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MG MGB Technical - brakes upgrade

i am possibly looking at upgrading my brakes as i intend to get my car up to 100bhp at the wheels... nothing amazing, but still a 50% increase.

1)can i put the larger v8 pads in a normal b calliper ?
2)in what way would braking be improved by changing up to v8 discs/calipers/pads ????... has someone felt the changes ..is it worth the money ?
3)has anyone upgraded to 4 pot brakes ? how does this imrove braking ..is this overkill for a 4 cylinder b

thanks
phil
phil tavaria

Phil-
1) Yes, but remember that they are "handed". That is, the inner and outer pads are not interchangable.
2) The V8 pads have a 20% larger surface area and thus take more time to overheat and fade, but don't expect a huge increase in braking power if you're using the standard organic material pads. To get that you'll need something that produces mor friction.
3) Yes, four-pot calipers are overkill. They're great for racing, but not necessary for street use.

Perhaps the best way to get more stopping power is to use V8 pads made of Carbon Kevlar material. They have a higher coefficient of friction and are more resistant to compression when hot, thus they increase braking power while fading less. They also produce less brake dust. I use them, so I know. British Automotive sells them. They have a website at http://www.mgbmga.com Ask for Part # LD48KEV. Try 'em, you'll like 'em.
Steve S.

Hey, Steve. Is this the same as the GreenStuff pads? Just bought a set and vented rotors as well, but haven't "stuffed" them in yet. Shough I actually get increased brake performance?

'69 MGB w/ booster (from '77).
Luis

Interesting thread. 4 pot calipers from a Rover sd1 or austin PRINCESS are the cheapest real upgrade that I have found. There are loads of threads. Greenstuff pads are great but on my daily car, a peugeot 306 rallye, they caused chronic disc warping after 6000 mostly motorway miles.
phil may

Phil:

I have the V8 pads in my GT. The car has seen a few track days and on a five lap sprint, there is no fade problem. As mentioned above, the retardation is based on more friction, so I would consider a more "grippy" pad if I knew of one. Also, the V8 pads were, like, 3 times the cost of regular!OUCH!

Pete
Pete

Phil,
The stock brakes should be fine. Your not increasing the weight of the car
and probably will not be driving much faster (just getting to speed quicker).
The B brakes are well balanced and very reliable. Just make sure you
keep them up but that going for any brake system.

Have fun with that hot-rod.
Leland Bradley

Has anyone ever thought of altering the brake pedal arm pivot points so that there would be more
mechanical advantage for pushing in the brake master cylinder?

You'd have to do the same to the clutch pedal, too, as they share the same relative pivot shaft and clevis point positions.

On each arm, if the clevis point were brought closer to the pedal arm pivot by, say, 1/8" or 3/16",
and then the pedal pivot shaft raised (on the pedal box) the same amount so that the clevis rod
alignment is maintained with both master cylinders - I would think there would be a noticable gain in
mechanical advantage. Some minor braze welding would be required to partially fill-in the existing
pivot shaft holes on the pedal box.

Total pedal travel would be increased a bit...but overall pedal effort would also drop, and it's a very
low-buck alternative to 4-pot calipers and vented disks, or converting to power assisting, etc.

Just a thought.
Daniel Wong

Phil,

My car has over 105bhp at the wheels (courtesy of a Peter Burgess 1840cc engine )and I use V8 'green stuff' pads (From Brown & Gammons £28 approx.)and they work fine, a bit 'dead' at first but get better after 500 miles or so.
However I am considering fitting different rear brake cylinders to reduce rear wheel lock-up.

ps. Peter Burgess supplies really good stuff I've dealt with him for 15 years, check his web site out.
www.peterburgess.co.uk

Nick
Nick Ashmore

Out of interest - what is the logic behind fitting V8 pads.

The reason for extra pots is Pad stability and fitting V8 pads has the opposite effect.

Phil,

From the data I've seen, EBC Greenstuff are by far the best pads available for road use but do need bedding in.

IMO the best method of improving braking is tyre grip.

Also IMO upgrading brakes must be worthwhile as you never know when a few feet will make all the diference. What would be useful is data on available callipers and discs and unsprung weight.

Paul
Paul

Luis-
The Greenstuff pads aren't the same as Carbon Kevlar. Carbon Kevlar pads are specialty items. At $100/set, they're far from cheap, but they'll stop the car real fast if your tires can handle the additional power. British Automotive also makes rear brake shoes with this material for $150/set (Part #ES437/KEV). However, the Greenstuff pads have a pretty good reputation. You say that you've purchased vented rotors? Which calipers are you going to use them with?

Perhaps one of the best things that anyone can do is to replace the old, bulging brakes hoses with braided stainless steel hoses. They improve the "feel" and thus the control of the brakes. Of course, there's little point in increasing maximum braking ability if the tires aren't upgraded to match, but that's another can of worms.
Steve S.

Along with the V8ads, I also have the braided steel lines and R compound tires. The lines made the biggest change as for the feel of the pedal (rock hard) and the tires are responsible for most of the increase in braking distance. I do not think I can even lock-up the front tires anymore. The larger pads were only used to avoid heat build-up and fade.

R compound tires may seem like an expensive way to up-rate the brakes, but you also get an increase in road-holding that will surpass any other mod you could make.

Pete
Pete

Sorry Steve, that should read bought "drilled" rotors. Couldn't finance a set of "vented" rotors and change calipers at this point in time.

Changed all my brake lines about a year ago to original unbraided. Will go for stainless braided next time. Can't wait to bed in the greenstuffs though. Next brake job though I'll investigate that Kevlar stuff and see what you guys are talking about.

Cheers
Luis

Steve,
British Automotive no longer supplies the Kevlar lined shoes.

Leland Bradley

Leland-
Drat! Now what do I use when the ones I've got wear out? Does EBC have a website? I need to find out what the friction coefficient of their Greenstuff Kevlar pads is so I'll know if they'll be compatable with the Carbon Kevlar pads that I got from British Automotive. (Drat, drat, drat.....)
Steve S.

Ted Schumacher at TSI carries carbon kevlar pads for MGB's at $90
and shoes at $175. A friend uses them on his TR-8 for autocrossing.
http://www.tsimportedautomotive.com/
Clifton
Clifton Gordon

Steve,

Off top of Head - Greenstuff COF 0.46 Carbon Kevlar 0.41.

They do have a website ebc-brakes.com

pAUL
Paul

Clifton-
Thanks for the website URL. I've bookmarked it for future reference. $175 for a set of brake shoes?! Looks like inflation is taking its toal.

Paul-
Thanks for the specifications. Now, if only EBC made brake shoes out of the same material to match!
Steve S.

Steve,
I have been using Carbotech Kellate lined brake shoes, from Cambridge Motorsports, with a coefficient of friction 0.48-0.50. But they are costly 120 pounds + shipping. However they stop the car. I am using the Carbon Kelvar pads and GT cylinders on the rear. I had to move the balance bar for more front when I changed shoe material.
Leland Bradley

For reference, does anyone know the friction coefficient of the standard rear shoes and the pads? Also does anyone have any experience with a shoe/pad upgrade combinations that don't require bias adjustments in the hydraulic systems?
I'm thinking that if I were to upgrade my front brakes, the fronts would go from doing 70% (correct %age?) of the work to doing somewhat more due to the higher COF (or bigger pads, or what have you). That would mean there's room to improve the rears to keep the rears contributing as much as possible without upsetting the proper balance. Or am I full of crap on this? If improvement at all 4 corners means fitting a bias valve, that's fine if I have to. There's enough kids and bad drivers around here that I think any improvement isn't overkill unless it overwhelms my tires, thereby either negating the brake improvement or giving me a great excuse to get some 15" k/o minilites and sweet tires.
Also, I thought I used to know this, but advantages/disadvantages of crossdrilled vs. grooved rotors?
Thanks, Wade
Wade Keene

Wade:
According to one of the tech articles on Doug Jackson's web site (http://www.mgbmga.com/):

"These angular grooves are essential when using today's modern brake pads. They allow gas buildup, between the brake pad and rotor, to escape, as well as channeling away water, brake dust and debris. This kind of brake rotor is preferred over the cross-drilled type brake rotor."

The cross-drilled rotors seem to have fallen into disfavor, but they do look really cool if you have wire wheels. I think they are prone to stress fractures during the drilling process, too.

Regards,
Jerry Causey
Jerry Causey

This thread was discussed between 28/09/2001 and 02/10/2001

MG MGB Technical index

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