After the Stoneleigh run today I have decided that I need bigger discs on the front, but retaining the Wilwood calipers.

The present discs are vented 245mm Capri jobbies. What is the next size up with the same offsets etc and are different caliper mounting brackets available? Cossie maybe?

Any guidance is appreciated as always

damn does that mean you won't be there tomorrow raz, i was hoping to see your car in the flesh

you can always run softer pads, makes quite a mess, but will do the job if you need it.

Try some solid brake lines

are you actually running capri brakes at the front -> e.g. capri hubs, struts etc?

if so, then check out these guys -> www.caprisport.com

they allow you to mount the disc on the front of the hub. you can then use 283mm cossie 2wd discs and mondeo / granada calipers.

this gives awesome brakes.

pjavon - Yep, I went yesterday as I didn't fancy the weather forecast for today

violentblue - That would be a good solution but I can't seem to find anything softer for my Dynalites. I've tried Greenstuff (scary) and Hawk 'fast road' versions but it still feels underbraked. A lot of this might be due to my low pedal ratio which is 4.5:1. I have fitted smaller m/c to reduce the pedal effort and tinkered with the bias bar but nothing seems to give me a warm feeling.

So I thought I would fit another pair of Wilwoods to the rear, replacing the std Sierra jobbies, and try bigger discs to increase the leverage effect on the front.

Peteff, Nowt wrong with the brakelines - they are rock hard despite using flexi hoses

saigonij - I'm using Cortina uprights with Wilwood Dynalites on Capri vented discs.

Have you looked at any of the Wilwood 'Polymatrix' pads? RallyDesign has them for DL's

T

Tralfaz - I was under the impression that the Hawk pads I tried were quite a soft compound but maybe a phone call to Rally Design (UK distributor for Wilwood) would be a good idea to see what they recommend.

Found similar with those green pads myself.

presume mintex don't do pads to suit the wilwood's?

Look at that first before doing anything else, what you have now should be fine.

If not, then the suggestion of using the caprisport granny caliper upgrade is a good one, used that on a capri years ago and it is great, depsite using "ungfashionable" single pot calipers and other std fordy bits, it works a treat and nice pads are avaialble for them at decent prices.

(i.e. a caliper that takes mintex pads is worth its weight in cast iron! )

I phoned RD today and apparently the Green Stuff pads are pretty soft and they have a Wilwood 'Smart Pad' which is on the same level. I don't think anyone does Mintex pads for my Dynalites so I'm stuck really.

I have tried the bias bar fully wound to the rear setting but I still can't get the rears to lock up - just the fronts. Consequently I have placed an order for Wilwood Powerlites & discs (for rears) as I am sure that the std Sierra jobbies are not up to the job on my middy.

really daft question but are you sure you're winding the bar the right way? (I've done it before!! )

RazMan, you can get Pagid RS14's to fit out of the box, but if you want to go softer still, as mentioned in my master cylinder thread you can get RS15s in there although they don't actually sell a pad off the shelf that will fit.

The ones Ive used are actually a Subaru fitment and the two ends need cutting off with a chop saw. Sounds dodgy but myself and 3 others ordered a set and did the mod having been told it unofficially by a Pagid distributor, and have had no problems at all, evidently this is Pagid's unofficial way of getting RS15 pads into Wilwood / Outlaw / Bremsport calipers like ours.

Chris

RazMan, I'm inclined to agree with you that the rear brakes may not be up to the job but reading this then if (Wild guesses BTW):

Car weight = 2000lb
Wheelbase = 100"
Weight distribution is 40% front 60% rear.
CG Height is 20"

Then static theres 800lb of the front and 1200lb on the rear.
A 1g stop would give a weight transfer of 2000 x 20 / 100 = 400lb
Add that on to the static and theres 1200lb front and 800lb rear load.

Now if it were a front engine car with 60-40 front with all else being the same at 1g braking we'd end up with 400lb load on the rear and 1600lb on the front.

If you run the above with your real numbers what do you come out with?

On the face of it to me you should have the same brakes on both ends of the car.

[Edited on 9/5/07 by Doug68]

quote:

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Originally posted by NS Dev
really daft question but are you sure you're winding the bar the right way? (I've done it before!! )

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quote:

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Originally posted by ChrisGamlin
RazMan, you can get Pagid RS14's to fit out of the box, but if you want to go softer still, as mentioned in my master cylinder thread you can get RS15s in there although they don't actually sell a pad off the shelf that will fit.

The ones Ive used are actually a Subaru fitment and the two ends need cutting off with a chop saw. Sounds dodgy but myself and 3 others ordered a set and did the mod having been told it unofficially by a Pagid distributor, and have had no problems at all, evidently this is Pagid's unofficial way of getting RS15 pads into Wilwood / Outlaw / Bremsport calipers like ours.

Chris

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quote:

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Originally posted by Doug68
RazMan, I'm inclined to agree with you that the rear brakes may not be up to the job but reading this then if (Wild guesses BTW):

Car weight = 2000lb
Wheelbase = 100"
Weight distribution is 40% front 60% rear.
CG Height is 20"

Then static theres 800lb of the front and 1200lb on the rear.
A 1g stop would give a weight transfer of 2000 x 20 / 100 = 400lb
Add that on to the static and theres 1200lb front and 800lb rear load.

Now if it were a front engine car with 60-40 front with all else being the same at 1g braking we'd end up with 400lb load on the rear and 1600lb on the front.

If you run the above with your real numbers what do you come out with?

On the face of it to me you should have the same brakes on both ends of the car.

[Edited on 9/5/07 by Doug68]

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quote:

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Originally posted by RazMan

That sounds like a good dodge Chris - the Pagid specs would seem to suggest that I need RS15 pads but they are bloomin expensive aren't they! so I had better be sure before I hack £150 of pads up If my rear upgrade doesn't have the desired effect I will give them a try.
Thanks for the tip.

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The 'polymatrix a' pads from wilwood are pretty damn snappy, and have a very high friction coefficient from cold. The wilwood site says they are race only, but all their calipers say that on too

They are rather expensive though

You can buy discs(rotors) and centre discs/spacers from rally design, as someones probably mentioned. Should let you build a system to whatever spec you need.

Next size up from 245mm is 260mm You could go larger though, as it looked like you had tons of room in your wheels? It all depends how underbraked the car is at the moment. You can do the calcs to roughly work it out though.

Let me know what m/c sizes you have and which calipers and what tyres and disc sizes you are currently running and i will attempt some number crunching. (Never guess what my dissertation was on?)

David

[Edited on 9/5/07 by flak monkey]

quote:

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Originally posted by flak monkey
Let me know what m/c sizes you have and which calipers and what tyres and disc sizes you are currently running and i will attempt some number crunching.

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Do you know what the piston size and disc size is on the rear by any chance?

Oh and tyre size please

[Edited on 10/5/07 by flak monkey]

I have a feeling that the Sierra rear caliper has one 43mm piston (sliding caliper)
My tyres are:
Front - 205/40/17
Rear - 245/35/17

I would interested in the change when I swap the rears to Superlites (34mm pistons) and 273mm discs - it should change quite radically

OK from the little spreadsheet i wrote when I was doin my calcs:

Based on a 1g max deceleration, which I would think is about right on road tyres, your clamping forces that are required are:

9939N at front
7094N at rear

With your 4.5 pedal ratio, and 245mm front discs and 253mm rear discs (i beleive thats the std sierra size?) and the rest of the system as you said then in theory you would need:

The bias bar set to 54% rear, 46% front (the front would lock marginally before the rears at this setting)
And a mahoosive 490N pedal effort to get 1G decelleration. Which to be honest is a fair bit.

I will change the numbers and see what size discs you need with a roughly 50/50 bias setting and a much lower pedal effort.

David

quote:

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Originally posted by flak monkey
And a mahoosive 490N pedal effort to get 1G decelleration. Which to be honest is a fair bit.

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OK, from my calcs, based on you using the powelites up back with 273mm discs and the dynalites up front:

To get a more reasonable pedal effort - 350N (still quite high, but I would guess about right for a non-servo car?) you would need to run 309mm discs at the front. That would leave you with a 50/50 setting on the bias bar too (again with a marginal tendency for the fronts to lock first).

So summary:
Fr - Dynalites with 309mm OD discs.
Rr - Powerlites with 273mm OD discs.
50/50 setting on bias bar.

I have based the calcs on a CoG height of 400mm, sound reasonable?

I can send you the spreadsheet if you want to have a look?

If you are on msn it would make it easier.

David

quote:

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Originally posted by RazMan

quote:

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Originally posted by flak monkey
Let me know what m/c sizes you have and which calipers and what tyres and disc sizes you are currently running and i will attempt some number crunching.

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Okay David, I would appreciate your calculations on this one

800 kg middy with 60/40 split
Front: 4 pot Dynalites (old version) 35mm pistons & 245mm discs. 0.625" m/c
Rear: Bog std Sierra single pot calipers & discs . 0.70" m/c

I have ordered the Powerlites for the rear - just typing this info down makes it pretty obvious which end needs upgrading bearing in mind it is a middy

p.s. I nearly forgot - Polymatrix pads don't seem to be available for the old Dynalites

[Edited on 9-5-07 by RazMan]

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Do the pads look anything like this?

quote:

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Originally posted by flak monkey

So summary:
Fr - Dynalites with 309mm OD discs.
Rr - Powerlites with 273mm OD discs.
50/50 setting on bias bar.

I have based the calcs on a CoG height of 400mm, sound reasonable?

I can send you the spreadsheet if you want to have a look?

If you are on msn it would make it easier.

David

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Bearing in mind my spreadsheet only gives you the ideal theoretical set-up, it doesnt take into account the fact that the brake balance is significantly different at lower decelerations. JAG helped me a shed load with my calcs for my dissertation. I just happen to have studied it for my dissertation.

I reckon, with 25mm 4 pots on the back and 273mm discs all around you will need (for 1G deceleration) clamping forces of:

8695N Front
6455N Back

To get this theoretically you need:

0.625" m/c on both front and rear circuits
59% rear bias on the bar
And you are back to a 485N pedal effort

I will email you a copy of the spreadsheet and let you have a play with it. I'll try to explain how it works in the email

David

Thanks for all your help David - it is much appreciated.

I just thought I would post a couple of pics of my rear brakes.

First there was this .....

.... and now there is this ....

Old disc was a bog standard Sierra jobbie - fine for stopping a Seven but a bit overworked in my middy.

The new setup is a 4 pot Supalite handbrake caliper and a 273mm solid disc. It should stop me far better but I havent had a chance to try them out yet as I discovered that I had the wrong type of brakeline fitting AFTER I had cut the old one off So I'm off to my hydraulic factor tomorrow.

They look good though

[Edited on 13-5-07 by RazMan]

These brakes are still a challenge but I think I have another plan.

I have now also fitted 285mm discs on the front and retained the Dynalites. This has increased the mechanical advantage of the caliper and therefore improved the braking ....... slightly.

There is no doubt that the car will now stop quite effectively but the pedal pressure required is astronomical! So I am now going to try and increase the pedal ratio which is presently at 4.4:1. If I raise the pivot point towards the bias bar I reckon I can increase the ratio to more like 6:1. I've just got to work out how to do this with the least amount of modification to the pedals and master cylinder mountings.

I recently asked Keith Wood at Aeon about any possible solutions to 'scary brake syndrome'. With some magic calculations and a lot of thought, Keith came up with the simplest solution - the pedal ratio needed to be increased. This was achieved by making a new pedal which had the bias bar moved 10mm closer to the pivot point, increasing the ratio from 4.4:1 to 5.5:1. The difference is nothing short of miraculous and I can now lock the front wheels at will, but still with plenty of 'feel' on the pedal.

For everybody's reference my setup is as follows:

Front - 285mm vented discs with Wilwood Dynalite calipers.

Rear - 273mm solid discs with Wilwood Powerlite handbrake calipers.

Presently the master cylinders are 0.625" front & 0.70" rear but Keith reckons both need 0.625" as the front is now somewhat overbraked, despite having the bias bar fully towards the rears. I might even swap them over and see how the brakes feel like that before investing in a new m/c. My theory is that a smaller rear m/c will need a smaller caliper piston to achieve the same amount of pedal travel & therefore balance with the larger fronts.

Flak, would you mind running this combo (and the swapped version) through your formula and letting me know which one would work best?

[Edited on 24-5-07 by RazMan]

If you want to borrow a 0.625 Girling (needs remote reservoir) I can lend you mine if you cover the postage

quote:

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Originally posted by RazMan
Flak, would you mind running this combo (and the swapped version) through your formula and letting me know which one would work best?

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quote:

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Originally posted by ChrisGamlin
If you want to borrow a 0.625 Girling (needs remote reservoir) I can lend you mine if you cover the postage

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quote:

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Originally posted by flak monkey
I'll do it tonight for you Raz

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Sorry about this Raz, day later than expected but heres the results:

With your current set up, with the 0.7 on the back and 0.625 on the front, as you are experiencing the rear is miles underbraked, even with the bias bar adjusted all the way which wont give you enough adjustment as you need it set at about 70% to the rear and 30% to the front. Your pedal effort is a more repectable 370N or so.

With 2 0.625 m/cs you will keep the same pedal effort but you will be able to reduce the brake bias to about 60% to the rear, which should be within the range of adjustment you have.

The balance is certainly miles better with 2 0.625 m/c's.

David

Thanks a million David - I don't think I'll bother with swapping the m/cs around and just get another .625" m/c for the rears. At least I will know that I've made the best of what I've got - with your help of course

Thanks again

I will run it with them swapped for you now. Will only take a couple of mins.

See, 3 minutes

With the swapped you can set the balance bar to 55% rear 45% front, but your pedal efforts back up to 430N according to my model.

Up to you, both will work of course.

[Edited on 25/5/07 by flak monkey]

In old money that is almost 100lbs (actually 96.5 pounds force)

Anything over 70lbs is really hard work.

quote:

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Originally posted by britishtrident
Anything over 70lbs is really hard work.

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