Any Reasons Not To Use A D18?

I recently bought a rolling 68 Cj5 chassis mainly because I wanted the Warn overdrive for my 45 GPW. Then I started thinking that it would make more sense to use the overdrive on my 75 CJ6 (if I ever get the project back out of mothballs). My reasoning was: I plan on using the CJ6 on the highway fairly frequently. I don't intend to run tires that are too much taller than stock. It has a 304 with a fairly small gas tank.

One issue I have is that I plan to run a T19. The T19 seems to be a Ford based on the measurements of the front portion of the input shaft. It is currently bolted to a Scout Dana 300 (Texas bolt pattern). I have not opened it up to see what the bull gear (if that is the right term) tooth/spline count is but I think I read somewhere that the Ford T18/T19 was six spline.

I know its a long shot but does anyone have an idea if a six spline, D18/Warn OD would work with a Ford T19 output shaft? I browsed Novak's sight but missed the info if it was there.

Also, are there other reasons not to run the D18 in this situation? I already expect to have to find an offset, flanged D44 or do something to the tapered axle D44 (hubs? FF kit?). Would the rear driveshaft be excessively low?

Is strength likely to be an issue?

Thanks.
Frank

 

The three main problems I see with the Dana 18 are 1) durability, 2) noise and 3) leaks. The rear wheels are always driven by the intermediate gear, so the intermediate shaft wears out faster than it would for a Dana 300 or Dana 20. The Borg-Warner Quadratrac has this problem too, though it wears out chains rather than intermediate shafts. The Dana 20 was advertised as a "silent" transfer case, not because it is so very quiet but it's a lot quieter than the Dana 18 which it replaced. The 20 is a little better than the 18 in terms of leakage.

Why not skip all this hassle and buy a conversion kit for the T-19 to the Dana 300? It's superior to both the 18 and 20. Strong, durable, good gearing, quiet. You can use your existing flanged 44. What ratio is it? The factory ratios are 3.73 standard and 4.27 optional. Both of these are fine on the highway with the 304. BTDT - I drove my '73 with the 304 and 4.27s all over southern California, at desert highway speeds. No problem. If you are thinking about fuel economy, I expect you will not see much difference with or without the overdrive as you propose.

The overdrive is great with 4.88s or 5.38s, but that era ended in 1972. I don't see a lot of advantage with numerically lower axle ratios.

 

the question is why do you think you need an overdrive?
with a 360/T18/scout300 3:73 gears and 33" tires I have no need for an overdrive..

save the overdrive for exactly what you bought it for.. L-head and 5:38 gears

 

x2

 

I will gladly trade you an offset flanged rear axle for a Texas Dana 300, BUT everything that Tim just wrote above details why it would be best to run your 300 with a t18 or t19 transmission. Simply no benefit to having an overdrive with higher then 4.27 or even 4.56 gears. If I remember right, your 6 has 3.73 gears.

 

I assumed he was getting the T-19 without the Texas 300... if the OP has the Texas 300, run it.

 

Correct me if I'm wrong(or call me crazy) but you have some nice parts that have value. This is also for a CJ6 mod that has a centered diff. Why not sell off some parts to fund a NV4500/Dana 300 swap? You will end up with a deeper 1st,OD and a better T-case. You have the wheel base to do it with.

 

Gentlemen, Thanks. All good points. I think I will leave it as I was originally going to do it. 304/T19/D300. Thanks.