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Brakes on a Conquest DJ252

ROSS70JEN
Posts: 52
Joined: Mon Nov 07, 2016 4:16 pm
Location: LOOE CORNWALL

Brakes on a Conquest DJ252

Post by ROSS70JEN »

HI all
The brakes on my DJ252 require a lot of pressure to stop .
I have changed the front shoes and fitted 4 new wheel cylinders.
My DJ260 is better but I think there was some changes on the MK2.
As I get older the foot pressure gets harder to do.
Could I fit a servo with a 3:1 pressure gain?
I have never done this with a moving master cylinder system.
Help and advice please.
Bryan

Peter Grant
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Location: Sydney, Australia

Re: Brakes on a Conquest DJ252

Post by Peter Grant »

Hi Bryan,
One of our members fitted a system to his DB18 Special Sportsd which included a booster and some electronic gizmo from a BMW and USA and it has transformed the car.
It is stopping like a modern. It comes up in a straight line and stops on a sixpence.
Really good. It was an expensive process but if you are having trouble with braking well worth it.
I will find his report and post it for the forum members.
Peter Grant

Peter Grant
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Location: Sydney, Australia

Re: Brakes on a Conquest DJ252

Post by Peter Grant »

Hi bran,
This is, in brief what was fitted to the DB18 Special Sports:

The car was fitted with a Silent Drive Vacuum Pump made by Master Power Brakes USA p/n AC 9001K coupled to a Robert Bosch Australia Hydropower booster VH40.
This combination increases the hydraulic ratio by 4 to 1. That results in the force applied to the brake pedal being increased by 4 times at the piston. Most modern cars are like this.

It really is fantastic.
Peter Grant

Peter Grant
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Re: Brakes on a Conquest DJ252

Post by Peter Grant »

And the article as written:
Special Sports Article 1.jpg
Special Sports Article 2.jpg
Hope these can be opened.

Cheers
Peter Grant

ROSS70JEN
Posts: 52
Joined: Mon Nov 07, 2016 4:16 pm
Location: LOOE CORNWALL

Re: Brakes on a Conquest DJ252

Post by ROSS70JEN »

Many thanks Peter
Is the DB18 like the Conquest ie rod brakes on the rear pulled by the master cyclinder?
If I fitted a Servo I am sure the front brakes would work much better but my little brain is not sure what would happen to the rear brakes?
Would they get a increase in force or less as the foot pressure is less?
Regards Bryan

Brian-H
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Location: UK

Re: Brakes on a Conquest DJ252

Post by Brian-H »

Having a DB18 Consort myself, I am intrigued about this potential upgrade.
ROSS70JEN wrote: Sun Aug 09, 2020 5:42 pm Many thanks Peter
Is the DB18 like the Conquest ie rod brakes on the rear pulled by the master cyclinder?
If I fitted a Servo I am sure the front brakes would work much better but my little brain is not sure what would happen to the rear brakes?
Would they get a increase in force or less as the foot pressure is less?
Regards Bryan
As Bryan says, is this modification only for the front brakes i.e. there is no information on the hydraulics themselves, bearing in mind that the master cylinder is directly attached to the brake pedal which moves to force fluid to the front brakes and uses a rod on the piston out of the rear to the rear brakes.

In order to give increased pressure, does the booster hydraulic line take feed from the reservoir and then output into the master cylinder ? If so, do the seals in the master cylinder require upgrading ?

Or does the hydraulic line take feed from the output of the master cylinder then output to the front brakes only ?

Mark Bullen
Posts: 219
Joined: Mon Feb 15, 2016 1:07 pm
Location: Wiltshire

Re: Brakes on a Conquest DJ252

Post by Mark Bullen »

The DB18 saloon has rods and cables with no hydraulics. They actually work quite well if adjusted correctly, they are however light years away from anything modern for pedal pressure.

Brian-H
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Location: UK

Re: Brakes on a Conquest DJ252

Post by Brian-H »

Mark Bullen wrote: Tue Aug 11, 2020 6:32 pm The DB18 saloon has rods and cables with no hydraulics. They actually work quite well if adjusted correctly, they are however light years away from anything modern for pedal pressure.
That article is about the DB18 Special Sports, and AFAIK the Special Sports had brakes similar to the DB18 Consort, plus, the article does say "no hydraulic leaks" before he decided to investigate the fitting of a hydraulic booster.

ROSS70JEN
Posts: 52
Joined: Mon Nov 07, 2016 4:16 pm
Location: LOOE CORNWALL

Re: Brakes on a Conquest DJ252

Post by ROSS70JEN »

MANY THANKS ALL .
How ever I am still not sure how to connect up the servo and what would the effect be on the rear brakes.
If the servo was in the master cylinder output as is normal in new cars the front would work much better, but what would be the effect on the back brakes?
If the servo was fitted on to the oil inlet line to the master cylinder would all brakes work or would it have no real effect?
Bryan confused .com

Brian-H
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Re: Brakes on a Conquest DJ252

Post by Brian-H »

ROSS70JEN wrote: Wed Aug 12, 2020 10:47 am If the servo was in the master cylinder output as is normal in new cars the front would work much better, but what would be the effect on the back brakes?
If the servo was fitted on to the oil inlet line to the master cylinder would all brakes work or would it have no real effect?
Bryan confused .com
I think that, in my earlier reply to you, and the questions that I put, I may have added to the confusion.

Re-reading what Peter says (and disregarding "hydraulic ratio" ) .....
Peter Grant wrote: Sat Aug 08, 2020 1:13 am ..... results in the force applied to the brake pedal being increased by 4 times at the piston. Most modern cars are like this.
i.e. there must be a modification somewhere on the metal link that connects the brake pedal to the master cylinder

i.e. a brake booster in a "modern" car (60s/70s onwards) gives mechanical gain from the pedal onto the piston that goes into the master cylinder.

So I assume that the booster modification provides assistance, in this case, by pushing or pulling the master cylinder forwards.
But how/where the booster sits relative to pedal and master cylinder is a complete mystery.

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