14 replies to this topic

[Big Jim]

Carroll Shelby noted that Phil Remington worked out a way to change the brake rotors on the GT40's in about a minute's time. Can anyone explain to me how the way that this was accomplished?

[Doug Nye]

I'm not sure I believe that... changing discs in 60 seconds?  Pads maybe - but discs?

 

DCN

[Tim Murray]

From this profile of Phil on the Road & Track site:

“The GT wasn't too bad to start with," Remington said. "It needed brakes and the wire wheels had to go, but it just needed to be sorted out."

This is a typical Remington understatement. The car needed a ground-up rethink. Shelby American was soon under Ford's control, with Remington in charge. He claimed this project was his favorite, and it's easy to see why—Ford wanted to take down Ferrari regardless of cost, and a handful of firsts emerged from the Princeton shop, including quick-release brake calipers, floating rotors that made fast pad and rotor swaps possible, and the first curved rotor-cooling passages. ("We had problems with rotors cracking along the straight cooling passages. We figured out that if the vents were curved, it fixed the cracking. Wasn't anything fancy.")

[2F-001]

I'm sure I've seen Aussie V8s swap discs in half that time, with a kind of split and articulated caliper.

 

I've seen a video of discs and calipers swapped as a unit, with dry-beak couplings on the hoses and new calipers already filled and ready; I forget what the event was - Le Mans GT or N'Ring 24hrs maybe? - which seemed a good deal quicker even than that. I will try try find a link...

 

Edit:

This is not the film I was thinking of - and I'm certain I've seen it done quicker than this - but go to about 2m 15s in this...

Edited by 2F-001, 30 May 2019 - 18:07.

[Jerry Entin]

This comes from Frank Lance, a Shelby GT Ford Team member in the day:

I can only talk about the 1965 Shelby American GT40’s that we ran at Daytona and Sebring. I was not involved with the 1966 and later cars.

What we did was mostly what I brought from Chaparral. When we ran the front engine cars at the 62 Road America 500 we knew that we could not run 500 miles without changing the brake pads. Hap Sharp’s mechanic, George Brand. made some quick latches for the Girling calipers so we could hit a pin and flip the pad hold down mechanism back and were able to extract the pads quickly. Once the pads were in place all one had to do was snap the latch shut and replace the wheel. We made basically the same thing for the GT40’s however we did not have to change the rotors for either race. We could do this pad change in around 3 minutes as I recall. We were to use this same system for the 65 Le Mans race but unfortunately we had engine and ZF gearbox problems before we needed a pad change.

One more thing. The Phil Remington quote in the Tim Murray statement as coming from the Princeton shop would not be accurate. The quick change discs did not occur until the shops were moved to the LA airport, and that was sometime after Le Mans 65.

This was done to the MK II cars. The quick pad change that we did for Daytona and Sebring was on the 289 engine cars and was done at the Princeton shop. Which was near what is now Marina Del Rey.

The move to the LA airport was done while we had the Daytona and Sebring cars in England and at Le Mans for the test session.

Frank Lance

[Jerry Entin]

At Road America in 1962 Frank and his crew seemed to have been progressively faster during the 500.

According to The First 10 Years of Road America, which describes the last of the three Chaparral pit stops:

“…their pit crew was magnificent, as witnessed by their last pit stop when new brakes on all wheels and 27 gallons of fuel were poured in exactly one minute and one second.”

All research: Willem Oosthoek

[Tom Glowacki]

Mark Donohue did something similar on his 1968 Trans Am Camaro:

 

Bill's (Bill Howell, GM engineer, who, of course, had no involvement with racing) idea was to put a vacuum on the master cylinder to pull the pistons back in.  We already had a source, in the brake booster system, so all we needed was a pressure regulator to prevent sucking air in past the pistons, and a valve so that the driver could actuate the system. . . By the time the wheels were off the pistons had retracted, and the mechanics whipped the old pads out and the new ones in - just like popping bread into a toaster."  Unfair Advantage, pp. 99-100

[Lee Nicolle]

This comes from Frank Lance, a Shelby GT Ford Team member in the day:

I can only talk about the 1965 Shelby American GT40’s that we ran at Daytona and Sebring. I was not involved with the 1966 and later cars.

What we did was mostly what I brought from Chaparral. When we ran the front engine cars at the 62 Road America 500 we knew that we could not run 500 miles without changing the brake pads. Hap Sharp’s mechanic, George Brand. made some quick latches for the Girling calipers so we could hit a pin and flip the pad hold down mechanism back and were able to extract the pads quickly. Once the pads were in place all one had to do was snap the latch shut and replace the wheel. We made basically the same thing for the GT40’s however we did not have to change the rotors for either race. We could do this pad change in around 3 minutes as I recall. We were to use this same system for the 65 Le Mans race but unfortunately we had engine and ZF gearbox problems before we needed a pad change.

One more thing. The Phil Remington quote in the Tim Murray statement as coming from the Princeton shop would not be accurate. The quick change discs did not occur until the shops were moved to the LA airport, and that was sometime after Le Mans 65.

This was done to the MK II cars. The quick pad change that we did for Daytona and Sebring was on the 289 engine cars and was done at the Princeton shop. Which was near what is now Marina Del Rey.

The move to the LA airport was done while we had the Daytona and Sebring cars in England and at Le Mans for the test session.

Frank Lance

On a good day I can change pads in about 3 min on the front of my racecar with 4 spot Wilwoods. Or the Jag 4 spots I used on another car. Remove pin/s, push old pads back with a expanding pliar, install new pads and replace retaining pins.
Though I would not do it that quick when red hot!!
In the GpC Touring car rules here once or twice a team replaced the pads and seemed to forget installing the retaining pin,,, pad came out about a quarter of the way and machined the rim in half!!

[Doug Nye]

And how long did it take to change discs/rotors, not just pads?

 

DCN

[Big Jim]

And how long did it take to change discs/rotors, not just pads?

 

DCN

Doug,
In the Carroll Shelby interview that I listened to, he said about one minute. He was speaking of the Le Mans cars.

[Tim Murray]

From Ford GT40: Production and Racing History, Individual Chassis Records by Trevor Legate:

Air ducts were certainly required for the brakes, an area where Ford had to admit it still had problems. Neither the technology or metallurgy existed to produce a braking system which could regularly curtail the prodigious speeds of which the Mk II was capable. Phil Remington came up with a design which permitted the rapid change of brake pads, but John Holman was credited for a unique piece of thinking which solved the Mk II’s main weakness - quick change discs. The whole brake caliper assembly could be swung away and new discs installed within seconds (although removing a red-hot disc must have been a popular pastime with the hard-working mechanics!)

and from this page:

Because pad wear and rotor cracking were insoluble, at least for this year, it seemed that methods had to be found for replacing brake parts quickly. Two neat solutions along this line came forth from the racing teams. Shelby American head Phil Remington devised quick-change brake pad retainers which allow rapid removal and replacement of the pads. A remarkable new feature was conceived by John Holman of Holman-Moody during the year's development: quick change discs! This is a first, and surely will start a trend. The disc hats are outboard of the hub flange and held in place by the wheel studs, the caliper and the wheel itself. Thus when the wheel is removed, and the caliper swung away (which requires only the loosening of two bolts), the disc may be snatched off and a new one slipped on in seconds. Design details and development work on this item were carried out by Ford and Shelby American engineers. Disc diameters remain 11.6 in front and rear, and Girling BR single calipers are used at both ends of the car.

On the linked page there are a couple of photos showing a disc being removed/replaced.

[Doug Nye]

Understood.  

 

DCN

[Lee Nicolle]

Most brakes these days are a hat over the hub. Remove the calliper with 2 bolts as described and replace rotor and hat. Even many OEM production cars use this set up and have for 20+ years. Though they generally have a retaining screw/s to hold the rotor on the hub.

From my point of view very easy to do in the workshop on the hoist, a lot harder when everything is red hot and you are  rushing, especially fitting the calliper back on. And on your knees doing it.

Though as I understand these days not a real problem with slow fuel fill. And a LOT of practice as well.

[mariner]

If the fourth picture on the link is meant to be a fast change disc set up I don't think it actually is.

 

You can clearly see the two caliper holding bolts close together and undone with the caliper hand held to avoid straining the hose.

 

To get a quick disc change system you really need the top caliper to upright bolt to be outside the disc diameter and the bottom one to be quickly removable. Then you swing the caliper up out the way and pull the disc off. 

 

If you don't have a brake servo like Mark Donaghue described you can screw a conventional pressure bleeder onto  the master cylinder cap and pull it out to pull the brake pads back.

 

That's  fine but the engineering challenge , I suspect, is to have the caliper bolts loose enough for quick  release but solid enough to stop the caliper moving under load. Modern road brakes do this all the time as they 95% use single swinging calipers but they are not as rigid as racing ones.

Edited by mariner, 04 June 2019 - 12:26.

[Lee Nicolle]

If the fourth picture on the link is meant to be a fast change disc set up I don't think it actually is.

 

You can clearly see the two caliper holding bolts close together and undone with the caliper hand held to avoid straining the hose.

 

To get a quick disc change system you really need the top caliper to upright bolt to be outside the disc diameter and the bottom one to be quickly removable. Then you swing the caliper up out the way and pull the disc off. 

 

If you don't have a brake servo like Mark Donaghue described you can screw a conventional pressure bleeder onto  the master cylinder cap and pull it out to pull the brake pads back.

 

That's  fine but the engineering challenge , I suspect, is to have the caliper bolts loose enough for quick  release but solid enough to stop the caliper moving under load. Modern road brakes do this all the time as they 95% use single swinging calipers but they are not as rigid as racing ones.

Sucking those pistons back scares me, very likely to suck air as well. Using the big 'pliers'  to get the pistons back before removing the calliper is the best way,, just dont wear the pads right down! having half a calliper flex out of the way means the calliper will never be stiff enough.

Most cars I see,, not a full range have either 2 piston floating head callipers or 4 and even 6 piston.

I use a now over 30 y/o single piston [front] calliper on the rear which compensates for the [live] axles moving in and out. Not ideal but works. I also use residual valves which limits the pad knock off. These days aftermarket ones from Wilwood but in the past from seventies cars that had them fitted external to the master cylinder.

If any one says they do not get pad knock off they are A.  not trying near hard enough. B. have the near impossible stiff stub axle / uprights. The trick proper fabricated ones should not be a problem, but it seems even they flex a bit at times.