Fastest ITB Opel GT is back!

[RallyBob]

Race Report: July 4th, 2006, Lime Rock Park, Lakeville, CT.

After a long 3 year hiatus away from racing, Jim MacMahon of New Hampshire has finally re-emerged and dragged his trusty Opel GT out to play.

A multiple NERRC and NARRC championship winner, Jim had not raced his GT since a new home and family obligations 'got in the way' of his racing. A freshening of the brake system, and some updates to the shocks and a few other areas in the suspension yielded a car that was largely the same way it had been when it was parked years earlier (old tires included!). Jim commented that he was going to treat qualifying easily, just to get a feel for the new suspension changes and the fact that he was rusty behind the wheel.

It turns out that 'taking it easy' must mean something different to Jim, since he promptly put the car on pole with a fast lap of 105.112. Jim would start the third race in position one for ITB, and 13th overall in the mixed field of cars.

The overcast skys had threatened all morning, and just before lunch during the last qualifying session the sky opened up and washed away some of the dreaded humidity and heat that had built up all morning. The real question was: What tires to run? Would the track be wet? Dry? Mixed?

As it turns out, the track was nearly dry by the middle of the second race, so Jim kept his trusty Hoosier dry tires on the car and rolled into the pre-grid. After one failed start, the pack finally got the start and was essentially drama-free from that point on. Slow traffic meant a drop back to 3rd place for Jim as a very fast Honda Civic and a well-driven VW Rabbit got ahead on the front straight. Those two battled for 1st and second place throughout the race, swapping leads a few times. The Honda making up time on the straights, the VW getting by in the turns. A few spots of rain never threatened to alter the tire choice most people chose, and the surface remained dry.

Jim's primary battle was not even with an in-class vehicle, but rather from a BMW 325 that was running in ITS. Although Jim was capable of running faster times than the BMW, he simply could not outgun the 6-cylinder BMW on the straights, losing 2-3 car lengths each time on the front straight, yet closing back that gap on the more technical sections of the track. The BMW, quite frankly, was holding him up and would not pull over to let him pass, even though they were running in different classes. Still the racing was good, the give-and-take aspect of it challenged both drivers.

The net result was a 3rd place in class (ITB), and about 20 car lengths back from the Honda and VW which finished ahead of him (but ran slower qualifying times). Not a bad comeback effort just the same, a podium spot on his trial 2006 effort! In impound, the GT was still overweight on the scales, so there's room for improvement. A freshening of the engine (6 years since it was last torn down) would certainly enhance his chances at future events.

Jim's next event is July 8th and 9th at New Hampshire International Speedway, Jim's home track where his record from 4 years ago still stands!

[opelwasp]

Awsome! It would be great if some pics or video was available. You going to be his team mechanic Bob? If so, he is sure to win.

[RallyBob]

Awsome! It would be great if some pics or video was available. You going to be his team mechanic Bob? If so, he is sure to win.

I took some pics today but my camera is on the fritz so I can't download them, gotta get a new one! I don't have any video, at least not anything recent.
Old pics of his car:
http://www.opelgt.com/photos/showpho...0/ppuser/11128
http://www.opelgt.com/photos/showpho...0/ppuser/11128
I'm not his mechanic, but I still lend technical advice to him. I did originally build his engine and suspension back about 10 years ago when I had my shop, but those days are gone now!

Bob

[Gary]

Nice write up Bob. Glad to hear of Jim's result. Keep us informed as to his schedule. I'd love to see him run. (I have plans for next weekend)

[opelgtguy]

Hi Bob:
Great job reporting the event. Thanks !
Was Jim at Carlisle this year ? If he's the guy I'm thinking of,
he seemed to be very knowledgeable as well as a good guy to
talk to.
Rick

[Tru-Craft]

Bob nice write up.
Jim did great, 3 years off, gets the pole and finishes 3rd!
Damn, when he gets more seat time.....a fresh rebuild....look out!

How many hours does his motor last, before a rebuild?
Lyle

[RallyBob]

Hi Bob:
Great job reporting the event. Thanks !
Was Jim at Carlisle this year ? If he's the guy I'm thinking of,
he seemed to be very knowledgeable as well as a good guy to
talk to.
Rick

Yes, Jim was at Carlisle.
Here's a link to a pic: http://www.opelgt.com/photos/showpho...0/ppuser/11128

[RallyBob]

How many hours does his motor last, before a rebuild?
Lyle

He's freshened it twice since 1996. He probably goes 30 races between re-rings and valve jobs. Most other cars freshen their engines every 10-15 races. Opels are tough!

[RallyBob]

I just received a phone call from Jim MacMahon, he had just left Lime Rock Park and is headed back home up to New Hampshire. He was out for his first race this year, and found that the competition had gotten a bit quicker since last year...he only qualified 4th on the pole. Turns out there are two new Hondas in his class that really run, and they were genuinely quicker than him by about 3/4 of a second per lap. Jim was running older Hoosier tires on his car, but he still normally gives nothing away!

Anyway, the 'great equalizer' started up mid-afternoon, and the talk in the grid was that the two front drive Hondas would run away from the pack when it really started to rain. Turns out they didn't know Jim had a set of Hoosier Dirt Stockers (the hot setup for deep water), and he had disconnected his sway bars front and rear for better weight transfer. Well, come race time, the only car that ran away from the pack was a 35+ year old Opel GT! Jim handily won his class and finished 4th overall in his race group (comprised of three different car classes). Nice one again Jim!

Bob

[timemachine]

Thanks for the write up Bob. Way to go Jim! Class winner and 4th overall is amazing. I am curious how disabling the sway bars gives an improvement on the track though.

Jim

[RallyBob]

I am curious how disabling the sway bars gives an improvement on the track though.

Jim

In the rain, the lateral grip is lower, therefore weight transfer is reduced. Removing the bars allows for more weight transfer in low-grip situations, increasing tire contact patch area. This car still has pure racing shocks, racing bushings, lowered ride height, and 500 lb front/225 lb rear springs. So it's not 'soft' by any means. In the dry, the tire grip is very high so the bars are used to reduce drastic body roll which can alter the tire contact patch established from the baseline alignment settings.

For rallying and for ice racing, I use no bars at all when possible. Even my rally Ascona (which like all Mantas/Asconas has an integral front bar and cannot be removed) has a milled front sway bar. It's reduced in thickness by .250" in the center to allow for more suspension compliance over rough ground.

Bob