GT40 driving

NickF

Lifetime Supporter
I am use to driving high HP cobras, and they are so easy to drive. You can see everything, feel the movement, and predict them easily. I am try to get use to the GT40, way diff. animal. Feels odd to me with power in back, cant really feel anything. Cannot see what the car is doing. Any advise? I hate to say it, but I am a bit shy to really nail the pedal down like I do in the cobra.
 
Nick,

As you've noticed there is a HUGE difference in the Cobra and the GT40. Is you car LHD or RHD as it makes a difference. The 40 is certainly more of a tight fit especially if you're tall. I'm only 5'8" so I fit in mine perfectly but my car was LHD so it made things a little more interesting as the foot box is small and there was no room for a "dead" pedal on the left side. RHD cars don't have this same issue. The fact you can't see a lot of whats going on behind you can also make things more confining along with its extremely low seating position. Side mirrors placed in the right spot can help with this. Once you get use to these factors the car can and is a real hoot to drive other then the fact you'll have so many gawkers and let's call them idiots trying to get pics of your car.

The rear weight bias is certainly different too. Knowing when to apply throttle in the corners is a learning curve but overall the car is very good and instills confidence pretty quickly. I still miss driving mine so I replaced it with another mid-engined V8 car.

Happy motoring.
 
Hi Nick,

I've often suggested to new GT40 drivers to get a fair amount of seat time at first to get used to the rear engine and small mirrors. I've heard stories on here of guys spending years building one, nailed it first time out, and nearly lost it and themselves. Others sold theirs after a month from being nervous due to the concentration needed to drive one. You'll get used to it. I've had mine for 17 years and am still addicted to driving it. When I drive and get out, I want to get right back in.
 
the main difference for me is the engine location for weight distribution this affects braking and turning since the Cobra is nose heavy you can brake inside the turn. On a rear engine you do not have the weight of the engine in front to turn. Brakes are small and non powered so they are both had to brake. The GT in my case handled much better than the Cobra. Depending on the engine a 302 or 332 ci is not match for a 427 on a Cobra.
 
NickF, The learning curve for me was pretty simple. I had owned only front engined cars so I knew how they handle, and quite frankly I had heard more horror stories of Cobras "loosing it" more than with 40s. With the almost even weight distribution the handling is easier(for me anyways). My suggestion would be to go to one of the Porsche dealerships that has a "driver's course" and do their competition driving school(done with an instructor) and you will get first hand info on how a "rear engined" car handles. They have a skid pad and a skid plate which kicks out under you and you try to control it along with high speed turning corners etc. I did it in a Boxer and it was a blast. They will give you suggestions on how to enter the curves and when to add power. You get about an hour or hour and a half of seat time. At the end if you aren't getting a little "sea sick" from all the twist and turns, the instructor will drive and show you some, lets say interesting driving.

Bill
 

Howard Jones

Supporter
All of this means almost nothing unless the car in question has been set up correctly, the tires are worth a damn, and even if the car has a limited slip and which kind for that matter.

A rear engine car can be tuned to understeer even when adding power in a low speed corner so it's not a given that GT40s are tail swapping monsters. That's a certainty. It will take some time and a will to learn how to setup suspensions but this is not moon shot science and there are many sources that explain completely how this works.

Tires. There are only two decent 15 inch tires that I know of. Avon's and DOT radial Hoosiers slicks. (I include all the dot slicks in this category). Any attempt to run junk like BF Goodrich Comp TA/s hard will only result in round balls of grease attached to the wheels. ANY GT40 with quality summer only 17 inch tires on it will run ANY cobra into the track that runs cheepo 15 inch poser white letter junk tires on it. AND the more power the cobra has the quicker the rears will overheat and sooner it will get run down by the GT40. I don't care if the cobra has 800 hp and the GT40 has 300 it won't take more than 15-10 minutes on track before it's all over.

Setup. Once it is understood what is going on with sway bars, spring rates, shocks and their tuning, tire pressures and limited aero mods then a 1/2 dozen track days will go a long way towards really improving a ill handing car. A nice big flat area of blacktop should be used for a skidpad the first time a new car is past shakedown systems testing and is moved on to suspension setup evaluation.

You can't just put a kit car together and expect it handle well at the limit of tire adhesion. Frankly most kit cars builders will have no way to predict which direction the car will go the first time they floor it.

Limited Slip. OK here's my humble opinion. If you build one of these cars with more than 250hp then you are crazy if you don't equip it with a limited slip diff. I have Quaife TBD's in both of my cars, SLC and GT40, and they are absolutely magical. Both rear tires do the same thing no matter WHAT YOU DO! My GT40 was transformed from a wicked unloaded single tire burner to a nice predictable corner exit with the Quaife I had installed in the Renault it has in it. So much so that I had to tune the LOW speed push out of it.

Take a $1000 out of your engine budget and put it into a TBD. You will thank yourself later.

So which car type is faster...…………...the one that is correctly tuned on the best tires.

Here's two good books on suspension tuning. There are many others.

https://www.amazon.com/Chassis-Engineering-1055-Author-published/dp/B00Y2RXW3E/ref=sr_1_14?ie=UTF8&qid=1539623795&sr=8-14&keywords=chassis+engineering+herb+adams

https://www.amazon.com/How-Make-Your-Car-Handle/dp/0912656468/ref=sr_1_1?ie=UTF8&qid=1539623910&sr=8-1&keywords=how+to+make+your+car+handle&dpID=51pYPr%2B0RcL&preST=_SX218_BO1,204,203,200_QL40_&dpSrc=srch

One more:

https://www.amazon.com/Race-Engineering-Mechanics-Paul-Valkenburgh/dp/1557880646/ref=sr_1_1?ie=UTF8&qid=1539624172&sr=8-1&keywords=race+car+engineering+and+mechanics&dpID=516N0JJG0ZL&preST=_SX218_BO1,204,203,200_QL40_&dpSrc=srch
 
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I can only echo Howards comments here - I too have the Quaife LSD, if you plan any brisk driving on track it transforms the handling. I did drive the car without and it was a complete handful out of the corners or in the wet.
I'm on 17" rims so much more track tyres available - I have the Toyo R888's. IMHO its not worth fitting standard road tyres on these cars as you'll only really use it in the summer months and the tyres will age faster than you can wear them out. The Goodyears I fitted when the car was new just went too hard after 3 years so became useless on track.
I have changed spring rates a few times and finished up having new stiffer sway/anti-roll bars made from spring steel.
 

Cliff Beer

Supporter
Ditto what Howard said. Absolutely. Start with tires, spring rates, diff, etc. then go from there.

My CAV drove poorly when I first bought it. Nice car, but had only been a trailer queen really. Shifter wasn't properly hooked up, the open diff gave the car a lot of torque steer and poor adhesion in the corners. Some suspension tuning at our local race vintage race shop helped a ton, and I got the shifter sorted out along with a LSD type diff. Magical transformation.

So, net, make sure you're GT40 doesn't have any major flaws in the suspension/drivetrain before you floor it. Then, go for it.
 
Ditto what Howard said. Absolutely. Start with tires, spring rates, diff, etc. then go from there.

My CAV drove poorly when I first bought it. Nice car, but had only been a trailer queen really. Shifter wasn't properly hooked up, the open diff gave the car a lot of torque steer and poor adhesion in the corners. Some suspension tuning at our local race vintage race shop helped a ton, and I got the shifter sorted out along with a LSD type diff. Magical transformation.

So, net, make sure you're GT40 doesn't have any major flaws in the suspension/drivetrain before you floor it. Then, go for it.
This.
Many cars are low miles because they don't work! Poorly set up suspension, overheating engines, etc. make for a garage queen. I have no problem with 6-8-10,000 miles on a GT40 because it works! Both of my SPF have been dead nuts reliable and I don't hesitate to jump in and go 200 miles because I'm pretty sure I'll get there.
 
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