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Discussion Starter #1
The car is a GTV 2000 of 1975. Gearbox after rebuilt with some bearings and dog rings replaced, including the upgrade mod of 1st gear. All gears change like a charm while the engine is stopped. BUT:
1. The gearbox checked for free rotation on the bench with no problem, engagement-disengagement of all gears was fine.
2. When the engine is working 1st & 2nd gears are, most of the times, hard to engage with clutch fully pressed. Reverse gear is impossible to engage as the gears are grinding.
3. Clutch set is new.
4. Oil used is RedLine MT90 GL4 suitable for manual gearbox, quantity used is 1.8 Ltr initially, then I removed 0.5 Ltr but situation remains unchanged.
5. Flywheel machined 0.2 mm both, on friction surface and ring surface, so no problem can be identified there. Unless the friction is too high till to accumulate some use and have the surfaces brake-in with new parts.
6. The whole situation gives me the impression that the clutch is not fully disengaging or disk still maintains some minor contact with flywheel and/or pressure plate and rotation is partially apply even with clutch fully pressed.
7. I checked the lever travel underneath and is almost touching the bellhouse, so I consider that travel (about 10mm) is satisfactory. The car has not tested on the road but only on the jacks. Even when I apply the brakes and shaft does not rotate at all I have the same issues.
8. With gear engaged the wheels are rotating normally, pressing the clutch I can apply the brakes with no problem.

What could be the problem? Any idea will be highly appreciated!

Thank you all.
 

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Discussion Starter #3
checks the clutch master cylinder stroke.
Checked already. I have the 134 mm of calibration as per specs. The slave cylinder is fully pushing clutch lever so I don't think to be an actuation issue. Most probably flywheel surface shall brake-in to match disk surface.
 

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Meanwhile I restored my GTV the clutch plate stuck to the flywheel.
I had to remvoe the gearbox to loosen the plate from the flywheel.
It was held by some minor rust spots. When I removed them an reasse,bled everything was fine.
 

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Discussion Starter #5
Meanwhile I restored my GTV the clutch plate stuck to the flywheel.
I had to remvoe the gearbox to loosen the plate from the flywheel.
It was held by some minor rust spots. When I removed them an reasse,bled everything was fine.
I see... I am almost sure that my clutch assembly need some break-in. The workshop that machined the flywheel did also some bead blasting on matting surfaces to improve friction... so the lightest touch even with clutch depressed transfer the rotation to the gear...
 

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It's a mystery. If everything it's checked, there remains then the flywheel which has perhaps been too rectified ?

I never had this problem, but it's true that I don't know how much the flywheel is usually rectified...

If all works fine on the bench, then the problem is in the actuation system, or contact system.
 

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The workshop that machined the flywheel did also some bead blasting on matting surfaces to improve friction... so the lightest touch even with clutch depressed transfer the rotation to the gear...
Why did they do that?

Why do people keep trying to reinvent the wheel? This sounds like the cause of your problem

Alfa Romeo designed the clutch, I'd suggest to set it up as they intended. There is no design weakness that needed addressing, that I am aware of
Pete
 

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Discussion Starter #8
Why did they do that?

Why do people keep trying to reinvent the wheel? This sounds like the cause of your problem

Alfa Romeo designed the clutch, I'd suggest to set it up as they intended. There is no design weakness that needed addressing, that I am aware of
Pete
The friction surface of flywheel was full of thermal stress hair cracks and discolored areas from overheating. Workshop manual indicate that machining is allowed provided that the distance between the friction surface and the surface that pressure plate is attached remains unchanged or between some limits which was followed. To my opinion the bead blasting was not needed because increased the friction of the surface that clutch disk is touching thus need to break-in and become less abrasive. At least this is the only explanation that I can give... I will try to break-in the clutch set with some intermittent slipping on the flywheel and see if my assumption is correct.
 

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It sounds like the disc is not releasing. If the hydraulic release is working properly, it could be that the disc is binding on the splines of the transmission input shaft. I always test fit the clutch disc onto the splined shaft. Use the proper lube too. I never saw the .880" spec for the flywheel step. I always used .900" found by phone and measured by a Dealer that had a new flywheel in stock (many years ago). I was pretty close!
 

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Discussion Starter #10
It sounds like the disc is not releasing. If the hydraulic release is working properly, it could be that the disc is binding on the splines of the transmission input shaft. I always test fit the clutch disc onto the splined shaft. Use the proper lube too. I never saw the .880" spec for the flywheel step. I always used .900" found by phone and measured by a Dealer that had a new flywheel in stock (many years ago). I was pretty close!
[/QU
The splines are fine and lubricated but yes, it seems that the disc is very slightly touching flywheel. I will try to break-in the contact surfaces to see if there is improvement. The real problem is to engage reverse...
 

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If you start the car, with the car in first, does the car lurch forward?
Did you bleed the clutch slave a second and third time?

Did the pilot bushing get replaced? If the bushing was too tight of a fit, the trans input shaft could bind on it. Which would cause your issue.
 

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Discussion Starter #12
Pilot bushing was replaced and fitting was verified also it was slightly greased inside the hole. As I said maybe need to make some break-in to the system... System bled several times and actuation lever is moving all the way pushing clutch bearing. In first start was almost impossible to engage 1-2 gears, after 15-20 minutes of operation and changing of gears became easier but still some times need to push gear lever harder. The real problem is on the reverse, if I will try to engage it the gears are grinding, 1-2 times I pushed harder ignoring this terrible noise and the gear engaged but certainly I will not do it again until to resolve this issue!
 

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This is an emerging issue it seems these days. Happened with my GTV somewhat out of the blue. >.500 inch release arm throw, initial symptom is severe grinding with clutch fully depressed going into 1-2-r. I replaced the master cylinder, pilot Bush, clutch, clutch line, and eventually motor (not for this reason).gearbox removed and input shaft runout checked, splines examined, nose checked and ok. Full gearbox metrology completed. No evidence of wear on any surface other than clutch disk - flywheel bolts ok and torqued proper, clutch disk no problem ever found. It is “fixed” at the moment. No cause was ever found.
 

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Discussion Starter #15
This is an emerging issue it seems these days. Happened with my GTV somewhat out of the blue. >.500 inch release arm throw, initial symptom is severe grinding with clutch fully depressed going into 1-2-r. I replaced the master cylinder, pilot Bush, clutch, clutch line, and eventually motor (not for this reason).gearbox removed and input shaft runout checked, splines examined, nose checked and ok. Full gearbox metrology completed. No evidence of wear on any surface other than clutch disk - flywheel bolts ok and torqued proper, clutch disk no problem ever found. It is “fixed” at the moment. No cause was ever found.
This is such kind of ghost issues that drive you crazy... Everything was working fine before repair except 1st gear light grinding when car was stopped. I did the known 1st gear fix and replaced several parts. When engine is off the gears changing like a charm(!), the input shaft is the original as before, the only suspect for me is the extra friction of flywheel due to beads blasting make it like very fine abrasive paper. I will try tonight to break-in and I will update.
 

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Aris64 said:
Oil used is RedLine MT90 GL4 suitable for manual gearbox
Lots written on the BB about what lubricants are appropriate for Alfa transmissions. RedLine MT90 GL4 is a synthetic oil. I have a dim memory of reading that synthetics can be too slippery for the old design/materials of the Alfa synchro rings. Someone should check me on this - my memory may be faulty here - but I wonder if replacing the synthetic with old-school 90 weight would eliminate the grinding.

The workshop that machined the flywheel did also some bead blasting on matting surfaces to improve friction
That was an odd thing to do. I would think that even if bead blasting did some good (which I doubt), the roughness would get worn off after a few hundred miles of driving.
 

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Discussion Starter #17
Reading your adventure, I realized that during assembly of the gear box ( I did myself alone under the car) I had, for a while, the hole transmission hanging on its input shaft partially inserted to the engine part, which in turns may had as a consequence to bend the input shaft(!) but can this happen so easy?
 

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I had this issue did all the checks it came down to the clutch master cylinder pivot arm, the weld had given way almost all the way around shaft allowing the shaft to rotate but the arm less
I checked the slave throw and it was fine but the car would try to pull like an auto gearbox with it in 1st and clutch pressed to the floor and it crunched gears on 1st and 2nd gear change
The only thing I changed was an uprated pivot arm and it fixed it, I still can't understand why as the slave cylinder throw was within spec but it did
 

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Discussion Starter #19
Lots written on the BB about what lubricants are appropriate for Alfa transmissions. RedLine MT90 GL4 is a synthetic oil. I have a dim memory of reading that synthetics can be too slippery for the old design/materials of the Alfa synchro rings. Someone should check me on this - my memory may be faulty here. Still, I wonder if replacing the synthetic with old-school 90 weight would eliminate the grinding?
As I remember I found somewhere here in BB that Red Line MT 90 GL4 was the best oil for this transmission but cannot be sure.
 

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I had this issue did all the checks it came down to the clutch master cylinder pivot arm, the weld had given way almost all the way around shaft allowing the shaft to rotate but the arm less
I checked the slave throw and it was fine but the car would try to pull like an auto gearbox with it in 1st and clutch pressed to the floor and it crunched gears on 1st and 2nd gear change
The only thing I changed was an uprated pivot arm and it fixed it, I still can't understand why as the slave cylinder throw was within spec but it did
I opened my master cylinder to renew the o-rings thinking that I have ordered the right parts but finally I re-assembled with the old o-rings, Everything seems to be fine and slave throw is fine as well. I have ordered already new master & slave cylinders just in case but honestly I can't see any obvious reason or malfunction there as you said also. I will go through troubleshooting approach so to exclude possible reasons but cylinders are to the bottom of the list. 1st step is to break-in my clutch setup. 2nd step (which I don't like) is to take out my gear box to check if accidentally have bend my input shaft...
 
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