What a cluster

[Bryan Boyle]

Old MC out. 

Whomever designed the mounting arrangement for the LHD Twink brake master should be strenuously talked to.  Needed to destroy/modify an “S” wrench (harbor freight...so not too painful...) to get that infernal top nut…which ended up unscrewing the stud thru the spacer into the frame anyway.  -10 points for where Lotus put the cylinder…+5 for welding nuts on the inside of the frame…because access to the back is well-nigh impossible...

Hint: if you are going to remove this thing…undo the nuts t from the center of the car, not thru the wheel arch.  you have a bit more room to actually get a wrench on that top nut after you disconnect the bundy pipes.  Bottom is a doddle.  My modified wrench was just the ticket.  If it works, it can't be ugly, right?

Going in?  A Spitfire dual circuit master.  yeah, That means building jumpers to change location of the outlet ports.  Dry fit it, and lines up ok.

Used the brake piston actuator rod (the one with the bell end and threaded shaft) from the old cylinder and took apart  the cupped washer and snap ring from new cylinder…threaded all together using the old domed actuator rod in the new cylinder…domed washer from new cylinder...snapped the snap ring back in place…it all fits together.  Yay for me.

Instead of using nylocs when I put it back together…use stainless 5/16-24 nut and lock washer plus flat washer combo.  Little anti-seize….should be ok.

Cleaned up the threads of the pins that mount the MC thru the adapter to the front of the frame.  5/16x24, if anyone is keeping track. 

[EuropaTC]

Hi Bryan,

If it's any consolation (probably not) the UK single circuit system is no easier. We didn't have the spacer block and the m/cyl mounts directly on to the front chassis which always made the brake pipe connection interesting.  Here's mine before I changed to dual circuit.... not the best of arrangements with the steering rack gaiter.

Brian

[Bryan Boyle]

Hi Bryan,

If it's any consolation (probably not) the UK single circuit system is no easier. We didn't have the spacer block and the m/cyl mounts directly on to the front chassis which always made the brake pipe connection interesting.  Here's mine before I changed to dual circuit.... not the best of arrangements with the steering rack gaiter.

Brian

Yikes.  I think you reach a point of diminishing returns in how much you can cram into a given space.  For all it's added complexity...I'm thinking the S2 arrangement was probably the easiest (at least on the LHD cars) to work on, especially if you riveted that tapped backing plate in place so you didn't have to stick your arm in from the center hole.

Now, Brian, THAT's a tight install on your photo.

[EuropaTC]

Now, Brian, THAT's a tight install on your photo.

You can say that again, I could never get a tight enough bend on the outlet pipe such that it didn't rest on the steering rack gaiter. I was always expecting the mechanic doing the annual roadworthy test to pick up on it and give me a fail, but it seemed to go through. I suppose the fact that where it is the rubber doesn't actually move across either the body or pipe, it's static there and never seemed to show any abrasion marks.

But it looks awful.....  bodge job #1.

[GavinT]

Is it possible to use a banjo fitting in that "tight install".
Presumably the port external surface would need to be a machined flat surface and perhaps some aren't? . . dunno.
I've noticed Wilwood have adaptors for banjo fitting so I'm not sure.

[EuropaTC]

Is it possible to use a banjo fitting in that "tight install".
Presumably the port external surface would need to be a machined flat surface and perhaps some aren't? . . dunno.
I've noticed Wilwood have adaptors for banjo fitting so I'm not sure.

A banjo fitting would be perfect there but as you mentioned it's going to need machining. You might get away with a thick copper washer but personally I'd want a machined surface on the high pressure side of the system.

[Bryan Boyle]

Got the new Spitfire .70 MC plumbed in…bench bled…EZBleed the whole system and flushed 1 qt of new DOT3 fluid through.  Kept bleeding till the new fluid ran clear…no bubbles.
 
Thinking the whole fluid dynamics thing…I've probably 1.5” of travel with the .7 MC.  I'd like the pedal higher a bit.  Now that I’ve got standard SAE fittings…may try a .75 and see if that gives me higher pedal.  Of course, have to adjust rear brakes, too.
 
In any case, going to send out my S2 MC and the one I just took off anyway.  I actually liked the original MC even sans boosters.  Only issue is now since I trimmed back the feed lines so I could put the jumpers in for the other side ports…if I do put the original back in…well, cross that bridge when or if it shows up.

Took out for a ride...seemed ok (if a bit more travel on the pedal)...and 8 hours later, no drips on the garage floor and the fluid level is still where it was when I took the EZBleed cap off.  Need to reinstall the chassis close plate (since it does provide the ground for the blinkers, rad fan, and who knows what else...

Off (maybe?) to the next project.

[EuropaTC]

That pedal travel sounds about right Bryan, when I was doing calcs on my system I got 1.49" travel for the standard disc/drum setup with a 0.7" m/cyl.

Ok, that does depend to some extent on what you expect the disc run out/brake shoe travel to be, but it's about there.

Brian

[GavinT]

A banjo fitting would be perfect there but as you mentioned it's going to need machining. You might get away with a thick copper washer but personally I'd want a machined surface on the high pressure side of the system.

Yep, and from my limited research, the Wilwood M/C's seem to have have a flat machined surface on the single pressure port versions but others may not, I guess.

Found a 40 degree banjo fitting, though - bees knees?

https://www.jegs.com/i/JEGS/555/100716/10002/-1

[Bryan Boyle]

That pedal travel sounds about right Bryan, when I was doing calcs on my system I got 1.49" travel for the standard disc/drum setup with a 0.7" m/cyl.

Ok, that does depend to some extent on what you expect the disc run out/brake shoe travel to be, but it's about there.

Brian

So...I'm not crazy.  That's good to know.   

Need to go on walkabout for the final time at my Real Job (tm) with retirement beckoning on the 31st to say goodbye and hand over the keys to the various sites to whomever the company is sticking in there.  Going to let the beast sit for a week or so...get the original MC out to Apple Hydraulics for an overhaul, then revisit when I get back.