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964 engine rebuild question

 
Old 12-25-2015, 10:22 PM
  #1  
Alex Sol
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Default 964 engine rebuild question

i mushed up my engine and the main crank requries three of the six connecting rod journals - machining. so i will machine them all to .50mm and require the oversized bearings. They come in .25 and .50 mm from factory oem...

so my plan is to get the 0.50mm oversized connecting rod bearings.

Looks like only available from porsche germany with 4 week wait time.

does anyone know who else may make em? mahle or otherwise.

the porsche bearings are expensive to boot.. $65 each pair x 6 from one of our fine sponsors on rennlist!!

plus my crank is bent and off by 10 thou.... that can be fixed also.

magna flux shows no cracks!

Merry Christmas...
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Old 12-25-2015, 10:29 PM
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Alex Sol
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Default pedal cluster question, clutch pedal engages/disengages just an inch off the floor

my clutch was not fully disengaging and had to put the pedal to the floor with full body weight just to disengage.. bled the system, and the clutch has 70,000 kms on it (being a pro driver, that clutch cannot be fried, plus it looks pretty good as i have it out along with the engine and trans... )...

i brought into local specialist and he had figures it's the roll pin and bushings so i ordered new.

i removed yesterday and:

1. cannot figure how to remove the shaft that is connected to the clutch pedal... seems it should slip out but so far no luck - light taps with my 5 lb mallet?

2. when i inspect the roll pin and remove, it appears to be in fine shape. i expected the pin to be broken or damaged so... ?

3. there is lots of play and and an adjusting screw. the play is from the giant spring that sits below the brake pedal / accel pedal size and is very loose. does that mean it needs to be replaced or can i just adjust the screw until the play is gone?

4. anything to change while i have it in my hands?

5. could me issues be the master cylinder?
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Old 12-26-2015, 06:44 PM
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FeralComprehension
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On those bearings, you should check out the PParts rebuilding forum. There's apparently an issue with the current Glyco bearings; some have actually moved to Clevite.
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Old 12-26-2015, 07:01 PM
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Rocket Rob
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Originally Posted by Alex Sol View Post
my clutch was not fully disengaging and had to put the pedal to the floor with full body weight just to disengage.. bled the system, and the clutch has 70,000 kms on it (being a pro driver, that clutch cannot be fried, plus it looks pretty good as i have it out along with the engine and trans... )...

i brought into local specialist and he had figures it's the roll pin and bushings so i ordered new.

i removed yesterday and:

1. cannot figure how to remove the shaft that is connected to the clutch pedal... seems it should slip out but so far no luck - light taps with my 5 lb mallet?

2. when i inspect the roll pin and remove, it appears to be in fine shape. i expected the pin to be broken or damaged so... ?

3. there is lots of play and and an adjusting screw. the play is from the giant spring that sits below the brake pedal / accel pedal size and is very loose. does that mean it needs to be replaced or can i just adjust the screw until the play is gone?

4. anything to change while i have it in my hands?

5. could me issues be the master cylinder?
You may want to replace the plastic bushings. Has the clutch always been this way or is this behavior a recent change? If its always been that way, have you checked the pedal throw distance? Is the pedal stop adjusted correctly? If yes, then I would suggest reading this thread. I had a similar problem and in my case, it was a problem with the angle that the clutch pedal was drilled.

https://rennlist.com/forums/964-foru...ake-pedal.html
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Old 12-27-2015, 02:01 AM
  #5  
Steve Weiner-Rennsport Systems
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Alex,

If you need .5mm undersize rod bearings, your only choice is factory and I'll warn you, they are not cheap.

.25mm ones from Porsche as well as Clevite 77 ones are available (very short supply) so if those will help, let me know ASAP as I have only one set left. More of them are several weeks out. These are reasonable at $350/set.
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Old 12-28-2015, 12:18 AM
  #6  
Alex Sol
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Steve, thanks for your input..

ugh... sounds like i'm going to need the .50mm as i can get away with five of the .25mm but cannot for the sixth which is 14 thou off and requires a 20 thou grind which means... .50mm.

i was told it would be best to grind the crank the same way all around to avoid confusion in future work on the crank shaft... which in my case may be next life?

i read somewhere that the glyco are not totally reliable?

would you mix up the grinds and con rod bearing sizes?
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Old 12-28-2015, 04:50 AM
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ALEX P
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Is there a huge cost differential between the expensive .5mm undersize bearings + regrinding + straightening the old crank and replacing it with a new GT3 crank?

Just thinking out loud but if it was me I'd be looking at all the options available at this stage before jumping in.
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Old 07-15-2016, 06:34 PM
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Michael D'Silva
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Would love to know what happened to this rebuild....
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Old 09-02-2016, 07:59 PM
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Alex Sol
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mike,

just looking at my old posts.

had the crank repaired and machined to fit oversized / thicker connecting rod bearings which i ordered and came from Germany Porsche... took long time

had the shop property torque on and installed with new (to me) connecting rods - all matching

resealed motor and with fresh main crank bearings (regular size) and runs great, purrs like a kitten at idle and makes good power

broke in at the track after 300 kms of original oil change

put on about 3 or 4,000 kms since rebuild
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