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I Finally Understand The Ap 4pot Kit, It Now Makes Sense


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#1 dw1

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Posted 19 May 2009 - 02:30 PM

Long post alert, but it might be useful if you're thinking about doing anything to your brakes as it will take you through my journey of discovery. As a result you might be able to avoid my issues and find a shortcut to happy braking that's right for you. I've written this so it's also accessible for people newer to VXs so for those knowledgable old timers some of this may seem like teaching your egg sucking granny.

Having had the big brake kit for the last 18 months I've never been fully happy with my investment and have struggled to understand the benefit versus the amount it cost. Bear in mind I went from all standard, to Mintex1144s all round then straight to the BB kit at the front with the Ferrodo 2500 pads. I was also running part worn Hankook RS2 tyres with the 16/17 wheel combo. I was expecting to stop quicker and harder, only to find that with the Ferrodo pads, my tyres and abs off, I was locking up in a blink. With abs on stopping was good but didn't feel any better than with 1144s and my 2 pots, in fact it seemed like there was less initial bite - what a disappointment!

I moved to RS14 pads on the front and RS15 on the rear, changed tyres to KU31s and things started to get a bit better, but again the braking force didn't seem a jump better than when I had 2 pots. Last week I changed to R888 tyres and it was only this weekend at the Nurburgring that I finally 'got' the point of my investment and am now actually happy with it. The brakes were faultless and worked in perfect harmony with the 888s, the Pagid RS14/15 combo and the softened off nitron suspension. Despite doing three laps back to back there was no hint of fade at any point, I was able to confidently brake late in certain safe places, there were no lock ups as the pedal feel was spot on and within 15 minutes the discs were cool to the touch.

LESSONS LEARNT:
Lesson 1. A Big Brake kit will NOT make you stop any quicker or give you eyeball popping braking! End of story. I thought it would and that's where I was going wrong.

Lesson 2. Be clear on what you want and what you're expecting from your upgrade - my expectations were wrong from my own lack of education hence why I was originally disappointed. The things to consider are...
i) Do you do a lot of track work? Then build up progressively on the mods to see their effect.
ii) Will you do more track work in the future? There's little point in going the full monty until your increase your track time and find the need to uprate in stages.
iii) Will you only be doing road driving? If you don't intend to go on track there is absolutely no point in going for a 4pot system, other than it does look very cool.
iv) Will you mainly be doing road driving with the occasional track day? Even standard brakes are ok for a track, uprate the pads and Bob's your mothers brother.
v) Do you want to stop quicker? That's not the brakes, it's mainly tyres that do that bit, so get some 16/17 combo wheels and a set of semi slicks like R888s or A048s along with any half decent pad and your stopping distance will shortern.
vi) Do you want better pedal feel? A 4 pot system may help here
vii) Are you getting brake fade a lot? A 4 pot system with larger, ventilated discs will definitely help, larger discs on their own might do the job.

Lesson 3. Its all about the whole braking system, rather than single components and there needs to be balance

Lesson 4. To get balance you need to consider tyres, pad compound, front/rear brake balance, suspension settings, discs and calipers all working together

Lesson 5. Modify your braking in stages
i) Change your fluid (at least annually), doesn't have to be 5.1, DOT4 could well be enough if you change often. Then if you need more...
ii) Try Mintex 1144s first. Then if you need more...
iii) Try more aggressive compounds from the likes of EBC, SBS, Pagids or Carbonne Lorraine. Then if you need more...
iv) Try bigger, alluminium belled discs. Then if you need more...
v) Try a 4 pot kit like the AP Big Brake kit - but don't forget that you may not be enamoured with the Ferrodo pads that come with it (which are ok ish) so put in Pagids or similar
vi) Get an ABS cut off switch (I was used to slamming on the brakes but with the extra force of the 4 pots you don't need to press anything like as hard and I found that difficult to adjust to, I realised I wasn't very good at modulating and have had to spend quite some time learning how not to lock up the fronts, especially on standard road tyres)

Conclusion: Off the track 4 pots (of any make) is an irrellevance. By gradually uprating your braking in stages you might get to your own perfect setup without the need to go to the extra expense of a kit. For all I know I might have got the same result by stopping at allu belled discs with standard 2 pots - I'll never know and I could have saved myself some money. However what I do know now is that for mere mortals like myself on track, when pushed hard, the Big Brake kit is the daddy, it gives confident, consistent, fade free braking and is a joy to use. Very pricey, but now at last I understand it and what to expect from it, I'm glad I went for it but I really would advise that you don't jump straight into it like I did unless you're very clear about what you want and will get.

Safe stopping out there.

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Brought to you by dw1 productions with the letters 'BB' and the numbers '£1699' ;)

#2 Retset

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Posted 19 May 2009 - 02:36 PM

Excellent advice which needs to go in the useful threads section thumbsup I would concur with you that standard brakes may well be enough. I have standard with good fluid and 1155's. My only criticism is the hard brake pedal in the latter part of a track day. It's not fade but some sort of vacuum issue and 4 pots would not help that. With discs at £100 a full set and pads a bit over that, it is a very 'disposable' set up as well ;)

#3 DarrylB

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Posted 19 May 2009 - 02:42 PM

Great post! Very informative thumbsup I suspect this'll help a lot of members with their brake choice queries

#4 MAXR

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Posted 19 May 2009 - 03:24 PM

There’s a lot of truth in what you’ve said. I’m still running standard Callipers, front & rear but have upgraded the front discs to AP 295’s and RS14’s plus the usual braided hoses, brake fluid & cooling ducts. It has constantly amazed me that everyone seems to think that 4 pots will give them a big improvement. Even after heavy use on track, my car has decent stoppers. The one area that is affected is the initial bite. I will be taking C.Randells advice & swapping to Carbon Lorraine pads next time, with a more aggressive pad for the rears than on the fronts. Although braking is obviously an important part of going quicker on track, it WILL NOT give you big increases in lap times, exiting a corner near the limit of adhesion onto a straight will however give you the best improvements in track times. Getting your sticky tyres up to an ideal operating temperature is extremely important for the ultimate stopping distances. Ultimately, my tyres go off first way before my brakes do. I have driven a VX turbo with AP 4 pots & RS14’s for 30 minutes then my car for 30 minutes back 2 back on track and I must confess that I did not think the 4 pots made any difference to the braking. But, presumably after many laps it may be a different story. Also, the tubby had standard seats with a harness, which to be fair, did feel awful on track compared to my MOG buckets & harness setup. Then there’s those who say that the arse end of the car tries to overtake the front...I don’t get it, surely any major heavy braking should take place in a straight line. If you’re braking hard right into a corner, chances are you’ve taken too much speed off & or have unbalanced the car & the corner will have been compromised anyway. Brake deep but try let your car settle before carrying through your speed on a good line under throttle, it will give you a few meters advantage coming out of the bend and your brakes will be used less. Max

#5 LazyDonkey

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Posted 19 May 2009 - 07:59 PM

You'll be telling us next that wider fronts don't cure understeer and that more bhp isn't necessarily going to make you faster :rolleyes: ;)

#6 southpaw

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Posted 19 May 2009 - 08:24 PM

Review


Well put thumbsup

#7 techieboy

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Posted 19 May 2009 - 08:33 PM

Phew, finished it. That's a great write up there DW1 and will hopefully help others through the minefield. Glad it all came together for you in the end. thumbsup

#8 danger7

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Posted 19 May 2009 - 11:10 PM

Nice write up thumbsup Reading your review certainly struck a chord with me as I did exactly the same thing, fitted an AP big brake kit and assumed the braking would improve markedly and was left wondering what had I just done. One comment I would like to add is that there is very little weight over the front of a VX and that also restricts the braking efficiency and with 16" fronts fitted it really screws up the ABS. I've just fitted 17" fronts with a 205mm width and the braking with ABS has become much more efficient and the ABS is not activating unlike when I had 16" fronts fitted. Also recently I drove a VX N/A with a brake bias kit fitted and that also highlighted that more rear biasing has a positive effect (although I had limited time to properly test it) on braking balance. Just thoughts. Cheers Ian

#9 siztenboots

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Posted 20 May 2009 - 06:54 AM

Nice write up thumbsup

Reading your review certainly struck a chord with me as I did exactly the same thing, fitted an AP big brake kit and assumed the braking would improve markedly and was left wondering what had I just done.

One comment I would like to add is that there is very little weight over the front of a VX and that also restricts the braking efficiency and with 16" fronts fitted it really screws up the ABS. I've just fitted 17" fronts with a 205mm width and the braking with ABS has become much more efficient and the ABS is not activating unlike when I had 16" fronts fitted.

Also recently I drove a VX N/A with a brake bias kit fitted and that also highlighted that more rear biasing has a positive effect (although I had limited time to properly test it) on braking balance.

Just thoughts.

Cheers
Ian


Ian,

What is the rolling radius of the new 205/??/17 tyre ?

#10 VXJON

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Posted 20 May 2009 - 07:47 AM

thumbsup

#11 JG

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Posted 20 May 2009 - 08:00 AM

chinky chinky thumbsup (although no suprise :) )

#12 chrisculpt

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Posted 20 May 2009 - 04:47 PM

I have just put a pair of AP ali belled 300mm discs on (£ 75 on ebay!) - not a big difference in dia, but coupled with 1144's, braided hoses, and dot 5.1 fluid - there seems to be a real difference in feel and stopping power tho' not had then chance to try on a track yet, just seems a huge improvement over standard set up, and I feel much more confident in the brakes now, doesn't feel like it would need 4 pot calipers, just the larger discs seems enough - it was even difficult to lock the wheels before, no matter how hard I braked , down side is , i now realise the abs could be a problem on the track tho.. maybe have to fit a switch

Edited by chrisculpt, 20 May 2009 - 04:48 PM.


#13 l14mha

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Posted 20 May 2009 - 05:02 PM

my 2p worth. my 1st track day i melted my brake pads, got frustrated with the abs and the brake pedal was a joke. i nearly smashed in to the back of my mate in an exige s. i simply could not stop for the hairpin at pembrey..... 2nd track day, snipped the abs, bought new disks and mintex 1144's all round. melted them and the braking was not that much better. they sound a little like preditor when they get really hot. th-th-th-th-th-th-th-th 3rd track day, pagid rs14's all round, braided hose, performance brake fluid, no abs. and i have never looked back. faultless braking, good brake feel and no fade. (combined with R888's) liam chinky chinky

#14 danger7

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Posted 20 May 2009 - 10:15 PM

chinky chinky thumbsup

(although no suprise :) ) meaning what exactly :)



#15 danger7

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Posted 20 May 2009 - 10:41 PM

Nice write up thumbsup

Reading your review certainly struck a chord with me as I did exactly the same thing, fitted an AP big brake kit and assumed the braking would improve markedly and was left wondering what had I just done.

One comment I would like to add is that there is very little weight over the front of a VX and that also restricts the braking efficiency and with 16" fronts fitted it really screws up the ABS. I've just fitted 17" fronts with a 205mm width and the braking with ABS has become much more efficient and the ABS is not activating unlike when I had 16" fronts fitted.

Also recently I drove a VX N/A with a brake bias kit fitted and that also highlighted that more rear biasing has a positive effect (although I had limited time to properly test it) on braking balance.

Just thoughts.

Cheers
Ian


Ian,

What is the rolling radius of the new 205/??/17 tyre ?


Hello, 254mm vs 260.9mm assumed dynamic rolling radius from wheel centre.

Cheers
Ian

#16 Pidgeon

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Posted 21 May 2009 - 05:24 PM

I think the first post could be abbreviated "Fitted Pagids - brakes now perfect" chinky chinky

#17 walkes

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Posted 22 May 2009 - 08:54 AM

Track = Braided Hoses = Stop sponge effect.... :D

#18 Crabash

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Posted 18 October 2009 - 07:22 PM

For me Pagid RS14's have been spot on, non of the ill effects I've heard people talk about with certain brake set ups, no fading and a new set of disks every 1 or 2 sets of pads at less than £100 for the 4 keeps it all tip top. Only reason I can see myself changing to a different disk or caliper is to save weight and tbh theres plenty of more important stuff to be done before that. I will try out some pagid alternatives next time I think, also I have always thought a bias adjuster would work wonders on the vx. 1 thing that bugs me with brakes is the "tat" that gets sold when more often than not the braking improvements came from replacing the rusty old things with new disks, so many people get sucked into buying ever more expensive braking systems that are not always needed or indeed any better than the original when refreshed properly wish some suitable pads. I,m not saying this is the case with the AP system for the VX but I certainly wouldn't blow £1500 on them, unless I was experiencing probs with NEW standard disks and suitable pads for my use of the car.

Edited by Crabash, 18 October 2009 - 07:23 PM.


#19 Leon_1984

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Posted 18 October 2009 - 07:52 PM

Track = Braided Hoses = Stop sponge effect.... :D


interesting thread. Braided's give a much better feel, different fluid is a must for a trackday and a bigger kit will generally just resist fade for longer.

Does anyone know how the vx front/rear bias works? most modern cars use the abs unit to stop the rears locking, how is this effected if people are switching the abs off? or does it not need it due to the weight over the rear?

ta

#20 Steve B

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Posted 18 October 2009 - 08:07 PM

With the talk of brake bias and the vx being better with more bias at the rear why don't people just fit a bigger diameter disk at the rear?




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