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-   -   78 CJ7 and 79 CJ 5 Drivetrain Swap (http://www.jeep-cj.com/forums/f2/78-cj7-79-cj-5-drivetrain-swap-19697/)

butler44 08-02-2013 01:53 PM

78 CJ7 and 79 CJ 5 Drivetrain Swap
 
I have a 79 CJ5 with the 304 V8, T-150, Dana 20 t-case. The transmission is shot and want to upgrade to a 4 speed. I have a buddy that has a 78 CJ7 with the 258 straight 6 with the T-18/ Dana 20. Well I have found (on here) that in 78 jeep only offered the T150 and T18. Would I be able to "bolt up" his tranny and tcase to my 304? I am assuming I will be able to if I use his bell housing? I am also going to use his axles because they have 411's which is MUCH lower than the 307's or whatever I have in my jeep now. Does the 78 CJ7 have the wide track? Thanks in advance for the help on this.

butler44 08-02-2013 02:00 PM

Re: 78 CJ7 and 79 CJ 5 Drivetrain Swap
 
I forgot to mention, my buddy wants $1500 for his jeep. The tub is in great shape and it runs great. I dont have time/money to build two jeeps and was going to take what i needed from his jeep and part out the rest.

How much do you think I could get for:

From the 78:

258 I6 Motor (complete)
CJ7 Tub

From the 79:

AMC 20 and Dana 30 out of my 79
T150 and D20

Hedgehog 08-02-2013 05:50 PM

Re: 78 CJ7 and 79 CJ 5 Drivetrain Swap
 
Going from a CJ 7 to a CJ5 will require different driveshaft lengths. The easier swap would be to put your 304 in his CJ7.

Saddle Tramp 08-03-2013 02:46 AM

Re: 78 CJ7 and 79 CJ 5 Drivetrain Swap
 
This is an easy no brainer swap. The 78 & 79 parts all interchange except as mentioned the drive line lengths will be different no matter what.

The AMC I6 and V8 to bell housing bolt patterns are all the same and the 77 through 79 bell housings all have the same transmission holes drilled and tapped (T150 Ford Butterfly & CJ T18) so same - same between the two jeeps. However there are a few parts from the CJ7 you will want to have. The T18 uses a stud that is presses in from the inside of the bell housing for the top driver’s side bolt plus the clutch throw out bearing fork is notched for the head of the inside stud. Both the stud (it has a flat head) and the notched fork are no longer available so if you need to replace it you will have to notch the new one yourself. From the fork to the peddle no changes so just use all of the T18 bell housing with the stud and the rest of the stuff from the CJ7.

The T18 is longer than the T150 so the linkage to operate the Dana 20 is longer too. Swap the linkage or just swap the whole 20 with the T18. Also note that the torque stud plate between the transmission and the transmission mount is a little beefier than the one for the T150 so get it too.

The next thing is the skid plate. There should be about a 1” drop kit between the bottom of the frame and the top of the skid plate. The holes for both transmission locations are already drilled and tapped in the frame. The skid plate bolts up to the frame with the front holes lined up with the front set of bolts for the T150 but the back holes of the skid plate line up with the back set of holes in the frame for the T18.

Both jeeps are narrow track and will interchange too but the brakes on the Dana 30 front of the 78 are a little larger but if the 79 has the gearing you want just use them. Be sure to check that the AMC 20 rear has one piece shafts. The drive lines will need to be reworked but a good driveline shop can fix you up or just get some new ones from Tom Woods.

$1500 for a running 79 CJ of any flavor sounds cheap so buy it. Check Craig’s list for local prices in your area on the spare parts.

Try this for additional info: http://www.jeeptech.com/convtrans/cjt18/

butler44 08-05-2013 02:36 PM

Re: 78 CJ7 and 79 CJ 5 Drivetrain Swap
 
ST,

Thanks for the information. My friend is actually going to let me swap out everything that I need from his CJ7 into my CJ5 for free! All I have to do is sell it for him (he doesnt use Craigslist). I JUST replaced the clutch in my 5 and I hope that I dont have to get another one? Is there anyway to do use cj5 bell housing? Or do I have to use the donor bell housing? I wish this was easy!!!! HAHA there is so many things that I want to do to that jeep and trying to plan ahead so that I am not having to do things twice or wasting money on parts that are going to be swapped out in 6 months...... Thanks for the info!

butler44 08-05-2013 02:49 PM

Re: 78 CJ7 and 79 CJ 5 Drivetrain Swap
 
ST:

Also, whats your opinion on SOA. I am torn up on this issue. I want to do it really bad, and do it right. But I will have to slowly put it together and I wanted to be able to use the jeep as I did so. But I am hearing some crazy things about SOA on narrow tracked cj's. Thanks!

Petescj 08-05-2013 05:18 PM

Re: 78 CJ7 and 79 CJ 5 Drivetrain Swap
 
Quote:

Originally Posted by butler44 (Post 160597)
ST:

Also, whats your opinion on SOA. I am torn up on this issue. I want to do it really bad, and do it right. But I will have to slowly put it together and I wanted to be able to use the jeep as I did so. But I am hearing some crazy things about SOA on narrow tracked cj's. Thanks!

Alot of people try to lean toward a SOA lift thinking it will be cheaper. This isnt true if its done correctly. I think everyone has seen those crazy zig zagged drag links that dont belong on any Cj , on or off road. What are you looking to do with the Cj and what size tries are you planning on running?

butler44 08-05-2013 09:40 PM

Re: 78 CJ7 and 79 CJ 5 Drivetrain Swap
 
I plan on running 35's MAX on this first build. Next build maybe bigger. I want to be able to easily go down 80% of the trails i come across here in California. I dont need to crawl over 4 foot boulders, just have a good time off road.

BusaDave9 08-05-2013 11:14 PM

Re: 78 CJ7 and 79 CJ 5 Drivetrain Swap
 
It's hard to follow up a thread after Saddle Tramp has already posted. He knows his stuff and has good information about the swap.
The thing with the bellhousings is they are specific for the engine so you will need the 304 bellhousing. The transmission end is often more generic and in your case the T18 should bolt right up to where you had your T150.
The clutch pressure plate will be reused.
The input shaft on both transmissions are the same size with 6 spines so you can reuse your clutch friction plate.

IMO SOA is not a good idea. That's 6 inches of lift. You also get a lot more axle wrap.

Peanut Butter 08-06-2013 08:40 AM

Re: 78 CJ7 and 79 CJ 5 Drivetrain Swap
 
Quote:

Originally Posted by BusaDave9 (Post 160637)
It's hard to follow up a thread after Saddle Tramp has already posted. He knows his stuff and has good information about the swap.
The thing with the bellhousings is they are specific for the engine so you will need the 304 bellhousing. The transmission end is often more generic and in your case the T18 should bolt right up to where you had your T150.
The clutch pressure plate will be reused.
The input shaft on both transmissions are the same size with 6 spines so you can reuse your clutch friction plate.

IMO SOA is not a good idea. That's 6 inches of lift. You also get a lot more axle wrap.

No S#@$^*£% t, have you ever thought of writing a manual Saddle Tramp? Rod


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