Notices
928 Forum
Sponsored by:
Sponsored by: 928 Specialists

My Flexplate - Crank Endplay Check Pictorial

 
Old 06-26-2007, 05:54 PM
  #1  
Bill Ball
Under the Lift
Lifetime Rennlist
Member
Thread Starter
 
Bill Ball's Avatar
 
Join Date: Mar 2002
Location: Buckeye, AZ
Posts: 18,482
Likes: 0
Received 1 Like on 1 Post
Default My Flexplate - Crank Endplay Check Pictorial

LATE EDIT: I should give credit to Tony Harkin for his nice write-up of the procedure that I just found after writing mine below. I like his even better. He used a simple micrometer to measure between the ring gear and the block. Very nicely done, Tony!
http://members.rennlist.com/v1uhoh/cranksha.htm
----------------------------------------------------------------


My car has 182K miles on it and gets treated to some high-speed stress in the Nevada desert a few times a year as well as routine driving, occasional burnouts and funrides in the local twisties. Because it is an AT, I check the flexplate preload every few months but haven't done crank endplay in at least 5 years. I almost always find 2-3mm of flexplate preload, but never more. The crank endplay was good when I checked it 5 years ago.

After a report yesterday of a car with some symptoms of TBF and 1/2 inch of preload found on the flexplate, I decided it was time for an endplay check.

Here's what I did.

1. Gathered these tools.
- torque wrench
- extension, adapter
- 8mm Allen
- prybar
- straightedge
- dial gauge accurate to .001 inch with mounting base and arms
- ratchet, extension and 13mm socket
- worklight
- 5/16ths (eh, 8mm seems too large) nut driver for bellypan screws. Many people will find some 10mm screws as well.


2. Get the car in the air. Looking up in the area you need to work on, this is what you see - the rear bellypan needs to be removed. Front bellypan can stay in-place.


3. After you remove the rear bellypan, the lower bellhousing cover is exposed. It is held on by 6 hex bolts with 13mm heads, 4 of which you can see in this photo.


4. If this is the first time you have done this and you have the stock exhaust and cats, you will be confronted with a problem getting the two rear bolts out of the cover. They are trapped by the H-pipe area. I have been in here many times, so I left those bolts out long ago. You probably will have to remove the front exhaust from the manifold and let it dangle down to get these bolts out. This is a real nuisance, as you will find if you have to do it. The exhaust bolts are often rusted on hard and require a variety of wrenches due to awkward locations and counterholding the bolt heads. Also, to separate and lower the front exhaust even a bit, the two lower 19mm bellhousing to block bolts must be loosened as they hold brackets to a couple of the exhaust bolts. Finally, the joint in the air line to the catalytic converted must be opened. Ugh! After the first time doing this crap, some people will shorten the rear cover bolts so they can be removed with the exhaust left untouched. I just left them out. When I shortened them, they were still trapped by the exhaust. Some have used a Sawzall the cut those bolts out rather than drop the front of the exhaust at all.


5. Once the lower cover is off you will see the flexplate and clamp. Here it is positioned so I can't get to the clamp bolt head to loosen it.


6. I use a prybar/large screwdriver to move the flywheel. The ring gear and flywheel on later cars are one piece and can be handled this way. The engine should only be rotated clockwise (which would be counterclockwise back at the flywheel). You could use a 27mm socket on the front crank bolt instead or tweak the starter until the bolt head is accessible.


7. Now I can see the 8mm Allen head.


8. Before loosening the clamp bolt, lay a straightedge across the flexplate. This isn't the best straightedge, but as you can see there is a tiny but insignificant bowing. There have been some reports of finding as much as 10mm bowing in some cars. As much as 1 or 2mm wouldn't bother me too much, but anything more would mandate an immediate endplay check after releasing the preload.


9. Loosen the clamp and observe the clamp and flexplate for movement. I think the clamp moved maybe 1/2 mm (compare the photos above and below). This is after I had beat the crap out of the car in the Nevada desert earlier this month. As you can see, I have very little of the splines showing. This seems to have decreased over the years, and you can speculate as to why. The TT is original. A few years ago the tranny was moved once back 1 inch so I could replace the rear main seal, and then slid forward back into position, but otherwise nothing has moved or been removed at any time. That should not have changed the geometry as the TT was left attached to the tranny when it was moved back and forth.


10. So much for the flexplate. Now it's time for crank endplay. Leave the clamp loose. Position a dial gauge against the clamp base. Actually you could measure at any of several places. You guys can argue about that, but this location, even though it is on a part of the flexible flexplate, is fine if the clamp is nice and loose. Others would use the more solid starter ring gear rear face, shown in the second of two photos below. I have the magnetic base mounted on the exhaust pipe. It took some maneuvering to get the dial gauge hardware lined up well enough.




11. Lever the flywheel toward the front of the car with the prybar and zero the dial gauge. I set the gauge several thousandths below zero and use this angle adjustment to bring it up to zero, assuring good contact at zero. Note the prybar tip between the bellhousing wall and the flywheel. You don't have to pry hard; just enough to make sure it is seated. Hard or soft prying will seat it firmly with no additional movement.



12. Zero'd, crank forward. Ready to go.


13. Pry the flywheel to the rear. You should hear a small clunk as it moves. Keep modest pressure against the flywheel so it doesn't slip back on its own.


14. Observe the reading. 0.008 inch. Release, pry the flywheel forward and observe if the gauge is again zero (mine was), then pry to the rear again and check the endplay reading again. Mine was 0.008 inch both times. That's 0.20 mm. Lucky me. That is essentially factory. The spec limit is 0.40mm (0.016"). Anything above that and the motor should be pulled for a rebuild. The stated range in the WSM (volume 1, section 13, page 8) is: New 0.110 to 0.312mm (0.004 to 0.012") with a 0.40 mm (0.016") wear limit.


15. Leave the flywheel in the rear position with no preload, torque the TT clamp bolt to 62 ft lbs (some use 66 ft lbs, others red Loctite the clamp to the TT, etc.). Put the bellhousing cover and rear bellypan back on, lower the car and go for a celebratory burnout!

Last edited by Bill Ball; 10-24-2008 at 10:56 PM.
Bill Ball is offline  
Old 06-26-2007, 06:01 PM
  #2  
Ketchmi
Super User
 
Ketchmi's Avatar
 
Join Date: Sep 2001
Location: Bountiful, Utah
Posts: 2,045
Likes: 0
Received 0 Likes on 0 Posts
Default

Nice writeup Bill!
Ketchmi is offline  
Old 06-26-2007, 06:17 PM
  #3  
SeanR
Running up the Odo'
Rennlist Member
 
SeanR's Avatar
 
Join Date: Apr 2006
Location: DFW Texas
Posts: 34,633
Received 14 Likes on 12 Posts
Default

That makes a lot more sense when you can actually see what you are supposed to do. Thanks for that.

SeanR is offline  
Old 06-26-2007, 06:28 PM
  #4  
the flyin' scotsman
Addict
Rennlist Member
 
the flyin' scotsman's Avatar
 
Join Date: Oct 2004
Location: Southern Alberta, Canada
Posts: 10,618
Likes: 0
Received 0 Likes on 0 Posts
Default

Thanks Bill.

Another project to add to the PM list.
the flyin' scotsman is offline  
Old 06-26-2007, 06:45 PM
  #5  
docmirror
Shameful Thread Killer
Rennlist Member
 
docmirror's Avatar
 
Join Date: Aug 2004
Location: Rep of Texas, N NM, Rockies, SoCal
Posts: 19,591
Likes: 0
Received 7 Likes on 6 Posts
Default

Please 'splain this part:

15. Push the crank back to the front

Very detailed. Should be required procedure for any 928 auto owner.
docmirror is offline  
Old 06-26-2007, 06:57 PM
  #6  
StratfordShark
Super User
 
StratfordShark's Avatar
 
Join Date: Sep 2006
Location: Stratford-upon-Avon
Posts: 2,644
Likes: 0
Received 0 Likes on 0 Posts
Default

Great write-up thanks.

2 questions:

Do you think it's possible to do this job on axle stands/ramps (I have enough room to get pans off when it's on ramps) or is it essential to get it up on a lift?

What kind of tool is a "sawzall" if I use the trick of cutting off bolt heads, and as an aside is there any potential problem with only having 4 bolts on the bell cover?
StratfordShark is offline  
Old 06-26-2007, 07:15 PM
  #7  
figgen
User
 
figgen's Avatar
 
Join Date: Jul 2001
Location: Calgary, Alberta - Canada
Posts: 313
Likes: 0
Received 0 Likes on 0 Posts
Default

Excellent write up.

Thanks for the time and effort to capture this !!
figgen is offline  
Old 06-26-2007, 07:15 PM
  #8  
Miguel928
User
 
Miguel928's Avatar
 
Join Date: Jan 2007
Location: Portugal
Posts: 57
Likes: 0
Received 0 Likes on 0 Posts
Default

Fantastic job.

Thank you
Miguel928 is offline  
Old 06-26-2007, 07:15 PM
  #9  
Ed Hughes
Addict
Rennlist Member
 
Ed Hughes's Avatar
 
Join Date: Jul 2002
Location: Bend, OR
Posts: 16,368
Likes: 0
Received 1 Like on 1 Post
Default

As with the others statements, kudos to a great writeup. Anyone with an A/T that hasn't done this yet is NUTS! (Ahem Sean!!)

As you mention, the worst part is dealing with the rear bolts the first time around. Since you need to drop the exhaust to get to these, it's an excellent time to do an X-pipe for those on the fence....

Now, that I'm on my soapbox, I should preach to myself: I've not checked mine in 13 months.
Ed Hughes is offline  
Old 06-26-2007, 07:16 PM
  #10  
Ed Hughes
Addict
Rennlist Member
 
Ed Hughes's Avatar
 
Join Date: Jul 2002
Location: Bend, OR
Posts: 16,368
Likes: 0
Received 1 Like on 1 Post
Default

BTW, it looks nice and clean there under her skirt. I'd hit it.
Ed Hughes is offline  
Old 06-26-2007, 07:28 PM
  #11  
anonymousagain
Addict
Rennlist Member
 
anonymousagain's Avatar
 
Join Date: Nov 2005
Location: NorCal - Bay Area
Posts: 861
Likes: 0
Received 0 Likes on 0 Posts
Default

Nice write-up Bill !!!

The Mad Scientist Rides Again
anonymousagain is offline  
Old 06-26-2007, 07:55 PM
  #12  
MGW-Fla
Super User
 
MGW-Fla's Avatar
 
Join Date: Mar 2005
Location: Fla
Posts: 4,150
Likes: 0
Received 0 Likes on 0 Posts
Default

Great write up Bill, especially with the pics!
Soooo,.... when are you movin to Sunny Florida anyways?? We need ya down here!
MGW-Fla is offline  
Old 06-26-2007, 08:04 PM
  #13  
docmirror
Shameful Thread Killer
Rennlist Member
 
docmirror's Avatar
 
Join Date: Aug 2004
Location: Rep of Texas, N NM, Rockies, SoCal
Posts: 19,591
Likes: 0
Received 7 Likes on 6 Posts
Default

Originally Posted by StratfordShark
Great write-up thanks.

2 questions:

Do you think it's possible to do this job on axle stands/ramps (I have enough room to get pans off when it's on ramps) or is it essential to get it up on a lift?

What kind of tool is a "sawzall" if I use the trick of cutting off bolt heads, and as an aside is there any potential problem with only having 4 bolts on the bell cover?

Ah the internet. If only folks would learn the concept of search;

http://www.milwaukeeconnect.com/weba..._192213_192137

Yes, possible to do on stands/ramps. No prob with only four bolts in the bottom cover.
docmirror is offline  
Old 06-26-2007, 08:19 PM
  #14  
dr bob
Chronic Tool Dropper
Lifetime Rennlist
Member
 
dr bob's Avatar
 
Join Date: Oct 2001
Location: Bend, Oregon
Posts: 18,026
Received 13 Likes on 12 Posts
Default

Bill,

What's the reason for preloading the cran forward against the thrust bearing? I thought we were trying to eliminate the preload in that direction...

I left mine midway, FWIW.
dr bob is offline  
Old 06-26-2007, 08:21 PM
  #15  
checkmate1996
Addict
Rennlist Member
 
checkmate1996's Avatar
 
Join Date: May 2002
Location: Columbus, Oh
Posts: 1,888
Received 3 Likes on 3 Posts
Default

nice work Bill!
checkmate1996 is offline  

Thread Tools
Search this Thread
Quick Reply: My Flexplate - Crank Endplay Check Pictorial


Contact Us - About Us - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: