Bad 1st Motion Shaft or Mainshaft Symptoms

[AUSMHLY]

I'm rebuilding my BJ8 transmission and replacing a lot of parts.
What are the symptoms of a bad 1st motion shaft or mainshaft?

 

[AUSMHLY]

The 1st motion shaft has wear on the front. I've replaced the engine bush spigot. I'm assuming there's still play there, but not as much.
There is some play between the 1st motion shaft and the mainshaft. I have a new cage bearing there too.
I belive I have the correct shims on the clutch housing and the OD to keep the two shafts pressed together.

What problems can worn shafts create?

 

[AUSMHLY]

I've replaced almost every part in the transmission. Found a used BJ8 transmission which included the case and all parts cheap on ebay. Was hopeful the input shaft and main shaft would be in better condition then mine.

The 1st input shaft area that rides in the bush spigot wasn't as worn as mine. It didn't have as much side to side movement
as mine does. Good news. However, the splines are really worn. I've attached a photo. Mine is the top, bottom shows the worn splines.

I placed the shaft in the clutch till it bottomed out and marked it with green tape. The gap between the wide tape and the thin tape on the spline is the gap between the outside of the clutch and the front of the clutch disk spline area. The worn spline area isn't contacting the clutch spline area.
Once the clutch housing is in place, would the input shaft be in a different place?

Is the clutch fully engaged right now?
Being input shaft doesn't move, what caused that wear?

 

[AUSMHLY]

This GIF show how the clutch works. ezgif.com-gif-maker.gif
When the clutch pedal is pushed, the clutch disc moves/slides on the shaft towards the transmission.

The clutch spline width and location on the input shaft is where the thin tape is.
(The distance between the tape includes the thickness of the thrust bearing. I'm assuming the part name is thrust bearing?)
When the clutch pedal is pressed, would the clutch plate spline move and settle where the wear is?
Seems odd for the wear isn't the same width as the clutch spline width.

Ebay seller said the transmission would sometimes grind getting into gear, but once in gear was quiet and worked find. He said some parts have wear and some should be replaced. (I thought grinding getting into gear would be related to the hub or synchro rings.)

Would the 1st motion shaft still work in the condition it's in? (would that make a grinding sound in neutral or shifting?)
Both input shafts have 22B140 stamped on them, correct for BJ8
How did that wear/damage happen?

 

[Bob_Spidell]

Try as I might, I can't imagine what could cause that kind of damage, except something seriously wrong with the throw-out/release bearing. Your first set of photos shows considerable heat damage and some scoring on the contact plate for the diaphragm; these usually don't wear against the relatively soft graphite bearing. Did you get the bellhousing and throw-out lever from the seller? Did he try to jury rig a ball or roller bearing somehow?

No way I'd use that damaged input shaft. If your original one is otherwise OK, a machinist can build up the tip with weld, then cut it down on a lathe. I've looked before; input shafts are pretty much unobtanium.

 

[red57]

I haven't worked on a Healey transmission for over 25 years (I run a Toyota) so I may be way off but that doesn't look like damage to me. It looks like a deliberate part of the shaft - these are hardened shafts and simply rubbing on something would not produce that smooth radiused reduction in diameter. Add to that, there is nothing in that area inside the pressure plate for it to rub on (and there is no heat discoloration from friction showing).

 

[AUSMHLY]

Your first set of photos shows considerable heat damage and some scoring on the contact plate for the diaphragm; these usually don't wear against the relatively soft graphite bearing. Did you get the bellhousing and throw-out lever from the seller? Did he try to jury rig a ball or roller bearing somehow?

Bob, the bell housing is mine as is the throw-out lever. Never had issues with them before. I don't know if the mechanic replaced the release bearing.
I did install a new Heavy duty clutch assembly from Denis Welch.
I use the input shaft to line everything up while I tighten the bolts.

What would cause the heat damage? Neither the release bearing nor the contact plate spin. Should one of them? The release bearing holder does pivot, but the graphite bearing doesn't spin in the round case. 2 photos of the bearing, dirty then wiped clean with break cleaner. When installing the clutch, I clean both metal plates, both sides of the disc and the contact plate with break cleaner. The scratches on the contact plate are from the front of the input shaft when trying to install the tranny.

This is all new to me, so forgive my not knowing how these things work....yet.

I'm going to start another thread about clutch and input shaft issues.
Till then, what's your take on the what's happening with the contact plate and release bearing heat issue.

 

[Bob_Spidell]

NOW I realize what seemed odd: All the clutch covers I've seen (several) have a triangular-shaped release plate--not sure exactly what they're called--like in this photo:

Austin-healey 3000 Pressure plate, cover, clutch, 10 inch - CA2882 | Portage MI

Pressure plate, cover, clutch, 10 inch diameter, bn7, bt7, bj7 to 29f-h4878. Austin-healey 3000. Genuine Austin-healey Part - CA2882 (BBHA2882, SC805, GCC142, 021-136, AEJ30, GCC116). Ships from Portage MI

www.englishparts.com

Your first photo looks to have heat discoloration, and a possible crack at about 2 o'clock, and possibly some concentric scoring. Something's amiss here, but I can't say for a fact what; if that is indeed a crack, or more than one, that plate could deform enough to grind the shaft, then flatten out when released. No way I'd use that pressure plate, DWM-sourced or not.

re: "I use the input shaft to line everything up while I tighten the bolts."

About all the ground down one is good for now.

 

[AUSMHLY]

Bob, Good eye. I didn't notice that. So I cleaned it more and took close up photos of both edges and the top. Glad to say it's not a crack but a scratch made from the input shaft trying to get in. You'll see a lot of other scratches. I've had the tranny in and out 16 times. (Remove once, install once = 16) in 3 months. It doesn't get any easier.

My shaft is the good one which I've been using. The one with the damaged spline came in the tranny I bought.
"About all the ground down one is good for now". Sorry Bob, I'm not understanding that sentence.

I'm not sure what I could have done wrong installing the clutch to have heat damage. I've made sure the plate is installed correctly facing the engine. The housing lines up with the 3 pins and bolts. I tighten them in a star pattern while I have the input shaft in for alignment. I move the shaft in/out as I tighten the bolts. When done, shaft slides in/out without problem.

 

[AUSMHLY]

I haven't worked on a Healey transmission for over 25 years (I run a Toyota) so I may be way off but that doesn't look like damage to me. It looks like a deliberate part of the shaft - these are hardened shafts and simply rubbing on something would not produce that smooth radiused reduction in diameter. Add to that, there is nothing in that area inside the pressure plate for it to rub on (and there is no heat discoloration from friction showing).

That damaged area should not be there. Compare to my input shaft.
As far as how it happened, I'm really curious and hoping someone will shed light on that. Almost looks like it was done on a lathe.
The thin tape shows the width of the disc spline and where it rests when engaged. I'm not connecting the dot to how the disc spline could make that damage.
This falls under welcome to Roger's world. I posted a photo of my damaged laygear which had a grove in the middle of every tooth on 2nd gear. Everyone said, we've never seen that before. Look at the damage in this input shaft. Repeat after me, we've never seen that before.

 

[Bob_Spidell]

"About all the ground down one is good for now"

Means I wouldn't install it, even if it could theoretically work. It would be OK for a clutch positioning tool (which you've used input shafts for). The first photo of a release bearing in your series looks to be glazed from heat. This isn't normal; no captions so I don't know its story.

 

[AUSMHLY]

The first photo of a release bearing in your series looks to be glazed from heat. This isn't normal; no captions so I don't know its story.

History, DW heavy duty clutch installed 10 months ago when I had the engine rebuilt. I remember now, the release bearing is new and replaced as it was part of the DW clutch kit. Has only 200 miles on it, being I'm doing test drives trying to figure out what's wrong with my transmission, which you'll find me dominating the forum about. The clutch fork in the bell housing works easy and smoothly. Why is the release bearing glazed from heat.

I'm trying to get the tranny fixed. Last week I screwed up the procedure of how to re-torque the cylinder head bolts and now I'm finding out I have an issue with the clutch release bearing. This rabbit hole is deep. All you retired guys who come here to help or find some of these things interesting, I feel like I'm writing a blog. Don't change that channel, we'll be right back.

 

[AUSMHLY]

Being I have wobble at both the Spigot bush and the bearing at the transmission case, could the 1st motion input shaft be slightly bent?
How do I check for that?

 

[roscoe]

Any machine shop can do that. You put the shaft on V blocks or in a lathe and set a dial indicator on the end and rotate the shaft.