drop or not Transfercase
 

I am doing a restro rod 80's look on my C20 LWB chevy, 35" tires and a 6" lift, i have rear that the transfer case drop is a bad idea because it drops the rear of the motor causing more of a angle issue with the front drive shaft, Anyone have any good information on this. thanks

Re: drop or not Transfercase
 

Welcome aboard. Might I suggest you ask a moderator to move this to the 4x4 section for more exposure to folks who have done it. And this kind of modification isn't necessarily model year relevant.

That being said you may also want to add more information about your truck and it's intended usage. Like year, long or short bed, engine and transmission/transfer case, and horsepower.
Good luck.

Re: drop or not Transfercase
 

Thanks HO455.

Re: drop or not Transfercase
 

C/20? If it's a Factory 3/4 ton 4 wheel drive it's a K/20.

Re: drop or not Transfercase
 

Yes, dropping the t-case does increase the angle at the front CV joint. It can be clearanced a bit with some grinding. Best way to check for any binding is to let suspension hang at full droop and spin the drive shaft. Jack it up, put jack stands in place, take off the tires and let the axle hang. No worries about vibration on C/V as it cancels itself out. Just want to make sure it moves free.

Re: drop or not Transfercase
 

Welcome to the site! I see your location is Hampstead. Would that be Hampstead, Maryland by chance?

Yep, if your truck is a factory 4wd it's a K/20. If it's a C/20 converted to 4wd it's time to start calling it a K/20 or simply 3/4 ton 4wd if you don't feel like explaining your conversion.

Anyway, I never drop the transfer case. I've been putting lifts on these 4wds since long before someone dreamed up that idea. The rear driveshaft angle is still a healthy one with no adverse reasons to warrant lowering the transfer case. The 1" that the transfer case drops give barely alter the angle anyway. I still have the supplied transfer case drop in it's package from the 6" lift I put on the '72 K/20 with 35s

Re: drop or not Transfercase
 

My '68 K10 had ~1" spacers between the transmission/transfer case crossmember and the frame. I forgot about those until I read this thread. I don't recall seeing those on anything before, but it didn't appear to be modified in any way (no lift). Were they installed at the factory on some of these trucks?

Like special-K said, I can't imagine that tiny difference in angle would warrant adding them, unless there was a clearance issue somewhere.

Re: drop or not Transfercase
 

Figure some longbed 4wds got 2pc rear driveshafts while others got 1pc. I never understood why. 2pc is obviously not called for if 1pc works. I have never owned one with a 2pc. If the truck has 2pc shaft I'd think if anything needed dropped for a lift it would be the carrier bearing, and then maybe a transfer case drop would be warranted.

I have never known of spacers from the factory. But I have read where members felt their truck had them from factory...on non-lifted trucks. It may have been your post I read, Base. I can't recall. Could be others have the same thing

Re: drop or not Transfercase
 

Yeah mine has the 2-piece, or did. I just removed all of that and the old 221 transfer case. I think the 205 case sits about 1/2" - 1" higher from the mounting surface than the 221, so it would make sense to add the spacer if you swapped 221->205, but mine still had the 221. I guess I'll probably never know what all has happened to the poor thing over the last 54 years.

Re: drop or not Transfercase
 

Thanks so much for all the information we build jeeps and clocking the transfer case can solve issues i am not 100% sure about the GM product, As for it being a C or K it was picked up as a cab a chassis. and the VIN shows a CK so if someone can give me a clue on that one. the original owner who is 81 now after a stroke has been to tell me little other than he ordered it withe the steep gears and heavy duty stuff.

Re: drop or not Transfercase
 

I think it would have to be a K-series with that front wheel locking hub option on the SPID.

Re: drop or not Transfercase
 

Very nice truck Special K, No its Hampstead North Carolina, we are the part of the state that pokes out like s target for Hurricanes. Topsail beach area we are 2 hours from Myrtle beach, 2 hours from Raleigh and 2 hours from the ferry ride over to the outer Banks. its living in a geographical anomaly we are 2 hours from everything !

Re: drop or not Transfercase
 

Nice area you're in. Yours is a K/20. Starting in '72 the VIN got an added digit up front to distinguish between Chevy and GMC. So Chevys got a C and GMCs got a T.

I'm not sure about t-case clocking. I don't think I've ever heard that you can't. Yeah, with Jeeps, or any short wheelbase, it's do all you can to help the shaft angles. That's a nice thing about the long bed trucks. The front is your limiting factor.

Re: drop or not Transfercase
 

Sure.
Up thru Model Year 1971, Chevy and GMC both used C for ''conventional'' [2 wheel drive] and K for Four Wheel drive in the VIN. Next letter was the engine: E for eight [V8], S for six [L6] and M (GMC-only) for V6.
But in MY '72 they added a letter. C for Chevrolet and T for GMC Truck, in front of the sequence.

So my '68 C/10 has a VIN of CS148Z123XXX. C = 2WD, S = L6 [292], 1 = 1/2 ton, 4 is the model: Stepside/cab, 8 is the year 1968, and Z is the plan in Frement, California. The 123 etc is the sequence.

I also have a parts truck, a '72 Chevy K/5 Blazer with the VIN:
CKE182F178XXX. So C = Chevy, K = 4x4, E= V8, 1 = 1/2 ton, 8 = K/5 body, 2 = 1972, F = Flint, MI, Sequence =178XXX.

GMC numbers are more confusing because '67 thru '70 they used a letter code for the year, while Chevy had used the last number of the year.

So a Factory Chevy 1972 3/4 ton 4x4 w/V8 longbed pickup would have a VIN starting with CKE2 34 2- [then the Plant code and production sequence].

Hope this is clear. It can get confusing, especially with the 1972 differences.
Anyway, Welcome to the Board.

Re: drop or not Transfercase
 

Rough country still sells a spacer kit for the trans cross-member. Though many have taken the stock spacers the trans cross-member uses on top of the frame for correct clamp load on the bolts and put them below the frame to drop the mount down.

Don't do that. Using a spacer like that puts an intense load on the frame in 4 very concentrated points. Cracks will occur.

As mentioned above, the factory spacer above the frame allows a longer bolt to get a sufficient amount of "stretch" and clamping force to hold the trans cross member to the frame.

If your driveshaft angles are that far out of whack to need to drop it down, use flat stock or square tubing to allow the force of the cross-member to be distributed evenly across the frame.

I've dropped mine about 3/8" with flat bar stock to lessen the rear shaft angle. While it might correct the rear angles, it will always make the front worse. If you have the later style front shaft with the flange mount at the t-case you will need to clean off all the nubs on the c/v cage and flange anyway.

Re: drop or not Transfercase
 

Thanks Zoomad we have built a load of jeeps and we clock the transfer case to get the drop we need for the drive angles, Everything i see its dropping the rear of the drivetrain, the motor mounts stay put and that increases the angle of the front drive shaft, it's a LWB truck so i was not as worried about the read shaft as i was the front, i am going to install the kit without the spacers, Check the clearance on the U joints and also shaft angle against the pinion angle. I hope it's not too much trouble but as with all projects it's the unknown that seems to be the issues, Thanks again for your input.

Re: drop or not Transfercase
 

Leave the case alone and change the rear shaft to a cv type .then
Turn the rear axle up to align w the driveshaft.problem solved

Re: drop or not Transfercase
 

Installed the lift with little issues, also installed a set of shims that give the rear end 4 degrees more of pinion lift, everything looked fine until i noticed when i slide the slip yoke in i am about 1 " short of being totally inside the receiver. Checking the angles its fine we unbolted the transfer case and lowered it 1" it didn't make up any of the difference that you could measure and made the front angles worse that they were stock. i bolted her back in place all 4 locations upper and lower trans case bolts now i am going to have my rear drive shaft made 1" longer !

Re: drop or not Transfercase
 

progress

Re: drop or not Transfercase
 

Awesome truck! I really like the stance and wheel/tire choice!

Re: drop or not Transfercase
 

You know, this talking about lower or not on the transfer case and I never mentioned on the truck I showed with 6" spring lift I had to have a longer driveshaft made. As I recall I had mine made 1" longer. It was 15 or so years ago. I also had longer brake hoses and cables made. Those were 2" longer. You know what you're doing. I figured mine to about the center of yoke travel... IIRC. Probably was just an inch since doing 4" lift needs nothing.

Re: drop or not Transfercase
 

You're ready for Hell or Highwater.
:devil:

Re: drop or not Transfercase
 

Thanks guys it's a work in progress. One day at a time.