justy75
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| posted on 17/6/13 at 11:22 PM |
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Brake performance question
Hi all,
I have just purchased a very nice Tiger Supercat that has recently passed its IVA. I am concerned at the distinct lack of braking power however, and
would just like some feedback and peoples thoughts.
It has decent Hispec front calipers with greenstuff pads on the front, and standard sierra drums on the rear.
Considering the weight of the car and the decent front calipers I was expecting it to work pretty well, however I have to really stamp on the brakes
in order to get the slowing down process to start!
This is my first kit car so I dont know whether this is the expected performance level of this setup and that my perceived problem is not really a
problem - they are just poor compared to modern cars and what I am used to. Or, there is something wrong - brakes not bled properly or something else.
I wouldnt be suprised if the rear drums were doing all the braking, thats how bad I think the braking is!
Apparently it passed the IVA and the braking felt the same then as it is now, so is this just me and are my expectations too high?
Thanks
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samjc
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| posted on 18/6/13 at 12:31 AM |
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Ask local mot centre to check on their machine cost £10 or bleed the system and see as sound like air in the system.
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iank
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| posted on 18/6/13 at 12:54 AM |
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Well it won't have a servo so will feel considerably different to a modern tin-top. Can you lock the wheels on an emergency with a good
shove?
Performance pads (depending on compound) can need a fair bit of warming up before they really start to perform, especially hard if you have vented
discs. Once hot though they should be able to throw you against the belts if you stamp on them.
Could be many thing, though passing IVA is a good sign that they are at least safe.
Brakes not bled would feel spongy - if you have a firm pedal it's probably not that. Next stop would be the pedal box, with pivot points and
actuator rod lengths to be considered along with cylinder sizes.
Don't worry too much about drums on the back as they'll be doing very little compared with the fronts.
I'm sure someone with a similar set up will be along soon to compare notes.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Bare
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| posted on 18/6/13 at 02:42 AM |
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IMO the Master cyl is incorrectly sized to the Bespoke Calipers. Result is poor to No braking.
Unless a Gorilla is available to stomp the brake pedal.
Common beginner mistake (all Too common) Once you've figured out the correct bore size master, appropriate to the fitted calipers Then you
needs find/buy and retrofit the rascal. Easier said than done unfortunately.
Lesson (if there IS one) is to TEST DRIVE any care ...before ...handing over yer $$
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MK9R
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| posted on 18/6/13 at 05:09 AM |
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The hispecs are absolute crap. They do stop the car if you really push hard but have no feel and are extremely wooden. Bin them and get some wilwoods.
Cheers Austen
RGB car number 9
www.austengreenway.co.uk
www.automatedtechnologygroup.co.uk
www.trackace.co.uk
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britishtrident
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| posted on 18/6/13 at 06:36 AM |
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Pedal effort to stop a given car really depends on two factors hydraulic pressure and pad friction material.
I assume your car has a Sierra master cylinder mounted with out a servo. The hydraulic pressure is low for a given amount of pedal force because
the Sierra master cylinder is designed to work with servo. Master cylinders fitted to servo systems have a larger bore than those fitted non-servoed
systems. Also in a Seven style car because of restricted space in the foot well the pedal leverage ratio is about half that of a Sierra. A lot
of people on the forum have converted to Fiat or early Fiesta or early VW Polo master cylinders to reduce the required pedal force to stop the car.
If you do a forum search on "Fiat master cylinder" it should turn up details on swapping master cylinders.
Provided the callipers are sized correctly the make of calliper has absolutely no effect on the pedal force required to stop the car, however
multi-pot alloy callipers can cause a spongey pedal due to flexing or incorrect mounting. What makes a huge difference is pad material, I suspect
this thread will soon have replies from those who have had similar experiences telling you Mintex M1144 pads are the way to go.
Once that is all sorted out you may find you have to do something to reduce the braking on the rear but that can wait until after the front is
sorted out. Sorting the rear may be as simple as fitting smaller bore rear wheel cylinders.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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melly-g
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| posted on 18/6/13 at 07:05 AM |
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I had the same thing on my Tiger,albeit with standard M16 calipers.
I put on a MK1 fiesta non servo master cylinder, it has made the feel so much better and I don't need half as much pressure on the pedal.
There is a bit more travel though,definetely worth it!
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cliftyhanger
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| posted on 18/6/13 at 07:40 AM |
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Wise wortds from BT above.
If that master cylinder is too large a bore the pedal will feel hard and dead. I made that mistake, fitting a 0.75 bore master to a car assuming it
was uprated therefore better. How wrong I was, going back to a .625 and harmony was restored.
I expect moving to a smaller bore will make things far more pleasant.
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theprisioner
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| posted on 18/6/13 at 09:45 AM |
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Mintex M1144 are indeed the way to go, but even then it takes a good 50-100 miles before they start to really bite. Only after a pad change would I
consider the master cylinder change. I have just gone thru the new 4pot and mintex route presenting to the IVA and passing the brake test. I had to
take for a few short runs (with my foot constantly on the pedal) to get the brake efficiency good enough to pass. The green pads are for frequent
track use and will need more pedal pressure but should still be effective. Some with the green stuff get their discs grooved, not sure exactly what
the benefit is but one guy I know suggested a better initial bite.
http://sylvabuild.blogspot.com/
http://austin7special.blogspot.co.uk/
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mookaloid
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| posted on 18/6/13 at 09:58 AM |
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Swapped my green stuff pads for Mintex M1144 pads and the improvement was immediate. try this first.
"That thing you're thinking - it wont be that."
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justy75
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| posted on 18/6/13 at 10:30 AM |
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Thanks guys, some excellent answers here and really helping me shed some light on to the situation. My general thoughts are having read this that it
may well be the master cylinder being too large as the pedal seems quite wooden and not spongy. I may well persevere with the green stuff pads for the
time being just because I think they need to bed in a bit first, but I don't think that that is the real issue.
I do hear what everyone is saying about the Mintex pads and it would certainly be cheaper to swap them over and start playing around with the master
cylinder I'm sure! So that may be the first step, I'm not sure.
So I will check out the threads on master cylinder size and type, is that what most people think will be the problem is?
Thanks again everyone for your help and input.
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40inches
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| posted on 18/6/13 at 11:04 AM |
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Second the Mintex pads, they work from cold and are waaay better than the Green Stuff pads, the difference is night and day.
I still have the Sierra master cylinder, I moved the push rod nearer the pedal pivot, that helped a lot, but the Mintex pads made me forget wanting to
change the M/C.
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justy75
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| posted on 18/6/13 at 02:05 PM |
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Hi all,
So just pondering responses and thought that I would have a quick look on good old ebay to see if there are any early master cylinders about, and
found this:
FORD FIESTA MK1 BRAKE MASTER CYLINDER ATE UNUSED FINIS CODE 6067715 | eBay
Do people think that this will fit and improve the braking situation?
Thanks again,
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britishtrident
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| posted on 18/6/13 at 03:02 PM |
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Thats the servo version 19 mm bore it will be a big improvement but the ideal is the relatively rare 17.5 mm bore non-servo version.
The standard 2 litre Sierra has either a 22 mm bore with ABS , or 23.8mm bore non ABS.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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ChrisL
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| posted on 18/6/13 at 04:56 PM |
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I've got basically the same setup as you but with mintex 1144 pad and find that I have too much pedal travel, plenty of feel but it feels like
I'm about to run out of travel!
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justy75
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| posted on 18/6/13 at 09:04 PM |
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Thanks for the replies.
ChrisL - are you saying that you have too much travel but the braking is ok with the Mintex pads? Have you tried to the push rod nearer the pedal
pivot as suggested on here? I will probably do this and change to Mintex pads and see how we go.
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justy75
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| posted on 18/6/13 at 09:10 PM |
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Britishtrident - Thanks for your response, much appreciated.
Do you think the one that I sent a link to would be a worthwhile change, along with some mintex pads, or should I hold out and try to find the one
that you suggested. Basically will I see a significant improvement with the ebay one and will it just be slightly better?
Thanks again,
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justy75
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| posted on 18/6/13 at 09:36 PM |
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Bare - thanks for your response.
I think you are probably right. I did test drive the car and was told that non servo brakes feel like this, and as I had no experience to compare it
to, I was unsure whether to proceed. I was however explained to, how the IVA tests the brakes so it gave me some confidence, and made me think I would
have a look in to seeing what could be done to improve the performance.
Fortunately there are plenty of nice people giving me the benefit of their experience 
Thanks
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Dusty
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| posted on 18/6/13 at 09:40 PM |
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Agree with proper survey of cylinder sizes, pedal ratio etc. Just to add my vote for mintex m1144 pads. I had greenstuff previously. They
couldn't have been worse if I had painted the discs with grease. After changing them to mintex I could tell braking had increased by about 400%
within 200yards of setting off on the first run.
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cliftyhanger
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| posted on 19/6/13 at 06:07 AM |
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Mintex do have a VERY specific bedding in process.
code:
BEDDING IN MINTEX “M” TYPE MATERIAL M1144 / M1155 / M1166 / M1177 1. Clean discs with brake cleaner or other solvent. 2. Apply 3 to 4
light applications of the brake from 30mph down to 0mph then...... M1144: 6 / 7 steady applications 70mph down to 30mph M1155: 8 / 9 steady
applications 90mph down to 30mph M1166: 9 / 10 steady applications 90mph down to 30mph M1177: 9 / 10 steady applications 90mph down to 30mph
FINALLY.... Leave to cool as long as possible ( They now work from cold ) NOTE: DONT LEFT FOOT BRAKE ! & DONT LOCK-UP THE BRAKES !
However, pad material is fiddling, ideally you want to get the pedal movement correct first
[Edited on 19/6/13 by cliftyhanger]
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ChrisL
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| posted on 19/6/13 at 08:23 AM |
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quote:
Originally posted by justy75
Britishtrident - Thanks for your response, much appreciated.
Do you think the one that I sent a link to would be a worthwhile change, along with some mintex pads, or should I hold out and try to find the one
that you suggested. Basically will I see a significant improvement with the ebay one and will it just be slightly better?
Thanks again,
Yes basically, feels like the pedal moves to far before the real braking begins, but I don't have to stand on the pedal to get good breaking,
like I did with the sierra front callipers. The pedal setup us standard sierra but with the pedals straightened
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PhillipM
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| posted on 19/6/13 at 09:36 AM |
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To be honest, that's a good guide for bedding ANY brake pad in quickly and properly.
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whitestu
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| posted on 19/6/13 at 10:16 AM |
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I swapped from a 22mm Sierra mc to a 19mm Fiat one and it made a big difference, so don't discount the 19mm Fiesta mc.
I use standard Sierra brakes with EBC yellow stuff pads [EBC advised me that Green stuff aren't right for a lightweight car].
Stu
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justy75
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| posted on 28/6/13 at 09:36 PM |
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Does anybody know whether there is a uprated performance master cylinder that would be a direct replacement AND provide the relevant brake performance
improvement?
Thanks
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justy75
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| posted on 19/7/13 at 10:43 PM |
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ok guys, have made some possible progress here. A chap who builds race cars and services high end bits like Ferraris, Astons etc.. had a look at the
master cylinder whilst tuning my webers, and said that it had been plumbed the wrong way, and that the wrong port was going to the wrong brake. Now
although I didnt build it, I am suprised that it would have passed the IVA with it like this.
Can someone please confirm:
Which end of the master cylinder is considered the front - i.e nearest the bulkhead or neares the front of the car?
Which port goes to which brakes?
I just would just like someone else to confirm the correct way the Sierra master cylinder should be connected.
Thanks
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