79 CJ5 drivetrain issues

[Rick2194]

I just brought home this jeep on a trailer. It has a AMC 232 i6 w/a T-18 4 speed and I need some help. I could not drive it till I got it home. First,as you let out the clutch it shudders badly, then at 30mph or so the vibration is very bad and feels as though it is in the rear. I do not dare go over 40mph w/it. If you let off the gas while going at 40 or so it heads right for the ditch and does it quickly like a lane change!! It has a Black Diamond spring lift and a 3 inch or so body lift. 32"X11.50 tires. It is an all fiberglass body. Any thoughts on where to start diagnosing these problems. Thanks!!

 

[CJ]

The clutch just may be worn out..

Are there spring shims installed? What are the drive line angles? Sounds like a bad mismatch between the Transmission and the diff...

 

[Rick2194]

Yes it does have the spring shims (3 degrees) I think. Angles I do not know. The Transmission is lowered about an inch. Any idea what the angles should be?

 

[Old Dog]

for the vibs. I would check the u-joints and as CJ said check the angles but with only a 3" lift they should be ok. I would also check the u-bolts to make sure they are not letting the rear end or front end walk around.
The other question is does it have a locker that could be acting funny.
Is there any noises coming from the rear as in a bad bearing or something like that, that could make it pull?

 

[Rick2194]

for the vibs. I would check the u-joints and as CJ said check the angles but with only a 3" lift they should be ok. I would also check the u-bolts to make sure they are not letting the rear end or front end walk around.
The other question is does it have a locker that could be acting funny.
Is there any noises coming from the rear as in a bad bearing or something like that, that could make it pull?

U-joints seem tight, If I push on the drive shaft I can make the diff move slightly. I will check the U bolts. No locker that I know of and noise is minimal but then again I can't drive it to far yet but nothing really obvious in the way of a noise. If it has a locker there is no air or switch or cable (Detroit maybe?). The PO said the jeep always shuddered some as he released the clutch but this is just not right I agree that the clutch may be gone,91,000 on the rig

 

[Petescj]

My 85 shuddered like you explain and the clutch was pretty bad. I replaced it along with the throwout bearing , pilot bushing and some springs and no more shudder.

 

[Rick2194]

Thanks guys for the info. Is there a way to know if there is a locker without a disassemble? I doubt that is it as the former PO said nothing about a locker and I think he should have known. However there is a rocker switch that the PO said was to activate those tiny little interior lights? I thought the regular light switch would do that.

 

[Rick2194]

I took the rear drive shaft out and drove it in "front wheel drive", the vibration and lane change action is mostly gone. I think it needs some tire balancing etc. The drive shaft seems fine in the hand and the u-joints seem good. So whats next. New shaft or new joints or both. Or does the rear end need more shimming or Transmission lowered a little more.I am encouraged to at least have this problem somewhat isolated. Any thoughts are greatly appreciated

 

[CJ]

It's very hard to diagnose without actually having the CJ. Don't forget to look for a bad bearing in the output of the Transfer Case (but I doubt it).

I strongly advise that you read these three links below as they will probably help you figure out exactly what you need to do...

Tom Wood's Custom Drive Shafts - Vibrations (Harmonic)
Tom Wood's Custom Drive Shafts - Slopes VS Angles
Tom Wood's Custom Drive Shafts - Driveline 101

Tom Woods site has a boat load of information! -->> Tom Wood's Custom Drive Shafts - Tom Woods Custom Drive Shafts Custom Driveshafts Specialist

 

[Old Dog]

Rick you said when you push on the driveshaft you can move the diff a little. unless you are superman this should not happen. I would put some jackstands under the frame so the tires are off the ground and see if you can move the axle
Also check where the spring mounts to the frame, the frame likes to crack there which if bad enough could let the spring mount and axle move.

 

[Rick2194]

I will look at that again and see whats up. I removed the shims and it seemed "slightly better". I measured the angles and if I am correct came up with 27 degrees on the drive shaft,which according to the folks at Tom Woods should be closer to 10 degrees,maybe 15. I don't see how to get anywhere near that with the current set up. May need to go to a CV joint/shaft. I checked my 76 CJ5 and it measured at 18 degrees w/a shackle lift and 2" body lift. I never had any vibration like I am experiencing with this CJ. By the way they were very helpful and free with the info at Tom Woods when I called today. I took a bunch of pics and am going to attempt to get them posted today.

 

[Rick2194]

I spoke with Tom and gave him the angles as best I could measure and it appears that I need a CV drive shaft to solve the problem. I really appreciate all your help with this jeep issue. Many more things to work on. I want to do an engine swap eventually. I have a few options for that. I have a AMC 304 that I have not run for 15 years, a 401 that is in a jeep frame that has sat outside for years. I'm not sure if it can be rebuilt or not. A 292 in a chevy van w/a 4 speed that runs like a top. Their are also any number of 350s that are pretty popular around here and some are reasonable to acquire. it also seems that I need a clutch as well for the "new" 79 CJ5 in order to actually get it so we can go for a ride. I would like to read any of your thoughts on motors and trannys etc. or what you would have done different,better etc with your jeeps.

 

[CJ]

~~If you let off the gas while going at 40 or so it heads right for the ditch and does it quickly like a lane change!!~~

I missed this little bit of your first post. That condition is almost always from a the castor being wrong on the 'front'. Does the front have any degree shims in place? There probably should 'not' be. Also, from looking at your gallery photos, I think I see some extended front shackles. They can really throw off the front geometry as well. Do you have a normal length set you can try? You might want to spend a few dollars, take it to a good 'truck' alignment shop and have them give you readings on what your alignment actually is. When I had my alignment don (years ago) I found out I needed 2 deg camber shims - what a pain to put on but driving became great! The money spent at my local 'truck and 4x4' shop was well worth it. I can crank down the road at 75 keeping up with interstate traffic and take my hands off the wheel... Not jerking or pulling on accel, cruise or decel. I have a 5 also, so it is possible!

One other thing. What size tires?

~~I want to do an engine swap eventually. I have a few options for that. I have a AMC 304 that I have not run for 15 years, a 401 that is in a jeep frame that has sat outside for years. I'm not sure if it can be rebuilt or not. A 292 in a chevy van w/a 4 speed that runs like a top. Their are also any number of 350s that are pretty popular around here and some are reasonable to acquire. it also seems that I need a clutch as well for the "new" 79 CJ5 in order to actually get it so we can go for a ride.~~

IMO - Stay with AMC, no adapters or special parts will be needed. The AMC 304 is a good bolt in - it was standard for your year. Are you sure you have a AMC 232 i6 and not a AMC 258 i6 / 4.2l ? The AMC 258 i6 / 4.2l is a great engine and would be direct swap with no changes needed!

As for the clutch, I would probably just change it and then have 'much fun' for a while... I see no reason to rebuild a CJ that is so close to doing what you want it to do... Be fun!

 

[Rick2194]

Thanks CJ for the responses. No shims in the front, there are shackles in the front that may need to go. The former PO said AMC 232 i6 because he put in a new Cam purchased for a AMC 258 i6 / 4.2l and it would not fit discovered at that point it was a AMC 232 i6 . Is there a way I can tell here in the dooryard? Tires are currently32X11.50.

 

[RoscoDude]

Thanks CJ for the responses. No shims in the front, there are shackles in the front that may need to go. The former PO said AMC 232 i6 because he put in a new Cam purchased for a AMC 258 i6 / 4.2l and it would not fit discovered at that point it was a AMC 232 i6 . Is there a way I can tell here in the dooryard? Tires are currently32X11.50.

Odd.... At least the earlier AMC 232 i6 and the AMC 258 i6 / 4.2l are the same block with just a different deck height. I ran a cam for the AMC 258 i6 / 4.2l (270 deration .470 lift) in my stroked AMC 232 i6 . (AMC 258 i6 / 4.2l crank with custome lenght rods and pistons) That was a nice motor with ported heads, bigger valves, clifford intake, long tube headers, and a Holley 390cfm carb. Sometimes I think it ran nicer the the Ford 302 in the CJ5 now.

 

[Rick2194]

I rechecked the vin and it's supposed to be a AMC 258 i6 / 4.2l . Hmmm. I took some numbers from the block (stamped) will that tell me what it is?? I want a V8 in it for the roar out the dual headers. This motor seems to run very well and sounds good. Oil pressure seems to drop quickly but as soon as you touch the throttle it goes up to 40 or so. I need to get the CV shaft and a new clutch in order to run it some,I may like the set up and leave well enough alone.

 

[OlivergreenCJ7]

Everyones advice seems to be pointing you in the right direction. I missed if you had 5 or 6 degree shims or not for your rear leaf springs which would raise the pinion angle up some. A couple things you could do to get you moving would be to lower the Transfer Case a bit. maybe 3/4" to 1" drop might help out some as well as new u-joints. I run 35's on a 4" lift with a 3/4" drop without any vibration issues... just something to think about.

Also, I wonder if your clutch linkage could be out of whack? Make sure you don't have any excessive play in the linkage between the clutch fork and ball attachment. Sometimes the nuts can work their way loose. While your in there check the condition of your Transmission mounts and engine mounts. A T-18 is a heavy pig and if there is a lot of play could be causing your clutch linkage to slacking up. With a rear locker make sure tire pressure is even if its off even a little it will effect the locker.
As for motors a AMC 258 i6 / 4.2l is a good motor ,but drive a V8 jeep and their is no comparison. Once all the smog is removed a AMC 304 works quite nicely even with stock manifolds.
Check to see if your 401 block spins freely and sell that to fund the rebuild or the refreshening of your AMC 304 . I've seen 401s go for $500 bucks needing a rebuild in certain areas. Master clutch kit would be wise but wait to see what engine you want to run(pilot bushing might be different). Luk and centerforce make nice kits. I'd choose the Luk if your gonna run in mud why trash a centerforce IMHO good luck