Brake master cylinder conversions

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Bob Craig

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Mar 24, 2019, 1:39:52 PM3/24/19
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After upgrading my already upgraded 2+2 brakes from Cosworth single piston calipers and huge discs to a much lighter Hispec billet 4 pot system, I can't get a decent brake pedal and have next to no braking force. I purged all the old brake fluid and refilled with dot5.1, pressure bled everything. I'm thinking that my master cylinder may be faulty and just looking at options. I know the later type cylinder is a bit like rocking horse poo these days and if going to the extent of changing, I'd rather have a more performance focused set up.
Has anyone fitted the Burton Power bias assembly. It does away with the standard servo and master cylinder.

https://www.burtonpower.com/adjustable-bias-brake-assy-ford-fiesta-mk1-mk2-mk3-brk061.html

Bob

Susan and Martin Scott

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Mar 24, 2019, 1:57:32 PM3/24/19
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Did you have dot 3 fluid in originally? If any fluid (other than 5.1) has
been used with the brake parts the seals won't last long if the fluid is
then changed to 5.1. due to fluid incompatibilty.
Martin Scott
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Darren Siepka

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Mar 24, 2019, 2:20:17 PM3/24/19
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I have the escort service upgrade on my saloon ( documented on the club site)
I am currently fitting a mgf servo ( with pedals and crossbar) and master cylinder in place of my later type servo etc to my 2+2 I hope to fit the abs too :-)
That master cylinder is available in non abs too. It copes with rear calipers and up to 4 pot ap calipers up front the plenty of fluid.

Darren

Darren Siepka

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Mar 24, 2019, 2:20:57 PM3/24/19
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Should say escort servo!

Robert Craig

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Mar 24, 2019, 3:31:59 PM3/24/19
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Hi Martin,
Not sure what was in it before but yes, possibly dot 3. I did wonder about switching to dot 5 but it seemed like a sensible approach when going to a higher spec system.

Bob

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Robert Craig

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Mar 24, 2019, 3:37:01 PM3/24/19
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Hi Darren,
That's an interesting MG conversion. Will your Escort parts be available or are you keeping them? Just weighing up options at the moment. Burton also do a floor mounted pedal box which would completely do away with all the Ford parts but it's pricey.

Bob

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Susan and Martin Scott

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Mar 24, 2019, 6:53:59 PM3/24/19
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Ignoring the fluid change..... What is the combined area of the pistons
compared to the previous single ones? I may know an alternative, but it
depends what the requirements are. It could be that a larger bore master
cylinder is needed, but some dimensions will be needed to calculate.
Martin
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Subject: [Quantum Owners] Brake master cylinder conversions


Darren Siepka

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Mar 24, 2019, 6:59:28 PM3/24/19
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If all goes well with the 2+2 conversion then yes the saloon will be getting the same mgf conversion too, but it won't be till later in the summer when it gets its new engine and autobox.

Susan and Martin Scott

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Mar 24, 2019, 7:01:03 PM3/24/19
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They can't be mixed - hence the IVA requirement to label the master cylinder
reservoir. I had 'a near issue' with guy doing an MOT test on my Rickman a
couple of years ago - he asked why I had a container of DOT5.1 fluid in the
car, and suspected I had a leak. I explained to him I didn't have a leak,
but if at some time in the future it happened miles from home it was
possible I could get home safely with a top up. He then asked why I couldn't
just buy a bottle of brake fluid if it happened, so I pointed out it was dot
5.1 and didn't mix with others and he'd never heard of dot 5.1 fluid !
Martin

Jim Hearne

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Mar 25, 2019, 5:12:59 AM3/25/19
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I had the same problem when i put Willwood 4 pot calipers on my 2+2, that
has the early brake setup.

There are 2 different brake pedals with the hole for the bar that goes
through the bulkhead in different places, one gives you more pressure on the
master cylinder but at the expense of more pedal travel.
I may have a picture somewhere.
I drilled another hole in the already better option pedal , even higher up,
this helped with the pressure but gave more pedal travel.

It certainly stops now, i did a couple of track days in it.
I also have a feeling that the brake pads either glazed or weren't the best
material choice, i bought another set of a more road spec but never got
around to fitting them to see if they made a difference.

I thought i may have been loosing travel with the servo brackets flexing so
i plated in the open sides and strengthened to ends, but this made no
difference.
You can also adjust the pushrod in the servo to remove any play before the
pushrod contacts the end of the master cylinder.
But, be careful with this, i got it too close and it wasn't letting the
master cylinder fully retract.
This had the effect that as the fluid got hot it gradually applied the
brakes, not so good.

What bore is your master cylinder ?, it should be stamped on the side.

I know anything with a bias bar won't pass an IVA test unless it's welded up
but not sure if it's an MOT failure.
Also, without a servo you will need some muscles.

Jim




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Subject: [Quantum Owners] Brake master cylinder conversions

Darren Siepka

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Mar 25, 2019, 5:27:14 AM3/25/19
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Whilst comparing setups for my swap I wondered how much effort we loose in the plastic bushes too, especially at the servo end with the shortest arm. The mg crossbar has needle roller bearings supporting both ends of the crossbar! This will surely help frictional losses.i wonder if similar could be done for the original fiesta setup? 

Darren

Jim Hearne

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Mar 25, 2019, 5:35:22 AM3/25/19
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I guess it may loose a bit in the bushes, mine were all new and smeared with moly grease.
 
Jim

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Robert Craig

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Mar 25, 2019, 9:12:58 AM3/25/19
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Hi Martin,
Not sure about the areas but the Cosworth calipers are certainly bigger than the original XR2 ones were and worked ok. The Hispec 4 pots are smaller diameter but spread over a larger pad area to give more even pressure.

Bob

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Robert Craig

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Mar 25, 2019, 9:20:50 AM3/25/19
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Hi Jim,
I didn't know that.
At the moment I have no pressure at the pedal and full travel.

I guess if I refitted the original set up that yourself and Matthew fitted and I have brakes again then it points towards the master cylinder being too small to cope with the Hispec set up (same as Willwood). Not a huge job, it's just finding time to do it that's the problem.

As it's only me that drives the car, I'm not overly concerned about removing the servo ( if I take that route).

Bob

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Darren Siepka

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Mar 25, 2019, 9:20:59 AM3/25/19
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Were they single pot escort / Sierra 4x4 cosworth or 2wd Sierra 4pot  cosworth calipers?
I have the 4x4 single pot front with Peugeot single pot rears on my saloon ( this is with the current escort MC)

Robert Craig

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Mar 25, 2019, 9:22:14 AM3/25/19
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Single pot Darren. 
Bob

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Darren Siepka

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Mar 25, 2019, 9:24:44 AM3/25/19
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Many moons ago when I did a 4pot conversion to a mini , I had to bleed the front brakes with the calipers off the car as they had to be manipulated due to the bleed screw being in the wrong place. If you didn't you had no pedal due to a air pocket in the caliper

bill

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Mar 25, 2019, 9:30:30 AM3/25/19
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Do you still have rubber hoses to the calipers if they are you could clamp them off, if the pedal still has long travel problem is in master cylinder, if the pedal has no travel problem is in callipers



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Susan and Martin Scott

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Mar 25, 2019, 9:48:51 AM3/25/19
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If the sizes of the pistons add up to the same area then the original master
cylinder will be suitable.
For my Rickman (using 4 pot Princess callipers) the pistons are 38mm each
but of course there are twice the number. The original Ford callipers were
54mm, so the same area, and the original master cylinder is suitable. I
suspect it's either air in the system or a master cylinder seal has given
out due to fluid incompatibility. Even purging the system fully won't get
rid of the old fluid because 1) some will inevitably be left behind and b)
the old fluid will 'swell' the seals and become absoorbed to soem extent.

Susan and Martin Scott

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Mar 25, 2019, 9:59:57 AM3/25/19
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Every day's a school day as they say... I've just done a 'net search and it seems dot 5.1 and dot 3 are compatible.along with dot 4. The oddity is dot 5  which is silicone based (nb not 5.1. The others, dot3, 4 and 5.1 are glycol based so are compatible with each other. Why are these things always so complicated, and confusing numbers, surely DOT S1 would have been a better label for the silicone one.  Good news though as it means Bob's car may just need the system bleeding. I've found in the past that if the system is drained fully it makes it a lot more difficult to bleed - I used both an easybleed to pressurise AND an assistant pressing the brake pedal before I was successful.  
Martin



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Jim Hearne

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Mar 25, 2019, 10:14:08 AM3/25/19
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Not 100% sure but it probably had DOT 5 silicone fluid in it as that was
what i used myself at the time.
The silicone fluid is a slightly purple colour.

Jim

Jim Hearne

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Mar 25, 2019, 10:15:39 AM3/25/19
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I remember working all this out on a spreadsheet years ago.
Does the Ford caliper being the sliding sort count as twice the piston area
?

Jim

Susan and Martin Scott

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Mar 25, 2019, 10:33:52 AM3/25/19
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I've got confused with all the dot numbers now........ I've just looked back
at the (now deleted) original note, and if dot 5 has been replaced with 5.1
that may create a problem given what I found earlier (if it's correct info)?
A crazy numbering system which could have been better managed - But the DOT
(like all gov't depts) know best :-)

Susan and Martin Scott

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Mar 25, 2019, 10:39:33 AM3/25/19
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I'm pretty sure it would do because 1 sliding calliper (the other pad
effectively fixed) means the pads have to move the same as with 2 pistons,
so the same amount of fluid will be displaced.

Michael Aitken

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Mar 25, 2019, 1:56:29 PM3/25/19
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Hi m8 where I put the wilwoods on my old car started the bleeding of the caliper at the bottom inside, bottom outside and then top inside and top outside in that order. Did not get much air out the top by loads out the top.

Robert Craig

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Mar 25, 2019, 2:03:10 PM3/25/19
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That's a fair point Darren and I've heard of that problem with mini calipers. 

I've got the calipers fitted with the bleed screws at the bottom but maybe they should be at the top, so effectively I may have fitted the n/s to the o/s and the o/s to the n/s (they came with the bleed screws already fitted). There are two on each caliper and they may be interchangeable top to bottom - need to check if there are blanks at the other end or swap them side to side. Worth a try at least.

Bob

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On 25 Mar 2019, at 13:24, Darren Siepka <dar...@siepka.me.uk> wrote:

Robert Craig

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Mar 25, 2019, 2:03:55 PM3/25/19
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Braided hoses Bill. 

Bob

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Robert Craig

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Mar 25, 2019, 2:05:38 PM3/25/19
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Thanks Michael,
Did yours have 4 bleed screws per caliper then?

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> On 25 Mar 2019, at 17:54, 'Michael Aitken' via Quantum Owners Group <quantu...@googlegroups.com> wrote:
>
> Hi m8 where I put the wilwoods on my old car started the bleeding of the caliper at the bottom inside, bottom outside and then top inside and top outside in that order. Did not get much air out the top by loads out the top.
>

Steve Kodź

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Mar 25, 2019, 2:09:54 PM3/25/19
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Bob,
The Wildwoods on my Xtreme have 4 per caliper.

Regards,
Steve

On 25 March 2019 18:05:43 "'Robert Craig' via Quantum Owners Group"

Steve Kodź

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Mar 25, 2019, 2:13:05 PM3/25/19
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I hit send too quickly there ..

The inner side of the caliper is easy to photo, but the outside is
basically the same.

Regards,
Steve

On 25 March 2019 18:09:58 'Steve Kodź' via Quantum Owners Group
IMG_20190325_181018_3240080238699621548.JPG

Robert Craig

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Mar 25, 2019, 2:13:09 PM3/25/19
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Thanks Steve,
I'll check if they have blanking plugs fitted at the top. It would be easier to fit bleed screws than to swap the calipers round.

Bob

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Robert Craig

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Mar 25, 2019, 2:20:16 PM3/25/19
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That's helpful Steve. The Hispec caliper is pretty much the same but only came with one bleed screw on each side.

Bob

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> <IMG_20190325_181018_3240080238699621548.JPG>

Robert Craig

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Mar 25, 2019, 2:28:54 PM3/25/19
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Pic below.

image1.JPG

Jim Hearne

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Mar 25, 2019, 2:43:11 PM3/25/19
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Yes, should certainly have the bleed screws at the top, you won't get much air out of the bottom.
My Wilwoods have bleed screws at the top and bottom but i've never bleed the bottom ones, didn't seem much point as all the air would be at the top.

Jim

Steve Kodź

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Mar 25, 2019, 2:54:14 PM3/25/19
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Hopefully you can move the bleed nipples to the top, otherwise you may have
to swap the calipers between the sides.

Regards,
Steve

On 25 March 2019 18:29:04 "'Robert Craig' via Quantum Owners Group"
<quantu...@googlegroups.com> wrote:

> Pic below.
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Robert Craig

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Mar 25, 2019, 3:07:01 PM3/25/19
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All makes sense now. Sometimes you just need another pair of eyes to look at things from a different perspective. I'll let you know how I get on.

Thanks everyone for your input.

Bob

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Michael Aitken

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Mar 25, 2019, 5:06:20 PM3/25/19
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Yes 4 on the wilwoods two top and two bottom.

Robert Craig

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Mar 25, 2019, 5:37:15 PM3/25/19
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Thanks Michael.
Only 2 on mine and no blanks at the other end. Need to swap them side to side to have them at the top.

Bob

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> On 25 Mar 2019, at 18:49, 'Michael Aitken' via Quantum Owners Group <quantu...@googlegroups.com> wrote:
>
> Yes 4 on the wilwoods two top and two bottom.
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Bob Craig

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Mar 30, 2019, 7:02:54 PM3/30/19
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Pleased to report that after swapping the calipers from side to side to have the bleed screws at the top, I now have working brakes.
Can't believe I made that schoolboy error but thanks to everyone who commented and offered advice.

dar...@siepka.me.uk

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Mar 31, 2019, 10:30:43 AM3/31/19
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Glad you got it all sorted and it was a relatively simple fix .

Tom Walker

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Apr 1, 2019, 3:50:49 AM4/1/19
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I fitted a similar thing from Rally Design meant for a MK1 escort iirc, with an adjuster for front/rear bias. And I've got a remote vacuum assist unit (Austin something) driving my 305mm front hispec "monster" discs and rear disc conversion.
However, due to various family issues, I've not driven the car since fitting the vacuum assist (4 years now) so I can't attest to it's behaviour yet. Maybe this summer (wistfully pondering)...


On Sun, 24 Mar 2019, 17:39 'Bob Craig' via Quantum Owners Group, <quantu...@googlegroups.com> wrote:
After upgrading my already upgraded 2+2 brakes from Cosworth single piston calipers and huge discs to a much lighter Hispec billet 4 pot system, I can't get a decent brake pedal and have next to no braking force. I purged all the old brake fluid and refilled with dot5.1, pressure bled everything. I'm thinking that my master cylinder may be faulty and just looking at options. I know the later type cylinder is a bit like rocking horse poo these days and if going to the extent of changing, I'd rather have a more performance focused set up.
Has anyone fitted the Burton Power bias assembly. It does away with the standard servo and master cylinder.

https://www.burtonpower.com/adjustable-bias-brake-assy-ford-fiesta-mk1-mk2-mk3-brk061.html

Bob

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Robert Craig

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Apr 1, 2019, 2:48:12 PM4/1/19
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That's a very large disc size for a Quantum. What size wheels are you using?

Bob

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Darren Siepka

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Apr 1, 2019, 2:51:49 PM4/1/19
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Are the rears solid or vented? I found my 280odd cosworth vented rears keep glazing up and never get hot on the road no matter how I drove ! The 280 cougar fronts work fab though. 
300mm would need 16" + iirc ?

Robert Craig

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Apr 1, 2019, 3:54:51 PM4/1/19
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I thought about the rear disc conversion but even on a twisty sprint track with heavy braking zones the rear drums never got any real heat in them. Perhaps with adjustable bias and maybe a bit more rear braking they might get hotter but I never felt that discs were a requirement.

Bob

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Susan and Martin Scott

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Apr 1, 2019, 4:49:14 PM4/1/19
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It's not a good idea to overbrake on the rear! That's why there is an apportioning valve on the donor XR2, so changing to discs will achieve no benefit and probably compromise the parking brake.
Martin



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Bill Allison

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Apr 2, 2019, 3:52:51 AM4/2/19
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Martin et al

On my saloon I have Honda Legend discs on the front with Wilwood Midilite calipers. The rear has Golf Gti alloy calipers on Peugot 205 discs with no apportioning valve. Can be seen here.  Brake balance is near perfect and the handbrake is sufficiently powerful to lock the wheels on dry tarmac.


Many people are not aware that drum brakes have a built-in servo-assistance characteristic so are more powerful, all other things being equal, than disc brakes. in my case correct balance was easily achieved with careful choice of pad material and the pressure reduction to the rear deleted. Handbrake effectiveness is a matter of ensuring that the combination of gearing inside the caliper and lever arm lengths (handbrake and caliper) applies correct force on the pads for the given disc and wheel diameters.

Best regards
Bill


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Susan and Martin Scott

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Apr 2, 2019, 4:42:25 AM4/2/19
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I wasn't suggesting it couldn't be done (ie. adequate handbrake and correct brake balance with rear discs), just that it wasn't necessary, and that drums are more than adequate for the job, certainly in a Quantum. For most Quantum builders it would be unecessarily costly, for no gain and a possibility of rendering the car dangerous if the brake balance ended up incorrect.

Jim Hearne

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Apr 2, 2019, 4:53:31 AM4/2/19
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I came to the same conclusion, that there was no need (apart from appearance) for discs on the rear of a 2+2.
There’s just no weight at the rear.
 
I’ve got 280mm discs on the front with Wilwood 4 pot calipers,  and standard XR2 drums at the rear with the inertia type pressure limiting values.
 
Jim
 
 
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Bill Allison

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Apr 2, 2019, 5:26:37 AM4/2/19
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Hi Martin

I agree that such a conversion isn't within the capabilities of many owners but, to not discourage those who are competent to undertake such a conversion, I must say that it is not true that there is no benefit.

Benefits include:

Reliability - self-adjusting mechanism and handbrake actuator is in a "nice" environment (bathed in brake fluid) and will typically work for many, many years without attention. The similar calipers on the Honda in my sig just had their first rebuild at just on 12 yrs old!
Condition of main components is visible without dismantling
Maintenance, when eventually it is needed is much easier - try removing a set of shoes, never mind replacing them. in the few minutes it takes to swap pads...
And this might seem trivial but bleeding the rears is so much easier with a large, accessible nipple than a small, rusted-in one behind the backplate
Oh - and the reduced unsprung weight is not to be sniffed at...

Best regards
Bill


Bill Allison
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Tom Walker

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Apr 2, 2019, 6:25:49 AM4/2/19
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16" (205/40 16)

chris...@btinternet.com

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Apr 2, 2019, 1:33:31 PM4/2/19
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>:And this might seem trivial but bleeding the rears is so much easier with a large, accessible nipple than a small, rusted-in one behind the backplate
I intend to overcome that with a stainless bleed nipple
 
Chris G
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