Misc. How much clearance is enough?

[Wild Heart Jeeper]

I put a SBC, 700R4, D300 in my 79 CJ7. I am having difficulty establishing enough lateral and/or vertical clearance between front driveshaft and transmission pan at the transfer case end. I have a Novak adapter from 700R4 to the D300 which allows clocking the D300 to 4 different positions. Clocking it down to the third position gets me approximately 1/4in lateral clearance between transmission pan and the balancing weight welded on the side of the custom Tom Woods small diameter driveshaft and close to an inch vertical clearance under the overhanging rim where the transmission pan mounts to the underside of the transmission. It appears to me that this close to the transfer case end of the driveshaft the vertical travel travel with suspension flexing would be pretty minimal, and the lateral travel would be almost none. But is 1/4in lateral and 1in vertical enough clearance? Any thoughts on this would be appreciated!

 

[CJ7Pilot]

I think you'll have to flex your suspension with a jack, and watch what it does. Also, with the weight of the vehicle on the wheels, have someone turn the steering wheel back and forth while you watch the axle. There will be some lateral movement, and it may well cause the driveshaft to touch the transmission. When you're off-roading, both of these factors will be in play.

I've never done this particular conversion, but 1/4" sounds pretty close to me. How much lift do you have? A little more lift might help move the drive shaft out of the way.

Have fun!

 

[duffer]

That is pretty tight but could work. As above, flex it to the max with a jack but realize that that probably isn't as far as the suspension is going to travel with dynamic loading unless you are tight against the bumpstops. You will also have to pay attention to the front shackles "down the road" and keep the slack out of them-something one should be doing anyway.

 

[Wild Heart Jeeper]

That is pretty tight but could work. As above, flex it to the max with a jack but realize that that probably isn't as far as the suspension is going to travel with dynamic loading unless you are tight against the bumpstops. You will also have to pay attention to the front shackles "down the road" and keep the slack out of them-something one should be doing anyway.

I think you'll have to flex your suspension with a jack, and watch what it does. Also, with the weight of the vehicle on the wheels, have someone turn the steering wheel back and forth while you watch the axle. There will be some lateral movement, and it may well cause the driveshaft to touch the transmission. When you're off-roading, both of these factors will be in play.

I've never done this particular conversion, but 1/4" sounds pretty close to me. How much lift do you have? A little more lift might help move the drive shaft out of the way.

Have fun!

CJ7Pilot Thanks for the idea of flexing with a jack! My lift is 3 1/2" with OME YJ springs and I am good with the height so don't want to increase any. I'm gonna play with the flexing during my next work session and see what it does. And thanks duffer for the increased travel from "dynamic loading" tip! I'll have to see what measurable difference the flexing with a jack makes and then make sure there is enough safety factor for some additional flexing. I will post how it turns out.