Master cylinder packing pieces [shims]

[steveg]

Dave -

Just checked and the most of the play (clutch) seems to be wear between the clevis pin and the pedal bellcrank. Then when I feel the pushrod move against the piston there seems to be a little more light travel before I'm pushing against the clutch itself - perhaps that's in the Toyota clutch operating lever.

FWIW my clutch pedal is about 1/4" higher than the brake pedal.

Will need to tighten the clutch clevis up a little.

 

[HealeyRick]

Looked in my BJ7/BJ8 Service Parts Manual. It shows 2 packing pieces required for both the clutch and brake master cylinders for all the non-servo BJ7s and BJ8s. BUT, the master cylinder on the BJ8 cars with servos is of a different design. It has an adjustable pushrod and the manual lists no packing pieces for that cylinder. Feel free to hypothesize further, gentlemen.

 

[vette]

Red57, In reviewing your pics i will have to say that it seems that adding shims will effect the height of the pedal, but I honestly don't remember that being the case. Also as seen in your pics the pedals will swing an inordinate amount of distance to the rear if not connected to anything. then it follows that what stops their rearward swing is the rod hitting the back/inside of the washer/spring clips in the bores of the master cylinders. But this rearward travel is not what I believe is the larger concern. I am still concerned that the shims are there to control the forward travel/insertion of the
piston irregardless of the height of the pedal. I have read generically about master cylinders and the cups on the pistons usually must travel in a very specific zone. Outside that specific zone you will either destroy the cups or the MC just won't work. Your study of the geometry of the layout is admirable but I don't have any idea why they did what they did, but then......the angle and distances of those short operating levers that attach to the clevis' were engineered, they weren't random. Here's another intrig. Don't be so sure that those pedals didn't come from another car.

 

[British_Recovery]

Regardless of why they are used, the design of the packing pieces suggests they could be installed without totally removing the master cylinder. The two-piece design, plus the open slot to go around the bolt, suggests a retro-fit. Some early illustrations show the two-piece shims without slotted holes for the bolts. I have never actually seen those on the cars I have taken apart, but have plenty of the slotted ones.
Bob

 

[Lin]

I put the new clutch and brake master cylinders in last week. My previous set-up had shims on the brake master and no shims on the clutch master. The brake pedal sat higher than the clutch pedal. With the new set-up, I installed shims on both the clutch and brake master. The pedals are now just about even. The shim definitely moves pedal height. I am not disputing Vette’s Theory about the degree of piston travel in the master cylinder, but I am of the opinion that the shims are all about setting a functional and comfortable pedal height. You need to have the brake pedal position properly relative to the accelerator pedal, and then you need to adjust the height of the clutch pedal to make it about the same height of the brake pedal. Just my thought - all theory. Sure wish the Healey men were around to respond to some of the esoteric discussions that we often find ourselves in.
Lin

 

[Marvin Gruber]

Never seen or heard of shims or spacers on the master cyl before. Must Have been a PO thing. With new parts nowaday who knows what we are getting.
Marv

 

[Bob_Spidell]

... you need to adjust the height of the clutch pedal to make it about the same height of the brake pedal. Just my thought - all theory ...

Offhand, I can't think of a solid reason why they have to be the same height; maybe a matter of personal preference? The last time I worked on my BJ8's clutch I forgot to install the shim that was in there when I bought it, but never gave it a thought one way or another. FWIW, my '19 Mustang's clutch pedal sits a good half-inch higher than the brake pedal, and I never thought much about that either (until now ). Any of you racers know a good reason to adjust clutch and brake pedal heights (besides personal preference?).

 

[RDKeysor]

I know I have encountered one or two shims while replacing my brake and clutch cylinders, and I have seen both adjustable and non adjustable versions. Not much that I would add to the discussion, but . . . . I posted a recent blab on this forum about my clutch function going away, i.e. the clutch locked out of contact, the pedal impossible to compress. When I loosened the hydraulic line at the slave, the clutch arm released the clutch into engagement. I determined that this event occurred because of what might have been an overly aggressive clutch push on my part. The slave piston was pushed so far out that it hung on some corrosion or buildup of unwanted material in the slave's bore, holding the clutch out of contact. I had an earlier experience of this happening briefly while underway but didn't recognize the issue. So clutch cylinder and slave motions can produce some little-recognized issues. My event occurred with a Smitty Toyota conversion, so the match of the slave cylinder and a non-factory bell housing, etc, was probably sort of trial an error when that system was being created. Though we aren't purists, I think most of us with these conversions find them pretty successful.

 

[Bob_Spidell]

I've had a couple cars with manual transmissions whose owner's manuals admonished drivers to be sure to push the clutch pedal all the way to the floor when shifting. I assumed this was to prevent grinding of gears and/or slipping the clutch but, presumably, the fluid volumes and piston volumes were carefully calibrated by the engineers.

 

[British_Recovery]

As far as even heights for the pedals, I have always added an extension to the clutch pedal, since it must travel more than the brake ( hopefully ). For a shorter person, this can be more comfortable. There even was a commercially made, one piece, aluminum pedal assembly to replace the original. It had a grooved, cross-hatch surface for grip instead of taking a rubber pedal pad. It was probably left on a car that got sold.
Bob