RCR 33 track test & chassis setup

[Dean Lampe]

I spent the day at the track today so I thought I would write a little report. Before I get into the performance of the car let me share some basic chassis set up data for you. I weigh 205lbs and I had 12 gallons of fuel, 6 gals each side.

Ride height F 3.87 R4.5
Lower front A arm angle 3.5 deg.
Front left 650 lbs Front Right 589 lbs
Rear left 763 lbs Rear Right 715 lbs (Edited by admin at request of owner)
Front% 45.6
Left % 52
Total 2717lbs

Springs front 550 Rear 375 lbs (wheel rate around 280 front and rear)
Ackerman 1deg toe out in 10 degs of turn

Toe F -1/16 (out) Rear 3/64
Camber F-1.9 R -1deg
Caster F 5.8 R5.6deg

bump steer left front bounce and droop
inch change
1 = 0.005
.75 = 0.002
.5 = 0.008
.25 = 0.002
0 = 0.000
-.25 = -.017
-.5 = -0.034
-.75 = -0.55
-1 = -0.07

bump steer right front
inch change
1 = -0.012
.75 = 0.001
.5 = 0.003
.25 = 0.005
0 = 0.000
-.25= -0.007
-.5 = -0.02
-.75 = -0.41
-1 = -0.052

These settings where achieve through a lot of chassis set up and a lot of trial and error.

To the track..........

This car drives so well that there is really no words to do it justice. I ran with a group of 75 Porsche's. I ran most of the day in Group 1 which is the advance group. I was consistently able to lap every car in the group over a 20 minute session. The car went where I turned and behaved very predictably. I was consistently faster than I had been the year before in my cobra. The car was tight with this setup and had a tendency to push in the corners although you could kick the rear end out with just a little pedal. I am going to take the rear springs up to 450 to loosen the car a little but I will also need to increase my front bar to correct a little boy roll issue. The goal is to net out a car that is a little less tight but not by much. I have a universal joint problem and the fuel pressure is running a little high for the Webers. I don't think I will make it back to the track tomorrow but today was a screaming success. For those of you just finishing your car, let me tell you that you will feel like a rock star when you go to this type of event. Everyone will want to come over and talk to you. People are fascinated by these cars. If anyone has any specific questions, just ask. I feel like I really bonded with the car today and let me say it again- There are no words to describe how well this car handles.

For those of you who wanted to reserve judgment on RCR until there were some on the track, Here you go.
Passenger side.jpg

[Bill D]

Thanks for the report Dean. Would you recommend this setup as a staring point?

Thanks
Bill D

[Jac Mac]

You might have your LH / RH wheel weights back to front there Dean.

Jac Mac

[Dean Lampe]

I would recommend this point as the finish point. I spent a week with an ARCA/BUSCH racing team to get to these numbers. Their mechanics really worked hard to get it set correctly. If you do the spring and bar changes I have outlined, you should be right on the money!

[Dean Lampe]

Thanks Jac Mac, Edited

[Pat Buckley]

I run my front ride height at 3.82...otherwise similar.

[Russ Noble]

So Dean,

Given that the car was set up by an ARCA/BUSCH racing team, why is the car set up dewedged with a 48% crossweight? Are you only doing oval circuit racing?

Cheers,

[Jac Mac]

Russ, I think you will find the weights are meant to be;
L Front 650 lb R Front 589 lb
L Rear 763 lb R Rear 715 lb

Jac Mac

[Russ Noble]

I think you're right Jac Mac. Now we've got to be mind readers too!

[John Lowe]

Dean

Excellent report and thanks for the detailed set up information. Look forward to hearing what difference the proposed changes will make.

Also underpins the "rightness" of the RCR basic design, well done Fran.

John

[Dean Lampe]

The wheel weights should be......

Front left 650 lbs Front Right 589 lbs
Rear left 763 lbs Rear Right 715 lbs

I could not edit my own thread, but here is the corrected numbers. Sorry for the confusion. Jac Mac, I didn't look close enoungh when you pointed out the error.

Russ, sorry to confuse you as well. You don't have to be a mind reader, actually I am glad you aren't.

[Mark Clapp]

Awesome Dean. The car looks as good as it's handling too. You said you were much faster than you were in your Cobra. Were you running much less horsepower in your Cobra? Way to spank the p-cars!

[David Morton]

Dean,
assuming IDA48's, what fuel pressure values are you seeing? Thanks
Dave

[theon]

Congratulations on the car set up and taking it to the Porshes.

Theon Karabatsos

[Julian West]

Originally Posted by Dlampe

Total 2717lbs

Attachment 24089

Diampe,

Great news, well done on all the hard work & thanks for posting in such detail.

Interestingly I note the all up weight is not dissimilar to my GTD. What trans are you using?

Regds,

[Russ Noble]

Originally Posted by Dlampe

The wheel weights should be......

Front left 650 lbs Front Right 589 lbs
Rear left 763 lbs Rear Right 715 lbs

I could not edit my own thread, but here is the corrected numbers. Sorry for the confusion. Jac Mac, I didn't look close enoungh when you pointed out the error.

Russ, sorry to confuse you as well. You don't have to be a mind reader, actually I am glad you aren't.

That's good Dean, I saw you had edited your first post and initially thought those were the corrected figures. I wondered whether you were one of those racers, peculiar to the US, that only turn left.

But at least I suppose that's better than the ones that don't turn at all and only race for a quarter mile

Cheers,

[Fran Hall RCR]

Russ,
how long before your build is race ready???...

Julian,
the weight is including driver and fuel...is the full up weight of a GTD the same??..ZF and dry sump, with AC also ....luxury racing..

[dicktownsend]

Fran
are you getting my e mails or PM s
regards Dick

[Dean Lampe]

Mark the horse power is a little better but not that much. It is more about how well this car handles and how predictable it is.

David the fuel pressure is a problem. Here is the story. Late in the day yesterday when things were real hot the car was continually loading up and was running irratically. I have a gauge on the dash that reads 1 to 2 psi when it reads anything at all. The mechanical gauge reads around 2 usually. The bypass regulator was preset at 3. I raise the regulator preassure until it read 3 on the mechanical gauge. The dash still reads 2 and the mechanical gauge read 3 for a while, now reads 2. The electrical pressure sending unit reads 240 at 0 and 33 at 15 psi. So if the sending unit is at 3 psi it should read 199.6 ohms. It doesn't. It reads 168 ohms which is probably closer to 5 psi. SO..... If the regulator was right to begin with and my mechanical gauge was wrong, then I increased the pressure by messing with the regulator and that would account for the loading up as the floats would clearly be to high as a result of the weak needle and seat. I am going to test the sending unit to see what it will read with a hose and water. 1 psi = 27.735 inches of water. So about 73 inches of water in a 3/8 tube should register 3 psi on the sending unit. If the unit reads 199 ohms the my pressure is to high as it reads 168 right now. Do you wish you never asked?