Brake Mods for Servoless TCS

[jbcollier]

Fitting new serves is a great idea.  I just get nervous when people “overhaul” their 50 year old servos.  Fitting new rubbers seals is not an overhaul!  Cylinders and pistons wear and new rubbers is at best a temporary fix, usually not even that.

[4129R]

The majority of the 14 servos I have removed have badly corroded internal bits which you cannot get out.

If I were paying a decent amount to buy a Europa, I would expect a new working servo.

[Pfreen]

Is modifying the pedal assembly really easier than fitting a smaller diameter master cylinder?

[dakazman]

 I’m here, I’m listening and reading every word . Undergoing this mod right now but without a moving vehicle it’s a guessing game. I’m in your wheel house now. Thanks for the advise.
Dakazman

[surfguitar58]

Is modifying the pedal assembly really easier than fitting a smaller diameter master cylinder?

Depends on your willingness to buy a new master cylinder, fabricate new brake lines (the Spitfire MC ports are on the opposite side of the MC) and bleed the system vs simply drilling 1 hole and putting spacers under the pedal assy. I also like the fact that I would be keeping the original equipment MC.
Tom

[Grumblebuns]

reading this thread, have a few random thoughts:

Swapping to a smaller master cylinder is not a permanent irreversible change and no fabrication is required. You can always change back to stock when you want to. The two jumpers can be fabricated in about a half hour.

What brake pads are you using? As others have said, try different pads before modifying the brake pedal.

If you're going to raise up the pedal assembly, make sure that you have sufficient thread engagement on the four bolts securing the assemble to the chassis plate. On my TCS I have about 6-7 threads at the most, ~3/8".

4129R, you mentioned that you are using a single servo? This is for a Federal TCS?

 

[4129R]

4129R, you mentioned that you are using a single servo? This is for a Federal TCS?

All 7 of my Europas have been converted to RHD with new single circuit brake master cylinders. I have put in new copper (cunifer) brake pipes and changed from twin servos to single servos.

So I have 14 old servos of various states of disrepair.

So I bought 7 new servos from MGB Spares in the UK at about £62 each, and I am adapting the fixing bracket (flattening one side and cutting off the bit not needed) and connecting them to the single circuit system. I am also renewing the vacuum pipes and all the clips that hold the pipes in place.

Alex in Norfolk.

[Clifton]

Is modifying the pedal assembly really easier than fitting a smaller diameter master cylinder?

Yes.

You can have the pedal assembly out in 10 minutes. No bleeding necessary.

As to the concern of a "weaker" part.  Most car will never see more than 100lbs on the pedal.

[surfguitar58]

Also... the OEM master cylinder has a stepped diameter (~.875” down to .803”) presumably to reduce pressure to the rear drums. I believe the Spitfire MC is a straight .700” diameter and would require a pressure reducing valve for the rears. I got fairly far down the path of planning to sleeve my stock MC down to a stepped .763”/.700”  ID before this lazier solution came to me.

D-man, thanks for the vote of confidence, but please keep in mind that I regard this as an experiment and there are far more knowledgeable voices on this thread than I.

G-buns, I share your concern regarding thread length. I haven’t retrieved my car from winter storage yet but pictures of the pedal assembly on rdent.com (autocorrects to “rodent.com”) look like the bolt heads are welded to the pedal assembly and are therefore fixed length. My thought was to use blind nuts, aka sex nuts (do NOT google “sex nuts”) from the bottom to get more thread engagement, but I will cross that bridge when I come to it.

Tom

[BDA]

In an earlier time, McMaster Carr listed "sex bolts" in their catalog. We thought that was a hoot. You can find them on their online catalog by searching for "sex bolt" or "sex nuts" but they are now called "binding barrels and screws." How long before the terms "male" and "female" will be expunged from our vernacular?

Those are not generally used for applications where strength is important and a quick look at some of the listings did not come up with any fine thread examples. They may be available elsewhere but I think you should be prepared to find a friend with a lathe.

[jbcollier]

If you fit a stepped Spitfire cylinder and have issues with the rear brakes, you can adjust the size of the rear cylinders.  They are available in three or more different sizes for dirt cheap.

One other consideration regarding raising the pedal assembly.  On mine the pedals are very close to the top of the footwell and the steering shaft.  Might be tight.  Just something else to check.

[surfguitar58]

In an earlier time, McMaster Carr listed "sex bolts" in their catalog. We thought that was a hoot. You can find them on their online catalog by searching for "sex bolt" or "sex nuts" but they are now called "binding barrels and screws." How long before the terms "male" and "female" will be expunged from our vernacular?

Those are not generally used for applications where strength is important and a quick look at some of the listings did not come up with any fine thread examples. They may be available elsewhere but I think you should be prepared to find a friend with a lathe.

Are the pedal bolts UNF (fine) threads? (Why?) I guess I assumed they were 1/4-20 UNC. As you suggest, something could be fabricated on a lathe. This would even be within the capabilities of my pathetic hobby lathe and my even more pathetic machinist skills.

I agree sexy nuts are not as high strength as conventional grade 8 nuts, but this is not a very high load application. I use these for deck hardware on my sailboat and I’m pretty sure they would rip through the cored fiberglass deck before the nut would strip.

t

[TCS4605R]

If you want to upgrade, take a look in the old Lotus-Europa website for drawings of the pedal assembly I made for my TCS. I removed the Lotus power brake system and installed tandem Girling master cylinders with a balance bar.

Tom - 74 TCS - 4605R

[BDA]

I didn't say that very well! You are right, strength doesn't really have much to do with the thread pitch but on cars, most bolted joints, other than with castings, fine threads are generally the rule. For what it's worth, to me, fine threads imply more precision I associated that to strength and that is not necessarily the case. "Binding barrels" would certainly be strong enough for this application.

If you're more comfortable welding, you could always grind the old bolts off your pedal assy. and weld longer 1/4-20 bolts in their place.

All this talk about what threads has given me pause. I could certainly be mistaken about the threads but if I'm wrong, you'll figure that out eventually and adapt.

[cazman]

Still reading up on removal of the brake servos.

Has anyone reported back on adding a new hole to the brake pedal and then moving the pedal assembly up?