T-5 Ratios With a Flathead

[jack orchard]

I have 3 T-5 transmissions. All of them are from S-10 trucks with the forward shifter. I don't know what the gear ratios are because the tags are either unreadable or missing. Some have manual speedos and some are magnetic pulse. I have a 1951 F-1 with 29" tires. Motor is 265" w/Max1 Cam.

(1) What is the best gearset ratio for use with a flathead?
(2) How can I find what gear ratios I have?
(3) What would be the best cruising rear end ratio?
(4) What would be the ideal cruise RPM?

Any opinions you guys have are greatly appreciated. Thanks,....jack

[BUBBAS IGNITION]

Jack ,

Just google T5 trans ratios using google they are all listed somewhere.
We have a 1949 Ford truck with a T5 in it and a .68 final ratio. Cruises at 1700-1800 rpm all day long ...With a 3:73 rear axle...........

[jack orchard]

Originally Posted by BUBBAS IGNITION

Jack ,

Just google T5 trans ratios using google they are all listed somewhere.
We have a 1949 Ford truck with a T5 in it and a .68 final ratio. Cruises at 1700-18800 rpm all day long ...With a 3:73 rear axle...........

Thanks for the info. By the way, this motor has one of the four modified SBC distributors I received from your shop. Very pleased, although my motor won't turn that fast....jack

[36tbird]

While discussing T-5's, what is the deal on the input shafts? Are the early, non WC ones, 14 spline? I am going to start looking for an early one with mechanical speedo and shifter forward to put behind a 60. I need to know what spline it would be to order a clutch disc.

[TomT/Williamsburg]

The S-10 T5s are 1" 14 spline - Mustangs will be different.

I have a T5 in my avatar with a .8 final rear gear in 5th - @ 2500 I'm doing about 75 with a 3:54 gearset and fairly tall tires - damn near perfect.

[Ol' Ron]

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The early S-10 had a 4. first gear which is useless in a light car, but the other 4 make a pretty good combination. I think the Ford T-5 has the best ratios but, nobody makes adapters for them, YHis supprises me because, GM went to the Ford Bolt pattern in 93/4.

[Kahuna]

If the bolt pattern for the Ford T-5's is like the Ford T&C toploader, then Gene Sanders in Ohio (M.E.C.), has a very nice aluminum adapter that will work.

[Pete]

Here is a URL that will give just about all info available on T5 ratios.
Most of the internals will interchange with most of the cases and tail shafts
so there is an almost unlimited number of combinations available.

http://www.britishv8.org/Articles/Bo...T5-ID-Tags.htm

I personally use the 225 combination in a GM case because it is the closest ratio
combination all the way through. This keeps the engine rpm in the best operating range all the time.
I have installed T5's behind strong flathead engines several times and all the customers were highly satisfied.
Also for what it is worth, you are LESS likely to break the transmission with close ratio gear sets.

[Flat Ernie]

Originally Posted by jack orchard

I have 3 T-5 transmissions. All of them are from S-10 trucks with the forward shifter. I don't know what the gear ratios are because the tags are either unreadable or missing. Some have manual speedos and some are magnetic pulse. I have a 1951 F-1 with 29" tires. Motor is 265" w/Max1 Cam.

(1) What is the best gearset ratio for use with a flathead?
(2) How can I find what gear ratios I have?
(3) What would be the best cruising rear end ratio?
(4) What would be the ideal cruise RPM?

Any opinions you guys have are greatly appreciated. Thanks,....jack

1 - It depends.

2 - Put the trans in 1st, mark the input shaft and the output shaft. Turn the output shaft exactly one turn and count the input shaft. If it goes 4 times completely around, you have the 4.03 gearset. If it doesn't quite make it to 4 times, you have the 3.76 gearset (it should end up 3-3/4 times around).

3 - It depends.

4 - It depends.

Honestly, if you are going to put the T5 into a truck and not change the rear, you'll likely be happier with the 3.76 gearset T5. If you're going to change the rear anyway, well now you can pick & choose. Since you're in FL with little danger of big steep hills, you can probably get away with a 3.25 rear regardless.

I'll give you a couple numbers based on a 29" tire and a 2200RPM cruising range, which I think is good - others may have different opinions and you can adjust from what I put here - the relativity will remain the same.

With the 4.03 gearset T5, the OD is 0.86.

To get 2200 RPM, you need an overall final drive of 2.75:1 and with a .86 OD a 3.25:1 rear will get you close. It puts you around 2260RPM at 70MPH.

With the 3.76 gearset T5, the OD is 0.72

To get 2200 RPM, you still need an overall final drive of 2.75, but with .72 OD, you need a rear ratio of 3.75 or so and that puts 70MPH at 2190RPM.

A stock 16T early Ford toploader has gears of 2.82, 1.6, & 1.0 and typically married up with a 3.78 rear. Crunching the numbers with a 4000 RPM shift point you get:

1st = 30mph
2nd = 1900RPM drop after the shift and then 57MPH @ 4000RPM
3rd = 1500RPM drop after the shift

The 4.03 T5 and 3.25 rear works out like this (same 4000rpm shift):

1st = 26MPH
2nd = 1700RPM drop after the shift and then 45MPH
3rd = 1500RPM drop after the shift and then 71MPH
4th = 1300RPM drop after the shift and then 106MPH (theoretically)
5th = 500RPM drop after the shift (but you can cruise @ 70 and 2260RPM)

The 3.76 T5 and the 3.75 rear works out like this

1st = 25MPH
2nd = 1650RPM drop after the shift and then 42MPH
3rd = 1450RPM drop after the shift and then 65MPH
4th = 1200RPM drop after the shift and then 92MPH (theoretically)
5th = 1150RPM drop after the shfit (but you can cruise @ 70 and 2190RPM)

Really, with the stock early Ford 3.78 rear gear, you can get pretty close to ideal with the 3.76 gearset. Many folks have put the 4.03 gearset T5 in front of a 4.11 rear and not been happy with 1st gear because it's just too low. The 3.76 gearset is better with the 4.11, but it's really pretty nice with the 3.78 to 3.50 gear. The 4.03 needs higher rear - 3.25-3.50 to be happy.

Originally Posted by Kahuna

If the bolt pattern for the Ford T-5's is like the Ford T&C toploader, then Gene Sanders in Ohio (M.E.C.), has a very nice aluminum adapter that will work.

No, the Ford T5 is different from the T&C toploader bolt pattern - unfortunately.

[Bassman/NZ]

Originally Posted by Ol' Ron

The early S-10 had a 4. first gear which is useless in a light car, but the other 4 make a pretty good combination. I think the Ford T-5 has the best ratios but, nobody makes adapters for them, YHis supprises me because, GM went to the Ford Bolt pattern in 93/4.

www.macsspeed.com

[Ol' Ron]

I see the unit you refer to and that works for the 59 and earlier blocks. I was referring to the late ford standard shift bell housing. Wich is a simple plate.

[Pete]

A stock Chev bell housing can be redrilled to bolt right up to an 8ba block.
They are dirt cheap, sometimes free for the asking.

[Dennis Jarrell]

Can I assume the 50's and 60's BW OD trans has the same ratios as an early 3 speed and ,7 for the OD?

[TomT/Williamsburg]

FlatErnie has all of the T5s info - good to hear from you - it's great that he keeps compiling things with regard to that trans. In my 40 coupe's first T5, it had the 4.06 first gear w/3:50 gearset - I usually short shifted out of it and it was OK - you get used to it - but not ideal. I had (and still have) 235/75-R15 tires and they are a bit on the short side - 29-30" is really ideal with my gearing and the 4.06 would have been a bit more tolerable.

On the flip side, I have a T5 in my coupe now taht has the opposite problem. I don't have a tag on it to say what the gears are but 1-4 are really good - 5th is a .6 ratio which means w/my combo and @ 75 MPH I'm at 2200 rpm, and it's terrible up any kind of hill - a 900 rpm difference from 4th. I'm leaning towards this being a Camaro gearset w/T5 tailshaft. Since it's popping out of first now, I'll be removing it and I will investigate further. My point in bringing this out though is that the flattie needs RPM and FlatErnie's calculations are really where you want your RPM range to be with the T5 and your rear, tire size, and how you want to drive the car play a part.

[MARVIN, CT]

My MGTD with a 60hp, '87 Mustang (2.3) t5, and 3.9 rear does just fine, rarely use 1st gear. What I'm looking for now is a way to adapt a 90 degree angle drive for the speedometer cable. Seems the Ford t5's speedometer housing aren't made for one. Any ideas would be appreciated. Marvin,ct

[TomT/Williamsburg]

Originally Posted by MARVIN, CT

My MGTD with a 60hp, '87 Mustang (2.3) t5, and 3.9 rear does just fine, rarely use 1st gear. What I'm looking for now is a way to adapt a 90 degree angle drive for the speedometer cable. Seems the Ford t5's speedometer housing aren't made for one. Any ideas would be appreciated. Marvin,ct

Make life simple (and cheaper) and use a GPS off the windshield!

Seriously, although a GPS is an option, check in with the Corvette forums - I remember something was available but whether it would work for you I do not know ....

[Richard in Florida]

If you're running a low rear end like a 4.10, the coveted 2.95 gearset as used in Mustangs and Camaros is the ideal. You have a first gear you can actually use, and with OD you can drive the interstates with ease.

Keep in mind that with few exceptions any gearset can be installed in any T5 case.

[Pete]

Originally Posted by Richard in Florida

If you're running a low rear end like a 4.10, the coveted 2.95 gearset as used in Mustangs and Camaros is the ideal. You have a first gear you can actually use, and with OD you can drive the interstates with ease.

Keep in mind that with few exceptions any gearset can be installed in any T5 case.

X2 on that.

I forgot to mention before about the short throw shifter adapters.
They are the second best thing in life.

[Richard in Florida]

Originally Posted by Pete

I forgot to mention before about the short throw shifter adapters.
They are the second best thing in life.

When choosing or settling for a T5 for your old Ford, keep in mind that the farther from your hand the actual shifter mechanism is, the longer the shift lever must be. The long the shift lever, the longer the throw between "front and back" gears.

This is why I love my Astro Van housing. An S10 puts the shifter WAY forward in my '53, and a Mustang or Camaro puts it under the edge of my front seat. The Astro Van is about in the middle.

And of course you can put any gear set in an Astro Van housing you wish. I have a 2.95 gear set in mine.

[JWL]

You need to clean your interior.