Brake servo for GT6 Mk1

[junkuser]

Servo assistance can mask brake fade as the pedal pressure remains about the same while fade is increasing so you can get a rude surprise if you need to actually come to a stop when you find there are no brakes.    

[James]

Richard_B wrote:

Sorry James, are you saying that driving with a 6 cylinder boat anchor in the front of a Spitfire was fun?  

(shhh)  (dance)

What Nick said :)

Besides — you can have fun in any car — even ones with badly positioned boat anchors :)

[TimW]

I only asked why. Sorry :B

[black6osprey]

339 wrote:

I only asked why. Sorry :B

Don't worry about it mate  :)

You'll notice I do suffer from overly opinionated verbals at times.

At least you have cool car.

[cook1e]

Nick_Moore wrote:

Well, as I'm old/lazy/feeble (feel free to cross out an which don't apply) I plan to fit a servo to my GT6. Are there any original Powerstop servos still out there? Here in Oz, PBR make VH44 servos, but I'd prefer an original one if they're still available and not hugely expensive.

As my GT has tandem circuit brakes, the plan is to fit the servo to the front circuit as the factory did. I'll probably have to change the rear slave cylinders to maintain some semblance of balance...

I changed from the original Girling power stop on my GT6 to the newer Lockhead type for a few reasons when my servo needed a repair. Firstly it was about 35% cheaper to buy a brand new Lockhead than have a power stop reconditioned. Secondly a brand new Lockhead was available off the shelf, where as the only place I know that recondition Powerstops, (Norton Classic Servos) would only recondition my own unit as they didn't stock exchange units and the leadtime was several weeks as it's a one man band and he had a load of work on at the time. Thirdly, the Lockhead is an improvement over the Powerstop as it has >25% more boost, Lockhead = 1.9:1, Powerstop = 1.5:1.

In terms of whether or not to fit a servo, each to thier own, I agree that a servo doesn't actually make the car brake any better, but if you drive modern cars a lot it makes it less of a difference in terms of the pedal pressure required when you keep changing cars... To be honest it used to be worse going from an old non servo spit which was my daily driver to then occiaional use of a  modern car as I used to stand modern cars on thier nose by using the same pressure as I would have used in the spit for moderate braking!

[Pom Down Under]

I heavily agree with cookie. Many years ago I adapted some Humber Super Snipe discs, upper control arms and stub axles into a 1939 Oldsmobile (heavy metal +); instead of using the old Girling booster I used a VH44EL booster from a Valiant Charger (top gear Nick) and pulled better than 1G under brakes when it went through the Government Garage - never seen a Snipe do that (not that I've ever tried though).

Also as cookie said, it is all about pedal pressure. The above vehicle, despite brilliant brakes was deemed to have too much pedal movement and too low a brake pedal pressure, can you believe that? So stupid! My local brake shop couldn't believe it when I discussed it with them and were horrified when I fitted an old VH24 drum brake booster to up the pedal pressure (knowingly reducing effect). It did just that, bloody solid pedal, but Govt Garage were happy with it - even though brakes were reduced to 86% efficiency. The VH44EL was back on the next day and the car never looked back!           :X

[Pete TR7]

In my opinion there is not a problem with Spitfire brakes, however I would not be without the servo.  It is very much a matter of opinion whether you want one or not.  All they do is reduce the amount of leg power you need, nothing else.

If you switch regularly between a servo car and non sevo you have to adjust quickly or face a  "moment".  I found it very risky on the daily motorway drive to work when my safe distance was removed by someone cutiing in front of me (thats me in lane 3), I did not like relying on adrenelin to power the brakes (its brown by the way) a servo gives me confidence in a predicable braking performance and no worries about changing between cars.

Yes you do have to use the right pads or you will have brake fade, I use green stuff which did not work properly until the servo was fitted.

I fiited the servo when I was doing 12-15000 miles a year a few years ago.

No point taking a risk.

[BrendanD]

I have a servo on mine, it just makes the car a nicer drive.

[rotoflex]

I really think Brendan has hit it.  It's more of a matter of taste for driving experience.

[Docman]

4196 wrote:

Lets just remove all the brake servos out there and watch the carnage :)

Ive had many cars with no servo. I even bought a new Lotus Elise back in 2000 at a time when going fast in cars was more imprortant to me than owning a nice house and  surpisingly it had no brake servo. The car only weighed about 650 kgs and for such a quick accelerating car to have no servo was absolute madness and the amount of near death experiences (all brake related as drove it very hard) I had in that car were enough for me to know that no brake servo = press brake not much happens, press brake harder and then press like your in a flintstone car, lock up and hope for the best. Not surpising that my Lotus no longer exists and was written off after I sold it. Wonder if it was the brakes that caught him out.....

I realise these car are bloody slow by comparison but unless you want one leg much thicker than the other a servo can only be a good idea on most cars.

Granted, my Europa Special wasn't as quick as an Elise, but that car had twin servos and I found it way too easy to lock up the brakes.  Is it possible that Lotus learned something by the time they launched the Elise?

[black6osprey]

3106 wrote:

Granted, my Europa Special wasn't as quick as an Elise, but that car had twin servos and I found it way too easy to lock up the brakes.  Is it possible that Lotus learned something by the time they launched the Elise?

They did. It was the first road car to use MMC brakes and it worked very well. The car I test drove had MMC but by the time I got my car (2 year waiting list at the time), MMC was replaced by standard vented discs and the brakes became a bit scary especially with 0-60 in 5.8 seconds and my desire to utilise this point to point acceleration at every possible moment.

[Tim Bancroft]

My GT6 had a remote servo when I bought her, this eventually gave up the ghost and I had to replace it about 10 years ago.

My car has the servo plumbed into between the master cylinder and 1st 3 way union and coupled with greenstuff pads has brakes that I find are just about as good as the little car needs. Plenty of feel and progression, in fact very good. I keep thinking about replacing the pads with some Mintex jobbies, but the greenstuff do not seem to want to wear out!

Before fitting a servo I would ensure that the braking system is all in tip top condition.