Divorced Case Woes

[agjohn02]

on top of particulate filters, this is another reason not to buy a 2007 diesel engine.

[uglyota]

All this so you can keep the mazda engine...
how's that coolant leak by the way?

[JB]

Nutz, accept the advice and questions and don't be so defensive

Fredo, serioulsy, its old.

[redcagepatrol]

Nutz, I think that your idea will work, but I don't think that you need the slip to solve the problem.

1) Motor mounts and tranny mounts are not designed to let an engine torque, they are there to isolate the vibration of the drive train from the cab of the truck.

2) only worn out motor mounts allow the engine to torque - good ones, or poly ones might only let the engine twist a degree or two.

3) the twisting motion mentioned above does not require a foward-backward slip, it will just twist in the driveline - sending a torque to the wheels.

I do not think that you need a slip - although it will probably lessen your problem. You need to clamp down your engine to eliminate the torque problem. If you clamp down the engine mounts (use some good poly ones), then your tranny mount will never see any torque and you won't have to worry about that breaking either.

remember - the tranny mount is not designed to take much torque - it is just there to suport the weight of the tranny and to isolate vibration. Let your engine mounts do all the work.

[Chadnutz]

When I hammer on it, the drivetrain moves. Even the slightest bit of movement will drag one on the cases around. Say the transmission moves even a half an inch to the side. What do you think that rear case will have to do to accomodate this movement. Because there is no slip, the rear case has to come forward to account for the new angle. The more the cases move around, the worse the driveshaft angle between them becomes. Because thatshaft is so short, I don't think it can move as freely as a normal driveshaft, so one case starts to move around in circles. I really believe there must be slip unless the cases are perfectly aligned and never move at all. It's the movement that kills the mounts. They weren't dead to begin with.

[fbronco86]

My 72 f250 had a divorced case with a slip shaft between the tranny and t-case. But it was also alot longer than yours. It was prob 1 1/2 feet long.

I think you either need to put in a slip shaft not sure how cause you have no room. Or you need to tie the tranny and t-case together.

[redcagepatrol]

When I hammer on it, the drivetrain moves. Even the slightest bit of movement will drag one on the cases around. Say the transmission moves even a half an inch to the side. What do you think that rear case will have to do to accomodate this movement. Because there is no slip, the rear case has to come forward to account for the new angle. The more the cases move around, the worse the driveshaft angle between them becomes. Because thatshaft is so short, I don't think it can move as freely as a normal driveshaft, so one case starts to move around in circles. I really believe there must be slip unless the cases are perfectly aligned and never move at all. It's the movement that kills the mounts. They weren't dead to begin with.

Yes, it is the movement that kills the mounts - but there shouldn't be any movement - especially a 1/2". How can the tranny move if all the mounts are good and solid? It might get the slightest bit of twist along the axis of the drive shaft, but there shouldn't be any foward-backward or side-side movement of any kind.

Fix the motor mounts so that the drivetrain will not move. Problem solved.

[Chadnutz]

Why do people chain motor mounts if severe stress during off roading doesn't cause the drivetrain to move? How to people's fans hit their radiators?

[fbronco86]

Why do people chain motor mounts if severe stress during off roading doesn't cause the drivetrain to move? How to people's fans hit their radiators?

I am with scott. Your engine should not be moving around that much. Get some soild type engine mounts and see what happens.

[tigweld]

Why do people chain motor mounts if severe stress during off roading doesn't cause the drivetrain to move? How to people's fans hit their radiators?

cause they too are using worn out shiaty mounts, I think that is your main problem the motor mounts are not up to the reduction you are adding with extra case. btw I know for a fact that a short mid shaft with no slip will work if the case and tranny are mount securely.(my old neighbor had a 4.3 vortec with a np465 and devorced 205 in a buggy with about a 100 w.b. ,mid shaft was 2 d-shaft yokes welded together)

[redcagepatrol]

Why do people chain motor mounts if severe stress during off roading doesn't cause the drivetrain to move? How to people's fans hit their radiators?

the chains are because the extra torque tears the mounts apart. The fans hit the radiator because the body flexes into the engine and they didn't design in the proper clearence to allow for the flex - any more questions?

This is exactly why they make the motor mounts solid - which is the whole point I have been trying to tell you to do. Get or make stronger / solid mounts that will keep the motor from twisting!!!

[stx4wheeler]

When I hammer on it, the drivetrain moves. Even the slightest bit of movement will drag one on the cases around. Say the transmission moves even a half an inch to the side.

Your tranny, and cases should not be moving that much. I would recomend changing your motor mounts, and your tranny mount as well. This is much cheaper than building a new shaft with the hope of fixing the problem. And after you build another shaft with a slip the trans and cases are still gonna shimmy around like they are now. I really dont see how a slip shaft is going to help the problem.

[eight]

I think a slip shaft will solve the problem of the toyoda case coming undone and that you really should have one. But if the mazda stuff didn't move around a few inches you probably wouldn't have a problem. You're gonna have to fix that anyway so might as well try it.

If you don't want to spend much time or money trying this, just drill a 1/2" hole through the motor mounts and install bolts with lock nuts. That's how I handle mine, keeps the stock mounts from coming apart, I used to go through them pretty quick. Also used to hit the driveshaft hard and take out the transmission mount and therefore the radiator. You have to have a kickass driveshaft to do that though. My transmission mount now consists of two 1/2" bolts through the transmission mounting area and the skid plate, with about 1/2" of rubber in between.

OK here's my reason why the output does move side to side. The transmission is mounted on the bottom and the output is higher than it. So the transmission pivots on the bottom and the output moves in an arc above it. It sounds like the motor mounts are completely ****ed so there's alot of movement. I'd try working in one of those flexible couplers I linked to above if you have access to a machine shop and the coupler's not overly expensive.

But then swapping in the 2wd transmission and the lower geared case makes things simpler and slightly lighter.