Transmission Advice

[dozerboss]

I am new to the jeep world and am looking for some advice. I am building a CJ5 and am looking for some advice. The first thing I am going to have to do is learn how to use this forum as I believe all my questions can be answered here by you all. My first question is this, I have put a 1979 Buick 3.8L engine in my 1966 CJ5. Behind it I currently have a T-14 with a Dana 20 . Both have been completely rebuilt. I am not happy with the T14 because it is so low geared which limits my top end speed. I am not looking to haul the mail, but would like some advice on some other Transmission options. My gear ratio in the front and the rear are both 3.73. The T14 is nice for offroad use, but I am rapped out at 40 mph. I would like another gear. Any advice would help as I am so new to the Jeep world so my knowledge is Limited . I appriciate your time.

 

[73CJ]

but I am rapped out at 40 mph.

Sounds like you're still in low range. Seriously. Dana 20 lever should be:

What size tires are you running?

I could get 70 with 4.27s and stock 28" tall tires. Screaming. That's what it came with from the factory on mine.

I really don't think it's the T-14 & D20.Engine RPM isn't in the equation either.

 

[dozerboss]

Yea after I referenced the rpm's I new I was off track. I have 31" Tires. So with the Dana 20 what position should it be in when out on the road? I have never had a D20 so this is all new to me. Thanks alot for your help.

 

[CJim7]

I dunno....My '65 was pretty rapped out at 40-50mph. (stock everything)

I see you're from Boise, welcome to the board

 

[IOPort51]

2-WD high the most forward position.
Does the T-14 not have a 1:1 high gear??
Boy, if your doing 40 in 4 low you must really be screaming.

Yea after I referenced the rpm's I new I was off track. I have 31" Tires. So with the D20 what position should it be in when out on the road? I have never had a D20 so this is all new to me. Thanks alot for your help.

 

[dozerboss]

Thank You. I lived in Twin Falls back in the 80's for about 6 years. This is my first Jeep project. I dove into it so I am learning on the fly.

 

[CJim7]

Thank You. I lived in Twin Falls back in the 80's for about 6 years. This is my first Jeep project. I dove into it so I am learning on the fly.

Good for you! It's a fun project, and you'll learn a lot here.
TF in the 80's...Had to have been nicer then the hell-hole it is now

 

[73CJ]

I dunno....My '65 was pretty rapped out at 40-50mph. (stock everything)

65 should of had a D18 T case. They were optional with an Overdrive because of the over all low gearing.

My wife was doing 40 on the highway years ago,coming to pull another CJ out and didn't realize it was in 4L. After she got 14 miles to us, it was so hot it triggered a global warming event. . . .

"Why wouldn't it go over 40?"

The Dana 20 in 2H is a 1:1. 4L is a 2.03 0r a 2.46 Bronco.

From Jeep Horizons :: RPM vs Gear Ratio Chart


If your RPM is 2x the above chart, you are in 4L.

Check out The Dana Spicer Model 20 Transfer Case - Novak Conversions

 

[IOPort51]

so we can assume the axle is not really a 3.73:1 ??

 

[Old Dog]

so we can assume the axle is not really a 3.73:1 ??

thats kinda what I'm thinkn.

 

[shays4me]

my 65 had 4.27 gears and I could still get 65 with the stock setup and 31" tires. Something is amiss........

 

[73CJ]

Do not <-BAD WORD->-U&ME. It doesn't cost anything and takes less than 5 minutes. Crank the wheel, disengage the lockouts and count the revolutions. Then you rule it out once and for all.

From Chilton's:
77-86 CJ7 , 2bbl Carb,

SAE Net HP = 114@3600 rpm
SAE Net torque = 196@2000 rpm

So screaming is 3800 rpm and up.

Check your Transfer Case and make sure it's forward.

If it is still "screaming" then it's time to look into the transfercase gear ratio.

Rule out the easy (cheap) stuff first and just keep looking.