Brake Servo Delete

[drdoom]

Any thoughts on how to quantify the force applied to the master cylinder by the servo? I intend to build an all-new system without servo for my S2, looking for a rock solid pedal for better heel-toe ergonomics.

Cheers

[silverfrost]

I will be intrested in your findings for this, but for a standard S2 unless you build a very fruity engine for it,  the brake upgrade packages such as drilled and grooved discs, better pads, and added billet front callipers would make a big difference, also now you can use the vw/audi callipers for the inboard brakes.

Very much trial and error setting up a good braking system, and can be hard to balance, and get it right,  Seems much more simple to me to just slighty upgrade from the standard parts,  at least that way you have a proven system installed as it has been tested by other members/owners etc.

just my 2 cents  

 

 

[Gis]

It depends on how much vacuum your engine produces. N/A engines are better than turbo engine in that regard. There is quite a lot of information on boosterless brakes on the net. A good one here:

https://www.trias-sozial.com/calculations-without-brake-booster-engineering/

one challenge you have is to get to a much needed higher pedal ratio given the limited space in the footwell

[drdoom]

Thanks, lads. I can nearly decode the Sanskrit in Gis' linked essay, at least well enough to discern the need to subtract valve area from that of the diaphragm in converting vacuum ( atmospheric, in fact ) pressure to pushrod force. Looks as if a German spellcheck utility was allowed to run amok!

My prior Lotus was an Elan, about 1550 lbs. curb weight which was just manageable in terms of braking effort without servo. Now the Esprit will be something on the order of 2200 - 2300 lbs. and my hope is to employ both better friction materials than were available 20 years ago and larger rotors. With all pertinent figures in hand I expect to determine what scale of larger bits the Esprit might likely need to at least match what was possible with the Elan. Ultimately, as one long time Esprit owning friend reminds me, there is nothing really deficient with the Esprit's braking other than heel-toe issues arising out of the tight footwell space compounded by the surplus pedal travel due to servo characteristics. 

[gvy]

Some time ago , I looked on line at the solution from Claudius on their website.

https://www.lotuspbc.com/s1---s2-brakes.html

It replaces the vacuum system by a hydraulic system. Looks expensive, but I have no idea how it feels. I think I've seen an episode of Jay Leno's garage, where Claudius and son was present with their modified esprit and as usual Jay Leno drives the car . I thought the braking was firm and fine.

Geert

[Chillidoggy]

1 hour ago, gvy said:

Some time ago , I looked on line at the solution from Claudius on their website.

https://www.lotuspbc.com/s1---s2-brakes.html

It replaces the vacuum system by a hydraulic system. Looks expensive, but I have no idea how it feels. I think I've seen an episode of Jay Leno's garage, where Claudius and son was present with their modified esprit and as usual Jay Leno drives the car . I thought the braking was firm and fine.

Geert

It looks like a version of the dreaded Delco to me!

[drdoom]

Just reviewed the Youtube clip, very tasty but Windows crashed somewhere well along for some reason. Just ran a quick system scan which came up clean, I'm pleased to say. I have had some communication with Claudius recently, they're rather tight-lipped but will state that the outcome of that electric brake servo is that it offers " . . . more braking power. The result is comparable to how modern cars brake, very responsive." I suppose most modern cars do offer reasonably firm pedal with low effort though those that  I drive are all run-of-the-mill, not particularly comparable to a Lotus. Search Ebay for "electric brake booster" for a look at the sort of piece Claudius offer.