Author Topic: Happy with brake pedal feel?  (Read 1255 times)

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Offline Clifton

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Happy with brake pedal feel?
« on: Saturday,December 12, 2015, 04:20:23 PM »
I'm looking for a poll. How is the pedal feel on light stops, hard stops and hard stops at speed. If one was driving at say 60 mph, is there enough front bite to stop the car without you wanting more or less front bite?


Reason, I have yet to ever drive the car to know the feel. The stock MC is rusted and I am going to run dual Master cylinders and Wilwood calipers. I am thinking Lotus went with a .700 MC and  2.78" piston area for a reason. I can run a larger caliper bore and MC if it is lacking.

Stock is 2.78", I was going to go with a 3.00" area, I can also go with 3.54 or 4.8"

Opinions?

Offline EuropaTC

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Re: Happy with brake pedal feel?
« Reply #1 on: Saturday,December 12, 2015, 11:22:47 PM »
Hi there,

Now this is one where you'll get as many opinions as there are posters....   ;)   

To start the ball rolling, I've run my TC with;

1. 1980s - 0.7" m/cyl, standard (M14) calipers, rear drums, servo. Standard pads/shoes.  Brakes ok, felt as good as any then-current (1980s) cars. 
2. 1990s - 0.75" m/cyl, M14 calipers, rear drums, servo. Standard pads/shoes. Preferred this as pedal travel reduced, felt more like a modern (90s) car.
3. 2010s - 0.75" m/cyl, M14 calipers, rear drums, EBC greenstuff pads, servo removed. Stops ok although not as impressive as (2) because higher pedal load.
4. 2010s - 0.7" m/cyl, M14 calipers, rear drums, EBC pads, no servo. Feels better. Longer pedal travel but more confidence in stopping, lighter load.
5. 2010s - 0.7" m/cyl, M14 calipers, rear discs, EBC pads, no servo. Pedal travel as calculated (4cm vs 3.8cm calc) Better feel to pedal.
6. Current - as above but with Mintex 1144 pads front, EBC rear pads.  Better initial bite, pedal travel/load similar.

I have additional experience with my Elan, similar weight car albeit different weight distribution. As standard that has the same m/cyl, M14 front calipers but rear discs which have the same piston size as the rear calipers I've used on the Europa.  That currently runs with 0.7" m/cyl, no servo but M16 calipers and bigger front discs. Stopping is great, better than the Europa but the Elan has a greater pedal leverage & longer travel, so the effort feels about the same.  One problem with the Europa is that you can't alter the pedal leverage very much and for my foot size the pedal is too close to the steering column so I don't like long travel.

Other factors apart from above - tyres. If you have standard tyres then the more effective the front calipers, the bigger chance of locking up in the wet.  Friction at the tyre is probably as important as anything else in the deal and I think if you're on standard widths then the M14 calipers are good enough for a road car.

I do have a 19mm bore m/cyl on the bench at the moment which I'm thinking of trying out at some point, but I need to bed in the new pads first to make effective comparisons.

Brian

ps - lots of brake calc. programs around to model any changes, plus this has been discussed several times on the Yahoo group and there's probably loads if info in the knowledgebase.

Offline fulmine

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Re: Happy with brake pedal feel?
« Reply #2 on: Saturday,December 12, 2015, 11:26:39 PM »
I changed the oil in September but the pedal is still too much soft to push.  I'd like to maintain the original system...maybe i have to refurbish calipers and master cylinder
Lotus Europa Twin Cam 1972

Offline Clifton

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Re: Happy with brake pedal feel?
« Reply #3 on: Sunday,December 13, 2015, 06:00:08 AM »
Thanks for the input. I have seen an excel page with brake calcs and I changed some but with out having a baseline of pedal feel and pedal force to stop, I am lost with it. I will be running a 205 width front, R comp, either NT01 or Trofeo. I will have quite a bit more traction. I have increased piston area on a 240Z road race car and it worked out good.

Offline EuropaTC

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Re: Happy with brake pedal feel?
« Reply #4 on: Sunday,December 13, 2015, 08:28:34 AM »
I'm using 195/50 at the front at 20-22psi.

I'm sure dry stopping would be better with the M16 calipers or 4 pot calipers with larger discs, but I'm not sure what that would do to brake balance in wet conditions. The Europa is light at the front and in a panic stop it's easy to lock up the front; back in the 70s a friend wrote off his TCS by exactly that problem - heavy braking on a wet road and he slid the bonnet under the rear of the car he was trying to avoid. The exhaust pipe cracked his windscreen and it was one of those "unforgettable" moments !

The brake calc programs generally show a low contribution from standard rear drums, IIRC something like 20-25%. Using the rear disc conversion I think that went up to 30-35% and the reason I've not increased the front calipers yet is because I need to explore the current set-up before making more changes.  If you're going for competition or a track day car then I'm sure you can go with larger front discs & caliper pistons - better heat soak and you're probably only driving in good conditions.

Brian

Offline Jesspo

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Re: Happy with brake pedal feel?
« Reply #5 on: Sunday,December 13, 2015, 09:16:19 AM »

Hi Fulmine

i have had the same issue with my TC. Did you have servos installed? on my we must also bleed on the servos because they are the highest point. After this the Feeling was much better.

greetings Frank

Offline fulmine

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Re: Happy with brake pedal feel?
« Reply #6 on: Sunday,December 13, 2015, 10:40:58 PM »
Yes i have. I'll try next time, thanks
Lotus Europa Twin Cam 1972