Lotus Europa Forums > Technical Articles and DIY tools and tips
Installing a Spitfire Master Cylinder on a Federal Europa
Certified Lotus:
I’m installing a proportioning valve for the rear brakes when I make all new hydraulic lines.
Grumblebuns:
--- Quote from: surfguitar58 on Wednesday,March 21, 2018, 11:00:17 AM ---
--- Quote from: Grumblebuns on Wednesday,December 28, 2016, 07:14:23 AM ---
I crunched some numbers from my spread sheet to determine rear braking percentages.
S2 stock - (rear) 486#/(front) 5528# = 9%
S2 Spitfire - (rear) 436#/(front) 5528# = 8%
TC stock - (rear) 300#/(front) 3504# = 8.5%
TCS stock - (rear) 263#/(front) 3504# = 7.5%
TC Spitfire - (rear) 434#/(front) 5528# = 7.8%
TCS Spitfire - (rear) 380#/(front) 5528# = 6.9%
There is a spread of about 2% between the stock S2 and the TCS with Spitfire MC. Both the stock S2 and TC have the rear brakes at about 9%. Changing to the Spitfire alters the balance a tiny bit, around 2%, more for the TCS than the S2 or TC. Assuming my numbers are correct, I'm wondering how many people will be able to detect the difference.
--- End quote ---
Joji: Digging into the archives here. I'm afraid I don't understand the above figures. Are these brake pad contact forces for rear (drums) and front (disks)? Are these without boosters? Please advise.
Tom
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This a while back but I think I was trying to show the change in braking force proportion, front to rear, between the Spitfire M/C to the Girlings due to the 0.70" straight bore of the Spitfire. The numbers I used was, I believe, just the pressure of the M/C on the front pistons/rear cylinders. As far as I know, the boosters are interchangeable so both boost the pressure the same amount. Brake force proportion is the same, with or without boosters. Does this make it any clearer? The numbers are not absolute, I was just trying to show how forces changed with the use of the Spitfire M/C.
surfguitar58:
Thanks Joji. I guess I am not getting why the proportions change when the M/C bore changes. Is the stock Girling M/C bore stepped? (i.e. different bore diameter for front and rear?) What am I missing?
I am looking into the possibility of sleeving the stock TCS M/C down to a .700 bore. There are brake shops that do sleeving, but not generally for diameter reduction. Pistons would have to be turned down and piston seals designed for a .700 bore adapted to the modified pistons. Maybe new springs too. I placed a WTB post in the classifieds section hoping to flush out someones old TCS M/C that they replaced with a Spitfire M/C to experiment on, but so far, no takers.
Why sleeve and not just do the Spitfire swap? Just to avoid the need for wrong-side adapter tubes and the funny angle of the reservoir, and also to keep the original-ish M/C. Is this a foolish exercise fought with danger on a critical safety component of the car? Yeah, probably. The most common fatal last words after "watch this" and "hold my beer" are probably "I got this, I'm an engineer".
Tom
Grumblebuns:
Tom, the stock Girling M/Cs are stepped and the Spitfire M/C is straight bore. With my calculations, I was just trying to show the difference in braking power for the rears with the Spitfire M/C.
It cost around $300 to get a M/C re-sleeved by White Post or Apple Hydraulics plus the cost of the rebuild kit. The Spitfire M/C costs around $70 brand new, plus another $30 for fittings and brake lines. I suppose White Post can sleeve a TCS Girling down to a smaller diameter but then as you said, you still have to locate the correct internal piston arrangement and hope the modification works. If you don't want to fabricate new lines. I believe you can order flexible S/S braided brake lines with the correct fittings to jumper the stock lines to the Spitfire M/C. Not much to say about the sloped reservoir, it's what you get.
EuropaTC:
--- Quote from: surfguitar58 on Thursday,March 22, 2018, 01:25:40 PM --- Just to avoid the need for wrong-side adapter tubes and the funny angle of the reservoir, and also to keep the original-ish M/C.
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Tom,
If you want to retain the original look and sleeve your old m/cyl to a reduced bore, can you use the pistons/seals from the 0.7" Triumph and thus have a source of new replacement parts to reduce machining costs ?
Bearing in mind the Federal TCS has a larger bore I can't think how moving to a smaller bore is going to upset the brake balance to any noticeable extent. If you have the OEM disc/Drum setup then the contribution from the rears is so down on modern designs in anything from light to 1G loading that I can't imagine a situation in which you'd lock the rears first. (but I do like your "I got this, I'm an engineer" which must rank alongside "how hard can it be ?" as one of the greats :) )
You might not like the increase in pedal travel though, that was something I initially liked and then ended up being uncomfortable with and finally changing to a 19mm (0.75") m/cyl. a couple of years later.
Brian
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