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Clutch not completely releasing - master and slave cylinder sizes?

Discussion in '"Stock" Alpine' started by howehap, Nov 7, 2019.

  1. howehap

    howehap Donation Time

    I'm helping a friend with his 1967 Alpine, I have several myself, so I have some experience with Sunbeams... The car does not want to shift into 1st or reverse if the engine is running, shifts fine if the engine is off. I found 90 wt oil in the transmission, changed it to the recommended 30 wt and it shifts a little better, but not acceptable. When the car is warmed up it gets a little harder to get in gear. The car was professionally restored as a side job, so it took ~ 10 years or so. Car shifted fine once-a-upon-a-time before the rebuild. I had no part in the restoration.

    I have looked over all the past threads related to hard shifting, and I am wondering if the master and slave cylinders are no longer a matched set. The master cylinder has been replaced, and the slave cylinder is old and has a 1" bore. He also had a parts car of unknown age that was used as a parts car, so I'm not sure that the slave cylinder is from this car. I'm wondering what the correct bore dia should be for the master cylinder and slave cylinder. I forgot to measure the bore on the master cylinder when I had it apart.

    I have honed out the slave cylinder that had some sludge and pitting, and reinstalled the old parts to see if there was improvement. I have bled the system several times using the various methods in the various threads. Might be some improvement, but not acceptable. I get roughly 3/8 to 1/2 throw at slave cylinder. Slave is mounted on the correct side of the bellhousing.
  2. Gordon Holsinger

    Gordon Holsinger Platinum Level Sponsor

    Check the position of the clutch pedal. Are the diagonal braces from the engine to the bell housing there? If not the engine and transmission flex apart. Is the fulcrum inside the bell housing the correct one series V used a different one because the clutch was thinner diaphram as opposed to the three finger spring clutch in earlier cars.
  3. hartmandm

    hartmandm Moderator Platinum Level Sponsor

  4. howehap

    howehap Donation Time

    Here is a photo of the master cylinder that is on the car. Yes, the diagonal braces are installed.

    Attached Files:

  5. DanR

    DanR Diamond Level Sponsor

    It doesn't mean I'm right, But, I have never seen a Master Cylinder like that one on an Alpine!
  6. 65beam

    65beam Bronze Level Sponsor

    It looks like a Tilton 74 master cylinder . They're available from Pegasus Racing in various bore sizes. FYI,
    I buy Girling 700 masters from Pegasus.
  7. rixter

    rixter Platinum Level Sponsor

    On a Series 5, how does the pedal height get adjusted? I cannot see any adjustment.
  8. RootesRooter

    RootesRooter Platinum Level Sponsor

    The pedal arms are pinned to the masters. There's a second hole on the arms to choose from.

    On the partial clutch movement, was the clutch slave attached to the correct side of the bellhousing after the rebuild?
  9. howehap

    howehap Donation Time

    Yes, Slave cylinder is mounted on correct side of bellhousing. Does anybody know the correct slave bore dia that goes on series V? Mine measures 1" dia.

    Mike said that the series V master cylinder measures 5/8. I could remove and disassemble mine to find out, but it would be easier to verify the slave bor first. I could also verify throw at the slave cylinder if somebody knows how much is normal on a Series V.

    It could be something else I'm missing, (fyi bleeder fitting is up).

    The owner is going to look through his spare parts and recepts to try to figure out what was changed. He is also going to talk to the restoration guy to see if he remembers anything. The car was not driven for several years after restoration because the owner installed the battery backwards and burnt up the wiring in the car. It then bounce around several repair shops with limited Sunbeam knowledge for several years, so the clutch issue was never recognized after the orignal restoration.
  10. Bill Blue

    Bill Blue Diamond Level Sponsor

    All of the above makes me suspect the master cylinder. Is there anyway you can plug the master cylinder output, then press the clutch pedal? It should be rock hard.

    belmateo likes this.
  11. Tom H

    Tom H Platinum Level Sponsor

    The replacement master is NOT the original style. As Bill said that would be my first suspect. I trust someone will be able to check the throw on their Alpine, but I am puzzled as to why you don't simply check the throw on one of YOUR Alpines? Your fist sentence in this thread says you "have" several Alpines, or did you mean you "have had" ?

  12. howehap

    howehap Donation Time

    Yes, I have several Alpines, only one of them is a Series V, and none of them have working clutch hydraulics. Now that I am retired, I hope to get going on repairing my Alpines. I also had a 1969 fastback, back about 1980 that was restored and on the road.

    I guess I could remove the master from my Series V, and see if it is serviceable, and try it out. I would gladly recommend the owner by a new master cylinder if that is the problem, but I want to figure out what is wrong first, so that I am not just replacing parts and hoping I fix the problem:(
  13. Tom H

    Tom H Platinum Level Sponsor

    OK, Bob, now we understand. Welcome to the Forum. Too cold to get under my car to check the throw, but I did check the slave bore by looking at my slave repair kit and measuring the inner seal. And yes, it's a 1" bore on the original SV slave.

  14. Gordon Holsinger

    Gordon Holsinger Platinum Level Sponsor

    If you have access to an original they can be sleeved companies such as White Post can do it at a reasonable price
  15. howehap

    howehap Donation Time

    I haven't fixed the clutch issue yet. Here is a updated of what I checked and results:
    Clutch master cylinder appears to be correct replacement for S5 Alpine. It appears to be from Sunbeam parts supplier in the UK, picture attached (5/8" piston bore).
    I tested the master cylinder by pluging the outlet, the master's piston moved about 3/16" and then the peddle became hard. This seems reasonable, the seal cup needs to move forward enough to cover the port hole in bore. The clutch pedal not hitting floor board, carpet, etc, so I am getting full stroke at master cylinder.
    I replaced slave cylinder that had some pitting (but not leaking) with new slave cylinder from VB (only $15, can't beat that!). Installed on correct side of bell housing, bleeder up, etc.
    Measured slave cylinder piston position inside cylinder bore. (With clutch pedal up .55", with clutch pedal down .12") = .43" stroke of slave cylinder that is moving clutch arm.
    Clutch still does not fully release, ie with engine running, hard to get into first, grinds going into reverse. Any ideas on what I can check next? I'm in CT we had a big snow storm, Alpine is put away in enclosed trailer for the winter.

    Attached Files:

  16. hartmandm

    hartmandm Moderator Platinum Level Sponsor


    I think there could be 4 possible causes:
    1. The clutch slave push rod is not the right length.
    2. The clutch slave push rod is not traveling far enough to fully engage the clutch pressure plate.
    3. There is an issue with the clutch pressure plate.
    4. The clutch disc is stuck to the flywheel.

    To check #1 & #2, you need to find out how far a stock clutch slave push rod extends from the bell housing lip at rest and then how far it travels when the clutch is depressed. Unfortunately, I have the boot cover installed over my push rod and pivot arm and it is not that easy for me to make those measurements.
    For #3, you'd have to pull the gearbox to inspect the pressure plate.
    For #4, are you starting the car in idle and struggling to get into 1st or reverse? If so, the clutch disc could be stuck to the flywheel. You could try this test. Warm the car up a bit, so it is easy to start with no choke required. Then turn off the car. Block the wheels. Apply the handbrake. Make sure there is adequate space behind the car in case it lunges backwards. Select reverse gear. Depress the clutch fully. Start the car. If the car will run and not lunge backwards, then rev the engine some while remaining in reverse with the clutch depressed. The clutch disc should have come loose from the flywheel. If the car only lunges instead of starting up, then I expect the pressure plate is not engaging enough to release the pressure on the clutch disc or is damaged.

  17. Filister

    Filister Silver Level Sponsor

    The master cylinder on my series 5 clutch is .75". It looks stock. Not sure it is stock but the clutch works great.
  18. Alpine 1789

    Alpine 1789 SAOCA President Platinum Level Sponsor

    I am sure this will be fine for your immediate needs, but I had a VB slave for a while and the piston popped out of the cylinder a couple of times, resulting in a loss of fluid and clutch. Mine may have been defective, but I replaced it with a rebuilt stock one and never had that problem again. Just a warning for when you solve the immediate issue.
  19. William Lewis

    William Lewis Silver Level Sponsor

    Bob, have you resolved your issue? I am having a similar but slightly different problem. I have a Series 2 car with Series 5 motor. The Series 2 tranny had a catastrophic failure, so I replace it with a Series 5 box. New pilot bush, clutch, pressure plate, and throw out bearing. All are Series 2 and matched what came out of the car, except my throw out was a bearing and is now a bushing (Rick says bearing no long available). At first, the car drove OK. A little stiff getting it into gear. After only a few miles, shifting became more difficult. Now, when I put it in gear, it wants to creep. I rebuilt clutch master and installed new slave. I have 3/4" travel on the slave rod. With the clutch pedal all the way down, I get a whirring grinding noise and the car wants to creep while in gear. Let up a little on the clutch pedal, grinding noise abates and the creep is better. Let up more and the clutch starts to engage smoothly. It will shift into 3rd and 4th with a little trouble. Second is harder. First is almost never and reverse grinds. I suspect something in my setup is causing the tranny input shaft to slowly turn while clutch is "disengaged". Any ideas? I suspect the pilot bushing is galled up as shifting was better at first and then started having trouble. It is a new Oilite bush. I didn't oil it prior to installation but it felt nice and slick. I know people argue whether oiling them is necessary. I don't want to pull it all out again, but I'm headed down that road.
  20. howehap

    howehap Donation Time

    I haven't resolved the issue yet, but it is driveable. I can now engage 1st and reverse with the engine running. From reading my thread, you can see I did various things to try to understand and fix the problem. The only thing that kind-of stood out for the car I'm working on was disassembling and cleaning the master and slave cylinders and making sure I really had all of the air bled out of the system. There is still some underlining problem.
    For your car I would make sure you don't have some miss- matched parts between the series 2 and series 5 combination of parts that you have. You say that you have .75 " of throw at the slave cylinder, this is a lot more than the .43" that I have. I'm wondering if you have too much movement inside the pressure plate causing contact / rubbing. If the slave cylinder is moving 3/4" instead of the .43" that I have, it indicates that your master cylinder piston may be larger, or slave cylinder piston smaller that mine (different movement ratio). There have been discussions on this in other treads too.
    If the clutch seems to work ok if you don't push it down all the way to the floor, you might want to try getting a smaller master cylinder (piston size) or a larger slave cylinder. You would need to disassembly the slave and master to find out for sure what size pistons you have, but it would be easier than pulling the engine/trany looking for a solution. I think there is also a different clutch fork on earlier Alpines that have a different ratio (length) that might not work with the .75" throw that you have.
    Good luck, I'm charging the battery in the Alpine now. I hope to pull the Alpine out this weekend.
    -Bob Howe

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