OK how about a different measurement M35A2 jackshaft ujoint center-to ujoint center installed distance.

[gentrysgarage]

OK I have went through all the trouble of using the M35A3 jackshaft and my eyes might be wandering....anybody have the measurement of the M35A2 jackshaft center of ujoint to center of ujoint? Reason being I am making alterations to the firewall and floorlan and with the transfercase set at the M35A3 5 3/4 inches the face of the transfer case is only 3 1/2 inches into the cab....so if the M35A2 is 9 1/2 inches or more it makes my life easier! Anybody have this measurement...Thanks!

 

[NY Tom]

I can get you this number tonight if no one else get's it sooner. I have the jackshaft out of the truck. Easiest measurement to provide for me would be face of pinion flange to face of pinion flange. Jackshaft is disassembled right now so can't measure that.

 

[gringeltaube]

M35A2 jackshaft center of ujoint to center of ujoint

6" (or 11" between flanges), fully collapsed. Extends about 1-1/8"

 

[gentrysgarage]

Thanks gringeltaube and NY Tom...
Hmmm measured the M35A3 between the flanges is 9 1/4" (at 5 3/4" ujoint center to center spacing. 11-9 1/4=1 3/4 + say 3/4" (not to the limit) is 2 1/2" more.....have to think about it...but right now (off the top of my head the only advantage is easier transmission removal.... decisions decisions!
Thanks Again guys!

 

[M37M35]

@gringeltaube @gentrysgarage

I measured my '66 A2 and the U-joint center-to-center is 7", which agrees with Gringeltaube's number.
But I measured an '87 Air Force A2 and the U-joint center-to-center is 9 3/4". It also looks like it uses different U-joints... I thought all A2's would be the same, but apparently not...

 

[M37M35]

Okay... I went back and figured out where the difference is... The '66 and '87 do use a different jackshaft, but they appear to be interchangeable. The difference is in the flanges on each end.

On the '66 it's 12" flange to flange, and flange to U-joint center is 2.5".
On the '87 it's 13" flange to flange, and flange to U-joint center is 1.5".

The '66:


The '87:

 

[gringeltaube]

On the '66 it's 12" flange to flange...
On the '87 it's 13" flange to flange...

OK, so it seems that that later-model propeller shaft does extend enough to solve the OP's problem.

Really wondering now where that 1"-difference originates (?) Since both trucks should have the very same engine- and transfer case mounting brackets, at the same relative positions, respectively. And even if the mounts were all loose on that '87 - it can't possibly add up that much.

 

[NY Tom]

There is a spacer on the transmission side that is about 1" long. Maybe some trucks have it left out?

Possible different styles of the transmission output seal retainer?

Since knowledgeable people are looking at this thread: My jackshaft had two small weld beads on the inside where the vent is screwed in. These didn't look factory. Didn't have the phone for a picture but is this a point of failure that is commonly seen? Looks like it would keep the shaft part from spinning on the knuckle part. Driveshaft from transfer to first rear axle may have the same modification. Anyone else see this?

 

[gentrysgarage]

THANKS GUYS!
I think I will pursue the later A2 Jackshaft...anyone have a spare?

 

[gringeltaube]

There is a spacer on the transmission side that is about 1" long. Maybe some trucks have it left out?
Possible different styles of the transmission output seal retainer?

Not the case. It would take much more than that to make our transmissions one inch shorter.
Also, the pics in post #6 clearly show a transmission with all stock parts.

So my question remains open, still: what exactly was changed in the later-generation A2s to require- or allow a longer jackshaft? Was the transfer case really moved to the back? Hard to believe, since all other propeller shafts remained the same length (same part numbers, respectively).

 

[gentrysgarage]

So my question remains open, still: what exactly was changed in the later-generation A2s to require- or allow a longer jackshaft? Was the transfer case really moved to the back? Hard to believe, since all other propeller shafts remained the same length (same part numbers, respectively).

First I have to add to my reply above and say I owe a few steak dinners for all the help I am getting.

As to what changed I think it was due to Spicer. In my pursuit of the driveline for my M135 I have been chasing many part numbers and styles of yokes and flanges...almost all of the 1410-1550 flanges for my particular rear end and even the Eaton 6 speed trans are discontinued (ended up with a female flange for the tranny as I could not find the mape one. Spicer wanted to get rid of the earlier 5-155x ujoint and go with the 1550 , so they dicontinued the yokes(hense the price we pay for the 5-155X ujoint) . I also feel that they have been phasing out the 1550 yokes lately for the more profitable M35A3 abortion joint that just adds more weight and dollars in Spicer's pocket.

So long story short, Spicer had discontinued the yokes and made jackshafts with the newer normal ujoint style.

PS please correct my part numbers if I got them wrong just shooting from the hip on them!

 

[M37M35]

Really wondering now where that 1"-difference originates (?) Since both trucks should have the very same engine- and transfer case mounting brackets, at the same relative positions, respectively. And even if the mounts were all loose on that '87 - it can't possibly add up that much.

This should have occurred to me sooner... The '87 I measured was in a wreck and the frame is bent. I was thinking if the drivetrain shifted, it would have all shifted together, but that may not be the case. That would account for the 1" difference. We just need someone else with an '87-89 deuce to measure theirs to confirm.

 

[M37M35]

...and transfer case mounting brackets...

Oh, and I noticed the older and newer trucks do have different transfer case mounting brackets... I'll take pictures later.

 

[gentrysgarage]

Oh, and I noticed the older and newer trucks do have different transfer case mounting brackets... I'll take pictures later.

Got pictures already of the A2 After mod (how it is designated in the M35A2 parts TM manual) here: https://steelsoldiers.com/threads/i...d-transfercase-mount-height-and-angle.196030/

 

[gringeltaube]

This should have occurred to me sooner... The '87 I measured was in a wreck and the frame is bent. I was thinking if the drivetrain shifted, it would have all shifted together, but that may not be the case. That would account for the 1" difference. We just need someone else with an '87-89 deuce to measure theirs to confirm.

Ah... that's most probably the cause...!

At least it proves that the newer jackshaft is capable of extending that much - without ripping off its slip-joint seal.

Oh, and I noticed the older and newer trucks do have different transfer case mounting brackets... I'll take pictures later.

If you refer to what bolts to the TC, those two styles are interchangeable and don't affect its position.


See this thread, also...

 

[M37M35]

Ah... that's most probably the cause...!

I went back and looked. It is.

At least it proves that the newer jackshaft is capable of extending that much - without ripping off its slip-joint seal.

True!

If you refer to what bolts to the TC, those two styles are interchangeable and don't affect its position.

Got pictures already of the A2 After mod (how it is designated in the M35A2 parts TM manual) here: https://steelsoldiers.com/threads/i...d-transfercase-mount-height-and-angle.196030/

Yep, that's it. I was thinking it was an A1 vs A2 thing.

 

[gringeltaube]

I went back and looked. It is.

Case resolved, then - and I can sleep again!