Just re-hashing my plans of putting a GM 4.3 V6/4L60 and NP241C T/C in my '71. It appears the frame is too narrow to allow me to clock the t/c up enough to gain decent clearance. What trans/tc/front axle/combo will tuck up nicely and still allow me to run a minimal lift with 33" tires? I would really like to keep the 4.3/4L60 setup, but the trans pan is offset to the right, making for little D/S clearance. Who runs this Transmission and what have you got behind it?
Here's some pics of Punkin, a '71 I built for my brother-in-law. It has a 4.3L/4L60E/D-300 combo. We used the Novak adapter, but couldn't get sufficient clearance of the front driveline with the tranny pan. The fix was to have spacers made that moved the xfer back another 2" which also required a 2" longer input shaft to be made at our added expense. Don't know if Novak ever changed their design, but I'd check out Advance Adapters to see if their adapter is longer for additional clearance. This will be the key with any right-hand drop front output xfer, to get it back far enough. As you can see, it doesn't hang down too bad. The 4" lift also helped adding a little more clearance.
And here's Ol' Red Beater, my '66. It has a 383/4L60E/Atlas II combo. As you can see, since its' size is bigger than the D-300, it has to be clocked lower to clear the frame.
Thanks for the info. I am exploring a few options, one of which is switching sides and using an np231t/c and a HP D-30 narrowed to use my narrow track axles. Another is switching to a manual trans. Is anyone running a 241c transfercase? Thamks again.
This is the same set-up I'm going except I'm using the original dana 20 t/c will I have the same problems? Also how do you like your combination and drivabilty on the hwy.
This is the same set-up I'm going except I'm using the original dana 20 t/c will I have the same problems? Also how do you like your combination and drivabilty on the hwy.
You're planning on a 700R4 or 4L60 or 4L60E with a D-20 xfer behind it?
If so, then yes, you will have the same obstacle of making sure the front output clears the transmission pan sufficiently. The longer the adapter is, the more clearance you will gain. An adapter that allows multiple clocking positions of the xfer is something of value too. Also a lifted vehicle will drop the front driveline down away from the pan more than a non-lifted vehicle.
As to drivability down the highway, it's great as long as you gear your axles properly for the size tires you're going to use. If you're not going to re-gear, then don't waste your time unless you're presently geared too low now. 2000 rpm at 60 mph in overdrive is what you want to shoot for. Anything lower and you will lug the motor on grades needing to downshift.
As an example, if you were to use 33" tires, I'd use 4.56 gears for a V-8 and 4.88 gears for a V-6. Go here to check different combinations: Randy's Ring & Pinion. RPM Calculator.
Tim, thanks for the good info, I will be using a 4L60E with 4.88 gears is what I had figured also but had not heard about the clearance problems. If you have any more useful info I'm all ears. The body is at the paint shop now and I'm just now getting to the frame and running gear.
but had not heard about the clearance problems. If you have any more useful info I'm all ears.
The 700R4/4L60/4L60E transmissions have their pans offset to the right side and GM never produced a 4x4 vehicle with these transmissions that had a transfer case and front axle with right-hand drop because of this.
Who's transmission to transfer case adapter and what transfer case are you using? How long is the adapter? Does the adapter have multiple holes that allow clocking of the transfer case?
With a right-hand drop xfer, the longer the adapter, the better. Clocking lower, to some extent, can help. Lifting the vehicle will also help drop the driveline away from the pan. The biggest issue is having an adapter that's long enough to allow sufficient clearance of the yokes on the front output and driveline to the right rear corner of the transmission pan.
I was thinking about doing the same thing. What would happen if you used a 2 piece drive shaft like the original three speeds had or is the transfercase yoke still to close to the transmission?
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