CJ7 Drivetrain Swap

[rielly]

So I've painted and lifed my 84. I went SOA on YJ springs and run 35's and regeared to 4:56. Engine is a 258 transmission a T4 with Dana 300. Engines tired and I'm curious what you guys recommend I do. I was thinking of either rebuilding my 258 or buying one already rebuilt from 4wd or somewhere similar. For the transmission I need to get a T5 in there because I think the 4:56 gears where a little to steep especially since I usually am just driving on the street. So keeping in my mind costs what do you recommend? I could go 258, 4.2, 304, or a chevy 350. I want do something that's not overly difficult.

Thanks,
Tom

 

[Saddle Tramp]

My vote would be to keep your jeep, jeep. Not only is it what I believe is the right thing to do, if cost is an issue keeping everything jeep will allow you to use off the self (or junk yard) parts that bolt together, no adaptors, plates, or hacking & whacking. At worst depending what year your jeep is, you may need to move or build a cross member.

 

[rielly]

I'm leaning that way but wonder if the 258 has enough power to turn 35's and get me up to highway speed (70 mph) with 4:56 gearing? Maybe the T5 will be enough help? So if I went with a 304 or 4.0 the cross member has to be moved???

Thanks,
Tom

 

[SteelHeadz]

Theres no crossmember that needs to be moved. The engine mount on a CJ is a saddle bracket thats welded to the frame but does not go straight across. You will need to cut them off and get the correct mounts for the application that your going to use it for. There are some aftermarket engine conversion brackets out there that may work instead of moving the original mounts.

 

[Rubiconrich]

The T4 and T5 tannys are not that good go with better 5 speed.
see Advance adapters. If you put in a say 304 you will pop the T5.