gears so I say roll with it

[SDFarmKid]

Wilma-Colorado: I will definetly post pictures of my install. I know what you are feeling before last fall id done very little mechanical work in my life and kinda felt overwhelmed by it, but i just dived right into the middle of it, and have thoroughly enjoyed doing and have learned alot, this site has been a great help in that success though.
Progress Report: I have the flyweel and pressure plate installed, but i tore my pedal assembly apart last night and the bushings were shot a loooong time ago. One of the two metal bushings was half gone and wore a groove a quarter way into the shaft. So my dads gonna get some bearings 2morrow and do my own version of mustang steves mod.Then ill get the pedals mounted again, mount the master cylinder, and get it all buttoned up, so hopefully ill have it done before christmas....hopefully

Ive also used some of them calculators but have since made an excel spreadsheet to do them calculations. I have 3.54s and with a .8 overdrive and 29 inch tire ill be turning 2133 rpms at 65 mph, but ive yet to set that in stone. If you have any others you want me to put in it it just let me know

Thanks everybody for the help!

[averagef250]

1st gear will be pretty short with 3.55's and 29" tires with the Mazda. 3.25 or 3.00's would probably feel better, but then you may lose the functionality of overdrive with a carb small V8.

See how it goes when you get her back on the road then switch gears if needed.