SLC 24 Howard Jones

Howard Jones

Supporter
I didn't keep lap times. The numbers really were not the goal this time. Just too much to do and I didn't want to get distracted. I could ask my friend what he usually does there but I think I have heard him say mid 1:30s. In the end we were running about the same pace but I would guess my times varied so much that one or two individual laps wouldn't mean much. I probably started out well over 2 mins and worked my way down into the low 1:40s high 30s. I think my best time in my GT40 on street tires is in the high 40's. This SLC is easily 20 sec a lap faster than my GT40. The potential is pretty clear considering I was able to best myself by at least 10 sec in less than 30 laps during the first shake down weekend.

I understand that the lap record there is 1:06 in a CART Indy car driven by Michael Andretti. Nigel Mansell also ran a 1:06 a few years before in a F1 car. Anything under one and a half mins is very fast.
 
Last edited:
Congratulations Howard. Really nice build thread and a good write up on your first track outing in the car.

Nice of the cobra guys to let you run with them. It must be nice to be the one taking the gun to a knife fight. :)
 

Howard Jones

Supporter
OH! I forgot John. I walked over to talk to the cobra guy just to make sure we were cool. No problems but he did tell me his cobra was a REAL ONE!
 

Howard Jones

Supporter
Mark, a couple of the socket screws that hold the CV joint onto the adapter (GXBX end) loosened up. I found them by checking them, along with a lot of stuff, after a couple of sessions. I re torqued them to 35 PSI but they will need to be cross drilled and safety wired from now on.

The check list goes something like this.

Write down and record impressions after each session along with settings and changes as they are done. Record effects of changes. Include air temp and track temps if known.

Tire pressures (every session)
Body stays (every session)
Wing mount (every session)
Lug nuts (every session)
suspension inboard, include shocks (pre check, lunch, conclusion of day)
suspension outboard, include toe link (PLC)
Roll bars (PLC)
Ball joints , axle bolt carter pin (PLC)
Half shafts all (PLC)
Calipers, mount bolts, pad stays (PLC)
engine mounts (PLC)
Starter tight (PLC)
GRBX mounts (PLC)

Oil level (PLC)
Water level (check for coolant in overflow tank) (PLC)
BRBX leaks (PLC)
Brake fluid leaks (PLC)

Shifter tight (in use)
Steering tight (in use)
Peddle BX normal (in use)
Seats tight (in use)

Anything you find at end of the day check (conclusion) and defer to tomorrow (or future work) write down in log book.

Anything else that you have time to do like camera mounts, mirrors, passenger seat and belts etc. Do when possible.

Pay special attention to driver controls all the time (brake peddle feel, steering tight, and shifter tight and good to go. Get into the habit of looking over gauges on straight on every lap.

IF SOMETHING FEELS WRONG, IT IS, SLOW DOWN AND STOP!!!!. figure it out and fix it or confirm you are ok before you go back out. Pretend you are checking out a airplane and you are a 1000 feet off the ground.

Develop you own system that will insure you check all the important stuff AND is a system that you will actually use. Make it simple but make sure you do this stuff. People will ask you all day long "what is this, did you build it , bla bla bla. Ask them to wait until you are done doing the check sheet stuff then enjoy the conversation. This is a important point because it will happen and you only have so much time to get things done.

Run a lot of slow laps to start with. Don't get caught up in the fun at first, just work your shake down plan. I'm not trying to preach but I have hurt myself on bikes by getting into a hurry and NOT adhering to carefully planned processes.

If you loose a caliper bolt, have a half shaft come off, or a rear clam blow off you will really have a very bad day! You should be able to come home with a lot of confidence and pride in your new build and a nicely written list of things to be done along with a cool story to tell your friends. Have fun but be careful.
 

Howard Jones

Supporter
I looked at my to do list:

1 Extend exhaust pipes to deliver exhaust gas clear of car at rear

2 brakes are a 5-7 of 10 at this point, stop straight, are safe but not happy with deceleration rate. Figure out. master sizes, caliper sizes, pad material again.

3 I think I want to decrease rear roll bar effectiveness, be sure to check this again next time out.

4 run 2 degrees of AOA on rear wing next time as baseline. Add AOA until the car pushes and see what I have.

5. Try running car on track with fans out of shroud to check water temp effect on track. Car ran near high end of temp range all day.

6 try shocks set to full soft and full hard to see effect and compare to previous base line

7 Plan for in car camera next time.

8 increase gurney on radiator exhaust duct

9 add small gurneys and fences on trailing edge and sides of front canards

10 read directions and set shift light correctly

11 set rev limiter to 6500

12 get carb tune better, idle still varies too much, running rich full rev range, talk to Holley guy about this.

13 add camber, set baseline to -2 front and rear, have checked on alinement rack to confirm my setup.

14 try lower baseline cold tire pressures 25-27?
 
I assume you meant 35 ft/lbs not 35 PSI. Allan quotes the driveshaft shop as recommending 57ft/lbs for those bolts: https://www.youtube.com/watch?v=HXvSETWJUiQ

I'd be curious to see what the porsche repair manual recommends, that would be a great data point.

BTW, I really appreciate you sharing your track data it is very valuable to the rest of us.
 

Howard Jones

Supporter
yes, mark, 35 ft/lbs That's a chart number for grade 8, 3/8 fine screw oiled.

When I go back a safety wire them all I will have a good look at the screws and re torque to suit. They may be metric sizes.
 
Howard, fantastic data. Thanks for sharing. This is entered in my noted so I'll always be able to refer back to it. I have a wild notion that next summer I hope to be shaking mine down, and this info/process will be invaluable.

Thank you for sharing your wisdom.

A.J.
 

Dr. David

Lifetime Supporter
Torque-Seal on every bolt and nut.
Most of you already know but for those who don't:
Doesn't prevent loosening, but does tell you, at a glance, whether any has occurred. You can check the integrity of every fastener on your entire car in minutes. Also reminds you of which fasteners you have not yet torqued-down during your build.
Multiple colors, available everywhere, $2.49 at Pegasus.
 

Attachments

  • IMG_1355.jpg
    IMG_1355.jpg
    228 KB · Views: 351
Do you know when and where you will take the Slc to the track again ? I think the next cocoa track days at willow springs are in May and October 2016
Next weekend I will race the VARA big bore bash and will do a test day on Friday
 
Wow, that's the way to sort out a car. Approached like a true scientist. Then again, your whole build was scientifically approached. I wish I kept careful notes like that. Your first track day had to be better than sex, considering all the work you've put in to yield those results.
One thing I think helped was going from a front camber of 1.2 up to around 2.0. I found turn-in to be even phenomenal, although it does tend to Camber-eat tire a bit faster. shrug
I also had CV bolts loosening like crazy, even with blue loctite. The 2nd time I installed my CV's I noticed the CV bolt holes with axle grease on the sidewalls. As I was inserting the CV bolts, they were getting a dab or grease. I surgically cleaned the bolt holes with a gallon of brake clean and that problem went away. I think a millligram of axle grease does bad things to thread locker as its all spun together and homogenized?
 

Howard Jones

Supporter
Maui, for now I don't have a future track event planned for the SLC. I have switched to fixing my GT40. So far I had a new core put into the radiator, replaced all the fuel lines in the engine room (they all leaked like a sprinkler hose), and just received a new set of halfshafts that I intend to install after I replace the GRBX stub axle seals. The SLC may see the track again in the spring if I'm still here in Calif. I am just starting a new home in Texas so I'll be pretty busy for the next 6-8 months or so. For sure COTA next fall.

Cam I think the only real solution is to thread lock AND safety wire the CV bolts. This is what I had to do on my GT40.

DRD we used that stuff for EVERYTHING at work. It is a good idea.
 
Howard

We just thread lock the bolts with blue locktite medium. We also torque to the spec printed on the shaft. I will look next time at the shop but 35 ft lbs seems to low from what I remember.
 

Howard Jones

Supporter
Don, That would be very helpful not only for me to get a number that isn't off a hardware chart but from an experienced example. It will help others that are building these cars. Please post here for us if you can.

I didn't know what to use so I just Googled a hardware torque chart and rechecked after a couple of sessions. 35 Ft/lbs did hold but I would use your known value for sure.

I'm all in with the blue lock tight. The safety wire is for my personal mental comfort level.
 

Ken Roberts

Supporter
It's good to note that Loctite has a newer blue formula called 243. It is formulated for use with slightly oiled bolts.
 
That number does sound low, but I just checked another chart and it was calling for 22# oiled, and 44# dry for 3/8 grade 8. I usually just use the feel "goodandtightski" method (unless internal engine components). You can feel once you start to get bolt stretch usually on those smaller bolts.
 
Back
Top