M5odr2

My ‘84 with 302 and M5OD ran around 65mph at 2000 RPM. That was with 3.08 diff. My tires were 275/60-15, but were the same OD as the factory 215’s that came on it. In any case, I checked it for distance and with GPS and my speedometer/odometer was bang on, so I know my numbers were correct. If I remember correctly, 4th gear at 60mph was more like 2300 RPM (which was the same with the original 3spd…3rd is the same 1:1 as 4th). My 5spd came out of a truck with a 3.08 diff, so the speedo drive gear stayed corrrect.

Hmmmmm, I have a pic of the panel and tach.  69mph indicated at 2300-2400.  My speedo is confirmed to be in the "somewhere near right" range.  So I'm turning more.  I have no tag on rear and painted over on trans.   There was a chart here somewhere with M5 ratios prefilled.  And by entering data, it showed I should have 3.55 gears I think.   So it's all speculation on my stuff.   Stock 235s

Truck is a hoot to drive.  Everyone likes that it has 5 speed.  It was all installed before I bought it.  

rcarlisle wrote

Hmmmmm, I have a pic of the panel and tach.  69mph indicated at 2300-2400.  My speedo is confirmed to be in the "somewhere near right" range.  So I'm turning more.  I have no tag on rear and painted over on trans.   There was a chart here somewhere with M5 ratios prefilled.  And by entering data, it showed I should have 3.55 gears I think.   So it's all speculation on my stuff.   Stock 235s

Truck is a hoot to drive.  Everyone likes that it has 5 speed.  It was all installed before I bought it.

https://www.garysgaragemahal.com/calculators.html
I used that Calculator a lot before I bought my Advance Adapter's Range Spliter over drive turning my 4sp into a 8sp transmission.

You guys with your high RPM v8's kill me
75 MPH at 2000 RPM with my 300 six, 2.75 rear gear 235/15 tiresand the AAOD.
70 MPH is like 1800 RPM and that is the same RPM at 55 MPH with out the over drive.
Dave ----

And I think that my issue is the installers didn't do their homework?  I have no idea of the history of this truck.  The guy I bought it from said the 5 spd was in it when he bought it.   I have receipts for the $5000 work he had done.  Nothing about trans or rear end.   So those are mysteries.  And as I've stated before - no tag on the rear and the trans tag painted over. door tag faded out completely.I have a VIN and that's about it.  

I think if it had a higher rear ratio, it might help the mpg?  Idk.   First gear would probably be a great burnout gear if I weren't terrrified I'd break something I can't afford to fix right now.   LOL  

If gas keeps going up, may have to cut back on even the little driving I do now.  

The one im building now im using an aod and a 3.31 gear . I expect it to be well below 2k rpm at 75.

rcarlisle wrote

I think if it had a higher rear ratio, it might help the mpg?  Idk.   First gear would probably be a great burnout gear if I weren't terrrified I'd break something I can't afford to fix right now.   LOL  

Yes, a higher rear gear ratio might help, but it might make the drivability worse. My '84 had 302 with M5OD 5spd, and 3.08 rear diff. I love the 302, but it's a bit of a dog at lower RPM's. Ford did sell trucks with the 5spd and 3.08 rear ends, but I think it was more of combo that went with the 300/6, which is quite content (and powerful) and the lower RPM's. Unless you were specifically wanting a low rpm highway machine, a 5spd should be mated up with a 3.55 or 3.31, or 3.25, or something like that.

My '84 would get 18mpg on the highway if I drove it easily, but it was more of a 15mpg truck for regular local driving. I had that truck/engine dialed in too, AFR was very good, tires and alignment good, etc.

Now if you talk to Rusty85 on here, he has some different theories on MPG. He is building a Bullnose with 302 and I think a C6 with 31" tires, and he's planning to get 25mpg at 2700 RPM/75MPH with that truck. He might have some information on how to do that, or hit those MPG numbers. It goes against what I know, but I'm certainly no expert.

I wonder what my truck would do after I install the M5ODR2 with a rear aXle ratio of 2:47….

Socnarftrucks wrote

I wonder what my truck would do after I install the M5ODR2 with a rear aXle ratio of 2:47….

With the inline six, you should be able to handle those tall gears. The 302 wouldn't like it much, but the 300 will.

I wondered about higher gears as well.  We live in hilly country and sometimes in 5th it gets a little boggy going up hills.  It kinda misses here and there.  So there is that.  I don't want to get into major changes anyway.  Just trying to get best I can with what I got for now.  

Just coming up on a year of ownership.  Knock wood, truck has started, run, and brought me home everytime.   And has hauled stuff anytime we asked.  

Socnarftrucks wrote

I wonder what my truck would do after I install the M5ODR2 with a rear aXle ratio of 2:47….

The RPM might be a little too low even for the 300 six.
I say that as I have 2.75 rear gear 235/75/15 tires and have Advance Adapter over drive.
it is just under 40 miles each way to work. By the high way I have maybe 5 miles of street driving rest high way 70 - 75 MPH
If I take roads the speed limit is between 45 & 55 MPH with stop lights.
For combo driving I get 15's MPG avg., some times high 14's to low 16's (not as much as I would like).

I have been working on the timing advance curve to stop the pinging and think I have it dialed in the best it will be. I can then start looking into leaning out the carb.

I do have a AFR gauge and it bounces between low 13's to high 15's, even saw 16 once. High way its high 13's to high 14's.
I do know the carb has been messed with as it was in poor shape (missing screws, wrong screws used and missing parts) when I got the truck and I think the AFR gauge should not be moving around as much as it dose.

I would be really happy if I could avg. mid 16 MPG or a little more on my combo driving.
It is pretty flat here only on the road part do I have 1 or 2 hills I would have to deal with.
Oh I am running between 1000 & 2000 (shift point or less) rpm so it dose not spin vary fast.
Dave ----

Brother: I went to the junk yard and located a the M5odR2 cross member, and the tunnel cover. The pickings are very slim and was not able to locate the 84-86 manual trans hydraulic clutch pedal set. Is there another option that might work? The rest I can order online. Thanks in advance.

Socnarftrucks wrote

Brother: I went to the junk yard and located a the M5odR2 cross member, and the tunnel cover. The pickings are very slim and was not able to locate the 84-86 manual trans hydraulic clutch pedal set. Is there another option that might work? The rest I can order online. Thanks in advance.

Not that I know of, no. I believe the hydraulic pedal sets are all specific to the truck generations. '84-'86, '87-'91, and '92-'96. I believe, and Gary can correct me if I'm wrong, but the hydraulic pedal set started in 1983 technically, but they were rare (only with 460 & diesel). Otherwise, they didn't show up on everything else until 1984, which makes them somewhat rare these days...since they were only used for 3 years.

Rembrant wrote

Not that I know of, no. I believe the hydraulic pedal sets are all specific to the truck generations. '84-'86, '87-'91, and '92-'96. I believe, and Gary can correct me if I'm wrong, but the hydraulic pedal set started in 1983 technically, but they were rare (only with 460 & diesel). Otherwise, they didn't show up on everything else until 1984, which makes them somewhat rare these days...since they were only used for 3 years.

You are right.

Socnarftrucks wrote

Brother: I went to the junk yard and located a the M5odR2 cross member, and the tunnel cover. The pickings are very slim and was not able to locate the 84-86 manual trans hydraulic clutch pedal set. Is there another option that might work? The rest I can order online. Thanks in advance.

If you can't find a set locally, check Car-Part.com and I think you'll find them. Here's a screenshot of a quick search in the Midwest. I know you're in Texas, but search around and you'll find a set that somebody will ship.

Any chance that the set from an 83 mechanical clutch would work?

If I remember correctly the cross shaft for the clutch pedal, or at least the arm on the end of it, is different.

Thank you. There are quite a few available. The one thing I am not sure is if all the 84-86  trucks with manual transmissions all were/had hydraulic clutches. How would i know the difference if it was a mechanical pedal set?.....

You are probably asking Cory, but I'll reply and let him correct me if I go wrong.

Yes, all 1984 and later trucks had hydraulic clutch assemblies.  As for telling the difference, go to our page at Documentation/Driveline/Clutches & Linkage and then go to the Clutch Linkage tab.  You can then click on the Mechanical and then the Hydraulic tabs to see the differences.

Just saw your previous reply. The answer would be yes then.

Thank you Gary