Author Topic: GT750 Powered Race Car (D-Sports Racer)  (Read 4137 times)

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Offline sav0r

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GT750 Powered Race Car (D-Sports Racer)
« on: July 22, 2019, 06:22:45 PM »
A little history on the project, my father built this car from '72 to '74. It was successfully given a log book and SCCA homologation to compete in the D-Sports Racer category. This chassis predated the modern steel roll cage rules, meaning an all aluminum (crash structure) construction was allowed, including the crash structures. Additionally, there was no minimum weight prescribed for cars under 850cc. The car is basically an aluminum monocoque, or maybe better described as a semi-monocoque as it uses effectively an aluminum tube frame with riveted and bonded panels. At the time of build the Suzuki GT750 was a popular engine, and given a proper tune could make over 100hp easily. The first engine build was performed by Eric Buell, this was back when he still lived in Pittsburgh. Later builds were performed by my father, and the engine evolved somewhat over time. The chassis was engineered by my father's friend, who at the time was a full time engineer at GM. My father constructed the car with the help of another friend and his wife. The car was raced from '74 to '79 with mediocre success and then mothballed. They participated at Nelson Ledges, Summit Point, and Mid Ohio, but with a limited budget and limited man power they never quite got it going like they had hoped. The car remained in the garage unused for 40 years. It had become such a burden on space that my father eventually mounted the car on the wall, it stayed there for something like 16 years.

Here's a bit of photo history of the car.











Here's the car as we were pulling it off the wall, I want to say this was in 2015, maybe 2016. It's hard to recall.





Once off the wall we put the car back on the fabrication table that it had sat on for something like 20 years before. The process began. The all aluminum crash structure simple wasn't adequate. After 40 years of competition in other areas of racing my father had learned a lot from the days when he built the car. So he took the chance to update and change a number of items, but tried to be sensitive to keep the original spirit of the car. The focus was mostly on engineering issues, especially those that could be a safety concern.




Progress





And, this last weekend we got to the track and managed to race the car. We fought with the master cylinders right up until the race, but managed decent brakes come race time. Then of course the car overheated. But I managed the best laps of the weekend in the race, so for having basically used the race weekend for testing it was a positive result. We simultaneously got the car on track for it's 40th anniversary of retirement, and my 25th anniversary of race driving competition. A true success!


https://youtu.be/pH5OCOBPmZg

I have other pictures as well. I can also publish more detailed specs if anybody is interested. We plan to continue development of the car. It actually fits the rules for the modern P2 class which is sort of the modern equivalent of D-Sports Racing. So we could compete in national competition if we wanted, of course the car wouldn't be competitive, but it would be fun.

« Last Edit: July 22, 2019, 06:34:05 PM by sav0r »
www.chrislivengood.net - for my projects and musings.

Offline Cobraace2

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #1 on: July 22, 2019, 09:14:18 PM »
Fantastic some specs on the engine . love how the chambers look like they made von a brake .

Offline ~JM~

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #2 on: July 23, 2019, 12:36:45 AM »
SUPER COOL !!!

Offline kar1zma

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #3 on: July 23, 2019, 02:45:28 AM »
that's a real blast from the past
its great that you have so many pics from way back.

nostalgic!!!
good luck with racing this beauty again

Offline RD7

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #4 on: July 23, 2019, 05:36:56 AM »
Great read , thanks for posting.

Offline mnein

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #5 on: July 23, 2019, 08:00:50 AM »
Man that is just cool.

Offline sav0r

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #6 on: July 23, 2019, 08:25:35 AM »
Fantastic some specs on the engine . love how the chambers look like they made von a brake .


The engine has the cylinder raised .04" as I recall. The cylinder was then decked, as was the head. The head was welded up, the spark plugs were moved into the center of each chamber, and then the domes were reshaped. In the current form, the heads are just a circular shape without a proper squish band. This is the head as it was built 40 years ago. The ports are drastically changed, and the engine runs three VM38's using an adapter plate on the intake side of the head. The engine would willingly rev well past red line, which was an issue, because I've never driven a motor that was so willing to do so. It easily would pull to 10k plus. As a result, it got over revved several times last weekend, we haven't had a chance to tear it down, but we hope it wasn't hurt.

We have plans to redo the head though, as we have several, all it will take is welding it up and machining it. We already did all the setup work to do the machining, we just didn't have the time to weld a head up. Here's the model I made, I matched the head volume to the current volume, but we have added a squish band and slight toroidal chamber.





Thanks, all for your enthusiasm. It's been a labor of love for my father especially. There are a lot of details to go through, as a result I'm confident we will be a lot more competitive in our next outing. The unofficial goal is to reset the all time lap record around the Schenely park circuit, it might take a year or two but I think we will get it.
« Last Edit: July 23, 2019, 08:27:50 AM by sav0r »
www.chrislivengood.net - for my projects and musings.

Offline cygnus

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #7 on: July 23, 2019, 04:33:56 PM »
Great history. Kudo's to your pop for keeping it and good luck with the record attempt !

Offline gwcrim

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #8 on: September 25, 2019, 07:54:54 PM »
Very cool story.  Very cool car.  I bet it's a GAS to drive!

Offline Evans Ward

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #9 on: September 28, 2019, 08:21:27 PM »
I’ve heard about the Ocelot- what exactly was it? Love the car BTW!  :righteous:
1984 Yamaha RZ350
1976 Suzuki GT750
1972 Kawasaki H2 750 Mach IV

Online RDFL

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #10 on: September 28, 2019, 11:07:40 PM »
Great car and story.

Offline sav0r

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #11 on: September 30, 2019, 01:17:39 PM »
Very cool story.  Very cool car.  I bet it's a GAS to drive!


It works rather well, once we iron out the bugs and I can drive it in anger, it should be a bit faster than a Formula Ford (if you're familiar).

I’ve heard about the Ocelot- what exactly was it? Love the car BTW!  :righteous:

This actually competed against the Ocelots. Basically in the D-Sport Racer" category at the time there were two displacement levels. One, I beleive 800cc set a minumum weight, it was something like 1000lbs. If you were under 800cc, then you could be as light as you wanted. My father chose that option. So he started with the 750 water buffalo and built a chassis around it. The Ocelots did the same, though they were much more successful than my father's operation.


Great car and story.

Thanks! It's great fun being able to campaign the car with my father some 40 years after he built it and after 25 years of driving myself. I visted my father last night and are scheming for 2020. Lot's of solid stuff in the works.
www.chrislivengood.net - for my projects and musings.

Offline sav0r

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #12 on: September 30, 2019, 11:56:59 PM »
Also, that wood block that's holding up the rear sub frame in the second picture is still in my father's shop. He still uses it in the same manner. It's just a lot smaller and more burnt, worn, and abused than it was 40 years ago.
www.chrislivengood.net - for my projects and musings.

Offline Evans Ward

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #13 on: January 20, 2020, 01:25:16 PM »
Anything updates during the off season for this Water Buffalo powered race car?
1984 Yamaha RZ350
1976 Suzuki GT750
1972 Kawasaki H2 750 Mach IV

Offline sav0r

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Re: GT750 Powered Race Car (D-Sports Racer)
« Reply #14 on: January 20, 2020, 03:28:25 PM »
Yes actually. I was just looking at the car with my dad last week.

We got the new AP floating pull masters in, both new for front and rear brakes. My dad also got a nice new balance bar TIG’ed up. Looking good! I’ll grab some photos the next time I’m up there. We also got a larger master for the clutch, and my father has gone through the clutch and is adding a high performance clutch pack and springs from Barnett. Hopefully the slipping issues go away.

I finally got my dad talked into welding up one of our spare heads and milling it completely, spark plug holes and all. And we are going to do a new base gasket, the current one obstructs the ports a tad and is in rough shape. The engine is apart right now. We are working on the sheared water pump drive, we haven’t decided on a direction for that. Maybe electric, maybe aftermarket gears.

From there it’s going to be minor stuff. Some stays for various body panels, double check all the suspension bits, scales, alignment. We hope to do four or five weekend this year and really hand it to the geezers on vintage circuits.

Also my boy is four, so I’m looking at some karting for him this year. So it should be a busy season.

www.chrislivengood.net - for my projects and musings.