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The Brian Redman International Challenge at Road America, Jim Hall Grand Marshal
Author: ArchitectPage
PH: "Brian, when did you first drive a downforce car?"
BR: "Must have been ..."
JH: "It was a strange thing that happened. Brian's sittin' there trying to remember and it's difficult. That was the winter of 1963/4. We started to run a little lip on the back of our car. Ferrari had done it, actually, a year earlier but the light bulb never went on. When those guys did it Richie [Ginther] was driving. He said, 'Well, it stabalised the car.' "
"Those guys thought they had built a bad car and they put the ducktail on it and that fixed it. There was no jump forward from there. There was no thought that they could take advantage of downforce. That never occurred to them."
BR: "No it didn't. Well Porche's whole philosophy, and we're talking about 1969, was all how fast can we go down the straight and how light can we build a car. That's all they thought about. No thought of downforce."
JH: "Clear till 1969 and that's after we were running wings. Downforce is like supercharging in a way. You take the same machine and you put a little downfoce on it and what happens is the traction goes up by the amount of the downforce. If you keep it balanced you can pick up that much corner speed and it's amazing what it does for you."
PH: "When I got out of school with an ME degree in 1966 I went to work for Pratt & Whitney Aircraft in Florida there were winged sprint cars racing on dirt. I looked at that and thought, that couldn't do anything, but then I thought about it and saw that higher normal force adds to the friction force."
JH: "In '66 we introduced the high wing and I actually heard Eric Broadley [deposed founder of Lola Cars] tell somebody, 'If Hall had the suspension right he wouldn't need that wing.' "
BR: "So three or four years after Jim started using wings these top teams still weren't using them."
JH: Laughs. "Isn't that amazing. If you think about the time span. Eric really thought it was a crutch that we had to use because our car wasn't very good. That's the way he thought about it."
BR: "In 1969 we took the Chevron B16 out at the Nuburgring. The car was brand new. It wondered all over the road. I know now that was lack of downforce. We played with it for three days. We actually went to narrower front wheels thinking it was picking up the cracks in the road. We tried Bilstein shock absorbers and it was better. Then on Friday qualifying, we were at an 8 minutes, 30 seconds lap time. The Abarth team had three cars qualified down in the 8 min, 12 sec. area. On Saturday we added a 2-inch tab on the rear of the bodywork and straight away we were 12 seconds faster. We put it on the pole and Abarth were running for their cars but it was too late. That was 1969 at Nurburgring."
All of us laugh.
BR: "But even then we didn't really follow up. It was just a tab, not a wing."
PH: "I remember going to races in the 60s at Riverside. I remember seeing the wings on your cars move. You had it rigged so the wing would flatten out on the straights and tip up when you got on the brakes."
JH: "We had some problems with that. We didn't test it enough. I thought we were safe and doing a good job but I really didn't have a good enough handle on it. We lost a lot of races because we didn't finish. We'd have something go wrong. We'd been a lot better off to run last year's car. Hap always said, 'Let me have the old one.' He thought he'd win more races in obsolete race cars because they would finish. And he's right."
PH: "In 1965 you wrote a couple of articles for Car & Driver magazine. I had lost those but a subscriber of my newsletter sent me copies a couple of months ago."
JH: "That's a fairly comprehensive, limited vehicle dynamics article. It's easy to understand and not too complicated but I think it's still technically correct."
PH: What kind of help did you get from General Motors?"
JH: "A lot from the standpoint of my education. There was a lot of interest on their part when they wanted to make the decisions on the Corvette. It's funny, they had all that stuff I wrote in that article written down too. A guy named Maurice Olley figured out most of the vehicle dynamics stuff in the 30s."
JH: "Another GM guy, Frank Winchell, invited me to go to Cornell labs and fly the B-24, the variable stability airplane. You could go through under and oversteer. You could program it in the air. I was 30 years old and it was a wonderful experience. That's what made me really. Probably Frank Winchell had more to do with my success than anything else. You ask what I got out of it, that's what I got out of it. They made some parts and pieces too. They could make things we couldn't. He'd say let me make one of those, I know how to do that."
PH: "But you guys did a lot of fab work in MIdland. I talked to Troy Rogers (Jim's crew chief from the early years) yesterday about that."
JH: "Yeah, almost all of it. If people come and tell you that the Chaparrals were designed and built at Chevrolet, then that's bull. Sandy {Jim's wife] and I, we mostly shaped all the bodies. The guys would work during the day and when they'd quit we'd come back in and we'd take a spatula and take some clay off and pad it in like we thought it should be and we'd be there till midnight. I'd leave a note and the guys'd be in the next morning at eight and smooth it up.
"It might sound silly but the Chaparral shape is pretty simple. We took all the pieces, the engine, the transaxle, the driver, the wheels, and we just put them in the minimum space you could put get 'em in. Then we started building body around that. We did a lot of mockups because I'm not a good draftsman. That's a part of engineering school I missed. I started school thinking I would be a geologist. When I switched to mechanical engineering and they didn't make me make up the drawing part of it."
PH: "When did you go to Cal Tech?"
JH: "1953 through 1957."
Brian gets a call on his cel phone and excuses himself.
PH: How do you think the engineering education helped you?"
JH: "I don't see how you live without it. That's the way I feel about life. How would you know what you were going to do about almost anything? I've got a terrible curiosity about how things work. It started out when I was a child. I'd tear shit apart and not be able to put it back together. Now I can finally put most of it back together. I'm really curious and that probably hampers me to some extent. I want to know how it works and then I want to make it work better. And that's the whole fun in life really, I've really enjoyed that. It's been great."
PH: "Well, I've run out of questions. I really appreciate the time and the conversation. I really enjoyed it."
JH: "You're welcome."
When our interview ended Jim got up from his chair and turned to move through the small group of people who had been listening to us. A couple of them thanked him for coming to Road America. A few asked for autographs. Jim Hall, ever the gentleman, smiled and obliged one and all.
Jim Hall Interview
The Brian Redman International Challenge, Jim Hall Grand Marshal
In June I learned that Jim Hall's Chaparrals would be featured at the vintage races at Road America, near Elkhart Lake, Wisc., July 20 to 22. The event title was The Brian Redman International Challenge. Jim Hall was the Grand Marshall. The black and white photos on this page are from the event program.
I called Cheryl Barnes, communications director at Road America to see if I could get some time with Jim Hall. The book I'm working on will try to explain some technical aspects of tires, vehicle dynamics, and shock absorbers. Jim Hall was one of the first technically educated people involved in designing modern racecars and I wanted to talk to him about his experiences.
?
The event at Road America, was titled Can Am Thunder. I decided to drive to the track from my home in Springfield, IL. on Thursday, stay somewhere that night and drive back home Friday afternoon. After a few phone calls I found a room north of Milwaukee less than a half hour from the track.
The drive up on Thursday proved uneventful taking about six hours. A friendly young lady quickly issued my credentials, and I found my parking pass into the into the paddock area right in the middle of all the racecars and haulers. Let me tell you that doesn't happen at CART or NASCAR events.
As soon as I drove through through the front gate I heard the unmistakable sound of big-bore race engines so I stopped at the first grandstand I saw. The treat layed out before me was the sight of a bunch of old Can-Am cars roaring down the hill from the right, tip-toeing into Turn 14, and then blasting up the straight pounding the ground with their exhaust. Ten minutes later I got back in the car and drove to the media center. The rest of the afternoon I walked around the paddock looking at the cars, an impressive gaggle of historic racecars from mundane Triumphs to the almost unique Scarabs to Formula 1 cars less than 10 years old.
Maybe the most beautiful Formula 1 car of recent years is this Ferrari from 1991 owned by Tom Murphy of Wilmette, IL.
The Interview
On Friday just after noon I sat in the media center over my notes. Then Jim Hall appeared in tow behind Cheryl and he sat down followed by Brian Redman. Brian's appearance was a surprise to me. He's a subscriber to the newsletter and I've talked to him at various races finding him to be a charming and delightful guy. I had only prepared questions for Jim Hall so I would have to figure out how to get Brian into the conversation.
We sat in three chairs in one corner of the media center and I explained the topics I wanted to cover. Jim started talking and I turned on the tape recorder. Almost immediately the other eight or ten people in the room began edging closer so they could listen in on the conversation without actually looking like eavesdroppers. It didn't work because Jim soon included them in his words and gestures and we were just a bunch of racers listening to a pair of our heroes telling stories.
As I transcribed the tape it was easy to recognize and differentiate the two voices. Brian's deep, rich British tones contrasted with Jim's tangy Texas drawl now softened by time and world travels.
PH: Early on you bought racecars made by other people. How did you get started designing racecars?
JH: I drove cars and tried to make them better. I'd make an educated guess as to what to do. And I used the feedback from the driver, which in my case for a long time was myself, which I think was pretty critical for my education. The feedback is kind of instantaneous and pretty reliable when you do it that way. I think that helped me a good deal. I got to do some work with what was probably some of the original instrumentation on racecars. Chevy R&D put together an instrumentation package because they wanted to know the numbers, not just the subjective driver feedback. So I got to see quite a bit of real data and that helped a lot. It's not anything like they have in data acquisition today but it was very useful even though primitive."
PH: "That was going to be one of my first questions, did it matter being a driver. So you were an engineer and you had some ideas and you were a drivers so you got instant feedback whether those ideas were good or not."
JH: "Yeah, I think that was really important to my career as both a designer and a driver. Sometimes I thought it helped me as a driver and sometimes I thought it hindered me a little because I was always thinking about ways that I'd like to make the cars better rather than just worrying about getting it around the corner. I think it might have hindered me a little bit in some ways but all in all, just looking at the guys I drove against and how I competed and so forth I was not unhappy because I felt like it was a good balance."
PH: "You bought a Porsche Spyder early on. So that was one kind of car you looked at."
JH: "Yeah, I didn't have any experience with Porsches up till the time I got to racing nationally in SCCA races. When I went to local races I always had a better car than the local guys so it wasn't good for them and it wasn't good for me."
PH: "You had some good battles with Delmo Johnson [Jaguar D type with a Chevy V-8 engine] at Green Valley Raceway."
JH: "Yeah, but that was a big car vs. a small car and that was good. I enjoyed those races. That was the real reason I got the Porsche and it was a great experience for me because it was a different handling car and it was a car that had a lot of racing history and I got to experience that.
"How I got that car is interesting. Buddy Berlin from Albuquerque was the VW dealer there and I knew him because I grew up in Albuquerque. He called me one day out of the blue and said, 'I've got an RS61 on the dock in Houston and I don't really want to take delivery. I don't have the money. Do you want it?'
"I asked him how much it would cost and he told me and I said I'd take it. I went and got it and drove it one time at Green Valley and, to tell you the truth, I didn't like it at all. It really pushed badly and it wasn't fun to drive.
"The next week I got a call from Roger Penske. I didn't know him at that point. He told me he needed an RS61 because Bob Holbert had one and was beating Roger with it. He suggested trading his Porsche RSK for my RS61 but we'd keep our own engines and gearboxes. He said make him a price. We figured out a deal and he sent one of his guys down with the car and we swapped engines and transmissions and he went off with the car.
"The K was a helluva car. It would take a set real nice and you could drive it around a corner with the throttle and it seemed like it had a lot of cornering power.
"We used to wonder, before we began to think of the science of it, why the little cars like the Porsches would beat the big cars. We'd go to the short tracks and they'd be all over us. They'd come off the corners a little quicker, they'd squirt for a little while, and they'd go deeper into the corners on braking. I'd wonder why I was having so much trouble staying ahead of this guy in this little 1600 cc car. What it was was he had about the same size tires as I did but the car was a lot lighter. He got a lot more cornering power than I did. That wasn't so obvious to everybody in those days, how important the tires are."
PH: "We know now how important tires are. For both of you, Jim and Brian, has there been some time when tire development jumped ahead and you went seconds faster? [At last I had figured out how to get Brian in the conversation.]"
BR: "I was driving a Lola T70 Can-Am car in England in 1966. We were running on Dunlop Green Spots, I think."
JH: "Only about five and a half inches of tread on those, I think."
BR: "Bruce McLaren was the official tester for Firestone tires. They brought three of their cars to Oulten Park in North England which was only an hour from where our car were garaged. The McLarens all blew up and the Firestone people asked us if we could bring our car to fill in the next day. We did. Firestone had a wider tire that was almost a slick and we went four seconds faster than our previous best."
JH: "That tire had almost no tread, only some little sipes cut in it."
BR: Even then the wider, slick tires didn't get going for several more years."
JH: "During that time I was with Firestone. Bruce and I were the guys that ran Firestone tires. I did the testing in the States and he did it in England. When we first built the so-called automatic car it was a single speed torque converter, with no transmission. All you did was put it gear and go. It had a two-to-one torque multiplication out of the torque converter so it was like having a high second gear. On the Dunlop Green Spots, the best tire we could get, we could spin the tires from about 10 feet out of the gate up to 80 mph or something. So we thought why do we need anymore transmission than this. It was fine not having any gears.
"Then I got with Firestone and they brought us development tires. The first tires we got were wider than the Dunlops. They had an inch or so more tread on the ground. We were runnin' 7-inch rims in the back I think or maybe 6-inch in the front and 8-inch in the rear. Or 5s and 7s. I don't recall exactly. They were 15-inch diameter wheels. We put the Firestones on and tried them in our skidpad testing.
"We had started runnin' skidpad tests, just going round and round on the skidpad. We did a lot of tire testing and that's the way they checked the friction coefficient to see what kind of cornering power you're actually getting. We got good at it and we found out we could balance the car this way. You could put the car on the scales and balance the weights but you go out there on the skidpad and it won't turn the same both directions because somethin' is amiss in the car.
"It was a little bit more technical than we could figure out. Either the chassis was tweaked a little bit or the caster was off on one side or somethin' and you'd find out running around on the skidpad that, in one direction, it would go up to 0.98 Gs and only 0.92 the other way.
"That skidpad was really handy. We'd crank a little weight in the car to balance it. You could look at the camber by looking at the temperature across the tire. We found a little time on the skidpad made a big difference, made a nicer car. We started setting up all our cars that way. We'd get them all ready to go to a race and we'd go a few rounds in both directions and make sure it was balanced. That was good for slow speeds, about 40 mph, and then we'd go out and run through a hig-speed turn, 150 mph, and we'd see how it was balanced. That was the way we set the aerodynamic balance.
"So Firestone told us their tire was built to run on a 7-inch wide rim. I had built some modular wheels and we could vary the width by what mid-section parts we used. We'd run the tires they gave us on a 7-inch rim and maybe an 8 and a 9 too. The wider rims made the sidewalls stiffer and istead of running a 0.95 average G you'd run a 0.99. So of course we put them on 9-inch rims.
"Well, we'd go to the next race and the Firestone guys would look at them and say, 'We didn't design those tires to run on a 9-inch rim. We better build a new tire.' They'd add an inch to the tread. They'd do them quick too. They can build prototype tires in a hurry. In a couple of weeks they'd have another tire. And we'd run it on a 9-inch rim and a 10 and maybe an 11. And we'd find it was better on a wider rim so it would happen all over again.
"In a matter of less than a year we went from those narrow little Dunlop Green Spots to a tire that was almost double the width. And our single-speed torque converter just couldn't handle all that grip. We immediately went to a two-speed transmission so we could get more torque multiplication off the slow-speed corners.
"So that's what happened with me on tires. In the middle 60s, probably 64/65, Firestone took us from less than 6 inches of tread with up to 12 inches."
PH: "Just because you kept skidpad testing them on wider rims."
JH: "Right."
BR: "Speed is the criteria, at the end of the day. Speed on the skidpad is speed around the racetrack."
JH: "Cornering speed is the key to everything. You can have more horsepower, you can accelerate fast but you got to stop it at the other end. But, if you leave the corner just that much faster, you carry that speed all around the racetrack. The whole thing is cornering speed, basically."
I continued the conversation by asking about shock absorbers, more correctly referred to as dampers.
PH: "At that same time what was going on with shocks? Did you have much choice? Both Brian and Jim look at each other and chuckle.
BR: "Konis."
JH: "We were running Konis too, I think. We tried some Armstrongs I think. They had an adjustment on them. Compression maybe?" He looked at Brian.
BR: "Yes, it was a compression adjustment. But people didn't take much notice of shocks at that time."
JH: "Well, we were running on light enough springs and small enough tires that there really wasn't much of a problem. The cars were more like passenger cars than the racecars of today. With those light spring rates the tires would ride over the bumps."
BR: "The tracks were much bumpier then. In those days most of the tracks were very bumpy. Formula 1 cars and Indy cars of today can't tolerate tracks that bumpy."
JH: "The tires stayed in contact with the gound most of the time and it didn't take a whole lot of damping to do that. We learned as the tires got stiffer that you had to back off on the rebound forces to let the wheel come back down and make sure the tire didn't jump up off the ground. But it depends on tire stiffness. Damping is a little bit black art anyway. Today it might not be but I'm talking about the 60s."
BR: "In 1969 on the Chevron cars we started using Bilsteins. They worked a lot better."
PH: "That was a gas-pressure shock."
JH: "That made a lot of difference, the gas shock. Before that the shocks used to overheat and they went away."
BR: "These days the teams have got guys who do nothing but make shock changes."
JH: "Yeah, all they do is change little features in the shocks all the time. Well, they've got good data. They go to test rigs where they can bounce the wheels at all the different frequencies. They can look at track data and tell what the hop frequency is at each track. They can duplicate that at these test rigs and start jiggling around with the shocks until you get the thing damped out. It's kind of the same thing that's happening with engines. It's not that everybody's so much smarter than they used to be but they can measure everything and tell what's doing on. They can fiddle with the fuel and spark and make the engine better."
PH: "When you had that first car built by Troutman and Barnes, what were the ideas you had built into that car that made it different from the cars you'd been buying from manufacturers?"
JH: "I'll tell you where I was at that point. Hap Sharp was a friend of mine and a customer, really. I sold him quite a few cars. He always tried to get the latest cars and I was similar. We worked a differenct path. He made his inroads at Cooper and I did the same at Lotus. I could talk to Colin [Chapman] and try to get the car that I wanted. Hap had the same relationship with John Cooper. But we realized that when we went to the West Coast races Jack Brabham and Sterling Moss would have later model cars than the one we just bought. Not only could they drive better but they had a better car.
"We figured this wasn't going to change and I thought I might be able to do better. I think I talked to Troutman at Riverside and he said they were going to build a car incorporating all the things they learned at Scarab. They wanted to build a lightweight, Chevy-powered racecar. I told them I was interested. I visited them at their shop in Culver City. They had the car layed out. They moved the weight back a long ways and it was going to be a simple car, easy to maintain, lightweight, stop good, with big tires.
"That sounded like a really good combination to me. We were running against Climax-engined cars with 2.5 liter, four-cylinder cars. And the price wasn't bad. I thought it was quite economical. So I told them, if they needed something to get going, I'll buy one. That's the way that happened. I got the first one and later another one."
PH: "So it was already designed, the chassis and suspension geometry?"
JH: "Yeah, I didn't hardly have anything to do with it. I made some comments about a couple of things. But it was basically their design.
PH: "As you started making the other cars and getting some downforce on them, how did you maintain the balance of the cars?"
JH: "That's a development. If you look at the history of the thing it's really quite simple. I had some experience and I started doing some driving for Chevrolet. I drove the Corvair for them. They had a lot of trouble with that car. They wanted a guy that wouldn't turn it over. I drove the Corvair a lot. I took expert witnesses for rides-maybe 25 of them-so they would understand how the car worked.
"We'd drive around the skidpad and take air out of the rear tires until the rim touched the ground. That was one of the allegations in the lawsuits that, if you had low tire pressure, it would flip. You cold flip it but you had to work at it."
PH: "That was the swing-axle car?"
JH: "Right, '63 and earlier."
PH: "Nobody wanted to notice that VW was selling a car with the same suspension."
JH: "That's right. When Chevrolet designed that car they said lets build a simple car. What's the model? Well if it works for VW it should work for us. There were some problems with that design but then they fixed it. That's where I got involved. They looked at our car and said, 'Gee you don't have that trouble. What are you doing?'
"Well we were doing it different with four-bar links and rear weight bias same as the Corvair. That' s how my relationship with Chevrolet started. I did a lot of driving and I got to instrument the car. I knew what the car was doing. It wasn't just what I thought, I knew. I knew."
PH: "That had to help, just driving the car and looking at the data."
JH: "That's right. We compared the Corvair to Formula Jr.s and to our car. You know a Formula Jr was really a high cornering power car. It didn't have any power but it was a good little race car. We compared all that stuff and that was really beneficial to me.
"So when we first built the Chaparral II, I ran it for a couple of months with no body on it, just the tub. We hadn't built the body yet. We were still claying up the model.
"I was running the tub around to try to get some reliability and find out if it would handle. When we put the body on it, all of a sudden it slowed down. We thought, Gee it's supposed to be faster with a body, slicker aerodynamically.
"Then we realized the front end had a lot of lift. At 120 mph you could move the steering wheel a little each way and it would go straight on. So I did my first instrumentation myself.
"What I did was just wrap a piece of welding rod around the A-arm, drilled a hole in the fender, marked it every half inch, and counted marks as I drove the car. I'd run it down a straight at 60, 80, 100 mph. So I had a curve, a lift curve. I knew the spring rates so I knew the lift force.
"Then we put that snowplow on the front and I ran at Riverside the first time. That was late '63. We took it to Nasau and Laguna Seca. I had mechanicals at all three places. But it was quicker by a lot than the other cars.
"That winter I ran it around the skidpad and it felt good, it cornered good. It was nicely balanced. And I thought, what you really want is a car that doesn't lift. You want it to be as good at 100 mph as it is at 40. So kept screwing around with it until I got it. I had the instrumentation, just the welding rod stuff.
"The other thing I had was a manometer with a bank of about 20 tubes. I just tapped the body everywhere and I had a polaroid camera mounted up front right near me with a cable release. I'd go 100 mph and take a picture. So I knew the pressure distribution and I started changing the body shape. I got it so it was a zero-lift car at 100 mph.
"But it wasn't worth a damn because it oversteered. That's when the light bulb went on. Right there! It was mid-winter 1963/64. I thought, Jesus, if I can get rid of 300 pounds of lift on the front, why don't I get it to push down. So we put the ducktail on and we started to get 2 or 3 hundred pounds of downforce in the back. Our lap times went down by 2 or 3 seconds. [Jim's leans forward and his voice goes up a notch. He's as excited now as if all this happened just last week.] In one week I dropped my own lap time at Rattlesnake Raceway by 3 seconds. That's a pretty big improvement."
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