Auto transmission help-interference between piston and carrier
Three Wheelin'
Joined: May 2001
Posts: 1,641
Likes: 0
From: Hudson Valley NY
Steve,
In one of your previous threads I recall that you recommended cutting the "T" teflon ring on the updated B2 piston, similar to a piston ring to get a better seal on the cylinder wall.
I note in one of the publication I have by "TransTec" that they recomment that the outboard side of the B2 piston be machined to give a 30 degree cut under the "T" ring. Do you agree with this modification, as it will give extra pressure on the ring against the cylinder wall without the need for cutting the ring?
Tails 1990 928 S4 Auto
In one of your previous threads I recall that you recommended cutting the "T" teflon ring on the updated B2 piston, similar to a piston ring to get a better seal on the cylinder wall.
I note in one of the publication I have by "TransTec" that they recomment that the outboard side of the B2 piston be machined to give a 30 degree cut under the "T" ring. Do you agree with this modification, as it will give extra pressure on the ring against the cylinder wall without the need for cutting the ring?
Tails 1990 928 S4 Auto
That B2 modification has changed; more pressure against the wall will prematurely wear the seal, the current procedure used today is the Butt Cut.
Thread Starter
Rennlist Member
Joined: Oct 2003
Posts: 1,094
Likes: 11
From: St. Louis, MO
Steve,
Thanks for the rough draft. It should help quite a bit.
Is there a reason why the B2 pistion should be replaced with the updated one? What are the drawbacks of using the original piston? What benefits does the updated piston offer?
Thanks
Thanks for the rough draft. It should help quite a bit.
Is there a reason why the B2 pistion should be replaced with the updated one? What are the drawbacks of using the original piston? What benefits does the updated piston offer?
Thanks
Thread Starter
Rennlist Member
Joined: Oct 2003
Posts: 1,094
Likes: 11
From: St. Louis, MO
Ok,
I finally dove into my transmission today. I checked the clearances per the WSM and Steve's writeup. The clearance is supposed to be 1.5-2.0mm. I came up with 6.40mm. I thought I had done something wrong until I measured the thickness of my fiber clutch plates. They are supposed to be 2.1mm thick. Mine were all about 0.90mm thick. So if you take the difference (2.1-0.9 = 1.2mm) and multiply by 4 discs, you get 4.8mm. This would be the additional if new fibers were installed. Take the first measurement of 6.40mm - 4.8mm and my new clearance would be 1.60mm. It looks like the factory steels and shims will be just fine. Thanks for you help on this.
The next thing I need to know is should I change out the fibers in the K1 or K2 clutch packs? Do these wear out prematurely like the B3 clutches? The B3 fibers are about $16 a piece so I assume the clutch pack fibers are similar price.
Can you let me know what you think Steve? I would like to know you past experience with these.
Thanks
I finally dove into my transmission today. I checked the clearances per the WSM and Steve's writeup. The clearance is supposed to be 1.5-2.0mm. I came up with 6.40mm. I thought I had done something wrong until I measured the thickness of my fiber clutch plates. They are supposed to be 2.1mm thick. Mine were all about 0.90mm thick. So if you take the difference (2.1-0.9 = 1.2mm) and multiply by 4 discs, you get 4.8mm. This would be the additional if new fibers were installed. Take the first measurement of 6.40mm - 4.8mm and my new clearance would be 1.60mm. It looks like the factory steels and shims will be just fine. Thanks for you help on this.
The next thing I need to know is should I change out the fibers in the K1 or K2 clutch packs? Do these wear out prematurely like the B3 clutches? The B3 fibers are about $16 a piece so I assume the clutch pack fibers are similar price.
Can you let me know what you think Steve? I would like to know you past experience with these.
Thanks
Thread Starter
Rennlist Member
Joined: Oct 2003
Posts: 1,094
Likes: 11
From: St. Louis, MO
Well,
since the K1 clutch drum was already out, I decided to open it up and check the thickness of the fibers/steels and compare them to the thicknesses listed for new plates in PET. These clutches turned out to be the same thicknesses as the new ones, so the wear on this set is very little if any.
I was going to check the K2 drum, but I am not sure how to get it out of the tranny. I want to keep my disassembly to a minimum if possible. What do I need to remove to pull this drum out? Is it worth even checking if my K1 drum is OK? Does the K2 drum clutches wear prematurely like the B3?
I am sure Steve Cattaneo has some past experiences with this. Please let me know.
Thanks
since the K1 clutch drum was already out, I decided to open it up and check the thickness of the fibers/steels and compare them to the thicknesses listed for new plates in PET. These clutches turned out to be the same thicknesses as the new ones, so the wear on this set is very little if any.
I was going to check the K2 drum, but I am not sure how to get it out of the tranny. I want to keep my disassembly to a minimum if possible. What do I need to remove to pull this drum out? Is it worth even checking if my K1 drum is OK? Does the K2 drum clutches wear prematurely like the B3?
I am sure Steve Cattaneo has some past experiences with this. Please let me know.
Thanks
Three Wheelin'
Joined: May 2001
Posts: 1,641
Likes: 0
From: Hudson Valley NY
If the only drivability problem was a delay into reverse, the K2 should have minimal wear; If you what to replace the K2 frictions the transmission must be TOTALY disassemble, if your not comfortable with the disassembly, leave them in. I always change all the frictions and more on a rebuilt. But do update B2 piston, seal and bushing I know its pricey, It will cost you more WHEN it fails,
My Web site server is down, that’s why the picture links don’t work.
Thread Starter
Rennlist Member
Joined: Oct 2003
Posts: 1,094
Likes: 11
From: St. Louis, MO
Steve,
I have never ran the tranny I am rebuilding. I bought it for the 2.54 gears. I just stumbled onto the B3 frictions wear due to the knicks shown on the pic in this thread. The K1 clutches looked great though. Not sure how this set relates to the K2 though.
This tranny is a '91, so looking at PET, it already has the updated B2 piston P/N that you listed on this thread. Is this correct?
I have never ran the tranny I am rebuilding. I bought it for the 2.54 gears. I just stumbled onto the B3 frictions wear due to the knicks shown on the pic in this thread. The K1 clutches looked great though. Not sure how this set relates to the K2 though.
This tranny is a '91, so looking at PET, it already has the updated B2 piston P/N that you listed on this thread. Is this correct?
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Three Wheelin'
Joined: May 2001
Posts: 1,641
Likes: 0
From: Hudson Valley NY
Steve,
I have never ran the tranny I am rebuilding. I bought it for the 2.54 gears. I just stumbled onto the B3 frictions wear due to the knicks shown on the pic in this thread. The K1 clutches looked great though. Not sure how this set relates to the K2 though.
This tranny is a '91, so looking at PET, it already has the updated B2 piston P/N that you listed on this thread. Is this correct?
I have never ran the tranny I am rebuilding. I bought it for the 2.54 gears. I just stumbled onto the B3 frictions wear due to the knicks shown on the pic in this thread. The K1 clutches looked great though. Not sure how this set relates to the K2 though.
This tranny is a '91, so looking at PET, it already has the updated B2 piston P/N that you listed on this thread. Is this correct?
Thread Starter
Rennlist Member
Joined: Oct 2003
Posts: 1,094
Likes: 11
From: St. Louis, MO
I am really worried about my K2 frictions. I think I am going to bit the bullet and diassemble the transmission. I have some questions....
I just had my mechanical LSD put into this '91. If I remove the diff and pinion gear, does this setup have to be redone, or is it OK as long as I put back the same number of shims for the pinion gear?
What keeps the transmission from turning when torquing or loosending the 275ft-lb pinion nut? Do I just put the transmission in PARK or is there more to it?
In addition to replacing all the frictions and sealing rings/gaskets, what else should be changed while I have this disassembled so far?
Thanks
I just had my mechanical LSD put into this '91. If I remove the diff and pinion gear, does this setup have to be redone, or is it OK as long as I put back the same number of shims for the pinion gear?
What keeps the transmission from turning when torquing or loosending the 275ft-lb pinion nut? Do I just put the transmission in PARK or is there more to it?
In addition to replacing all the frictions and sealing rings/gaskets, what else should be changed while I have this disassembled so far?
Thanks
Three Wheelin'
Joined: May 2001
Posts: 1,641
Likes: 0
From: Hudson Valley NY
I am really worried about my K2 frictions. I think I am going to bit the bullet and diassemble the transmission. I have some questions....
I just had my mechanical LSD put into this '91. If I remove the diff and pinion gear, does this setup have to be redone, or is it OK as long as I put back the same number of shims for the pinion gear?
What keeps the transmission from turning when torquing or loosending the 275ft-lb pinion nut? Do I just put the transmission in PARK or is there more to it?
In addition to replacing all the frictions and sealing rings/gaskets, what else should be changed while I have this disassembled so far?
Thanks
I just had my mechanical LSD put into this '91. If I remove the diff and pinion gear, does this setup have to be redone, or is it OK as long as I put back the same number of shims for the pinion gear?
What keeps the transmission from turning when torquing or loosending the 275ft-lb pinion nut? Do I just put the transmission in PARK or is there more to it?
In addition to replacing all the frictions and sealing rings/gaskets, what else should be changed while I have this disassembled so far?
Thanks
Install the original shims and all is well. Use a breaker bar with a piece of pipe as leverage, Transmission in park and a helper holding the case, reverse the procedure when installing, us a foot pound long handle torque wrench. Change all of the K2 seals and also change the Two K2 sealing rings, use Vaseline to hold the rings and washer in place. Install the K2 drum with the planetary as an assembly. I will post a picture.
Thread Starter
Rennlist Member
Joined: Oct 2003
Posts: 1,094
Likes: 11
From: St. Louis, MO
Steve,
I broke into the transmission today. I did not have any problems. You mentioned that all the sealing rings should be changed in the K2. What about the K1? Should the inner and outer boot be changed? They are located inside the drum.
Also, here are pics of my B2 piston. Can you tell me if this is the updated one or not?
Thanks
Mike
I broke into the transmission today. I did not have any problems. You mentioned that all the sealing rings should be changed in the K2. What about the K1? Should the inner and outer boot be changed? They are located inside the drum.
Also, here are pics of my B2 piston. Can you tell me if this is the updated one or not?
Thanks
Mike