The bottom gear in the t-18 is more like 6.28 There were close ratio t-18 trannies, but I think they were not ever in Ford trucks, but instead in IH Scouts.

Here are the ratios that I have usually seen mentioned:

1st 6.28, second 3.09 3rd 1.68, fourth 1.00 These are the "wide"

The close ratio tranny has:
1st 4.02 second 2.41 third 1.41 and 4th 1.00

The bottom gear in a close ratio t-19 is much more useable as it is much closer to 2nd than the wide ration 6.xx first. Moreover, the syncro first become much more interesting city driving, where downshifting is more frequent.

There is no magic to an overdrive -- it is all in the distribution of the various gears. I admit that the jump from 4.02 to 2.41 is still a bit much in the close ratio. But better than the 2x change seen in the wide ratio.

As long as the distribution is good, you can adjust your final RPM by swapping the right rear differential in.

Just trying to find a cheaper alternative.....

 

don't know about 3500 I have the same setup in my 66 I think it runs around 3000 at 70 I have done 80 in the truck however and still had petal travel and didn't hit my mid rev limiter

 

Here is what I did with my 300ci T-18 Added a Gear Vendors OD
https://www.ford-trucks.com/forums/1...d-details.html

 

Hey guys great info on this thread - I have a 1968 T10 transmission and I am looking for better highway economy and I am wondering if a borg warner R10 overdrive would mate up to the t18. I'd have to shorten the drive line etc but wondering if anyone has done this or seen it done. Thank you.

 

This is an old thread, but your post is new. It got my attention. Here looks to be the cheapest OD solution I have found, and would like to have one in my truck.

https://high-impact.net/rangeroverdrive

 

Thanks for that Yardbird. Still $1500 which is more then I want to get into just for overdrive but I do appreciate it. I might just have to get a whole new trans or go to a T5 which I don't want to do but I gotta get that final drive ratio down - its 1:1 now.

 

That is the Advance Adaptors Range spliter and that is the cheapest OD unit you will find.
The Gear Vender's OD unit is like $3000 and can only split gears when going over 30 MPH.
Dave ----

 

What rear gear are you running now and what trany?
The T5 is a car trany used in Mustangs and the WCT5 IIRC has a 2.95 first gear, not bad in a light car but in a heavy truck then add a heavy load and its not so good.
If just a street truck and never a load then a 3.73 rear gear with a WCT5 may be ok but just remember the weight of the truck is more than a Mustang the T5 came in.

I don't know what motor you have or bell the motor takes but maybe you could use one of the modern tranys with the bell housing part of it like the M5-R2,this is a 5sp with OD used in the 80's trucks.
Does not have a granny gear but could go lower out back to help on take off's.

Me I do plan on pulling a car trailer at times so want to keep the T18. Just got a NP435 that has a little lower 2nd than the T18, you drive them as a 3sp, so that helps.
The truck has a 2.75 rear gear in the 9" and is not to bad on the high way at 70 MPH here. I would love to get a range splitter to get the OD and be able to split all the gears when needed but that will be down the road.

If you want to play with ratio numbers they here as it will give you them for a bunch of transmission, just input your tire size and rear gear ratio and it updates the charts
Calculators - Gary's Garagemahal (the Bullnose bible)
Dave ----

 

Hi Fuzz - I have a 351 with a light cam, intake and headers. The tires are stockat 235/75R15. Carb is a Holly 4180 4bbl which should also probably go. I think it has 4.10 or for 4.11 rear end in it. Its stock and I have never changed it. Stock motor was the 300 I-6. Ideally I would like to keep the t-18 in it because I agree with you the T5 trans is less truck capable and apparently there are issues with it coming to far back which impacts the stick placement etc etc. Currently 70 MPH has the engine screaming

I really just want something that I can cruise on the highway and not be using 20L/100 km at my very best most efficient driving.

 

The Ford 9 inch makes it really easy to change the third member out. This makes a cheap and easy fix. I have a 65 f100 with the 240 T85r11 combo. I ended up changing the third member out twice once to 3.0 then to 3.55. The 3.00 was to tall for the overdrive to work with but the truck had no problem with it other than that. I went to the 3.55 so I could still use the overdrive. If I was doing it without the overdrive I would use the 3.00. my stock 240 will start the truck out in second gear with out a with the stock gears and if i slip the clutch just a little it would start in 3rd.

 

Hate to burst your bubble, but I was driving these "back in the day" and 240's a 300 were very capable of 75 on the hyway. And we never had a farm.

Eric

 

Wizzard, I"ve been looking for that website for awhile, couldn't remember their name, I had finally decided it didn't exist anymore. Thanks.
Do you know anyone that has one installed, that may be my #1 choice at this point, and right on time, I'm almost done with my air ride mods.

 

I can only imagine that the Ranger is the overdrive being described.

https://www.advanceadapters.com/cate...lete-units/91/

They sit between the engine and transmission and are about 7 1/2" long, usually requiring the transmission to be moved further back.