78 CJ7 and 79 CJ 5 Drivetrain Swap

[butler44]

I have a 79 CJ5 with the AMC 304 V8, T-150 , Dana 20 Transfer Case . The Transmission is shot and want to upgrade to a 4 speed. I have a buddy that has a 78 CJ7 with the AMC 258 i6 / 4.2l straight 6 with the T-18 / Dana 20 . Well I have found (on here) that in 78 jeep only offered the T-150 and T-18 . Would I be able to "bolt up" his tranny and tcase to my AMC 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]

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:

AMC 258 i6 / 4.2l I6 Motor (complete)
CJ7 Tub

From the 79:

AMC20 and Dana 30 out of my 79
T-150 and Dana 20

 

[Hedgehog]

Going from a CJ7 to a CJ5 will require different driveshaft lengths. The easier swap would be to put your AMC 304 in his CJ7 .

 

[Saddle Tramp]

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 (T-150 Ford Butterfly & CJ T-18 ) so same - same between the two jeeps. However there are a few parts from the CJ7 you will want to have. The T-18 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 T-18 bell housing with the stud and the rest of the stuff from the CJ7 .

The T-18 is longer than the T-150 so the linkage to operate the Dana 20 is longer too. Swap the linkage or just swap the whole 20 with the T-18 . Also note that the torque stud plate between the Transmission and the Transmission mount is a little beefier than the one for the T-150 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 T-150 but the back holes of the skid plate line up with the back set of holes in the frame for the T-18 .

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 AMC20 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]

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]

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]

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]

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]

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 AMC 304 bellhousing. The Transmission end is often more generic and in your case the T-18 should bolt right up to where you had your T-150 .
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]

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 AMC 304 bellhousing. The Transmission end is often more generic and in your case the T-18 should bolt right up to where you had your T-150 .
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

 

[Saddle Tramp]

Bell housings are interchangeable between the AMC V8 (AMC 304 /360/401) and the AMC I6 (AMC 232 i6 /AMC 258 i6 / 4.2l ) as the rear bolt pattern is the same between the two engines and in your case the 1978 and 1979 CJ bell housings are identical regardless of which OEM Transmission so no problem as to which bell housing you want to use. Clutch systems are also interchangeable between the two as well. The only part that you can’t swap is the flywheel; the AMC 304 can only be used on the AMC 304 and the AMC 258 i6 / 4.2l can only be used on the AMC 258 i6 / 4.2l or the engine will not be balanced.

As far as SOA I have a pretty conservative view of the issue. I am not a fan. It can be done correctly but the bump steer issue makes the conversion more expensive than it looks but part of my conservative view on the subject is my concern of jacking a CJ too far off the ground. CJs of all of the Jeep products ever offered have the narrowest frame width between the rails and as such have a greater tendency to roll over than their brethren and larger tires add to that height raising the center of gravity even further. Don’t miss understand as I get it when it comes to clearance and trail worthiness but to me the CJ has its limits unless the rig is gutted to the point the body may be a CJ but not much else is.

 

[butler44]

ST:

Have you ever rebuilt a jeep T-18 ? I went to drop the one out of the donor jeep and when i drained the tranny, there were LARGE chunks of metal that came out with it...... HELP!! Is it better to pay the $900 that they want at the tranny shop to have it done right? Or pay $230 for the master rebuild kit and attempt myself? Thanks! Anyone else have any thoughts?

 

[Saddle Tramp]

The T-18 is a relatively easy Transmission to rebuild. I suspect the $900 price quote includes a bunch of additional part other than the master kit as a quick internet check shows that Herm the Overdrive Guy only charges $175 for labor (plus parts) to rebuild a T-18 . Take the top off of the Transmission and see what you got. Are gears worn or damage? How about the main shaft? Is the stick out worn? All these bits cost money. If you are not comfortable with doing the job, shop around. Show the shops the tranny with the top off and see what they think. Is there a true “jeep” shop in town as opposed to an auto Transmission mostly shop? You might get a better price. Below is a link to Novak Adaptors and Herm:

http://www.novak-adapt.com/knowledge/t18_t19.htm

http://hermtheoverdriveguy.com/?page_id=1432

 

[butler44]

Well I am putting waggy axles underneath it in hopes of mitigating the rollover issue. Correct thinking? It also has the flat knuckle for high steer. I REALLY appreciate all of your help on this! It has been HUGE to have this input from you and everyone on the forum.

 

[jdarg]

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!

Having done it to my YJ "correctly" w/ a traction bar, proper hi-steer setup, etc., I definitely wouldn't do it again.

If 4" leafs and a mild body lift won't get it done, link it. If you are looking for 33-35" you should be good without SOA. It won't be a flex monster but it will get you down the trail.