Clocking the Dana 18 t-case

Has anyone tried to clock the dana 18 t-case to rotate the passenger side of the case up closer to the floor to accomplish a flatter undercarriage? I 4-wheel mostly in lava rock and get snagged up a lot, so I'm thinking about moving my tranny and t-case up a bit, reworking the cross member so it isn't so deep, and I'd like to clock the t-case so the side with the driveshafts doesn't hang down so far, then I'd like to put as flat as possible of a skid plate under the whole thing so I don't punch holes in anything or get snagged up any more. I plan to do this during my swap to a T-18 tranny this winter, and realize I will probably have to cut out a decent amount of the floor and re-work it to get the tranny and t-case up high enough. So, has anyone else done this? How'd it turn out? How flat can you clock the dana 18? Thanks for the help guys. Any pics would be awsome too of what you have done. Thanks.

 

Clocking the D18 or D20 sounds pretty difficult to me. The TCs that are usually clocked are New Process types, and they have a circular pattern. This makes rotating the mounting straightforward; either new holes or a ring adapter to rotate the holes. The D18 and D20 have the texas pattern (looks like the state), which would not be easy to rotate. If you were an expert machinist, you could likely make an adapter to go between the trans and case, and maintain the proper center line. Not sure it would be worth it though.

 

yeah, the texas pattern definitely doesn't make matters any easier, just wish the darn thing didn't sit so freakin' low on the driveline side of the case...

 

The other thing to think about is the shifters. With a T-18 trans and an 18 transfer case the front output housing shifter bosses are already very close to the T-18 case. You would at the least be grinding on the inside boss and possibly cutting it off necessitating fab work to build a workable shifter system.

 

rather than rotating it you can probrobly get away with jacking the whole thing up closer to the floor board. Or even modify the floor to tuck it up farther

 

Was thinking (small amount of rotation at front) will make bigger rotation at rear. Would it be possible to re-drill the 225 bell-housing to rotate the complete unit (d-18&t-18). You would have to bend the shifters and might still have a front shaft issue. But with your 4 inch lift, maybe not. (Just thinking)

 

the more I look at my 'case and the more I think about it, I'm probably just gonna have to move the entire setup up higher in the framerails rather than clock the t-case. Just cut the floor out, get everything as high as I can for as flat a skid as possible, and re-fab some floor to go back over the top. This should make for an interesting project, but getting an additional 4+" of ground clearance under the belly will sure be sweet...

 

Think you would be money ahead when swapping to the T18 to added a D300 and centered rearend.

Not to say clocking the D18 can't be done, but I see off the top of my head:
Custom adapter plate, with a spacer (2 plates with a tube between them). This would allow for the oddball front bolt.
Custom output shaft
Maybe a second output bearing since it wouldn't be right off the back of the trans.

Would the time, money and headache be worth it? Only you can answer but I don't think there is an easy answer for your question.

 

I know I've seen some nice pictures from somebody on this forum who has tucked everything up high under the frame, and then put a super heavy duty skid plate under it. The end result was exactly what I think you are talking about.

Good luck!

 

I've got to ask how you gonna deal with the front driveshaft problems you create when clocking or tucking all this up higher. Cause the front driveshaft is close to the starter now, you tuck it up 2" and you can kiss the starter and bellhousing good by the 1st time you twist it up good.

 

2x on the body lift. Raising the entire drivetrain should give you more clearence on the front driveshaft at the starter. The only down side is that it will increase the drivesaft angles, something a double cardan joint will cure. I have been pondering building a high pinion rear axle to tuck things up even higher (and yes, I know it will be running on the "wrong side").

 

Don't forget about maintaining the proper oil level and low location.

 

I agree that clocking a d18 would probably me more trouble that it's worth. That's not to say that you shouldn't do it.

One thing I've been thinking about is a skid plate made from the UHMW plastic. It would still hit in the rocks but would (possibly) be much easier to slide on. Or, make a large flat steel skid plate and cover the bottom with the plastic and counter sink the screw heads.

Around here the latest thing is to cover the bottom of jet boats with this plastic due the rocky, shallow river bottoms.

 

I know you said you are swapping in a T18, but Advance has a new adapter for the SM465 to D18 or D20 that allows for clocking the case.

http://advanceadapters.com/product/1719/50-4703.html

 

This is not gonna clock the transfercase up any as the case already hits the transmission in stock form and requires some grinding just to fit so if anything it is clocked down farther not up.

 

Guys,
I'm in the process of putting my '69 back together with the SM465 adapater from Advance that allows clocking the D18. I had to do some grinding on the TC shifter lever boss to clear the side of the SM465. I elected to do all the grinding off of the TC shifter boss (twin stick conversion) but in retrospect I would try grinding some of the side of the transmission case to avoid thinning the TC shifter stick boss as much as I did.
I did find that I could use all three available clocking positions, and I have it clocked all the way up. This looks like maybe 5° up from the stock position. It looks like none of the three positions duplicate the stock clocking angle exactly, based on having the TC shifter stick pivot pin sitting level. The center clocking position has the shifter sticks angling slightly to the right, and the lowest clocking position angles the shifter sticks noticeably to the right. The highest clocking position that I am using has the shifter sticks angled very slightly to the left, hardly enough to notice with just enough room to fit the OD shifter in between.
I'm still waiting for the OD shifter stick from Herm, I'll get some pics up on my build thread when I get in in.
As far as body clearance, I'm still not too sure. I have the stock crossmember underneath the SM465/D18 adapter with Herm's mount adapter kit, and no spacers between crossmember and frame rails. I will do a trial fit soon as I get some room cleared out in the garage, and adjust body clearance with the right thickness spacers. Herm's mount kit comes with 1' thick wooden blocks for spacers (looks like oak) but I would prefer not to have the bottom of the SM465 hanging down that far.

 

Meh, no biggie to raise it all up. I've done both. First the Spicer 18 just about flush with the bottom of the framerails (the SM420 pokes down a bit, though), and then with the Dana 300 clocked in similar fashion to the Spicer 18. Not much more room to clock it any flatter or framerail clearance could be a factor depending on your drivetrain layout.


Hole for SM420 and Spicer 18 (notice how far forward for longer rear driveshaft). I did this 'cause of the V-6. A V-8 wouldn't have the room for the rear shaft I'm able to run in that rig.


Spicer 18 under the frame.


Modified crossmember from the Spicer 18. Cut and welded the Novak bracket on for the Novak D300 adapter.


Dana 300. Pretty much the same clocking/orientation as the Spicer 18, but the rear output is much higher, which causes some driveshaft angularity buzzing.