I just got myself an '88 S10 T5 trans with the .72 OD gear. It was $100, a deal I couldn't pass up. My F1 already has a 3.25:1 9" rear. I'm using a stockish 239cid EAB flathead. Tires are 215/85/R16. Overall appearance is to make it look stock.

With the .72 OD, my 65mph rpm is 1659. If I use a stock transmission, either a LD 3sp, or crashbox 4, (I have both) at 1:1, I get 2336rpm.

I also have a '47 Ford sedan that's getting a 239cid 8BA, and is retaining the stock banjo rear end, which I haven't figured out yet, but most sites point to them being 3.78:1. This car has a LD 3sp. 1:1 final.

I've been looking for a T5 for awhile to put in my F1, but with the one I got, it seems better to go into the sedan, and just drive the F1 with the stock transmission and 9".

What would you guys do?

Scott - if it was me I'd put it in the one that would get the most use the soonest. Then decide it you like the swap well enough to do it to both. Stu

Stu, you may be right. After doing some research til my eyes got blurry, it appears the 4x4 version of T5 would be better suited for my sedan. There's an adapter available to use that tranny with the torque tube. Since my T5 is 2wd, it's better suited for the F1. If I can find another 4x4 T5, I'd put them in both.
That's where I'm leaning towards now. Tomorrow it may change again, lol. I can always still use 4th gear at 65mph with that 9" rear, if that works best. I'll have to look at 1st gear ratios next.

Hey Scott,

F-1’s rule and come first ……..always! (said by someone that also has in the long term scheduling stage a 1953 Canadian Dodge WAGON that is actually really a Plymouth complete with Savoy fender badges and a dodge Rams Horn hood ornament, makes a Ford seem almost rational!)

I drove my 48 with the stock HD3 until I could find a T5 to go with the 3.50 9" rear end.

12 years later it still has the T87D cause I'm too busy driving and enjoying it.....but someday it will have a T5.

Misc T-5 ramblings...........

My truck has a mostly stock flatty, T5 and 3.00 gears. Short tires.....about 27 in. It's geared TOO high!
Problem with tall gears is you gotta have the HP to pull them. Mine doesn't. Also the F-1 has the aerodynamics of a brick. As a result my truck gets lousy mileage because it is working too hard at too low rpm (my theory) Leaving it in 4th makes it run better, but that makes the OD useless. The flatty seems to run best around 2200 rpm....

Before the T5 swap I had the 3.00 rear gears and the 3 speed with the same tires. Cruised just fine, but sucked on hills and around town because of the wide ratios. The T5 is soooo much more drivable....a gear for every speed. Makes the truck a lot more fun to drive!

Bottom line, I am changing the rear gears to 3.50-3.89ish....depends on what I can find. Hoping to find the best of both worlds, mileage and driveability.

Scott, your experiences are what I was concerned about. Even the 3.25 gear ratio my 9" has seems like it would be too high.

I wonder if the 3sp. would be better with the 3.25's as opposed to your 3.00's? Or was your your 3sp. the HD version with the steeper 1st gear? I have a 3.50 chunk I could swap out, but IIRC, it's a 31 spline unit, and that would render the swap useless.

My truck had the lite duty 3 speed.....it drove pretty good just cruising around. 3.25's would work fine I think.
Many years ago I had a bone stock '51 f-1 with a flat V8 and 4 spd....swapped in a 9 inch with 3.25's. Drove out nice, i ran that thing all over the place. Shifting was an adventure though.......

I'm hoping the higher ratio will kinda split the difference and still keep the rpms where I want them in O.D. I'm not switching back to the 3 speed......

Well it's decided.... I'm putting the T5 in the F1. I have an F2 crossmember (thanks again, Bob) I thought about using, but even that one will probably need modifying, so I think I'll modify the extra F1 crossmember I have. I'll need to retain the stock crossmember for frame strength and brake MC/pedals, but drop the center section out, and fab something to hold it all together. The fact that the extra crossmember is out of the truck should make it easier to build.

The sedan will stay with the original 3sp. and rear. Even with the T5 4x4, the torque tube needs cutting, and this car is supposed to be an original custom from the 50's in my mind, so I guess I can live with maxing out at 55-60 mph.

Change of plans again. I'm starting to sound like a broken record, lol. What I thought I threw out in the scrap pile, was the F2 crossmember from the $100 8BA I got some years ago. That one was ripped from the PO's removal, I think. Anyway, if I can use that one, I'll save my good F2 crossmember, and my F1 crossmember. That may mean I just add another separate crossmember for the T5, like most of ya have done.



First up is to remove the extras, and see if the F1 rivet holes can transfer onto the F2 crossmember ends.

Removed all the extra crap, and froze my toes off doing it, lol.

Today, I started cutting it, and set it next to the good one I got from Bob.

shredded my finger at work with a grinder a week and a half ago, so haven't been doing anything on this project. That, and I'm still waiting for enough snow to melt that I can drag out the F1 frame.

Tinman52 question for you or anyone else who's been there and done that.
I noticed in one of your post you had a 52 F1 with 3.0 rear gears. I am in Florida and have a 52 F1 six cylinder with 3.92 gears. About to change. Seems 45mph is comfortable as it sits. Didn't think going to 3.50 would be much of a change and planned on going to 3.08 from Randy's Ring and Pinion. Looking for 55-60 cruise speed. No hills here. Would you go to 3.50 or to 3.08? Thanks

galderman said:

Tinman52 question for you or anyone else who's been there and done that.
I noticed in one of your post you had a 52 F1 with 3.0 rear gears. I am in Florida and have a 52 F1 six cylinder with 3.92 gears. About to change. Seems 45mph is comfortable as it sits. Didn't think going to 3.50 would be much of a change and planned on going to 3.08 from Randy's Ring and Pinion. Looking for 55-60 cruise speed. No hills here. Would you go to 3.50 or to 3.08? Thanks

Click to expand...

The general consensus from those that have "been there, done that" is that 3.50 gears are optimal. High enough to have good cruising capabilities, low enough to let the truck get out of it's own way. 3.08's don't let the engine rev enough quickly enough to get into the torque band at the low end. The engine bogs and is doggy.

Thanks for the input. Think I will go with the 3.50 set up.

Yes, 3.50ish would be better....the 3.00
s made the truck pretty gutless. It would go 70 on the flat, but took a looong time to get there.

I've re-thought my direction as well. Looking at the stock flathead V8, stock 4sp., and 3.25 gears. Gonna use the T5 for something else instead. I'll still build the crossmember, for a later time, as I plan to use a T19 in another project.

After reading here, and a couple other places, I agree that 3.00 or 3.08's seem high.

I run 3.50 now. Just about optimum with a 1:1 ratio trans and would be better with a T5.

I've thought about switching to 3.25's so I'll be curious to know how it works for you Scott.

Here's a question: .72 OD tranny ratio, 4.09 rear axle ratio, stock 6X16 6 ply tires/wheels.... what's the rpm at 60, 65, and 70 mph?

None of the ratio calculators that I know of, factor in old tire sizes.

Here is a calculator I've had bookmarked for ages...

http://www.csgnetwork.com/multirpmcalc.html