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Replacement Clutch Linkage Plates Too Short

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dschwartz1957 David Schwartz
Framingham, MA, USA   USA
1950 Morris Minor "Moyshe"
1968 Morris Mini Traveller "The Tardis"
2000 Mazda MX-5
My left hand drive 1950 Morris Minor Tourer was fitted with a 948cc engine from the late '50s.

Today I installed new clutch linkage plates (COM120) and clevis pins (COM121). The clevis pin holes in the old plates didn't match up, and the pins had deep grooves.

http://www.morrisminorspares.com/clutch-c15/clutch-all-models-c18/clutch-linkage-plate-2-required-each-p829546

I suspect the old linkage plates may have been home made, which is why the holes didn't line up. The replacement plates are 0.75 inches shorter than the old plates which has made the clutch impossible to adjust. With the old linkage plates, the clutch adjusting rod (COM123) domed adjusting nut (COM125) was about 1/3 of the distance up from the 90 degree bend in the rod. With the new plates, the domed nut is at the very end of the rod. As a result, there is no free play in the clutch pedal and the clutch may not be fully released.

Does anyone know if the linkage plate length varied between early and later Minors? The old plates are 4.75" and the new are 4".

I didn't measure the clutch adjusting rod on my car. Did the adjusting rod length vary over the years? If the later rod (or a replacement rod) is 1 to 1.5 inches longer, that would make up for the shorter plates.

http://www.morrisminorspares.com/clutch-c15/clutch-all-models-c18/clutch-adjusting-rod-p829548

It would be helpful to know the length of clutch plates and the connecting rod on other Minors.

If necessary, I can make up a longer set of plates from bar stock and drill the holes correctly.

Thank you,

David Schwartz

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John in Eugene Avatar
John in Eugene Platinum Member John Quilter
Eugene, OR, USA   USA
Keep in mind the two connecting plates were a later Minor fitment. Perhaps with the 948cc engine on. The workshop manual on the earlier OHV cars shows that there was a "U" shaped bar that connected the relay arm to the clutch pedal shaft arm. There have also been cases where the clutch fork has been known over many hundreds of miles and decades of use to bend slightly making adjustment with the threaded rod problematic. I offer this just as some background info. My convertible (192,000 miles) suffers from the bent clutch fork which will get replaced on the next gearbox removal. In your case as a work around I would make up custom plates from metal stock. From my parts inventory are the following measurements. Plates, overall length 4.5 inches, holes on center 3.75. Adjustment rod, 8.375. Hope this helps you.

John F. Quilter
Eugene, Oregon USA

0123 Mike D
Biddulph, Staffs, UK   GBR



Edited 3 time(s). Last edit at 2019-02-02 10:13 AM by 0123.

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0123 Mike D
Biddulph, Staffs, UK   GBR



Edited 1 time(s). Last edit at 2019-02-02 10:12 AM by 0123.

emjay Jim English
Etters, PA, USA   USA
The only difference in your fitment that I can think of is the engine might be mounted forward a bit to clear the original straight cross member of the Series MM cars. With the pedal in the up position the pedal arm and the relay linkage arm should be fairly vertical to slightly forward. If the relay is rearward pointing then longer plates are needed. The rose joint upgrade would be a good option.

0123 Mike D
Biddulph, Staffs, UK   GBR



Edited 2 time(s). Last edit at 2019-02-02 10:12 AM by 0123.

emjay Jim English
Etters, PA, USA   USA
Yes, max leverage and max usable pedal stroke would be with the levers perpendicular to the link at mid stroke. Originally, I think that are just a bit forward, maybe 15° when the pedal is up. The levers should also be roughly parallel, so the plate length would be the same as the length between axis.

dschwartz1957 David Schwartz
Framingham, MA, USA   USA
1950 Morris Minor "Moyshe"
1968 Morris Mini Traveller "The Tardis"
2000 Mazda MX-5
Thanks for the measurements and suggestions. I have seen the "rose joint" photos and this looks like a clever upgrade.

My 1950 Tourer has a 948 engine (9M-U-98803). The engine may be mounted a tiny bit forward (a previous owner mashed in the cross member at the rear of the engine), though the transmission mounts line up correctly. I assume the old (home made) clutch plates were fitted when the engine was swapped. The overall plate length is 4.75" long and the holes are 4-1/8" inches on center. They are 3/16" thick, while the new replacements are about 1/8" thick. The old plates rub against the brake line clip that is welded to the frame rail. Even with the new plates, there is very little clearance from the brake line clip or brake line. Not to go off on a tangent, but I can't believe that they routed the brake lines so close to the clutch plates. Would it have cost too much to weld another set clips at the top of the frame rail, instead of sharing clips with the fuel line!

For the 9M engine, the Haynes manual states: Clutch Pedal Free Movement 3/4". The manual defines free travel as:

"The distance the clutch pedal will move under the pressure of one finger before the resistance of the pressure plate springs are met. When this point is reached a pressure of about 50 lbs. per square / inch is required to depress the clutch pedal further."

Adjusting the clutch is truly an exact science ;-)

It doesn't take much effort to depress the clutch pedal by hand, so the pressure plate springs may be worn. I did install a new clutch pedal return spring.

Given that the current adjustment is at the end of the relay arm, I won't know whether the clutch fully disengages until the engine is running again. At that point I will look into the rose joints, or make up a new set of plates that are a .75" longer.

David

0123 Mike D
Biddulph, Staffs, UK   GBR



Edited 2 time(s). Last edit at 2019-02-02 10:11 AM by 0123.

John in Eugene Avatar
John in Eugene Platinum Member John Quilter
Eugene, OR, USA   USA
When adjusting Morris clutches, I set up the maximum amount of free play at the pedal consistent with a clean, no clashing, engagement of 1st gear when the clutch is fully depressed and the engine at idle. I have found the full available travel of the pedal is sometimes more than is needed. If the full travel is actually used it can cause the clutch cover to be "coil bound" and puts additional stress on it and more importantly the carbon release bearing. If one is not comfortable with excessive free travel one can always put a block of wood under the pedal and adjust the linkage accordingly.

John F. Quilter
Eugene, Oregon USA

geezer Avatar
geezer Silver Member charles durning
Magee, MS, USA   USA
1958 MG Magnette ZB "Chick Magnette (sold)"
1967 Morris Minor 1000 Saloon (2-door) "Marvin"
1974 MG MGB GT "Foghorn Leghorn"
I solved the excessive action by drilling a new hole in the arm attached to the clutch pedal shaft (arm on the left in the pic). Made the clutch much easier to modulate.



If it was good 60 years ago, does that mean it can't be improved?

Though the task may seem to be too daunting or difficult at first, the result will be worth the effort in the end.


Attachments:
IMG_0458.JPG    56.7 KB
IMG_0458.JPG

0123 Mike D
Biddulph, Staffs, UK   GBR



Edited 1 time(s). Last edit at 2019-02-02 10:10 AM by 0123.

geezer Avatar
geezer Silver Member charles durning
Magee, MS, USA   USA
1958 MG Magnette ZB "Chick Magnette (sold)"
1967 Morris Minor 1000 Saloon (2-door) "Marvin"
1974 MG MGB GT "Foghorn Leghorn"
Nope, same size just moved it in



If it was good 60 years ago, does that mean it can't be improved?

Though the task may seem to be too daunting or difficult at first, the result will be worth the effort in the end.

0123 Mike D
Biddulph, Staffs, UK   GBR



Edited 2 time(s). Last edit at 2019-02-02 10:10 AM by 0123.

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