Rebuild Transmission and Transfercase into High Ratio?

[Hormel]

I recently broke a tooth in first gear on a series 1 transmission (#151....) that is in my ‘65 series IIA. My mechanic and I decided not rebuild this older transmission and wanted something later and stronger. So I have bought a rebuilt unit (254...F) and hope to swap that in next month.

Now this is the odd part. This weekend I was fortunate enough to pick up a free (thanks Steve off of Craigslist!) series 253...D transmission and transfer case . Aside from some rust on the main shaft in the bell housing and typical leaking seals the unit seems to turn well, shift and what gears I can see don’t show much wear. I have read that these transmissions are fairly easy to rebuild, do you agree and could I make it into high ratio with a couple of gear changes in the transfer case while I am at it?

I realize that the 2.25 does not have much power for my 109 with a high-ratio but I don’t use first gear all that much anyways so maybe with the H/R I would or at least get over 50. I hope to pass on my transmission karma so in the future you may see a Series I transmission with a knackered first gear, hole filled with a cork in the bell housing, and another hole over the starter motor shaft up for takes on CL.

Thanks
John

[KevinNY]

The Hi ratio cases are not just a swap of internals but a new remachined case to reposition the intermediate shaft.

[Hormel]

Kevin,
Thanks, that is what I needed to know. I may have some mechanical inklings but I am not machining a case.
John

[KevinNY]

Ashcroft sells the kit with a machined case and the new parts or you can buy it from RN all set up and ready to bolt on including the parking brake.:thumb-up:

[TeriAnn]

I realize that the 2.25 does not have much power for my 109 with a high-ratio but I don’t use first gear all that much anyways so maybe with the H/R I would or at least get over 50.
I shudder when I think of that drive train combination. But a lot depends upon how you drive, where and what your rig weighs.

If you don't use low range much, you could save a lot of $$$ by replacing the Series diffs with a pair of Range Rover Classic diffs. A lot of Range Rover Classics & Disco I's are hitting wrecking yards. Depending upon the age of your housing it would either be a slide in or you might need to remove a pin and grind the housing opening a little. You might be able to get a pair of coiler diffs cheap and you can keep your old ones in case you want to swap back .

What is important is that a 3.54:1 R&P provides an almost identical axle ratio to the Ashcroft high range kit. It would provide the same high range experience at potentially way lower cost. And if you don't like it you have the 4.7's to swap back. An Ashcroft conversion is expensive and takes a lot of labor. BTW if you run the numbers, 3.54:1 diffs or ashcroft conversion is a taller ratio than an overdrive will give you.

I have an Ashcroft conversion myself and love it. But I have a 5L V8 turning those high ratios.

Aa a compromise ratio, your 2.25L might be able to push a 4.1 R&P OK

Axle ratios high range 4th gear:
Stock Series with 4.7:1 R&P = 5.4:1
Stock Series with 4.1:1 R&P = 4.7:1
Stock Series with 3.54:1 R&P = 4.07:1
Ashcroft with 4.7:1 R&P = 4.01:1


Engine RPM with 32 inch dia tyres at 65 MPH:
Axle ratios high range 4th gear:
Stock Series with 4.7:1 R&P = 3686 RPM
Stock Series with 4.1:1 R&P = 3208
Stock Series with 3.54:1 R&P = 2788
Ashcroft with 4.7:1 R&P = 2737

[LH Drive]

Axle ratios high range 4th gear:
Stock Series with 4.7:1 R&P = 5.4:1
Stock Series with 4.1:1 R&P = 4.7:1
Stock Series with 3.54:1 R&P = 4.07:1
Ashcroft with 4.7:1 R&P = 4.01:1


Engine RPM with 32 inch dia tyres at 65 MPH:
Axle ratios high range 4th gear:
Stock Series with 4.7:1 R&P = 3686 RPM
Stock Series with 4.1:1 R&P = 3208
Stock Series with 3.54:1 R&P = 2788
Ashcroft with 4.7:1 R&P = 2737

What about the ratios with a Fairey OD or is the fairey the same ratio as an Ashcroft?
I installed New 32" tires on my Series and when driving 65MPH with the Fairey OD on I loose power on any incline. Taking the OD off helps the engine and I only loose about 10MPH vrs dropping down to 45MPH if I leave the OD on.
I need to install a Tach to see what is going on. This may help me choose the right gear so I don't TAX my engine and it can live longer.

[LH Drive]

I just did a search and found answers to my questions...
Fairey OD ratio: .78:1
Ashcroft OD: .87:1

2.25 L petro with 8:1 head @ 70 HP 4000 RPM's
But Max HP peak @ 3200 RPM's

So if I shift from 1st to 2nd up to 2000 RPM's ( max torque 120 ft lbs)
1st gear- 10 MPH
2nd gear- 15 MPH
then 3th gear up to 3200 RPM's this will put me at 37 MPH.
4th gear up to 3200 RPM's ,,56 MPH
Add OD, get up to 3200 RPM's and I'll be at 62 MPH
with room to pass slower traffic, 4200 RPM's 74MPH