interestedparty
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| posted on 24/3/02 at 06:57 PM |
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best pedal/master cylinder set-up to use
My car will have a vertical panel at the end of the footwell where the pedals will mount. I wish to use a twin circuit master cylinder (sierra or
similar) and a hydraulic clutch. Any suggestions as to which donor will supply my needs?
John
As some day it may happen that a victim must be found,
I've got a little list-- I've got a little list
Of society offenders who might well be underground,
And who never would be missed-- who never would be missed!
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Fatboy Dave
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| posted on 24/3/02 at 07:33 PM |
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I always used Crapi/Escort master cyliders on my cars, with only the last one using a floor mounted setup using twin Girling cylinders.
Make sure you get any proportioning valves fitted to the donor, and always overhaul it at the very least, if not buy a new cylinder.
As for the clutch, it depends on what engine/gearbox combo you are using. There's no point converting a cable clutch to hydraulic. If you are
hydraulic, then you can use a Girling individual type cylinder for the master, and a slave from your donor (again, new is best), don't forget that
you need a big bore size for the clutch.
Dave
Stop the planet, I want to get off
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interestedparty
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| posted on 24/3/02 at 08:16 PM |
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Thanks for the advice, Dave, but it has to be hydraulic clutch, so what I really need is a pedal setup from a car that already has hydraulic clutch so
that the pedal will suit the pushrod
John
As some day it may happen that a victim must be found,
I've got a little list-- I've got a little list
Of society offenders who might well be underground,
And who never would be missed-- who never would be missed!
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bob
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 posted on 24/3/02 at 08:41 PM |
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A lot of kits of old used a marina/Ital pedal box because they could be taken out of doner complete with master cylinders on.
Ive seen a few cobras with V8 Rover and manual box using this config if that helps 
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interestedparty
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| posted on 24/3/02 at 10:29 PM |
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I would be happy to use the marina pedal box if it was just for one car, but I am hoping to make more than that, and so am trying to avoid any donor
cars that have been out of poduction for a long time, similar situation to the allegro steering column specified in the 'book'. Thanks for all the
replies so far
As some day it may happen that a victim must be found,
I've got a little list-- I've got a little list
Of society offenders who might well be underground,
And who never would be missed-- who never would be missed!
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Dick Axtell
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 posted on 25/3/02 at 03:51 PM |
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Hi all -
Problems with using servo-mounted mcyls in non-servo application.
1: Servo output rod provides backstop position for mcyl, and therefore determines cut-off (mcyl travel to commence pressure generation).
2: Servo output rod is factory-adjusted to ±0.15mm.
3: Using mcyl in non-servo application, actuating rod (from brake pedal) must be clear of mcyl primary piston (unless you can replicate the ±0.15mm
setting).
This last measure ensures that the mcyl returns past cut-off, to allow rapid pressure release.
Westfields of similar spec to Locosts use Ø17.8 tandem mcyl. Suitable item is from early Fiesta (p/n 74066198).
Re: proportioning valves - use later Fiesta type (screws into mcyl outlet port). Don't use Sierra G-valve (requires very carefully angled
installation).
Dick Axtell
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interestedparty
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| posted on 25/3/02 at 05:53 PM |
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Was that last posting for me? I should have said that I want to use servo brakes, my plans allow room for conventional servo.
John
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Dick Axtell
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| posted on 26/3/02 at 04:45 PM |
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quote:
Was that last posting for me? I should have said that I want to use servo brakes, my plans allow room for conventional servo.
John
Why will you need a servo? How heavy will your Locost be? After checking out various combinations of kit, with Rob Lanes' suggested design weights
(600kg for the vehicle + 2 x 75kg for people), I concluded that no servo was needed, using 4:1 pedal ratio.
You might find that your pedal will feel ultra-light (i.e. typical Jap-mobile), and this may suit your preference, but beware emergency brake
applications.
Dick
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interestedparty
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| posted on 26/3/02 at 06:09 PM |
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How heavy will it be? good question. A fair bit more than the average Locost I fear. Firstly, it's been a long time since I was only 75kg. Secondly,I
will be using Jaguar front and rear suspension (quite chunky, though I don't have any figures yet, and the Jaguar AJ6 3.6 24v engine, all alloy but I
wouldn't want to drop one on my foot.The chassis will be longer, wider and incorporate some larger sections. All in all, I reckon to be nearer to the
average Cobra replica in weight than to the average Locost, and AFAIK all Cobra replicas use a servo (Ford Sierra is popular, but clutch is cable).
Naturally I'm hoping for good news in the weight department but I think it would make sense for me to plan on a servo. If it turned out that I don't
need one then I would be tempted to get a dual master cylinder set up.
Thanks everybody for all the info so far
John
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Dick Axtell
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 posted on 28/3/02 at 04:44 PM |
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Hey John -
Your variation on the Locost theme certainly won't weigh in at the 700kg level!. Do you intend using the Jag rear suspension saddle complete?
Presumably that will mean the use of rear disc brakes. All these factors suggest that a booster will be required.
If you check out the sportier, later Fiestas (or those with ABS), they will be fitted with booster/mcyl assemblies. I specified the sportier/ABS
models because they use Ø23.8mm mcyl (which is the black-painted, steel tube type). A similar booster was fitted to Sierras, but with cast iron
Ø22.2mm mcyl.
Regards
Dick
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Nick Davison
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| posted on 29/3/02 at 08:39 PM |
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Has anyone used the brake bias bar set up from Locost? If so how does it work?
I havn't seen one to copy yet but have the pedal box, from a Reliant (not the Scimitar the other one but don't let on!). It looks the same as
Locosts so it will be adaptable once I know the principal of it's mechanics.
I can see from pictures that it uses a threaded bar between the two M/Cs push rods to adjust the amount of force applied to each M/C. But this is at
right angles to both push rods and not as I would have expected, in line with the foot pedal pivot and M/C push rod.
A photo or web page link with a photo of one would be great.
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