Cosmo Kramer

Car is up on jacks getting some winter maintenance and I thought I would check to see how the PKlamp held up.

Pull off the inspection plate and see no movement (painted the splines). I thought, great! Put staight edge on the flexplate and it is bowed about 3 - 4 mm. Loosen the clamps and the hub slides 3-4 mm back, now I have less splines.

Is it possible that the shaft is elogating or somehow it is slipping at the rear clamp? I torqued it in the spring and it felt like it was binding in the hole but I was able to get it tightened down to spec. I know that the bolt at the rear of the torque tube goes into a groove so it should not move, but has anyone else seen this before?

Pics attached, hard to tell the before shot didn't turn out too well.

the flyin' scotsman

Was the rear (torque tube clamp) pinch bolt checked?

Cosmo Kramer

Yes, torqued to spec in the spring. The bolt was binding in the hole a bit but I got it to torque OK.

Mrmerlin

time to start over before you do this order 2 new pinch bolts.
Then remove the front pinch bolt then the rear.
Note you may have to slide the drive shaft forwards or back to get the rear bolt out,
once you get the rear lined up and the new bolt goes in easily then check that the front bolt also goes in easily.
Use some blue loctite on the bolt threads, torque to 66ft/lbs..
Its also quite possible that your supercharged engine is making more torque than the clamps can handle.
BUT follow the above instructions, and monitor the flexplate

928mac

Hmmm a new dilemma.

PorKen

Interesting. I'll have to add something about this to the PKlamp manual.

Is is possible to tighten both bolts on the rear coupler? I've never tried.



Hmmm... 3 PKlamps per car?

Cosmo Kramer

Hey Ken

I think I torture tested your clamp pretty well. I ran the car pretty hard this year lots of WOT tuning the S/C, dyno run and a trip to the dragstrip. No movement (at the front) at all.

Merlin: I will take your advise. I will get a new bolt for the front and rear pry the shaft back and tighten to spec. I wonder how much play there is in the grove in the drive shaft that the bolts sits in at the rear, anyone know?

Imo000

I don't think there is room for additional clamps at the rear.

Mrmerlin

Ken there is only one clamp on the rear its connected ( rather placed onto the input shaft) to the input shaft of the transmission,
NOTE the rear clamp can sometimes be loose once the bolt is removed , in other words the clamp itself will spin on the input shaft, so you have to be careful with this.
The alignment of the clamp to input shaft can change when the bolt is removed .
The clamp can be be repositioned with a long screwdriver and a shop light..


Cosmo the relief cut into the drive shaft is about 3 mm wider than the shank of the clamp bolt, , you will know that the driveshaft is out of position if the bolt has grooves cut into its shank

PorKen

Oops, braincramp. My pic is of a 5-speed clamp. Doh. The rear auto clamp connects to the rear flexplate.

Mrmerlin

Also the rear clamp on a 5 speed is very similar to the auto

Bill Ball

The rear TT clamp is located by a groove in the shaft that the bolt must go through and there is not much play at all. So, even if the rear pinch bolt is a bit loose, there's no where for the shaft to go. Yet, I too have observed less and less of the front splines visible at the front flex plate clamp as well over the years, although this was very gradual and has stabilized. This would argue that the shaft stretched (not too plausible) or that the torque converter has moved forward or balooned, which is possible but I can find no evidence of it in my case.

Warren928

Maybe it's better not to think of the torque tube assembly as something that if set up right, that those splines will not move at all. Too many variables could still change the load on the engine bearings and then you have thrust bearing failure even with good clamping.

What if, this torque tube was thought of more like a driveshaft going to a solid axle, where some room to move back and forth is what is needed. I had some front axle maintenance to do on a 4x4 and noticed the same splines on the front axle driveshaft. The difference was that it had a grease fitting where the inner/outer spline met. Easy sliding in and out with the shaft grease.
I wonder how the outcome would be if this grease modification was done and the pinch bolt was reduced back to just the original, and torque setting was minimal, like 15- 20 ft /lbs?

Goal would be: Still works fine, but also minimizes thrust bearing load pressure becauise the shaft can slide some.

Mike Frye

Ted,

Please keep us posted. The slot in the shaft at the rear that accepts that pinch bolt goes all the way around the shaft IIRC and it's probably got a couple of mm of play if it was previously all the way to the back and now is all the way forward. 3-4 sounds like a lot.

Maybe after doing everything Stan says, also mark the rear clamp location so you can tell again after a few months?

Mrmerlin

Warren with the way the splines are made a slip fitting would soon wear the splines till eventually they will wear out and spin in the coupler.
IIRC the couplers are made of softer metal than the shaft
Putting grease on the splines will make it harder for the clamps to hold the shaft in position.

I know Constantine has a lot more info about the clamping and fitting of the driveshaft