Brake Servos

[igosling]

All,

The Fiat servo seems to me to be a very rare item. Only seen one or two examples up for grabs in the last year or so.

That being is there a more sensible long term option to consider for brakes. Is there an alternative servo option? If so does this mean recalcualting any of the brake details (ratios etc.). Going to use the Calipers from an Alfa,

Any information or links to other threads would be gratefully received. As a new builder really looking for a list of parts to go and purchase to move this phase along

Regards

Iain

[strat6v]

Twin remote servo, Stafford vehicle components(SVC) Ask Catswhiskers about that one.

John.

[chris.richard]

Ian, do a search for "brake" and you'll come up with a number of threads.
There must be a simple substitute. The material factors are:
1) M/C size
2) Servo assistance ratio
3) mounting bolt pattern.

131 M/C is 19mm, a common size.
Servo is 6" diameter, most servos are 1.5 - 1.9X assistance.
The flat plate that the servo/MC attach to could easily be redrilled for different attachments if necessary.

I'm just finishing the installation of a dual remote servo (from SVC) to function with dual mastercylinders. See attached pic. I'll post some pictures of the installation once I've finished it.

[catswhiskers]

I installed one of these over the winter. Have to say it's a brilliant piece of kit. Not oversensitive either. I think the ratio is only about 2:1
Very easy to install and connect.
Mick

[chris.richard]

I think the ratio is only about 2:1
Mick

1.9:1 to be exact!! :)

[igosling]

Both,

Many thanks. I think I understand how it all works and it looks like a neat option. But are you actually getting better braking or just better feel through the pedal.

As my first priority is to get through SVA, can I assume this is SVA compliant?

Thanks again

Iain

[igosling]

Just picking up on your point about any servo with a 2:1 ratio and about 6" in diameter.
Is anyone out there using a servo from a different manufacturer with a standard single M/C.

Understand this will mean reworking the standard mountings of the HF3000

Iain

[catswhiskers]

But are you actually getting better braking or just better feel through the pedal.

Iain

Hi Iain,

From my own experience, I am getting better braking and have actually found the pedal to have a better feel. This have given me much more confidence when driving hard. Before the servo was fitted, I found the pedal a bit 'dead' and lacking much feedback.

Mick.

[Martin K]

I found the pedal a bit 'dead' and lacking much feedback.

Mick.

I think this is down to the pedal ratio. From experience, the Hawk pedal ratio was obviously selected to work with a servo; without a servo a higher ratio brake pedal is needed to give more leverage and more feel.

[igosling]

OK, so I think I read somewhere that the Hawk pedal ratios suit 2:1 or there abouts, so this SVC unit should be a perfect fit, without having to do any pedal alterations. Can you confirm please.

I'll do some digging on Master Cylinder sizes for front and back, I am sure there was a thread somewhere.

Thanks for the great info

Iain

[chris.richard]

OK, so I think I read somewhere that the Hawk pedal ratios suit 2:1 or there abouts, so this SVC unit should be a perfect fit, without having to do any pedal alterations. Can you confirm please.

That's my understanding.
With no servo the pedal was rock hard and I could hardly lock the wheels without risking a rupture. i tried a single servo on the front, the pedal feel was great, but too much front bias to dial out with the balance bar (0.625 front & rear, I'm currently trying 0.625 rear, 0.7 front). I'm nearly ready to road test the latest incarnation.



what calipers are you using Ian?

[igosling]

Chris

Using the standard 164 calipers ?

[igosling]

Chris,

I just sent Mick a PM, which basically suggested that I could copy his setup. He seems to be using .875 front and .750 rear (from a previous thread) and is also using the Alfa calipers.

I guess your differences may be the addition of tolerances in the pedals and servo and the feel you want and stopping power you need.

As I said initially I really want to get through the horrors of SVA, but have a good quality option. Locking the wheels is not a priority at this time !!!

If you can advise on an SVA friendly option and If I could cheekily get a parts from you that would be fantastic.

Iain

[chris.richard]

Snap! Nico has the same setup - 164 calipers, 0.625/0.7 & twin servo, so it should be OK. His servos are 2 separate AP lockheed, but I don't know the ratio off hand. Roger Donnan uses the 19mm Fiat tandem M/C with the 164 calipers and races with no problems. I haven't yet tried to understand the relationship between tandem and dual M/C piston sizes.

[chris.richard]

Remember that Mick is a Corse and his pedal ratios may be different.

[chris.richard]

I'm not familiar with the SVA so may not be best to advise. I have an LSD, so they can't test the brakes with a roller, we did it with the tester sitting on the floor where my passenger seat wasn't, with a decellerometer sitting in the footwell. The braking performances, especially the handbrake felt crap, but were above the standard deemed satisfactory. PM me your phone number and we can have a chat if you want.

[catswhiskers]

Iain,
You have a PM. ;)

Mick

[chris.richard]

Road tested the latest setup tonight. Brilliant. easy switch from front lockup to rear lockup with the balance bar, nice pedal feel. Now I need proper front tyres and some practice! :)

[catswhiskers]

Nice one Chris.
Dont you just love it when a plan comes together. ;)

Mick

[chris.richard]

Nice one Chris.
Dont you just love it when a plan comes together. ;)

Mick

yep! :) Pity it was the 4th setup that produced the results! :o Could have saved some money if I'd gone there first!

[pimms]

I installed one of these over the winter. Have to say it's a brilliant piece of kit. Not oversensitive either. I think the ratio is only about 2:1
Very easy to install and connect.
Mick

Do these remote sero's have different cilinders installed or all they all the same? What i mean is, if you change yuore brake master cilinders, do you also have to change the size cilinders on hte servo?? :confused:

[pimms]

Do these remote sero's have different cilinders installed or all they all the same? What i mean is, if you change yuore brake master cilinders, do you also have to change the size cilinders on hte servo?? :confused:

Would 2 of these servos do the job? They are also available in 1.9:1 ratio and cheaper then a dual one from SVC. The only disadvantage i can see is the take more space?

: http://cgi.ebay.nl/Remote-Servo-all-single-line-brake-systems_W0QQitemZ160183975687QQihZ006QQcategoryZ27 380QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[Sptwoman]

Hi Pim, The servo ratio preferred on the site is the 1.9:1. The servo doesn't change if you change your master cylinders (Within reason). The servo just provides you with some boost when applying your brakes.
I bought a pair of the 1.9 Ratio kits off this seller. (£77.50 each) I wanted to be flexible. You can site them anywhere.
I've now changed my plans though so they're now surplus to requirements :o

[pimms]

I've now changed my plans though so they're now surplus to requirements :o

Hi Allen,
If you don't need them anymore and are willing to sell, I might as well buy them from you???? Let me know , if you will keep them, i will try to buy them from the same seller.

[Sptwoman]

You have a PM Pim...

[AndyH]

Hi,

I have 164 calipers all round and 0.625" and 0.7" masters.

New discs / pads and no servo gave NO stopping. VERY scary.

Fitted SVC dual unit and immediate improvement.. Easy stopping and locking.

Sailed through SVA with this set-up. However, SVA does require that the car will stop without the servo, so I was glad the the pads must have bedded in a bit by the time SVA came around. No problems. Great bit of kit.
Don't let the 1.9:1 put you off... It really make a huge difference (Much more than you'd believe.) If you read the paper that comes from SVC, it does suggest much better than 1.9:1 initially, but this ratio diminishes the more pedal pressure you apply. This makes more sense and would explain the huge difference it makes.

Andrew