Looking to do a 5 spd tranny in my CJ7

Looking to do a 5 spd tranny in my CJ7

JakeRod13

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Location
The South
Vehicle(s)
78 CJ7
SBC 350
T150 tranny
d20 t-case
Im looking to do a 5spd tranny with overdrive in my CJ7. It has a sbc 350 with a T-150 tranny and a Dana 20 t-case.....any suggestions
Thanks
 
what gear ratio do you have in the diffs. Is it low enough geared to handle a 5 speed?
 
What's the stock AMC20 number, and would it have any problems with a 5 speed? Someone had a T-5 locally I was thinking about dropping in my 81 CJ7 since it would be a straight swap from what I've read. I didn't know the diff. ratio would have anything to do with it.
 
what gear ratio do you have in the diffs. Is it low enough geared to handle a 5 speed?

What size tires?

Someone had a T-5 locally I was thinking about dropping in my 81 CJ7 since it would be a straight swap from what I've read.
The T5 is a simple swap into a '81 CJ IF you have the Dana 300 TCase. The Dana 300 is the normal tcase found in the '81 but you said you are a Dana 20. Are you sure about that?
Either way keep in mind the T5 is a very light duty tranny that is worth avoiding. Read more: http://www.jeep-cj.com/forums/f105/manual-cj-transmissions-12112/#post97094
I would go for a NV4500 or a AX15 but first you have to make sure you know what transfer case you have.

EDIT: My mistake, you have a '78. Yes, you are right, you have a Dana 20.
 
Last edited:
It's a dana 300 tcase with an AMC20 rear diff. 33" tires, I-6.

I've heard people say that about the T-5 a lot. What exactly does it mean to be a weak transmission? My biggest reason for going with it is the apparent ease of installation and the fact that I can get one for $150.
 
It's a dana 300 tcase with an AMC20 rear diff. 33" tires, I-6.

I've heard people say that about the T-5 a lot. What exactly does it mean to be a weak transmission? My biggest reason for going with it is the apparent ease of installation and the fact that I can get one for $150.
Flex BT, you're confusing us. This is JakeRod13's thread and he is saying he has a '78 with a SBC and a Dana 20.
Flex, if you want to do a swap, you might want to start a new thread to avoid confusion.
 
I have a sbc 327 in my CJ7 and just swapped out my 3 speed manual for a th350. It bolts up easily to a dana 300 with an adapter from Novak or Advanced. Pretty straight forward swap especially since you already have a 350 ci in yours. The th350 is cheap and bullet proof! Bought one for $150, dropped another $100 in it for a rebuild kit just to make sure it was solid and added a shift improver kit for about another $50 bucks. If your not up for rebuilding your own, you can still find a solid th350 for around $200 and add the shift improver kit yourself.
 
I am running 33" tires.....I have heard that the TH350 is a great tranny, but i really want to do a manual.
 
I wouldnt recomend putting a T-5 behind a 258 , more a less a 350. Unless you like bench pressing transmissions. How about a SM465 4spd? If not Id go back to post #2 and dont look back. :)
 
I run a nv4500 in my jeep. For a Chevy engine get the gm model and it will bolt right up. I run 4.56 gears with 33" tires. Check Novak conversions web page, they have some formulas that help figure rpm with different gear ratios in the axles and tranny. I had the t 150 before, no comparison. I am happy with this swap.
 
I would not use the T5 myself.
With 3.54 gears, I cant see why you would want a 5 speed. (my opinion)
65 mph will be about 1687 rpm. thats pretty low to pull any fuel economy from that engine.
You should be about 2330 rpm at 65 now in top gear. Thats just about right, for me.

I run 4.10's with a T176 four speed on my I6. I love it!

Hear is the site I use!
Gear Ratio Calculator
 
Thanks for all of the input fellas, keep it coming. My RPMs are at about 2900 when running 70ish thats why i want a over drive.


Purpple77, How hard was your nv4500 conversion and what t-case do you have?
 
I have a Dana 20 transfer case. I followed Moses Ludel's book, Jeep CJ rebuilders manual. He goes through step by step. Also Advance Adapters has some booklets on the NV 4500 and install. It was a challenge to install and make fit. I needed an adapter to go to my AMC 401 and an adapter to go to the Dana 20. I bought the whole kit from Advance Adapters, with clutch. Not a cheap install. I am happy with the install and like the overdrive. I have the 1992 GM version with the 6.34 first gear. If you use the Dodge version you have to put in a GM input shaft.
 
My OG rear had 2.90 gears..I guess to get some decent fuel mileage. Althought I had to run up hills here in 3rd gear.
 
If you are running 33 inch tires, T-150, Dana 20, 3.54 gears, Hi-range 2 wheel drive.
70 MPH is 2523 RPM.. NOT 2900.
Either you are running by the incorrect speedo reading, due to larger tires?
Or you do not have 3.54 gears!

80 MPH would be about 2880 rpm.

Or 4.10 gears would be 2922 rpm at 70 mph.
 
If you are running 33 inch tires, T-150, Dana 20, 3.54 gears, Hi-range 2 wheel drive.
70 MPH is 2523 RPM.. NOT 2900.
Either you are running by the incorrect speedo reading, due to larger tires?
Or you do not have 3.54 gears!

80 MPH would be about 2880 rpm.

Or 4.10 gears would be 2922 rpm at 70 mph.

Maybe my speedo is way off.....Im going to take my GPS with me in the morning and see how off the mph is.
thanks
 
well I finally purchased a tranny..ended up going with an ax15. Now I am saving up for the adapters. If anyone has put a ax15 behind a sbc and has any advice I would love to hear it. Thanks:D
 
I have just about saved up enough $$ to pull the trigger on the adapters for the swap....any preferences between Novak vs advance adapters from anyone who has done this swap?

Thanks
 

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