Lotus Elan

dual servo????

PostPost by: albercoc » Sat May 29, 2010 2:49 pm

Good afternoon.

took a while the engine is disassembled, and now that I have time, I checked the brakes, I saw that the two servos are flooded brake fluid,

My car has two servos installed (seems original (LHD federal), my question is whether this is normal, and if it is possible to mount only one, as they take up much room, and I have no really clear if necessary.

Greetings. John
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PostPost by: stugilmour » Sat May 29, 2010 3:17 pm

John

Did not catch if your car is two seat Elan or Plus 2.

At any rate, two servo's is normal for the Federal Plus 2, and assume similar for Federal Elan. If you wish to mount only one servo, you will need to change to a single circuit brake system from the dual circuit (front and rear) Federal system. For the Plus 2 this would involve changes to the brake piping, changing the master cylinder to a single piston from the dual piston, removal of the pressure differential warning (PDW) valve on the left inner fender area, and possible change of the brake light switch on the pedal box to a hydraulic switch located on the right front piping fitting.

Others have posted they have removed both servo's. Opinions vary regarding pedal effort and brake performance. Usual setup involves change to master cylinder diameter, front brake pad material, and possible strengthening of pedal box mount. If two seat Elan, posts indicate refitting with Plus 2 front rotors/calipers is an option as well.

If you change out the stock dual master cylinder, consider offering it for sale to others. I understand they are no longer available new, but can be re-built.

Hope this helps as general overview of options available. Suggest posting model and year for further details as looks like several listers have done brake system modifications you are considering.
Stu
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PostPost by: albercoc » Sat May 29, 2010 4:21 pm

thanks for the reply.

I forget, is a +2 in 1972 (502 121)

What I toil in the change is that I need to make more force on the brake pedal, if the effort is the same, I think that makes the change.

I did not know that dual servo was normal for federal cars, is the first car I see with that system.

Greetings. John
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PostPost by: stugilmour » Sat May 29, 2010 5:08 pm

John

From my readings of various posts regarding removal of the boosters, the opinions on pedal effort and feel vary; some like the result and some don't. Obviously it is hard to describe, and opinions vary. Some have made the change, and then re-installed the boosters. Some report better feel and reasonable pedal effort.

Gerry Minors (gerrym) had a very nice thread/post recently on his efforts to remove his boosters and replace the master cylinder with an available smaller diameter dual circuit replacement unit. I don't know if he got it on the road yet, but definitely worth a search to read that one over. General limitation with the available replacement dual circuit master cylinders is the outlet ports are on the wrong side of the master cylinder so some re-piping is required.

For a very good illustration of the Federal two booster set-up compared to the single booster set-up, check out the parts manual on Ray's site at rdent.com. Under Plus 2 manual, Brakes, Bundy Piping he has the same illustration I have in my parts book. It can be a bit confusing at first as it shows both systems in one illustration, but it is all there. Other pages show the different pedal boxes, etc.

http://rdent.com/manuals/index.html


For what it is worth, I considered this modification to my car, which is a LHD Federal model, 50-2181. I decided to get it running using the two booster set-up first, and will consider this change at a later date depending on how I like the stock set-up. Both my boosters appear to be working well and were re-built prior to me picking the car up. Prior to my on-going body off re-build, I experienced difficulty locking the brakes even with mashing the pedal full force, so not sure.

Main reason I saw for removing the boosters was to provide more room under the hood. I was unable to mount a replacement side tank wide radiator because the top inlet pipe fouls the front booster. If I experience cooling issues with the stock radiator I will consider brake mods to accomodate the radiator.
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PostPost by: Uboat » Sat May 29, 2010 5:17 pm

Hi John,
I also have dual servos, and this was standard equipment on all Elans also in Sweden...
/Ulf
1974 Lotus Elan +2 130/5
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PostPost by: albercoc » Sat May 29, 2010 8:23 pm

thanks for the link, Stu, did not know him. is very useful,

yes, my only reason for making the changes is to gain some space in the engine compartment. what keeps me here is that the brakes, so far, work very well and with a soft touch.
in fact had no intention of reviewing, but I do not know why, take them out. and found them full of liquid, but at no time had brake problems, or noticed the level go down.
this week bought two new servos (arrived yesterday), I have located a master cylinder that can go well, so according to what I do, I'll have a spare sevo.
Thanks for reminding me about the switch, I had not considered.


regards Juan
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