windshield glass

[cikmontanan]

I'm the newbe, and glad i found you. Does anyone have experience with the timken/rockwell 221 transfer case? I'm specifically interested in strength. I'm planning on puting a built 406 small block in an original 63 4x4 suburban. I want to keep mostly stock, but still have the rodder in me. Thanks for any input.

[FetchMeAPepsi]

Why did you call this topic "windshield glass" if youre asking about the rockwell?
Messin with my head? ha ha :D


Anyway the Rockwell is a tough transfer case. They are used by a lot of rock climbers.

I Edited because i was probably too rough in the first post. I will say this, sell the v6 to someone that will cherish it for the thing of beauty it is.

[cikmontanan]

Sorry, that subject was for another post. I need to proof myself better. Thanks for reply. The V6 isn't going anywhere. That's why I am trying to keep rest original, if I decide to swap back. I love these old rigs. Have two burbs and a 1960 2 ton cab over with the 351. Thanks again.

[bigblockv6]

Some will tell you the 221 is indestructible but from my experiences with a 62 and 68 GMC trucks in my family both purchased new, these transfer cases were trouble prone. Both ate up bearings, the 62 was tied up for two weeks at a GMC dealer in a remote area of California back in 1966 because of bearing failure. The 68 had bearing problems as well, those were replaced but it's eventual demise came with a bearing failure in the main shaft that ended up with stripped splines that goes to the coupler between the transmission and transfer case leaving the truck motionless. At that point I made a decision which I'd been thinking about for quite some time and that was to upgrade to a NP205. No more whiney transfer case, this is the case that has a real reputation for being indestructible and I was happy with the conversion. A 205 from a 60's to 71 Dodge would be the one to use, I've seen it done and it would require the mounting and crossmember from the Dodge that would have to be modified to fit the GMC frame. What also like to add is both the 62 and 68 saw a lot off off road use as well as hauling camping gear and towing a long wheelbase Jeep CJ6 behind them and combined with the torque of the V6, too me it's apparant the 221 transfercase just could not hold up to this kind of use hard usage. Pete Chronis Northern Cal 68 GMC KM-2500 478M V6

[BarryGMC]

I agree With bigblockv6. These old t cases cant handle the torque or highspeed high load for very long. The bearings dont seem to oil properly. It really is the only full size gear drive t case I have consistently seen self destruct. Use a 205, The dodge ones are good if you change the yokes to the u bolt spicer ones. Or you can find the divorced 205 with the good yokes in fullsized International trucks. BTW I destroyed a nos 221 in a 67 chevy with a 454 in 2 months. Granted it was a front and rear lockered beast with 36 inch tires and about 550 ft lbs of torque. The greasy 205 that went in its place never did fail even though that truck had a habit of twisting 14 bolt axle shafts until they would break.

[turbobill]

I'm the newbe, and glad i found you. Does anyone have experience with the timken/rockwell 221 transfer case? I'm specifically interested in strength. I'm planning on puting a built 406 small block in an original 63 4x4 suburban. I want to keep mostly stock, but still have the rodder in me. Thanks for any input.

My experience with the Rockwell 221 t-case is that it won't hold up to a lot of power or heavy loads.

The problem is that it's a "drop box" and as such has an idler shaft. While that in and of itself is not a bad idea, in the case of the 221, the gears are helical gears (for quieter operation) and therein lies the main problem. The helical gears create thrust loading and forces that try to angle the sliding gear on it's shaft.

The more power/greater load placed on the unit, the greater the thrust forces become and it will eat bearings, develope more heat, and the sliding gear (splined to it's shaft) will start to excessively wear it's own internal spline and the splines on it's shaft. In the mid 80's, I tore one apart (a 1965 model) to repair the damage and found that only about 1/3rd the hard parts were still available new. I replaced what I could find along with all the bearings, but in my application it did not last long.

I replaced it with a New Process 205 out of an early 70's International 3/4 ton truck. That NP205 is still in service in the same truck.

As the wear increases, it gets noisier and starts to chew itself up with the metal introduced in the oil.