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Brakes vs. Tires

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Brakes vs. Tires
#1
Brakes
  This topic is about my 1977 MG MGB MkIV
Thurlowb Avatar
Thurlowb Silver Member Brad Thurlow
Coquitlam, BC, Canada   CAN
First... I'm sorry for bringing this up....

As far as I can tell, my front brakes are working as well as can be. As a 10/76 build, the car has a brake booster system.

During yesterday's autocross, it occurred to me that I had not locked the front brakes at all this season. So I set about to try to do it. After crossing the timing lights at the end of each run, I hit the brakes as hard as I could. Rears locked...that is for sure.... but it took me three attempts before I was able to get the front R to lock and the front L never did...and it took all my effort to do that.

You race guys maintain that you can still lock the fronts, with race rubber tires, using the stock braking system, right? My 205/50-15 RE-71Rs are pretty sticky, but not compared to a true race tire.

Why might I not be getting all I can out of my front brakes? Brake pad recommendation? (brake fade isn't an issue) I suppose I could do a brake fluid replacement, just to see.

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twentyover Avatar
twentyover Greg Fast
Lives in SoCal, Resides in the Burbs of Detroit MI, USA   USA
What pads are you using?

Thurlowb Avatar
Thurlowb Silver Member Brad Thurlow
Coquitlam, BC, Canada   CAN
I don't know. What would you recommend for autocross/street use?

Brad

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Steve64B Avatar
Steve64B Steve Opitz
Phoenix, AZ, USA   USA
1966 MG MGB
If, you're not getting equal performance from the front's, then a change of pad composition won't change anything.

Get the front's braking equally first. Rebuild the calipers and, if you're going to change to a different pad compound, get the disc's turned so they offer a fresh face for the new compound pads to bed in on.

Plus, when you go to "performance" brake pads you have to be prepared for more noise (squeel when cold) dust and a difference in initial brake bite and changed modulation.

Also, if your system if too rear biased, then back the adjuster screw off a little to keep the rear,s from locking first.

Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
In reply to # 3748781 by Thurlowb I don't know. What would you recommend for autocross/street use?

Brad

Hawk brake pads, make entire series of brake pads for almost every purpose you could think of, heck they make three series of different race brake pads, they make track day pads, autocross/aggressive driving street pads, all the way to normal brake pads. I have used Hawk brake pads now for 20 years, great product.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


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Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd, Florence, KY, USA   USA
If your front brakes won't lock up you aren't getting enough pressure to the front calipers. Period, end of story.

Why, is the question. Could be lots of things. Improper brake balance. Improper matching of bore sizes. What are your front calipers? Stock, or otherwise? If you've replaced them you could need a larger or smaller M/C.

Jim

Thurlowb Avatar
Thurlowb Silver Member Brad Thurlow
Coquitlam, BC, Canada   CAN
Everything about the braking system is 10/76 stock. Front rotors and pads look good.

I think I will back off the rear adjusters a touch. There is no front/rear adjustment, right?

V8MGBV8 Avatar
V8MGBV8 Carl Floyd
Kinggsport, TN, USA   USA
In reply to # 3749672 by Thurlowb Everything about the braking system is 10/76 stock.

Replace the front brake hoses with quality stainless steel hoses. Leave the back one alone for now. May help the brake balance.

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Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd, Florence, KY, USA   USA
Glazed pads could cause that too.

Jim

tvrgeek Avatar
tvrgeek Silver Member Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
Try some Porterfield pads. Had them on my Morgan, Spit and new Mini. Behaved almost as quickly as stock, but far more breaking. They are on my short list for my B

Sure your booster is working?

Different car, but I was not at all impressed with Hawlks on my RSX. Took forever to bed, longer to warm up ( OK for race, manageable for street, not for autocross where you have that corner 100 feet from the start) and even at peak, not sure they really were any better than stock Honda pads.



Cogito ergo sum periculoso

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bills Avatar
bills Bill Spohn
W. Vancouver, , BC, Canada   CAN
Hawk has a large range of pad materials only some of which work best on a street car.

I run EBC Red Stuff on my Solstice and Porterfield R4S on the BMW and both are excellent with good initial grip and enough fade resistance to cope with anything you could do on the street.

The OP cleary has an issue with the front brakes - I've seen a lot of cars with old rubber brake hoses experience deterioration inside the hoses which can result in flaps of flaking inner liner acting as valves and reducing brake action.

First, replace the hoses - all three - and replace all the brake fluid and bleed it properly. Only if that doesn't work will you need to look more deeply, in which case there are a number of possibilities (I've seen corroded calipers with one frozen piston, for instance - that will put a crimp in you braking pressure!)



Bill Spohn www.rhodo.citymax.com/carstuff.html
Current: 1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1957 Jamaican MGA (200 bhp)1965 1971 Jensen Interceptor (350 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
2007 BMW Z4M coupe (340 bhp)
Recent: 1969 MGC roadster (175 bhp),Jensen CV8 (375 bhp),
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
North Vancouver BC

joron Avatar
joron Silver Member Michel Joron
Roxboro, QC, Canada   CAN
1977 MG MGB "Victoria"
Something is wrong with the calibers or the hoses.
It should be possible to lock all the four wheels nearly simultaneously at 30-45 mp/h with the rear brakes lock slightly before the front brakes do.

Rear brakes are adjustable the front brakes are not.

The rear brakes are adjusted so the emergency brake holds the car in down hill at 75% of its course.



1977 MGB Red 'Victoria'
All Classics:
Married, 2 children, 2 dogs, MG MGB May to December.

Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd, Florence, KY, USA   USA
I always liked having the front brakes lock just slightly ahead of the rear ones. Goes back to the oversteer/understeer argument, it is usually better to have the front plow a little than for the rear to break away. Plus, if you get off the brakes when the wheels start to lock it means you have just a little more braking because the fronts are more effective than the rear.

But it's better to have them all lock simultaneously.

Jim

Blueosprey90 Avatar
Blueosprey90 Jeff Sienkiewicz
New Milford, CT, USA   USA
Oh Boy! Another chance to share a video.




MGA: I run Vredestein Sprint radials and use Porterfield R-4 front brake pads. On the rear, probably a Moss brake shoe, compound unknown. I found that the R-4S Porterfield pads that Bill mentioned glaze up more than the R-4.

If you have sticky tires, I think it would be harder to lock up your brakes, all other things being equal.

If one of your brake rotors ever heated up significantly, that could explain why one front locks and not the other. Supposedly the metallurgy changes from the excessive heat, making the rotor a bit more grabby. I used to experience that problem and solved it simply be swapping out the suspect rotor.

bills Avatar
bills Bill Spohn
W. Vancouver, , BC, Canada   CAN
Jeff, I always ran R4 on the race car after I ran out of DS11. They seemed to have no downside - certainly never glazed. I'll take your word for it that the R4-S do that - they really aren't a race pad, more a high performance street pad. I've been quite happy with them on my BMW sports.



Bill Spohn www.rhodo.citymax.com/carstuff.html
Current: 1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1957 Jamaican MGA (200 bhp)1965 1971 Jensen Interceptor (350 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
2007 BMW Z4M coupe (340 bhp)
Recent: 1969 MGC roadster (175 bhp),Jensen CV8 (375 bhp),
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
North Vancouver BC

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