GTM roll cage modifications and race car build log

[LCD Gauges]

Nice John, you've been working hard I see! Love the engine details; that canister looks great too.

[kabacj]

Nice John, you've been working hard I see! Love the engine details; that canister looks great too.

Thanks Tino. Still lots to be done but itst progress.





Saturday started a beautiful sunny day. I breezed through tech and was out on the track by 10am. First laps were a test if I had fixed the clutch and master cylinder. All was well. I can put the power down. The car REALLY takes off now. The hardest thing is keeping the motor on full boil without upsetting the car. Smooth is the operative word here. I'm definitely not used to driving a car on the track let alone a car like the GTM. It's only my second time on the track in a car I own, however by the end of the weekend It was starting to feel more normal to have two extra wheels.

A few basic observations. I'm not going race pace yet but i am going much faster then you ever could on the street. The car is very neutral and forgiving. The front suspension anti roll bar and spring rate are a great starting point. The rear seems a bit soft. In a quick right left chicane. The front carves a turn without any push but the rear slides slightly then take a set and sticks. I ll try adding some preload in the rear and also make sure the cars alignment is correct.

So far I'm just out there lapping not changing anything. I keep going faster as I learn that the car is not going to put me into a spin without warning.

Saturday ended with a mad dash to fix my buddies rear brakes .




it's pretty common for the corvette active handling to over use the rear brakes and build so much heat it melts the aluminum pistons in the calipers. That groove you see is actually the impression the back of the pad made in the piston! We could not find anyone with extra calipers at the track. All the salvage yards were closed. He went home for the weekend. See I knew I did not like those safety systems for a reason.

Saturday was looking to be a wash out. Steady rain and standing water for the first session. I'll pass. My car does not have the front splash guards installed yet. Just the trip to the gas pumps had water splashing in the leading edge of the doors.

By 11 am the rain was tapering off and the standing water was minimal. I had the inner conflict of do you really want to go off the track without anybody here to help? I don't have windshield wipers... I have little kids... Oh please John take your skirt off and get out there. So I did. It was wonderful! The rain was a perfect way to check the brake balance. The brakes that Stop Tech custom built are perfect. Tons of power. Easy to modulate and I never needed to touch the balance bar. Rain ex solved the wiper problem.

The wet laps were very productive. No unexpected spinning. i locked the brakes a few times and had quite a few white knuckle moments. But again great car. I could easily hook up exiting out of the corners. Once I got pointed WOT was no problem. I clearly have lots of setup to do yet, but for a car that has not been cross weighted or aligned very well I'm very happy.

With a car as radical as the GTM. Everyone wants to measure their car against yours. Even in the rain I had something for the WRX drivers and even the guy in the nissan GTR. Nobody could keep up once I was on pace even in the rain.

Lots of people went home due to the steady rain.




The after noon session had a dry line. Going much faster now that I have a better feel for what the car does at the limit. Rain is such a good way to learn the cars limits. You are going so much slower there is much more time to recover from a situation. Getting the car slowed down is a little scary however. It was just a matter of trusting that the car would actually slow from 130 in the wet. No technology to bail you out on this car. I love that.

The final session was fully dry and I was really cooking. I had dropped 7 seconds from my former fastest dry lap on this track in my friends c5. My top speed was 139 vs 121 in the c5. I have tons of time to gain with a clear lap , suspension setup as well as a proper alignment.

Here is a comparison of my c5 and GTM lap

Yellow is +1 G. Red is + 1.15G.


The c5 lap




The GTM lap




Things on the list to fix, improve, and finish

I need telemetry with CAN info from the ECU
Install the accusump since I am starting to pull more then 1G
Front splash guards
Transaxle cooler
Oil cooler
Install diffuser
Trim out the rear wing. (On full downforce currently)
Make a new front splitter and add canards

Still far from finished but having a GREAT time testing.

John