Rockwell T-221 durability for the long haul

[72cs20]

Hello all,

My newly acquired 66 K20 has the stock T-221 t-case and it seems to work normally. But I've read that they may have oiling issues and get hot, which can end badly.
My intended usage for my truck will see many miles of prolonged highway travel, loaded heavy. Will this be a problem for the T-221? Or should I start looking for an NP-205 to swap in?

[dieseldude4bt]

I have run one for about 80k behind a cummins 4bt and have had no problems, but if you plan to run highway speeds, 70+ loaded heavy for prolonged travel it will get hot, so an NP205 upgrade would be wise.

[maxwoof]

I have been running my 62 for about 10 years now. Not a lot of miles, but a few times a year, I make 120 mile highway trips. I havent had a problem. I max out at about 55-60 mph - its a k-20. I would say keep the oil level up and the input shaft bearings fresh. They make a "high oil level kit" which is a street elbow that goes where the fill plug is. Let's you keep the oil level about an inch or so higher. I'm not running one, but plan to. I think the problem is they leak, and when the oil gets low, they fail. Good luck with yours.

[dieseldude4bt]

Originally Posted by maxwoof

I have been running my 62 for about 10 years now. Not a lot of miles, but a few times a year, I make 120 mile highway trips. I havent had a problem. I max out at about 55-60 mph - its a k-20. I would say keep the oil level up and the input shaft bearings fresh. They make a "high oil level kit" which is a street elbow that goes where the fill plug is. Let's you keep the oil level about an inch or so higher. I'm not running one, but plan to. I think the problem is they leak, and when the oil gets low, they fail. Good luck with yours.

I have made 800 mile highway trips towing but usually only tow at 55 to 66 mph. You want to keep the shaft speed of the rockwell at 2500 or lower to help keep it cool. synthetic oil in it also helps as well as Lucas synthetic gear additive.
loaded heavy and extended highway speed are what will cause him problems if it was just a daily driver with light towing or occasional heavy towing as I do I would say keep the rockwell.
Sorry for all the edits.

[72cs20]

Thanks for the replies guys.

I am putting this truck together for travel into the back country. It will be carrying my All Terrain pop up camper and all the stuff you would carry for remote travel. I estimate a load of 2200 to 2500 pounds. This would mean long stretches of highway or interstate travel to reach these destinations or trailheads.

I would like to be able to do sustained 65-70 mph speeds where possible. So I would like to have the strongest drivetrain possible without breaking the bank. I just wasn't sure how the 221 would handle such use.

[dieseldude4bt]

Originally Posted by 72cs20

Thanks for the replies guys.

I am putting this truck together for travel into the back country. It will be carrying my All Terrain pop up camper and all the stuff you would carry for remote travel. I estimate a load of 2200 to 2500 pounds. This would mean long stretches of highway or interstate travel to reach these destinations or trailheads.

I would like to be able to do sustained 65-70 mph speeds where possible. So I would like to have the strongest drivetrain possible without breaking the bank. I just wasn't sure how the 221 would handle such use.

For that use I would not be worried about a good rockwell t221 case.
I would use fresh input shaft bearings and adjust the preload on the rest of the bearing if they are in usable condition new seals and synthetics and you will be good to go.
I consider 8 to 10k loaded heavy not 2500lbs.

[BILT4ME]

The T-221 is a great case and will do what you need.

I had a 60 frame that I placed a 69 body on and installed a 375HP 350 in it with a SM465. 4.11 gears and 33" tires. I ran 75-80 MPH all the time in it for long distances, then used it on the farm to pull grain wagons from the field to the farm or to the grain elevator.

The only issues I had was that it leaked oil ALL THE TIME. The gear oil would seep through the shims on the side. I caulked the outside of everything in an attempt to keep it in.

I tried the "overfill" thing by parking it on a sidehill, then filling it a bit more, then driving it. Unfortunately, it puked out all the extra oil from the vent plug on the top of the housing, so it coated the underside of the truck in gear oil.

IMO, it's a HD T-Case and will withstand everything you give it. I also had (3) spares in the basement.......

['63GENIII]

As many have said here, the little Rockwell can be run somewhat hard if taken care of, sealed VERY well, synthetics and an extra quart doesn't hurt either. I ended up swapping mine out with a 205 out of a Dodge (divorced) because I didn't have the means to go through the 221 at the time. It was starting to leak pretty bad which led to getting hotter than I was comfortable with.

For several years, I towed a 4500# boat + 1500# in the bed in 3-4 hour stretches at 70 - 75. This was behind a mild 396.

Only toward the end did it start making a little more noise than normal. Thus the swap.

Although the 221's design lends it to running hotter than the 205, it is still a good case if set up right and can work quite well for most all jobs. The 205 is a little overkill unless you have a good one sitting around just waiting to be popped in (which I did and even then it didn't just "pop" right in. It was a lot of work).

My 221 is still patiently waiting for some attention under the work bench. Every once in a while it reminds me by jumping out and stubbing my toes for me.

Make every effort you can to get some good bearings into it which will help keep the seals in one piece and then put some thought into the extra quart of oil and better venting. I ran +1 qt for a while with no issues and it made a difference.

[Short 3/4]

Never heard the +1 oil trick mentioned here, I like it. So just a street 90 with a plug in the top gets it high enough, or is there more? Vent upgrades?
While I love the fact that your truck is still so original, if you do swap stuff out, please consider offering for sale on this site, as I'm sure others (myself included) could use.
Please don't think I'm preaching here, as my truck is certainly not as it left Fremont back in 65, so I will not be casting stones!
Have fun with the project, hope to see you on the trail,
Tom

['63GENIII]

Originally Posted by Short 3/4

Never heard the +1 oil trick mentioned here, I like it. So just a street 90 with a plug in the top gets it high enough, or is there more? Vent upgrades?
While I love the fact that your truck is still so original, if you do swap stuff out, please consider offering for sale on this site, as I'm sure others (myself included) could use.
Please don't think I'm preaching here, as my truck is certainly not as it left Fremont back in 65, so I will not be casting stones!
Have fun with the project, hope to see you on the trail,
Tom

I had used a street L + a 3/4" hose barb with about a 2" piece of some clear (poly something or other) tubing on top. It was capped with another HB and a 3/4" cap. Venting was an issue and it would puke some out occasionally. This was an issue I thought could be overcome during a rebuild but never got there.

I kept running dino in it and it kept leaking but I always knew what the level was with the clear tube.

Had the bearings been new, the seals would have held and I would have spent the scratch on some Amsoil, Redline or even Motul synthetic. Im certain it would have run somewhat cooler.... even without the extra quart because that darned idler gear would have stayed well lubed.

Ill go out in a minute and see if I have a pic of the hokey sight tube that I rigged up.

['63GENIII]

Here's a pic of the hokey sight tube. IMO, with the extra oil inside, enough was thrown up at the vent baffle to get out. Extra baffles might control the oil.

Also the seals that I picked up at NAPA. Same SKF part #s for all 3.

Please excuse the mess. Lol, still working on my 10 year plan of organizing the garage.

[Cranemech]

Originally Posted by '63GENIII

As many have said here, the little Rockwell can be run somewhat hard if taken care of, sealed VERY well, synthetics and an extra quart doesn't hurt either. I ended up swapping mine out with a 205 out of a Dodge (divorced) because I didn't have the means to go through the 221 at the time. It was starting to leak pretty bad which led to getting hotter than I was comfortable with.

For several years, I towed a 4500# boat + 1500# in the bed in 3-4 hour stretches at 70 - 75. This was behind a mild 396.

Only toward the end did it start making a little more noise than normal. Thus the swap.

Although the 221's design lends it to running hotter than the 205, it is still a good case if set up right and can work quite well for most all jobs. The 205 is a little overkill unless you have a good one sitting around just waiting to be popped in (which I did and even then it didn't just "pop" right in. It was a lot of work).

My 221 is still patiently waiting for some attention under the work bench. Every once in a while it reminds me by jumping out and stubbing my toes for me.

Make every effort you can to get some good bearings into it which will help keep the seals in one piece and then put some thought into the extra quart of oil and better venting. I ran +1 qt for a while with no issues and it made a difference.

I don't mean to threadjack, but is there a thread somewhere where you documented the process for swapping out the T221 for the NP205?

As far as lubrication in the T221, I was considering using the Lucas hub oil. We've used it on the crane planetarys and noticed a 40-50 degree temp drop over the syn. 85-140. The only bad characteristic we've noticed is that it likes to "climb" out of the breather.

[72cs20]

Thanks for all the input everyone. I'm going to go with the stock drivetrain for now and see how it works out. The only immediate modification I will do is to install a dual reservoir master cylinder and booster for the braking system. Power steering is a strong maybe.

To make it roadworthy I need to go through the front axle first. It definitely needs drivers side king pin bearing work, so might as well go through the whole thing. Also needs a steering box re-build.

'63GENIII, I've read your posts on all the work you've done to your 63. Well done. Excellent information. I may have to steal some of those ideas!

[maxwoof]

Hi. I found the parts list that shows the "high oil level" elbow, if anyone is interested...numbers 197-199.

[dieseldude4bt]

If you over fill it comes out the vent is my experience, I just keep it full and run synthetic 75-90w Valvoline and Lucas synthetic additive, seems to work fine.

[61K10]

Had one of those on mine. Just a pipe 90* nipple. Took it off. Fix your leeks and you won't have a problem.

[Hotcorner]

My T-221 seems to want to leak and when we replaced the rear output shaft seal, there was a fair bit of metal in the lube. Still leaking after the seal replacement, so I think I’ll have to go deeper and replace bearings and seals to tighten up the leaks. Doesn’t seem to be any noisier though, so I hope it can be saved.