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Kirkham Motorsports

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  #181 (permalink)  
Old 05-06-2014, 06:36 PM
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Bob - I read this as you want to control jacking.

Trivia -

If one believes the car rolls around the geometric roll centers; at 3 degrees of roll, the front has moved laterally 20 inches (still inside the ball joint) and the rear has moved 1.5. Our roll axis is now at a significant angle (in plan) to the mass centroid line which does not intuitively seem like a good thing to me.

If I did not want to run it so bad, I would seriously look at moving the front inner pivots inboard .5 inch and lengthening the arms accordingly.

.5 inches cause it looks like it could be done and it would cut the difference by half.



chr
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  #182 (permalink)  
Old 05-06-2014, 07:58 PM
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Bob ... does this also mean that keeping the lower control arms as level/parallel to the ground is more important to handling than lowering the front and changing the roll centers ??

Bob
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  #183 (permalink)  
Old 05-06-2014, 10:31 PM
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It is in my world. Lower it and the roll moment increases. Raise it and jacking is increased. Raise it or lower it and the camber curve is more aggressive which could or could not be beneficial. Putting them parallel is a good compromise. A rule of thumb is to run the longest virtual swing arm you can. One would have to test if raising or lowering the roll centers would be of benefit. i.e. the car is quicker with more roll as opposed to more jacking and the reverse. With mine set parallel the front is 1.2 off the ground and the rear is 1.9. It seems one would opt for lowering and controlling the roll with bars or springs provided it did not ruin the camber curve and or mechanical grip.

I can't see how adding jacking could ever be good which is why I never opt to raise them beyond parallel to the ground. That said, the 26.5 tires have not helped me

chr
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  #184 (permalink)  
Old 05-07-2014, 06:05 AM
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Quote:
Originally Posted by ERA2076 View Post
... A rule of thumb is to run the longest virtual swing arm you can...
chr
When we first started out, we did tire testing with BF Goodrich. (Back then the CompTA was the hot tire.) It was their recommendation that we shorten the virtual swing arm length in order to increase the camber gain. Street tires haven't changed that much since then. We're still using the same sizes and profiles in 15" sizes. The profile of 17" wheels is somewhat different, but the tires still require some camber correction on roll.

Formula cars are different. Roll is negligible and tires are very wide. For them, roll compensation is neither necessary nor desirable.

On our cars, you could run a lot of negative camber, but that has negative consequences on tire wear and loss of traction of the inside tire. We're still better off with the compromise of some partial camber gain on roll.

Or you could put in springs so stiff that roll would be near zero, and bounce down the road from hump to bump.
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  #185 (permalink)  
Old 05-07-2014, 11:03 AM
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Or we could spring it for max grip and screw with the bars to manage the roll.

chr
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  #186 (permalink)  
Old 05-07-2014, 11:30 AM
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Anti-sway bars are wonderful, but there are limitations. For one thing, they don't reduce squat or lifting under power. Secondly, when one tire hits a bump, it transfers some of the force to the other tire. Everything is a compromise unless you go to a very sophisticated electronic control system that is much smarter than we are.
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  #187 (permalink)  
Old 05-07-2014, 11:38 AM
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nah - lot's and lot's of great performance cars have been built with old school tech. The last thing I would ever want is some kind of active suspended Cobra.

chr
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  #188 (permalink)  
Old 07-03-2014, 12:17 AM
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Chas - we have been open tracking the Mustang and it has been getting all of the attention. The FIA got pushed to the back of the shop. I hope to get it back on the rack tomorrow. I ordered the rear wheels a couple of months ago but have not seen them yet. I was close to ordering the fronts but needed to check clearances one moer time and Bill pulled the car before I could get it done.

Some pics and a vid -

The air dam cracked so we rebuilt it with UHMW


Splitter and dam are riveted together. Dzus and nut inserts to attach to car.


Welded in a subframe and integrated with a roll bar. Spot welded the body pinch weld to a jacking rail and tied jacking rail to subframe connector.

Tied the roll bar to the rear shock tower brace. Seats are FIA approved and we finally went to belts. What a treat.


We did not reinstall the interior. Bent up some aluminum to cover the tunnel wiring and used some builder parts from Jegs for the boot. Riveted ABS to the floor.


Boxed jacking pads


The car has had CO since new 375/550. With the added Aero it was getting to the point I was over driving it and it was getting very frustrating. I called Maximum Motorsports and they set me up with 525/700 springs and dampers and 3 degree camber, 1/32/ toe out, and 6.5 degree caster of which we could not obtain. We just tried to get as much as we could 2.5, 1/32, 4.5 and it is an absolute blast to drive. There is some left but I need a new K member to optimize the front geometry.

I don't have the whole GoPro thing worked out so skip forward to around 5 min and you can see it run. Shift light is set at 6100 rpm.

The yellow Lotus is the first target for the FIA. If we cannot get him I will be bummed. He has much newer technology and some of the best engineering in the world. - I am counting on being able to control the FIA to 7000 - set shift light at 7100. We will have gobs more HP just hope we can use it.

[ame="https://www.youtube.com/watch?v=1NG_YWQEp0Q"]https://www.youtube.com/watch?v=1NG_YWQEp0Q[/ame]

It just takes a lot of time but there is no way to get to the FIA w/o going thru the Mustang. I did get signed off to drive solo with Pro Drive. I have been driving solo with some of the clubs, but it was gratifying get signed off by a PD instructor.

We are going to try to have the FIA running by the end of summer. I am searching for some kind of a skid pad so we can test and tune some before we put it on a track. I am excited and a little nervous about tracking the FIA. The thing should be very fast - The Mustang weighs 3500 wet. Trying to get the FIA to 2315 race. The FIA has more HP than the SVT.

Such a short wheel base.
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  #189 (permalink)  
Old 07-21-2014, 07:43 PM
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Rears finally came in - beautiful. Every non machined surface powder coated. Steel inserts for the studs to pass thru.



My biggest fear turned out to be nothing. There is plenty of room for the caliper. They are almost a cylinder with nothing more than a slight taper as you move outboard.




Heavier than I would like (24 lb) but a full 10".





I talked to Roger Kruas Racing about running the CR6ZZ on the FIA.

(-) 1.5 degrees camber front, (-) 1 degree rear.

Less (or is that more ) than I expected on the front.

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  #190 (permalink)  
Old 07-22-2014, 03:55 AM
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Get that engine lit off!
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  #191 (permalink)  
Old 07-22-2014, 08:05 AM
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We have to pull the drive train back out to finish some odds and ends, but dry fit looks pretty good. Your day is coming and it will be grand - I keep spinning it.

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  #192 (permalink)  
Old 07-22-2014, 08:02 PM
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FWIW , I sent an e mail to Avon several months ago about the CRZZ6 tires on the track . The Technical Director recommended 1.5 to 2 degrees negative on the front and 1 to 1.5 degrees negative on the rear as a starting point and then use tire temps starting from the inside to outside to set final camber .
Looks like Roger Krause talked to the same guy I did ... and Roger has a lot of actual track experience with Cobra replicas on these tires .
I have 2 degrees negative on the front and will probably reduce that very shortly as insude temps are too high .
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  #193 (permalink)  
Old 07-22-2014, 10:34 PM
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Quote:
Originally Posted by Bobcat View Post
... and Roger has a lot of actual track experience with Cobra replicas on these tires .
Interesting - one of the first questions was - which Replica ?

chr
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  #194 (permalink)  
Old 07-23-2014, 11:49 AM
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Don`t know . He just said during our conversation that he supplies the Avons and the Goodyear Blue Streaks to a lot of the West Coast guys . And here I`m dating myself as I used to run the Blue Streaks way back in the day .
Yes , one is a radial and one is a bias ply . I think he told me that the Goodyears were slightly faster when warmed up on the track and gave more warning before breaking away , but you can drive the Avons on the street also and be as fast or almost as fast . However , as you know , how fast the car goes on one set of tires over another is determined a lot by the suspension setup and the driver .


P.S. I run 15" wheels .
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  #195 (permalink)  
Old 09-26-2014, 02:52 PM
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The motor mounts are not working out as well as we would like. With the engine sitting level in both directions the output shaft on the transmission sits 3/4" too high. We re-worked the trans mount and bracket and it is sitting 1/4" too high with respect to ERA's 3.5" dimension to the top of the "X". We would go ahead and lower it to spec, but we checked the engine for level and we now have slope and lowering it anymore will just amplify the problem which is not the best for the Webers.

Also, the mount does not have full surface contact to the frame horn. We have decided to go to solid mounts.

Question 1 - How critical is the 3.5" tail shaft dimension?

Question 2 - Anyone ever play around with lowering the engine and trans?

We are considering going to electro fuel pump. I spent some time searching and it seems several have run 7lb pumps with no return?

Question 3 - Can you guy's shine some light on this?

Got my valve covers in from Nick - perfect.

x-chr
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  #196 (permalink)  
Old 09-26-2014, 03:14 PM
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ok - so lowering is out- headers are pretty tight.

chr
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  #197 (permalink)  
Old 11-18-2014, 08:52 PM
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So sorry to hear of Rick Parker. I spent considerable time reading his posts. A great contributor.







We will gusset top and bottom



Will add a second parallel tube


The cowl will be boxed. We have material to try some door bars.
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  #198 (permalink)  
Old 01-11-2015, 07:20 PM
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I finally got the front wheels for my FIA. Took some time (months). I had the side pipes and headers ceramic coated. I actually purchased some titanium exhaust bits - tube and resonator - unbelievably lite. Pipe and res weigh around 4lb. I would not expect more than 6 for a full pipe. Mine weigh 16 each. Have not exactly figured out how to weld it together yet, but we are working on it.

I am taking a bunch of stuff for powder coat so we do not have a steering wheel right now. The steering is quite lite. We are able to roll it around and turn the steering column with one hand. I really thought the steering was ready to go, but while cycling the suspension and steering with out the steering shaft installed, I noticed that the spline on the pinion does not run out true as it is welded a little off center to the center line of the pinion. This may have contributed to the stress cracks seen in the foot box. Quite dis heartening.

I spoke to Woodward and am seriously considering abandoning the original rack and having them build one. I would raise the rack some which would decrease the steering knuckle angle at the pinion. It would also decrease the distance from the tie rod end to the steering arm which is increased from stock because we are running extended ball joints. I would also be able to get 2 turns lock to lock.

As we were rolling it around tonight I thought about just running it this way as it is so lite, but it is just not correct.



Nick welded up some valve covers. We are working on the puke tank.
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  #199 (permalink)  
Old 07-10-2015, 05:29 PM
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Finally got the Penskes installed at the rear. The shocks are very short so we had to use remote reservoirs. ERA left us some nice cavities to mount them in.



I made a bit of a mistake when ordering them. It would have been convenient to have the swivals rotated outboard 90 degrees. We were able to clearance the mounting tabs.





Cycled everything on the bench.

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  #200 (permalink)  
Old 07-10-2015, 06:34 PM
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I have been wanting to show you guys this stuff for awhile.



Since I am replacing the steering rack I took some time to seriusly research a spindle alternative. I do not know if you are aware of these. They are Gen 2 Camaro replacements. They run C6 ZR1 hubs.

They are some lighter than the Gen 1 spindles.





They run a 7 degree Steering Axis angle as opposed to 11. This reduces positive camber on turn in of the outside tire.

They are forged with a 1" drop built in. This will eliminate the extended ball joints. They are quite compact with respect to the SA to the mounting surface. So much so that I am considering building longer LCA's. They do not come with steering arms - I purchased some for a Gen 1 setup which we will copy from.




Any C6 Wilwood brake kit will adapt right onto them with the caveat of a minimum wheel size of 17" It has been some work adapting for 15" rims but we are very close. We tried several Wilwood adapters finally ending up with a C6 adapter and the machining it until we got it where it needs to be. We modified a hat to get the spacing right. I have an .5 offset hat coming which looks like will need no modification.



Interestingly while upgrading the Mustang front suspension I happened to notice that this caliper was lighter than the calipers on the ERA. I had forgotten I purchased a street setup for the Mustang instead of road race. I have since upgraded the Mustang and am going to run these calipers on the ERA.

It seems like I weighed all this stuff, but I cannot find it. I think I have 10lb of un-sprung weight out of the system (per side). With magnesium wheels I will have 20. That would put me close to 80 per side which is reasonable.



I have not purchased the new rack yet. I want to have the new spindles complete and installed and then we will measure for the new rack. Tony Woodward was quite helpful in teaching me how to spec the rack.

I purchased some turntables and measured the stock Subaru stuff which gives a ratio of 17:1. That is very slow for such a short wheel base. I most likely will build at 15:1. but am seriously considering 14:1. Unfortunately you cannot re-gear the racks.
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