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MG MGB Technical - Uprated brakes

Would like to upgrade front calipers. The V8 one's are the obvious choice, but as rare as can be. I can make em' using some Triumph 2000 ones but the same problem exists. I saw on the net a comment about using volvo calipers, does anyone have experience of this?

Gary
G Roberts

Gary,

I think they also offer V8's in mag advets, worth a call

http://www.cambridgemotorsport.com/product_templates/product_default.cfm?menu_temp=brakes.cfm&dep_id=10&prod_id=444&ass_id=180

Paul
Paul Wiley

No problem in getting V8 calipers from Clive Wheatley the last time I needed them.
Paul Hunt

Gary,

You may know this already but the only real difference with the V8 caliper is that it will accomodate the slightly wider V8 disc.

The V8 used pads with a larger area than the 1800 but these larger pads will fit the standard B caliper.

So unless you need the thicker disc you can get V8 braking performance just with a pad swap.

I would try Greenstuff pads in the V8 size before spending money on the calipers.

If you do go to the V8 disc there are alternative calipers of higher performance than the V8 caliper that can be fitted quite easily. The 3 pot Jaguar XJ6 caliper form before they went vented bolts staight on I believe. Then there is the Pricess/Ambassador 4 pot unit, some people use shouldered bolts with these. Also some Rover SD1 4 pot calipers can be used to good effect.

David
David Witham

After an emergency stop which I didn't quite make, (managed to get over and stop on the shoulder)I replaced the Front Brake Pads with Bendix D81 from a TR8. Just slid right in.
If I remember correctly this gave me 20% more brake pad surface area. FWIW
Bruce

D/B- 20% is about the overage attained with the V8 Greenpads, same as TR8 yes? Effectively, per your collective seat of pants evaluation, does that translate into noticeably better stopping power? I just emergency stopped at freeway speed in the non-servo 71 front disc/rear drum, and was shaken at the long distance taken. The larger pads sound tempting, but I'm now considering the dual pump callipers instead. What do you gents think, bigger pads($$) or dual pistons($$$)? Vic
vem myers

A question forom the uninitiated:

I can manage to lock all four wheels on the B I have, and the brakes are nowhere near as good as some cars I have driven. Why is there a need for better brakes?

Thanks,

Dave.
Dave Pothecary

Standard B brakes are well up to the load put on them with normal road use, esp. if you have a servo. Having said that the mod I have done, was to use steel braded flexible hoses. This has helped to make a firmer feel to the pedal.
BTW I also used a steel braded hose for the clutch too.
Cecil Kimber

I've been driving Bs for many years and have always had to be on the alert for brake fade when they get the least bit hot. Maybe my version of normal road use is more severe than most. Brake servos make absolutely no difference in their effectiveness, either.

Mr. Witham, let's here more on the Jag 3 pot caliper subject.
Cheers,
David
David

Dave, did you ever consider different brake pads? If you experience brake fade, a new higher performance pad may solve your problems.

While I see all this talk of bigger calipers and brake pads and I don't hear anything about bigger rotors. Rotor size is an essential part of reducing brake fade and shortening the braking distance. Rotors are really just a giant heat sink to dispell the heat of the friction. W/o bigger rotors bigger calipers may not help all that much. You need to get rid of heat or a way to absorb more heat by using mass and ventilation.
Mike MaGee

Mike,
I've tried Ferodos and Mintex but not green stuff, which is probably my next step. Like Gary, I would also like to upgrade my calipers if for no other reason than to be able to install thicker rotors for the reasons that you state. I know that TR2000 (MkII)/TR2500 calipers are a bolt on if you use 15" wheels and that would enable 1/2" V8 rotors to be fitted, but just try to find a pair of TR calipers over here. I met a guy at the last British show in Titusville, Fl. who sells a Wilwood kit with alloy 4 pots and vented rotors that bolt on, too. It was a beautiful piece, but it costs $600+ and I am just a cheapskate who has two cars to do brake mods on. The idea of the Volvo or Jag bits is very interesting. I drive my wife's Mini Cooper S once in a while and after tearing around in that thing my B seems to slow down like a locomotive.
Cheers,
David
David

I got my Triump caliper halves from Austrailiaia through this BBS. He had c aouple halves and sold me a set for about $65 USD- and shipping was another $85 USD.

Rebuilt the calipers, and their waiting to go on the race car. only went to V8 calipers to run V8 rotors, to try to keep brake temps down on a vintage race car- No aftremarket calipers allowed
Greg Fast

Dave pothecary,

There is a difference between stiction and friction.


Everyone harps on about brake fade and uprated pads. I use my B for mainly track days, I have used uprated pads, but at the moment I am using stock pads. I have yet to experience brake fade.

I would much prefer to spend a bit of time sorting out some air ducts to the front brakes and make the best of what I have before upgrading. Thats what I have done and it costs about 10quid.

Joe
Joseph Phillips

Joseph,

You must be very lucky not having experienced brake fade yet...
Last summer I went for a drive with a friend who took his MGF (no vvc, standard car).
We drove, rather spiritedly, along the country lanes and I don't think we ever went over 70 km/h (about 45miles per hour) yet after half an hour of driving, it felt as if my brakes were sponges.
The brakes have been renewed last year(pads, calipers, discs), and the only mod to the car back then was a pb fast road head.
I too am looking around for better brakes, as a short while my car will have a tad more power than standard and my parents are getting a bit worried...

The hybrid V8 solution is the most attractive one to me, for the instant...
please keep this thread going, it's already been very very interesting.

Alex
Alexander M

Is there any real world problem with removing the front brake backing plate to aid cooling? Other than offending the members of the Abingdon Inquisition, of course.
David
David

Thanks for all the comments. Living in the UK gives me various options. The V8 route I'm not sure about as it does not give any additional braking efficiency other than the ability to have a thicker disc (rotor) which will help with brake fade. I think I will pursue the Princess 4 piston option if I can get them over my Rostyle wheels. Does anybody know if this is possible?
G Roberts

About the Volvo calipers, the holes to mount them are about 6 mm too close but that can easily be fixed. This friday, i'm gonna pick up a set from a volvo friend and try and work with them. they are 4 piston calipers, and because th evolvo disks are vented and wider, they can handle a wider disk. the discs to use are either peugeot 505 and modify the back of the front hub to bolt them on, or use 84-86 nissan 300zx and make an adapter in case they need to be changed. i will be exploring all of these options and will post my results when I have some. both types of discs are vented. results will be on my webpage, http://www.roverv8.com
Jake

David -

I've actually cut away the upper half of the disk dust
shields for aided cooling (it still retains four mount bolt holes). It's been like this for at least 20 years
and I've had no problems with this.

Of course, California does not experience the
drenching rains as do some other parts of the globe.
Daniel Wong

David, From Florida
if servos make no difference then why did M.G. fit them as standard on later models? Every manufacture counts the cost of every screw nut or addition equimnet and if the said item is considered not to be required then it is ommited. Servos do help!
Cecil Kimber

Cecil,
No they do not. They are there simply to reduce pedal effort and to make certain cars more attractive to those who fancy such niceties by giving the illusion of better brakes. Stopping distances nor any other aspect of the braking sytem, other than pedal effort, improve with a servo. If a non-boosted car can have it's tires locked with normal effort it will not benefit performance-wise from having one added.
Cheers,
David
David

I have removed the disc brake dust cover to aid cooling, it doesn't cause me any problems. One point I would say is make sure that you have decent quality brake fluid and its change often.

Alex,

If you are suffering from brake fade and not doing more than 45mph there is a problem. MG Motorsport run an FIA spec MGB with standard brake components (they use race pads and fluid) and they don't even use any cooling ducting. They don't suffer any brake fade.

Remember driving fast is about being smooth, and carrying corner speed and momentum. There is no need to brake at the last second for every bend.

Joe
Joseph Phillips

Joe,

You're absolutely correct that speed is about being smooth, but at that time, we were just making fun. I should have mentioned that the lanes we were using have a lot of very slow corners, and we used the bits in between of those to accelerate of course :-)
Nonetheless, I am amazed to learn that the MG Motorsport FIA MGB does not seem to suffer any probs.

Anyway, I still have to convince my parents that the car is up to the power and to be honest, I want to make sure that the car can stop safely in any condition too...

Does anybody have any experience/info on the hybrid v8 brakes?

Alex
Alexander M

Alex,

Have you got 15 inch wheels? If so, have a look at Wilwood brakes. They are good value for money IMO.

Joe
Joseph Phillips

Alex, when did your friend last change his brake fluid? Any moisture in the b/f and hard braking could cause the soft pedal.

The only time I overcooked my brakes was in Colorado going down a steep mountain at which time I downshifted and tried to use engine braking but that was of no use either so I just went fast, faster and faster.
Mike MaGee

I may just remove my backing plates. Joe, do you have any info on the Wilwood calipers? I have 15's.
David
David

Ive been using wilwood calipers and discs for a few years and have been very happy with them. On the front I have 297mm vented discs mounted on custom ally bells with superlite four pot calipers and on the back I have 273mm vented discs again mounted on ally bells which double as a spacer. Also using Compomotive ML 15x7 wheels.
Have photos if anyone is interested.
Some people have said that wilwood calipers are noisy but I have not experienced this.

Mark
Mark

Mark,

Can you mail me some pics, hehe. I like your car.

Cheers Joe
Joseph Phillips

David,

Have a look at www.wilwood.com

Joe
Joseph Phillips

Mark,
I found Wilwoods to be noisy (chatter) unless you use m spring, the Hawk pads are good but squeal so change to Greenstuff unless you want to stand out in crowd.

Paul
Paul Wiley

With hi performance pads your discs can be glowing and you still have brakes. The intermediate hi perf. pads will stop in the cold and wet and still work well in very hi temp conditions. 1st change pads, 2 check your fluid. Ordinary alcohol based fluids will pick up moisture in a humid climate, quickly. Water boils at a relatively low temperature and can produce major brake soft/sponginess. Finally, 14" alloy wheels fit very close to the disks and limit cooling air. The old narrow wheels or 15" wheels provide more cooling to the brakes.
Check the basics before you move to the exotic.
Barry
Barry Parkinson

Paul
Which wilwood calipers did you use?
I have tried green stuff pads and dont like them at all. Best Ive tried so far are wilwood Poly "D".
Never had a squeal problem. The pads can move in the calipers slightly causing a slight tick when the brakes are applied but if you alter the stainless abutment plated this can be sorted.

Mark
Mark

One thing I will add it that in my opinion the standard brakes are OK for normal road use.
I agree with Barry, first change pads.
Joe Ill sent some pics this weekend.

Mark
Mark

I agree with Barry and Mark. A change of pads and fluid and your brakes should be adequate.

Joe
Joseph Phillips

If you want to stop faster, get better Tires!

If you are able to lock up all four tires with the existing system, then there is no brake improvement that will help. If you are not able to lock up all four, then you have some other problems to attend to.

I have "Track Dayed" my car on stock, V8 and now Hawk pads, with silicone fluid in the lines, and stainless flex lines. Never have I had the brakes go away due to heat (Max of 10-15 laps per session).I am aware of some deterioration as the heat builds, but not yet a problem. I can't imagine heat related braking problesm ever comming up with street driving.JM2$ worth.

Pete
Pete

Peter,

That is not totally true. Poor brakes can still lock wheels.

joe
Joseph Phillips

Pete,

I can't believe this! So you are saying I am hallucinating then?
Let me tell you another story: a while ago, a friend of mine (fellow B-owner) decided to try to follow an MG RV8. The RV8 driver instantly knew and tried to shake hime, which eventually worked as my friend's brakes were smoking. (remember, this was on public roads, so no excessive speeds were attained, which reduces the RV8's power advantage).
BTW, I can lock up all four of the wheels without any problem.

Mike,

I had renewed the brake fluid on my car a couple of months before (my friend had no problems, his MGF was fine).

Alex
Alexander M

Pete,

My apologies, didn't mean to be so mean... (I had better re-read what I wrote BEFORE pushing the button)

It seems to me that people who're using silicone brake fluid do not suffer from the fade, so that's something I'll definitely look into!
What brand is the one to get?

Alex
Alexander M

So...anyone got a tried opinion on the extra function, if any, on the 20% more surface area TR or Greenstuff disc pads?
vem myers

Vem;When I installed the Moss supercharger I replaced the discs and went with the Mixtex V8 pads. They seem to have improved my stopping ability quite a bit. Ray
Ray

Alex,

don't rush into using silicone fluid. Give a few motorsport and tuning companies a call and see what they say. I think you will find they won't advise using silicone fluid.

Joe
Joseph Phillips

Gary,
I went to the U-Pull-It today and found two Volvos there. One is an '82 240 wagon with 4 pot calipers and vented rotors and the other is an '81 240 sedan with 4 pots and solid rotors. I'm going to try to find out the specs on each type and then go back and get the correct pair, if there is even any difference. They want $20.00 for the pair and at that price I can afford to experiment some.
David

I'm using volvo brakes. There's a kit put together by "MG workshops" here in Melbourne Australia.
If you don't want to buy off the shelf, take a set of Volvo calipers to a brake shop and ask them to reco' and cross drill, then redrill the mounting holes (get a quote first).
Each volvo caliper has two hydrolic lines, so one of the lines out needs a bolt put in it and the internal lines connected by crossdrilling. The caliper mounting holes (which are roughly 5mm too close to gether) are redrilled with a slight offset so both bolts take the force equally. YOu end up with slightly V shaped holes. If I were getting this done, and not buying a kit, I'd also ask the brake place to maybe press in a bit of rod before redrilling for appearance sake.
You need to get some hoses made up, metric at one and and MG at the other. For the caliper end you need to use a type of fitting that I don't know the name for(Doh!) . It's similiar( but smaller than)the one on the back of the clutch master cylinder and the one used on the SU fuel pump. Bolt in the middle and circle around the edge type. This is important as you need to adjust the angle of the hose to clear the suspension.
(you could buy a set off MG work shops)
Peter

For some tips on how other cars converted to Volvo calipers and some of the problems encountered try this link. Although not for MGBs it may give ideas to some of you.

http://www.311s.org/tech/brakes/volvobrakes.html

Mike MaGee

Forgot to mention, I'm using ventillated disks from a nissan, although peugot disks will work. I guess the my calipers must be off a later volvo than Mikes. By cross drilling you oviod the messy pumbing.
Peter

David, Florida

You were interested in my comment about Jaguar 3 pot calipers. I got the information from an article in a leading UK mainsteam car magazine called Autocar.

In about 1979 they did an article about an MGB built and owned by a man called Bill Nicholson whoused to be a famous competion car builder and competitor as well. (At one time his daughter was married to a certain Mr Senna)

Any way Bill had used the 3 pot calipers from an early Jaguar XJ6 with MGB GT V8 discs. The calipers bolt straight on the MGB. Later the XJ6 went to vented front discs so its calipers became wider. The calipers in question were used on certain other UK cars of the time. Possibly Jaguar 420, Rover P5B & P6B.

Having just written the above an idea comes to mind. The later XJ6 calipers that were used with vented discs may fit if you can find suitable discs. Has anyone tried Rover 800 front discs on a B. The stud holes will be in exactly the right place. (I carry a Rostyle in the boot of my 800 in place of its space saver). I would give this mod a try if I was not in the standard class of the MGCC spedd championship.

David
David Witham

Just uprating your front brakes will increase your braking distance.
Leland Bradley

About "braking capacity"

It's been mentioned in this thread, but some people are missing it. It's also not relevant to the original question, which was "I want to upgrade" without details on why.

Addressing the issue of the "emergency highway stop". We assume that the brakes are cool at this point. You press on the brakes, and the car begins slowing. If you are _able_ to lock up the brakes *just before stopping*, then your braking system has enough capacity. No brake upgrade could possibly help you reduce that distance.

Why?

Because you are limited in this case by the amount of friction between the tires and the road. You are able, at any point, to apply more friction to the rotors than the tires can transmit to the road.

Now, there are many things that can change the way that the brakes FEEL. A booster will make it easier to push, but will not change the amount of force on the brakes. Stainless steel brake lines will remove some of the initial pedal mush that the rubber lines have as they expand, but will not change the amount of force on the brakes. Bleeding your brakes of crap and air bubbles will remove some of the initial pedal mush that the rubber lines have as they expand, but will not change the amount of force on the brakes. Changing compounds will affect the coefficient of friction between the pads and rotors (and thus how hard you have to press the pedal to get the same amount of braking power) but will not change the amount of force on the brakes. (It will up the maximum amount the system is capable of, but you are already exceeding the tires friction limit, so you can't use it).

Again, all of this is running under the assumption that the brakes start cool, and at the end of the stop, are still able to lock up all four tires.

Summary: IF YOUR BRAKES CAN STILL LOCK THE TIRES AT THE END OF THE STOP, WHAT LIMITS YOUR STOPPING DISTANCE IS THE TIRES.

Now, new topic: what about *repeated* stopping? Ahh, like road racing, or "spirited" driving. Well, here, upgrades can help you. All three components, pads, rotors, and fluids, can reach heat levels where they become near useless. My RX-7 Twin Turbo will exhibit this after three or four 120mph to 30 mph stops within a couple minutes. Everything just gets too hot. So, if I wanted to be able to do that kind of thing for hours on end, some new equipment would be in order.

But what to upgrade? Fluid? Pads? Rotors? Calipers? You'll need to do some research in some racing books; it's possible to determine which of these is your problem by looking at the symptoms.

Cheers,
Anders
Anders Green

OMG! Whats this 'my brakes are so good because the will lock the wheels' business all about? Even some of the worst brakes will still lock the wheels! Why? Because stiction and friction are two different principles.

If you read some books or find out about the basic physics involved then you will realise that some of this tyre rubbish is well.....rubbish.

Yes tyres will make a big difference, but by being able to lock your wheels does not mean that your brakes can't be improved.

Joe
Joseph Phillips

Joseph Phillips wrote:
>Why? Because stiction and friction are two different principles.
>If you read some books or find out about the basic physics

I checked my physics books, "stiction" wasn't listed. *grin*

>being able to lock your wheels does not mean that your brakes can't be improved.

The statements I made don't disagree with this statment. Mine are qualified for a particular situation.

Cheers,
Anders
Anders Green

David Witham,
Thank you for adding the information on the early Jag XJ6 calipers. As luck would have it, I know where a series I XJ6 is sitting. I'm going to rob the gauges from it on Monday and to get a Renault Alliance FI system from the same junkyard. I'll take a look at those calipers!
David
David

Anders,

Interesting comments which may be worth further comment.
However, this is key
My RX-7 Twin Turbo will exhibit this after three or four 120mph to 30 mph stops within a couple minutes.

Most of above relates to vented, larger pads - which aid heat loss and better quality pads which maintain high coefficients of friction, or increasing number of pistons aiding pad stability or lighter callipers reducing unsprung weight.

Tyres make a huge diff.

Paul
Paul Wiley

Joseph: Can you elaborate? In my field (Effort and motion testing) we use the concept of "stiction" to reffer to the combination of an interference fit and friction. This combination would be seen in a axle running in a TIGHT bronze bushing, for example.The combined interference fit(IF ANY)) and coeficent of friction of the components will resist the initial turning of the axle. Once a part starts sliding along another, the coeficient of friction goes down. Take two clean gauge blocks and rub then together; they will "stick" together due to friction.

How does this apply to stoping a car in a shorter distance?

Pete
Pete

This thread was discussed between 04/12/2003 and 20/12/2003

MG MGB Technical index

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