Overdrive

Thinking about an overdrive, but have a few questions. "Rattle Cans" transmission is a T-14 with no major problems (Leaks like a screen door on a submarine and has no syncro between 1st and 2nd). The T-case (single stick) has no problems but leaks as well and neither one has been rebuilt that I am aware of. I would like to rebuild them but have to admit I am reminded, "If it ain't broke don't fix it".

Anyhow, I guess my questions is will the overdrive get eaten alive if suddenly the "18" decided to give up?

 

I think the overdrive should be ok if the dont share the same fluid. The only other concern I would have is if the 18 locked up would it stress load the overdrive unit at speed.
sory I cant be more help I have never messed with a overdrive unit.

 

The overdrive is lubricated by the gear oil, and gear oil moves between the transmission and transfer case.

These overdrives are very sturdy and as long as you keep oil in the transmission, they will be fine.

JMO - leaks are a problem that should be addressed. All of these Jeeps drip, but with some effort you can get the drip down to a few drops when you park.

 

My transmission and transfer case looked intimidating. All of those gears and parts cramed into a small metal case. The hardest part for me was removing the transmission/transfercase and reinstalling them.

 

Not to hi-jack this thread.....but how difficult is it to install a overdrive unit on a D-18?

 

Uhhh this isn't right, your transmission is either not a t14 or the synchro is wore out. T14's are syncro'd in all forward gears. Oh and if they leak as bad as you describe, they are technically broke. You should try to pull them and at least fix the leaks. My honest opinion!!YMMV

 

The installation of the OD itself is not difficult; it bolts right on to the back of the transfer case, and you don't have to take anything down to do it. But, if your JEEP was not installed with it originally, you will have to put in some linkage. Might have to pull the floor pans to do that part.

 

Thanks for the reply......putting another hole in my floor wouldn't be any problem......R)

 

are you sure you have a t-14? the t14 has a 10 spline output. the t-84/86/90 family are only syncro'd between 2nd-3rd, and have 6 splines.

 

Sorry for head up butt, the t-case has the leak and not the tranny. I believed the tranny to be a T-14 after having it looked at by other JEEPers. I also was told by the PO that 1st to 2nd shifting had become a "Double Clutch" affair at times.
I have had it at speed on the "101" with no problems other than whinning from the divertrain over it push'n 4.88's at 50 MPH

 

Here is an easy way to tell the difference between a t86 and a t14. The t14 has its fill plug on the passenger side and the t86 has it on the drivers sdie. The t14 is syncro'd in all forward gears. If you have a t14 and you're double clutching to shift from 2nd to 1st your syncro's are shot.

 

After working on this T-18 project of mine for a little bit, I would recommend just diggin into it and replacing the synchros. The T-14/D18 unit is a light; you could drop them down as a unit by yourself with a jack. There isn't much to the transmission, a bit of a learning curve, but they are just not that complicated. If the D18 is leaking, sealing it up is cheap and could be done at the same time.

Prior to my teardown, I was running the T-14/D18/Warn/4.88 combo in my '70. I could cruise 65mph without problem on 33" tires. Check the classifieds if you are looking for parts.

 

www.hermtheoverdriveguy.com
he helped me with my O.D. and sells and rebuilds them plus has parts.
He's a great fellow to talk to.

 

A most worthy investment if you have 4.88's easy install.

 

Thanks for all your help guys. I confirmed the Tranny is a T14, which is pretty stained with the 4.88's and 31" tires. After this past weekend the overdrive is going to be a must. Got "Rattle Can" up to about 55 MPH on the way back from the trail and "REALLY" upset it's delicate balance. It popped loud enough to scare the kids!

P.S. Less means more parts!