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Discussion Starter · #1 ·
CJ-can\'t shift tranny when all twisted up!

Finally was able to take my new and improved Jeep out this weekend. I'm very happy with the new axles and the SOA and 38's just need to get use to the altitude!

During the buildup I also put in a sm420 tranny and the low gears are great. But, when the jeep is all twisted up, you know on ledges and the suspension is all twisted up I can't change gears. I have to push in the clutch and let it roll back a little and then it's real difficult but sometimes I can shift it then. Then when I'm over the ledge or rock or whatever it's easy to shift again.

I think it's got to be the frame twisting and putting stress on the tranny and t-cass but is there something I can do about it. If I add a cross member or beef up the frame will that just cause the stress to go somewhere that's not able to handle it?

Thanks for you thoughts.

Steve
 

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Re: CJ-can\'t shift tranny when all twisted up!

2 easy solutions...
1. get a hydrolic clutch.. they ARE reliable and plentifull
2. jeepgod has some really cool heim jointed clutch linkage..seems to work good
one other thing... do you have a body lift??? if so.. they often put strange angles on the linkage.. sometimes you can just drill the holes lower and straighten things out...
 

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Re: CJ-can\'t shift tranny when all twisted up!

Are you having trouble shifting gears or is the clutch moving. Elusive gave some great ideas on the clutch. If you are having problems shifting. Is the hole big enough or is the body twisting so bad that the shifter gets jammed up against the hole. Take the boot off and twist it up and see what happens.
 

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Re: CJ-can\'t shift tranny when all twisted up!

What gears are you having trouble shifting into? All of them or first and reverse? Both first and reverse are non-synchro in those older trannys. That can give you trouble when you are on weird inclines. Some times you have to double-clutch them to get them into gear on steep inclines.

Check:
Enough travel from the pedal to the clutch fork for the different clutch to work right? Does it disengage the clutch all the way, or just barely enough when on dry ground?

Manual clutch linkage adjusted correctly? Too loose and it will do just that.

Body/tranny/motor mounts nice and tight/not broke?

Too much slop/wear/free travel in the pedal assembly?

Shifter not making contact with body tub or under-body parts? If it is close on flat ground, it is probably hitting something when flexing.

If nothing from above, then check
Loose bolts on the shifter assembly and on tranny?
Drive shaft binding on steep angles?
Synchros in the tranny not worn out?

Good luck

John
 
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Discussion Starter · #5 ·
Re: CJ-can\'t shift tranny when all twisted up!

Thanks Guys!

1. get a hydrolic clutch.. they ARE reliable and plentifull
2. jeepgod has some really cool heim jointed clutch linkage..seems to work good
one other thing... do you have a body lift??? if so.. they often put strange angles on the linkage.. sometimes you can just drill the holes lower and straighten things out...

Chris, I don't have a body lift and your right about the hydrolic clutch. That's something I was planning on doing during next winter. (maybe I should move that up now)


Jim and John, I replaced the synchros' before it was installed but I didn't think about 1st and reverse being non-sysc. The tower for the shifter is above the floor so that's O.K. The clutch was way off so I adjusted the the linkage and now I have a good firm feel to it but it still does it.

When I'm twisted up I can't get it out of gear, when I engage the clutch forward movment stops, rpm's go up until I'm off the gas and jeep rolls backward and when I'm not so twisted any more then I can pull the stick out of gear.
Maybe drive shaft bind? If so, how do I check for that.

I've got to figure this out, it got a little hairy a couple of times.
The kids don't call me 'brown streak' for nothing!


Thanks again.

Steve
 

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Re: CJ-can\'t shift tranny when all twisted up!

Here is my take on this; Transmissions CAN wrack from torque and from frame stress and that CAN cause the shafts in them to bind slightly such that the sliders won't move easily. Years ago there was a truck tranny which was the first "combined" tranny with a single lever to shift all gears.
The trucking companies thought it was just great
since the drivers could shift without taking one hand off the wheel to make the double gear in the main box/auxillary combination.
It was later discovered that the extended length of the case was the culprit
in the premature failure
of many of these boxes. The case was actually twisting slightly when the torque of those diesel engines got real high. That not only caused hard shifting, but the bearing fits in the cases washed out as well.
I suspect that in your case with the Chev-Lay up front and the D-300 adapted to the tranny, that you have some wracking of the gearbox when the frame twists. The engine/tranny combo is trying to hold the frame from wracking and is itself being wracked slightly. What you could do is perhaps arrange for more "float" in the rear engine mounts to remove strain from the engine/tranny combo.
Anyway, that's my
idea.
 
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Discussion Starter · #7 ·
Re: CJ-can\'t shift tranny when all twisted up!

Thanks Dave, I just went out to my local rock quarry (after hours of course
), and the front driveshaft is not the right length, at least it's not now. The leaf springs have settled down quite a bit and with the shackle reversal the driveshaft's just to long now. When the front-end is push up to something it moves toward the rear now and with the springs a little longer (you know what I mean?) the shaft is totally compressed and pushes into the t-cass and twist the tranny, it's a mess.

I'll get the shaft cut and see how that works and then I'll try the motor mount idea.

Thanks to you all, for some reason the driveshaft never crossed my mind.

Steve
 
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