Jump to content


Photo
- - - - -

Brake setup


  • Please log in to reply
24 replies to this topic

#1 Renessy

Renessy

    Mini Mad

  • Members
  • PipPipPipPip
  • 275 posts
  • Local Club: minisevenclub Holland

Posted 27 March 2007 - 04:38 PM

Been trouble shooting withe the brake setup I'm going to use on the Vtec....

Been looking through the build pages and seen many different ones

Know that I'll be useing the discs from the Zcars kit on the back (Sierra ones I believe) and Tar-ox big brakes on the front (6 pots)

But now the pedalbox and cilinders.....
I can buy the KAD system with the two brake cilinders and brake bias. This so I can get the 60/40 brake power which is needed for the SVA. .....
Or I can use the standard mini master brake cilinder and conntect the front brakes direct to the cilinder and place a proportioning valve in the brake line to the back?

Posted Image

I prefer the second one cause I've got a good mastercilinder and will only need to buy the proportioning valve (Wilwood) The only thing I'thinking about is the amount of fluid that is needed to drive the 6 pots. Will the master cilinder be sufficient for that?

Hope you guys can share some light on this....

Laters!

René

#2 Ade

Ade

    the bogie man

  • Members
  • PipPipPipPipPipPipPipPipPip
  • 2,357 posts

Posted 27 March 2007 - 10:07 PM

Probably not the answer your after but it'll depend what master cylinder you've got. I had a Mk1 on mine as it was the only thing that fitted and it couldn't supply enough fluid for the 4 pot metro calipers with z-cars rear discs so 6 pots would be no hope.

However Pete had a later servo assisted set-up and his were fine but I don't know how that would be with 6pots.

#3 markrally

markrally

    Z Cars

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 1,377 posts
  • Local Club: Miniaddicts.co.uk

Posted 28 March 2007 - 08:21 AM

Probably not the answer your after but it'll depend what master cylinder you've got. I had a Mk1 on mine as it was the only thing that fitted and it couldn't supply enough fluid for the 4 pot metro calipers with z-cars rear discs so 6 pots would be no hope.


You may be ok with your 6 pots as there is actually less piston area with the tarox 6 pots than the KAD or metro 4 pots.
I am having to get a smaller master cylinder to get more pressure behind them.
The total piston are for KAD/Metro 4 pots is 7696mm squared and the tarox 6 pots are 7064mm squared so these require a smaller master cylinder than what you would use on 4 pots so renne you may be ok, its worth trying it before you go buying pedal box etc.
I have a kad pedal box and i now need to purchase a very small AP racing master cylinder just for the front circuit.
However these fibures only apply to my tarox caliper which only just go under 13" wheels and cost about £700+

Posted Image

However they do do a smaller setup in a 6 pot aswell
Which is pictured in here clicky 6 pots




Cheers

Edited by markrally73, 28 March 2007 - 08:28 AM.


#4 koss

koss

    One Carb Or Two?

  • Members
  • PipPipPipPipPipPipPip
  • 1,397 posts
  • Local Club: The Greenbank working mens social club

Posted 29 March 2007 - 02:21 AM

Been trouble shooting withe the brake setup I'm going to use on the Vtec....

Been looking through the build pages and seen many different ones

Know that I'll be useing the discs from the Zcars kit on the back (Sierra ones I believe) and Tar-ox big brakes on the front (6 pots)

But now the pedalbox and cilinders.....
I can buy the KAD system with the two brake cilinders and brake bias. This so I can get the 60/40 brake power which is needed for the SVA. .....
Or I can use the standard mini master brake cilinder and conntect the front brakes direct to the cilinder and place a proportioning valve in the brake line to the back?

Posted Image

I prefer the second one cause I've got a good mastercilinder and will only need to buy the proportioning valve (Wilwood) The only thing I'thinking about is the amount of fluid that is needed to drive the 6 pots. Will the master cilinder be sufficient for that?

Hope you guys can share some light on this....

Laters!

René

If you are going to use a wilwood adjustable valve. Make sure it cannot be adjusted from inside the car. Box it in or place it
out of site. They are a definite fail at my local sva centre. Then put it where you like after the test.

#5 Renessy

Renessy

    Mini Mad

  • Members
  • PipPipPipPip
  • 275 posts
  • Local Club: minisevenclub Holland

Posted 29 March 2007 - 11:48 PM

Thanks for the help everybody. Decided to try using the mini master cilinder for the brakes. Then fit a brake adjuster for the rear.
Once it's all finished I know if it worked..... :thumbsup:

Will work the adjuster away for the SVA. Don't know how and where but I'll figure it out. Any ideas, suggestions or experiances are always welcome.....

Though Mark, if find it a bit strange to hear that a 6 pot uses less oil then the 4 pots or metro brakes. How and where did you find that out???


Laters!

René

#6 markrally

markrally

    Z Cars

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 1,377 posts
  • Local Club: Miniaddicts.co.uk

Posted 30 March 2007 - 08:22 AM

Though Mark, if find it a bit strange to hear that a 6 pot uses less oil then the 4 pots or metro brakes. How and where did you find that out???


Laters!

René


Well i measure the total piston area of the calipers?
Ie, KAD/Metro 35mm diameter x 8 pistons (962mm squared x8 = 7696mm squared [Total piston area])

--------------------------------------------------------------------------------------------------------------------------------------

Tarox 6 pot
30mm diameter pistons x 4 (706mm squared x 4 = 2824mm squared)
26mm diameter pistons x 8 ( 530mm squared x 8 = 4240 mm squared)

2824 + 4240 = 7064mm squared (Total piston area)

Does this make sense now??


Cheers

Edited by markrally73, 30 March 2007 - 08:24 AM.


#7 Renessy

Renessy

    Mini Mad

  • Members
  • PipPipPipPip
  • 275 posts
  • Local Club: minisevenclub Holland

Posted 30 March 2007 - 08:45 AM

Does make sence to me now, thanks!

We'll see if t all will work.....

René

#8 Poly_Patje

Poly_Patje

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 82 posts

Posted 30 March 2007 - 09:00 AM

Though Mark, if find it a bit strange to hear that a 6 pot uses less oil then the 4 pots or metro brakes. How and where did you find that out???


Laters!

René


Well i measure the total piston area of the calipers?
Ie, KAD/Metro 35mm diameter x 8 pistons (962mm squared x8 = 7696mm squared [Total piston area])

--------------------------------------------------------------------------------------------------------------------------------------

Tarox 6 pot
30mm diameter pistons x 4 (706mm squared x 4 = 2824mm squared)
26mm diameter pistons x 8 ( 530mm squared x 8 = 4240 mm squared)

2824 + 4240 = 7064mm squared (Total piston area)

Does this make sense now??


Cheers

Hey Mark,

That is a long ago :thumbsup:

About the brake power. The part that touches the discs are the brakepads. The brakepads of the Tarox kit have a larger surface then the KAD/Metro pads.
In the long run, the Tarox kit should have more brake power because of the larger brakepad surface and 1" larger discs.

Please correct me if I am wrong, but I had the same experience with the modified brakes on my motorcycle. First it had 4 pot calipers with large pistons (Suzuki GSX600F calipers) and now the 6 pot calipers (from a Hayabusa) with a smaller piston area are bolted on with the original brake discs. The brakediscs are still original, so these are not replaced with larger discs. With the 6 pot calipers the brakepad surface increased and there is also more equal brakepressure. First I used the original GSX600F master cylinder (13mm (1/2")) with these 6 pot calipers and heavy braking was getting fun. After a while I changed it with a 19" mm (3/4") master cylinder from the latest non-radial GSX-R1000 brake system and now braking is scary when you do not expect this amount of brakepower. Performing a stoppie (braking with the rearwheel in the air) can be done easily.


So from my point of view, the 9.4" Tarox kit will have much more brakepower then the 8.4" metro/KAD kit because of the larger brakepad surface and larger discs.

Edited by Poly_Patje, 30 March 2007 - 09:02 AM.


#9 Gr4h4m

Gr4h4m

    Camshaft & Stage Two Head

  • Members
  • PipPipPipPipPipPipPipPip
  • 1,785 posts
  • Location: Chester
  • Local Club: Club less.....

Posted 30 March 2007 - 09:54 AM

Deleted -base data wrong

Edited by Gr4h4m, 30 March 2007 - 01:26 PM.


#10 Renessy

Renessy

    Mini Mad

  • Members
  • PipPipPipPip
  • 275 posts
  • Local Club: minisevenclub Holland

Posted 30 March 2007 - 11:26 AM

Haven't been doing as much reading and calculating as you guys but it seems that this braking stuff is harder and more important than many people would think.

Text was intereting and easy to read too. I find it very important to stop the car too when it's finished....

Still, I don't know if the setup I was thinking about (as explained above) will work.....

For practice and fun you can calculate it for me....... :thumbsup:

René

#11 markrally

markrally

    Z Cars

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 1,377 posts
  • Local Club: Miniaddicts.co.uk

Posted 30 March 2007 - 11:35 AM

Right, All this maths is getting far too complcated!!!

As i can now speak from personal expiereince my first z-cars mini with a busa, Kad pedalbox and kad 4 pots on 8.4" discs stopped ok but for my preference it wasnt enough, (Hence why z-cars have produced a brake kit of their own!!)

My second zcars mini now has tarox 6 pots on 10.25" discs, bigger pads but less piston area than KAD's, same cylinder sizes and similar weight and performance, On first impressions i was expecting the 6 pots to stand on its nose when applying the brake but the difference was hardly noticeable, They are only fitted with ferodo 2500 pads so no getting them up to temperature etc. So hence the need to get more line pressure (smaller master cylinder)as im movig to much fluid and not getting enough line pressure to the calipers. :thumbsup:

Cheers

#12 Poly_Patje

Poly_Patje

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 82 posts

Posted 30 March 2007 - 11:37 AM

Now this is where is gets interesting.... Mark has been schooling me on this subject and I have been doing a lot of reading. The maths gets a lot more difficult when you start changing part of the system but there are some simple rules:

To get a balance is the key factor, I'm no expert I have just been massing loads of data and so far I have found out:

- the larger the Master cylinder bore the lower the line pressure, but the more fluid you move.
- the lower smaller the cylinder on the caliper side the lower the pressure the revers is therefore also true.

This is why matching the systems, calipers, MC's are crucial, even more so when you don't have a split system as the rear also effects the front (Old single circuit), unless you use a valve to limit the rear pressure so your not locking the rears before the fronts.

Its also true that the larger the disc the further the caliper can be spaced which acts like a long bar when removing a nut so you get increase braking.
Overall there is a trend line that shows bigger is better as long as the MC is balanced with the setup. If the MC is too small you get a long pedal but you will eventually get the high pressure, too big and you get a short pedal but you will need to push very very hard to get the car to stop...

Then on top of this you get the effect of even pressure on the pads to ensure the best contact. If you look at the sq area of piston size of the 8.4" mini 2 pot setup against the minispares / metro 4 pot there is not a lot in it but the 4 pots produce a more even pressure across the pad and the pad area is larger.

Then enters heat ... as if you use a whacking great big pad with loads of pressure on a small disc the heat build up will reduce braking, hence why the 4 pots are alloy, why you can get vented discs... and new compound pads.

There is also brake feel which is driver preference, most road drivers prefer a short lighter pedal as is give confidence, buts its all down to choice.

A couple of useful links I have found along the way

http://www.calverst......they work.htm
http://www.calverst....siderations.htm

I have found this subject very interesting over the last couple of days. I have spoken to a few people including BG developments (01527 873716.) who have an interesting new pad compound from Germany called autobahn pads which they have said are good hot or cold.

KC is sending me the AP racing table which shows the data posted in the second link, which I have used to create a graph showing the trend line so that I could plot my Fiesta brake upgrade onto it, once I have the MC data is should help ID a good starting point for MC size... Talking to BG they were going with feel so pedal too long try a larger MC... AP step them up in small increments and they are available from a number of outlets.. expensive route at about £100 a MC....

Anyone else got any more data I can look at? The attached pic shows the Fiesta setup mapped on the trend line of the graph as I don't have all of the data, these figures are shown in RED. Once I have which MC was used to create the original AP deta from KC via AP it might make some more sense....

P.S I forgot to add weight of the car and wheel size also effects performance of your stoppers. e.g small wheel large disc better than large wheel small disc... Plus loose some weight in fact I will go for a run tomorrow :-)


Hi Gr4h4m,

That is interesting, I just sent you a PM.

It is true that you get more feeling with the brake pedal when a smaller MC is used. Most Zcars builders are using a split brake system so the rear brake pressure can be adjusted with an inline Wilwood brakepressure adjuster or the KAD adjustable brake bias box with 2 separated MCs.

For what I have calculated with a very simple MS Excel sheet, is that a 3/4" MC give very little brakepedal movement and a quick brake response so there is little space for errors and less brake control because the brake will lock up quickly. The 5/8" MC would be a good choice for brakepedal movement and brake control. The 1/2" MC should give lots of pedalmovement and control, but you must 'put the pedal to the metal (or floor)' for a lot of pressure. I do not think that this is good, because you would never reach maximum brake pressure.

I think that all our thoughts about braking will help lots of other Mini (re)builders, especially the (re)builders who wish to have a massive brake system for their fast Minis.

#13 Gr4h4m

Gr4h4m

    Camshaft & Stage Two Head

  • Members
  • PipPipPipPipPipPipPipPip
  • 1,785 posts
  • Location: Chester
  • Local Club: Club less.....

Posted 30 March 2007 - 12:09 PM

Deleted -base data wrong

Edited by Gr4h4m, 30 March 2007 - 01:26 PM.


#14 Gr4h4m

Gr4h4m

    Camshaft & Stage Two Head

  • Members
  • PipPipPipPipPipPipPipPip
  • 1,785 posts
  • Location: Chester
  • Local Club: Club less.....

Posted 30 March 2007 - 12:11 PM

Deleted -base data wrong

Edited by Gr4h4m, 30 March 2007 - 01:27 PM.


#15 Gr4h4m

Gr4h4m

    Camshaft & Stage Two Head

  • Members
  • PipPipPipPipPipPipPipPip
  • 1,785 posts
  • Location: Chester
  • Local Club: Club less.....

Posted 30 March 2007 - 01:21 PM

ok I think some of the published data may be wrong which has thrown out the calcs on the trend line as I know the original data for the 4 pots showed the only the area for the 2 of the pots.... based on 36mm pots. So as the data in the article is unclear as the title states that the PSI is load on one side of the disc, which but the SQ area is for all of the pistons (with the exception of the 4 pot which only showed 1/2 of the area it make the calcs meaning less. as I was working the force backwards as it wasn't included in the original data.

So basically as I the base data is a bit hard to understand... ignore me.

Sorry for making this all confusing I have deleted the posts...

Edited by Gr4h4m, 30 March 2007 - 01:31 PM.





0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

Mini Spares