Brake Survey - Servo or No?

[jcocking]

I am curious after the recent brake circuit question, How many have removed
the brake servo?
If you did, what is the result? Have you added one to a vehicle that did
not have one?
For those who have driven similar elans with and with/out a servo, Any
comments?

For background, the brake servos were first made available on S2 SEs around
1966. The servos were part of the SE package and available as an option on
all cars up to the sprints. Then the servos became standard equipment.

jeff

["Jason Farmer"]

Hi

Mike Farmer from Warwickshire England here.

I have an Elan Sprint DHC and I threw the brake servo away 2 years ago!

Firstly I replaced the front pads with softer material as per the early
non-servoed cars.

This has improved the brake balance reducing the tendency of the front
brakes locking and dramatically improved the FEEL through the pedal.
Remember that the Elan is a light car anyway. Admittedly you have to push
the pedal reasonably hard and the harder you push the quicker you stop.

Personally I would never go back to the Assisted brakes.

Mike Farmer ) )

-----Original Message-----
From: Jeff Cocking [mailto:[email protected]]
Sent: 27 September 1999 18:06
To: [email protected]
Subject: [lotuselan] Brake Survey - Servo or No?


From: "Jeff Cocking" <[email protected]>

I am curious after the recent brake circuit question, How many have removed
the brake servo?
If you did, what is the result? Have you added one to a vehicle that did
not have one?
For those who have driven similar elans with and with/out a servo, Any
comments?

For background, the brake servos were first made available on S2 SEs around
1966. The servos were part of the SE package and available as an option on
all cars up to the sprints. Then the servos became standard equipment.

jeff

[S3_SE/DHC]

My 67 S3 SE was originally fitted with the Girling servo. As such, I
thought the brakes were excellent--light touch, easy to modulate, no
uncontrolled wheel locking, etc. Several years ago, while living in the UK
with this car, we installed the replacement Lockheed servo, following the
onset of some brake problems, which we diagnosed as a servo leak. This was
about the same time we installed a Spyder spaceframe chassis. The chassis
replacement was done by a shop in the UK, who I think overall did a fine
job. But it appears that running of the brake pipes was something of a
"rush" job. In any case, since the chassis change and the Lockheed servo,
the brakes have never been the same. They are primarily characterised by a
very squishy pedal, regardless of the amount of brake bleeding to remove
trapped air. Unsatisfactory, to say the least. I am currently rebuilding
all of the calipers and the master cylinder (having decided to stay with the
single circuit system), and replacing all 4 flex hoses. The next task will
be to redo all of the brake pipes on chassis. I am hoping that this work
will restore the original pedal touch and solid feel to the brakes. If not,
I will begin to suspect the Lockheed servo. In that case, I may dig the old
Girling servo out of my box of spares, somehow test it and try that, try a
new replacement servo, or perhaps eliminate the servo altogether. But with
my memory of the very good brakes with the original servo, I would very much
like to have a well-functioning servo assisted system.

Best Regards,

Gerry Snow
Spokane, Washington, USA
67 S3 SE DHC

-----Original Message-----
From: Jeff Cocking <[email protected]>
To: [email protected] <[email protected]>
Date: Monday, September 27, 1999 10:08 AM
Subject: [lotuselan] Brake Survey - Servo or No?

["Jason Farmer"]

I had problems with my servoed S4 Sprint.

An easy way of testing things to home in on the problem area is to
disconnect the servo hydraulically from the circuit by using a short piece
of brake bundy tubing fitted with a male nipple on one end and a female on
the other so bypassing the servo completely. Upon doing this I eliminated my
Spongy brake pedal and subsequently through away the servo fitting softer
grade front pads.

Mike Farmer - UK

-----Original Message-----
From: Gerry Snow [mailto:[email protected]]
Sent: 27 September 1999 21:49
To: [email protected]
Subject: Re: [lotuselan] Brake Survey - Servo or No?


From: "Gerry Snow" <[email protected]>

My 67 S3 SE was originally fitted with the Girling servo. As such, I
thought the brakes were excellent--light touch, easy to modulate, no
uncontrolled wheel locking, etc. Several years ago, while living in the UK
with this car, we installed the replacement Lockheed servo, following the
onset of some brake problems, which we diagnosed as a servo leak. This was
about the same time we installed a Spyder spaceframe chassis. The chassis
replacement was done by a shop in the UK, who I think overall did a fine
job. But it appears that running of the brake pipes was something of a
"rush" job. In any case, since the chassis change and the Lockheed servo,
the brakes have never been the same. They are primarily characterised by a
very squishy pedal, regardless of the amount of brake bleeding to remove
trapped air. Unsatisfactory, to say the least. I am currently rebuilding
all of the calipers and the master cylinder (having decided to stay with the
single circuit system), and replacing all 4 flex hoses. The next task will
be to redo all of the brake pipes on chassis. I am hoping that this work
will restore the original pedal touch and solid feel to the brakes. If not,
I will begin to suspect the Lockheed servo. In that case, I may dig the old
Girling servo out of my box of spares, somehow test it and try that, try a
new replacement servo, or perhaps eliminate the servo altogether. But with
my memory of the very good brakes with the original servo, I would very much
like to have a well-functioning servo assisted system.

Best Regards,

Gerry Snow
Spokane, Washington, USA
67 S3 SE DHC

-----Original Message-----
From: Jeff Cocking <[email protected]>
To: [email protected] <[email protected]>
Date: Monday, September 27, 1999 10:08 AM
Subject: [lotuselan] Brake Survey - Servo or No?

[rodbean]

Jeff Cocking wrote:


I removed the servo on a Lotus Cortina I once had. The result was more pedal
pressure but better feel. Also nice and solid. I think I'd increase the size
of the master cylinder bore if I was ever going to do it again.

I have driven Elans with servos but none of mine have had them. The Elan is
so light that any increase in pedal pressure is lost in the noise. I don't
know if the servo equipped Elans had small diameter master cylinder bores
too. In that case, I'd replace that with one of non-servo spec.

Rod
Currently Three S1, One S2

[types26/36]

I have driven quite a few Elans (S1-S4) that had wonderful braking with no
servo. This includes my S3 Coupe with completely rebuilt system, 5/8"
master cylinder and standard Girling pads.

The servos add complication, weight, and expense to the system. I'm not
aware that they provide any benefit except perhaps more comfort for those
accustomed to highly-boosted brakes.

-Randall

[JohnIngham]

I notice in this dialogue on servos and braking a lot of commentary about
brake pads.

I've just fitted a pair of Mintex 1188 pads that are actually for a modern
car (Escort?) but apparently are being used with great success on racing
Elans. However, on the road they feel quite dead unless I'm really working
the car through the corners. I'm sure, too, that it takes longer to stop
than with the previous pads.

Am I correct in understanding from the comments that soft pads are better
than hard for the Elan? (An S2.) Does anyone have recommendations on
brand/type?

Regards,

John

[saarhus]

Pads such as the Mintex and Ferodo are designed to operate in a higher
temperature range than the standard "soft" (normal production) pads. This
was alluded to when you described the better feel when "working it through
the corners". With heavier use, such as competition, as the pads are worked
harder, the temperature raises, and as the higher working temperature
increases the friction, giving you back the "grabbier" feel that the street
pads have at normal velocities. The street pads though, when subjected to
the higher braking loads of competition will overheat, which causes fade,
which combined with street grade brake fluid, can result in brake fluid
boiling, resulting in VERY soft pedal.
Stan
-----Original Message-----
From: John Ingham <[email protected]>
To: [email protected] <[email protected]>
Date: Monday, September 27, 1999 11:41 PM
Subject: Re: [lotuselan] Brake Survey - Servo or No?

[Richy-dick]

I had a servo on my 1967 S3 S/E but after a while it started to drink brake
fluid. There was no-way of fixing it at the time. People like Classicar
Automotive weren't offering reconditioned units then so I left it off. I am
quite happy with the system unservo'd and think that it gives a better feel
to the brakes without it.
Having said that though, when this thread, started it made me think about
having it reconditioned and re-fitting it to see what I thought of it now
(its about ten years since I removed it). I might have changed my
perceptions & my driving style and I've definitely changed my weight!

Richard A Clifton
Wakefield (& Ipswich)

["Peter Boegli"]

My first Elan was a S3 DHC built 1968 and had a servo. Later I bought a
Sprint FHC, built in 1971, which came _without_ servo (Swiss specification).
Subjectively I did not feel a difference in pedal force. Certainly the pad
materials were different, too. After this experience I would anytime throw a
servo out, change the pads accordingly and enjoy the car's weight reduction.

Peter

----- Original Message -----
From: Jeff Cocking <[email protected]>
To: <[email protected]>
Sent: Monday, September 27, 1999 7:06 PM
Subject: [lotuselan] Brake Survey - Servo or No?

[sprinterdave]

I

it that hard to stop the car. One car my hillclimb/sprint car is fitted
with "green stuff" brake pads which give good feel but do not lst very
long.
Dave
--
David Shiers

[BrianMartley]

Hi John,

I've never used the pads you mention, but it sounds like you've got a
"harder" pad material there. If they have poor performance round town, maybe
a bit of squealing, then it sounds like you're not getting them up to
operating temperature and not really getting any benefit. (except maybe
they'll last a long time )

The non-servo elans had a higher friction material (softer) pads than the SE
servo-equipped cars. Years ago when my servo packed in I ran the car
without, and the lack of initial response was scary. If you hammer along,
maybe the odd track day or deserted roads, then harder pads sound a good
idea.

Incidentally, I have an old (1970s) Ferodo catalogue. The Elans with servo
used FD533(M) pads, the non-sero Elans used FD533(H) - the M & H standing
for Medium & High friction linings - higher friction being "softer". The
Ford Escort of the day used FD533(M) as did the Hillman Avenger - a car
about the same size/weight. The FD533(H) pads were used by non-servo cars.
Sounds like things don't change very much ?

Brian

[BrianMartley]

Jeff,

I've driven my car with and without servo.

Without a servo - If you changed the pads to a higher friction material for
use without a servo then it was ok. Low friction pads ("harder") with no
servo isn't a pleasant way to drive in conditions under which you have to
make sudden stops from low speeds when the pads don't get time to warm up.

If you're hammering round a track, or out on a Sunday morning run on
deserted roads, you won't have a problem as the pads will get up to and
maintain operating temperatures under heavy braking.

With servo - I re-installed a servo on my S3. The pedal did feel harder and
with less travel without the servo, my conclusion was to increase the master
cylinder bore and retain the servo & lower friction pads. Now there is less
travel than the previous servo setup thus it feels a harder pedal, plus I
get the benefits of reduced fade from the "harder" pads on the odd occasion
that the roads are clear.

Other (non-servo) cars - I have also owned a Marcos 1800 which didn't have a
servo. The leverage on the brake pedal was such that you just didn't get the
high pedal pressure problems, and I used harder pad materials. My new Elise
also doesn't have a servo, but again it's designed that way.

You can run the Elan either with or without servo but I would ensure the
correct pad friction material is used.

Brian

[types26/36]

My restored-to-stock Elan Coupe has stock Girling brake pads and no servo.
I have spent many hours on racetracks at full speed over the last ten years
and only noticed a tiny bit of brake fade on one very hot day. At these
open track sessions I drive the car very hard and brake hard - but perhaps
not as hard as I would under racing conditions.

Also, the original Girling piston-type servos are virtually un-rebuildable.
So far as I know the only servo worth installing is a new Lockheed
diaphragm-type unit.

-Randall

At 00:07 9/28/99 -0500, Stan Aarhus wrote:

["Ina&Buc Bailey&]

I currently have the original servo out of the vehicle, and following the
recent discussion I have decided to leave it out, but my questions are;
1. Do I simply reroute the brake lines to the various wheels, or is there
more to it than that.
2. These softer pads, how does one locate them? I am stuck, sorry that
should be living in Norway, not a country reknown for its Lotus\ sportscar
parts availability!
Many thanks
Adam Bailey
69 S4 DHC