T70 Spyder Track Day Outing #2 Completed

Ron Earp · Feb 13, 2010

We’re planning on a second track outing at VIR with the T70 this coming Friday. We’ve been working steadily on various aspects of the car and I think we’re to the point now where we’re ready to go. Our last outing in October was the first time we’d ever had the car out on track and it was a successful outing, but we were sorting through a number of issues that we’d not had time to correct. I think we’ve got a handle on things now.<o

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Most of our work over the last couple of weeks has been dialing in the suspension setup. Having a fully adjustable suspension is one thing, but taking advantage of it and setting it up correctly is a big job. Most of the final setup was accomplished today with Jeffrey G. and Jeffrey R, without those guys and their knowledge it’d not be nearly as far along. We took the time to mount bars to the chassis to string the car easily and the time invested was well worth it.<o

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The final setup that we’re going to start development with is:<o

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Front: -1.0 camber L/R, 110mm ride height, and 1/16” total toe in. We have zero bump steer on the front and that is a big change from the setup we went out in October with. The ride height is also higher than what we used in October as well as we found it was very helpful to get it up in the 4.5” range in order to get everything adjusted correctly.<o

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Rear: The rear was far more time consuming to adjust than the front due to the number of adjustments and their interwoven nature. What we went worked toward here was -1.0 camber L/R, 120mm ride height, zero toe, and 7.0 caster. We get a tiny bit of toe in on compression through the range of motion for the rear suspension, but it is less than 0.25mm total and symmetric, thus we’ve got no rear bump steer either. Ride height is good, a bit of rake in the car, things are looking good. Camber can be added or subtracted and through careful adjustment of the radius rods adding or subtracting camber doesn’t bother the toe or bump.<o

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Weights: with a 185 lb driver (a bunch of cinder blocks since Jeff Young was on holiday) the car came out extremely close to being perfect. Cross weights were less than 14 lbs difference and we didn't see any need to mess with it given how all was setup with the ride heights. Good.
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I’d never setup a car like this one and the big departure for it over say a sedan is the amount of adjustability in the rear. For example, you can adjust toe at the both the top of the upright, bottom of the upright, and using the radius rods. Camber is somewhat similar on the upright. However, what you find is that you can get the upright setup in such a way that can you use the radius rods to alter your caster/king pin angle and put the suspension in a place that compression/rebound throughout the range of motion won’t result in any ill effect. Good stuff.<o

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I think we’ve got a good baseline to work from. We’ve got no bump steer front and rear, can add or subtract camber if needed, and we should be able to use the double adjustable shocks to start some chassis tuning. Got a couple of more minor things to sort before the test day but as long as the snow will go away we should be ok.

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TimOz40 · Feb 14, 2010

Re: T70 Spyder Track Day Outing #2

Hi Ron,
It's great to see your T70 move from the "build" thread and now appear on the "race track' thread !!

You're right about having "too much" adjustability. Sometimes we can over complicate things. Do you have a recipe to work with or a similar car to base your settings on?

Good luck with it. I'm sure plenty of us are looking forward to hearing some race reports.

EGLITOM · Feb 14, 2010

Re: T70 Spyder Track Day Outing #2

Hi Ron

Thanks for that info. What is the caster adjustment on the front ?

Also i´m a little curious about your front roll bar legs. Won´t they fold in in case of a roll over without having any crossbar and diagonal support ?

Thanks
TOM

Ron Earp · Feb 14, 2010

Re: T70 Spyder Track Day Outing #2

Hey Tom,

There are support under the front bar, up under the ally cross piece that ties the two sides of the chassis together. There are also down tubes from that bar to the floor, and two forward tubes that tie into the suspension mounts and the front of the car. I'll take some pictures if you're interested. I can see what you're saying about maybe folding in at the bend, but, it isn't a lot different from straight down tubes except that in this case straight down tubes would not leave room for a driver of any height. It is both SCCA and NASA legal as it has logbooks for both sanctioning bodies. In fact, it has to have an annual this week for both logbooks, new year and all.

I've got the caster written down for the front and look in a bit and post back. As I recall when we first had it out on track the caster was around 5.5 degrees and steering was just fine. Can't remember what it is now but I'll let you know.

Ron

Ron Earp · Feb 14, 2010

Re: T70 Spyder Track Day Outing #2

Tom, the caster upfront is about 4.35 degrees. I just quickly measured it with "the angle cube", not our suspension equipment, but it is generally very close.

Ron

flatchat · Feb 15, 2010

Re: T70 Spyder Track Day Outing #2 Planned

I'm really struggling to get my mind around that bumpsteer correction device --tie rod extension bolt :huh:-- especially on a vehicle intended for competition use .

The settings look pretty good for a start --may need more camber on the front --listen to what the tyres have to say -ultimately

gt40fran · Feb 15, 2010

Re: T70 Spyder Track Day Outing #2 Planned

Many suppliers of the same type of kits....pretty standard stuff when setting up a car for the track, and having muliple ride height requirements...one size does not always fit all.

http://www.rebelracingproducts.com/Suspension/Steering.html

http://www.tarett.com/items/914-products/adjustable-bump-steer-kit-211090_-detail.htm

Steeda Bumpsteer Kit - '79-'10 Ford Mustang

http://www.mustangdepot.com/OnLineCatalog/images/Suspension/TIER-08_AT.jpg

http://www.jegs.com/p/Competition-E...ering-Bump-Steer-Adjuster-Kit/749736/10002/-1

Ron Earp · Feb 15, 2010

Re: T70 Spyder Track Day Outing #2 Planned

flatchat said:
I'm really struggling to get my mind around that bumpsteer correction device --tie rod extension bolt :huh:-- especially on a vehicle intended for competition use .

The settings look pretty good for a start --may need more camber on the front --listen to what the tyres have to say -ultimately

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ersonal; mso-style-noshow:yes; mso-style-unhide:no; mso-ansi-font-size:10.0pt; mso-bidi-font-size:11.0pt; font-family:"Verdana","sans-serif"; mso-ascii-font-family:Verdana; mso-hansi-font-family:Verdana; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; color:windowtext;} .MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.0in 1.0in 1.0in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> </style> You could do a lot of things to adjust the front suspension – your ride height, rack height, arm location, bump steer kit, etc. If you haven’t mounted everything else in your car you might want to move the rack a bit if you wish and play with ride height, you could get really close to spot on that way. I think this same kit will fit on my Mustang when I get around to building that. Hardened tapered spindle, 5/8” heim joint, it isn’t going anywhere. Tell you what, it works beautifully and curve is great.

The front is pretty easy to setup. I think you'll find the rear is easy too, but will take a lot more time and beer. Everything is interconnected in the rear the way the front is not. Hard to explain, but you learn in a short amount of time how adjustments with the radius rods affect the geometry and toe/camber curves with suspension movement. And, over time you'll get it dialed it to what seems to be perfect.

The proof will be in the track drive. We wanted the camber conservative and we'll monitor tire temps and see what story they have to tell. We've also got a plan for dialing in the double adjustables too (my race cars have only had single adjustables to this point), concentrating on compression (bump) first and then rebound, as Mr. Carrol Smith and the helpful guys at Koni suggest.

We've got to do annuals on the cars today, fun fun. I dislike doing annuals at the track due to the time involved so what we do is get a bunch of cars at my house and bring our tech inspector there. Really nice fellow and agreeable to doing it this way thus saving us a bunch of time.

flatchat · Feb 15, 2010

Re: T70 Spyder Track Day Outing #2 Planned

Uh huh! thanks Fran --didn't know all that stuff was available-- still looks 'orrid though

jac mac · Feb 15, 2010

Re: T70 Spyder Track Day Outing #2 Planned

Me no likee either.....:sad:

Ron Earp · Feb 15, 2010

Re: T70 Spyder Track Day Outing #2 Planned

jac mac said:
Me no likee either.....:sad:

Well you don't have to drivee then!

Yep, that will work as well. We learned about that solution a few weeks ago and drew/theorized it as well, but, wasn't sure it'd do with the ride height. Might be that we end up doing that as we tidy things up. First things first though, get it back out and see if this is doing what we need it to do. From running the suspension through the range of motion is appears we have it set where it needs to be. If what we have is correct then we can look at other ways to accomplish it.

We're a bit pessimistic that we've got everything "perfect" because that just never seems to happen to the best prepared of outings. Now if the weather will cooperate we'll be able to make it out.

JeffYoung · Feb 15, 2010

Re: T70 Spyder Track Day Outing #2 Planned

Hey, if the bump is gone, the bump is gone.

Can't wait to find out on Furday.

jac mac · Feb 15, 2010

Re: T70 Spyder Track Day Outing #2 Planned

JeffYoung said:
Hey, if the bump is gone, the bump is gone.

Can't wait to find out on Furday.

As long as curee for bumpee doesnt breakee & result in hotee squishee sensation between L&R cheekee's then U bee Okee Dokee then.

Ron Earp · Feb 15, 2010

Re: T70 Spyder Track Day Outing #2 Planned

jac mac said:
As long as curee for bumpee doesnt breakee & result in hotee squishee sensation between L&R cheekee's then U bee Okee Dokee then.

Is that a brown pancake? We hope to not see any of those.

JeffYoung · Feb 15, 2010

Re: T70 Spyder Track Day Outing #2 Planned

I already had one brown pancake in that car....would prefer to avoid that next time.

I also agree the steering arms look odd, but if there is no bump and the stuff don't break, then I'm good with it.

Ron, Jac is probably right though that we may need to rethink that for 13 hours of use/abuse, especially if we bump wheels with someone.

Ron Earp · Feb 15, 2010

Re: T70 Spyder Track Day Outing #2 Planned

JeffYoung said:
Ron, Jac is probably right though that we may need to rethink that for 13 hours of use/abuse, especially if we bump wheels with someone.

Jac Mac is always right. But for now we have to get the car right and then we'll go for the "final" setup. I don't want any brown pancake on Friday either. I too had some of that action, albeit at about 50 mph slower than you were cruising.

Now quit posting on the interwebz and get to work.

jac mac · Feb 15, 2010

Re: T70 Spyder Track Day Outing #2 Planned

While your pondering what action you might take if any over this, have a think about the attached drawing, it attempts to explain that while your bumpsteer may now be minimal in the straight ahead position, the cure.. with the rack in its current forward position & outer tie rods in a trail position... induces a toe in situation on either lock... now any ackerman built into the steering will be reduced or reversed as lock increases, the car will have a violent reaction when its in a spin situation where loads swap sides while rolling backwards & a few other nasty's that I cant be bothered typing up.. looks like the rack needs to be moved rearwards a bit if your going to use the shorter steering arm configuration.

Silly thought.. I see my post count is now just over 50% of Master Earp's

Ron Earp · Feb 15, 2010

Re: T70 Spyder Track Day Outing #2 Planned

jac mac said:
Silly thought.. I see my post count is now just over 50% of Master Earp's

Hey Jac Mac,

I hope my earlier comment about you always being correct wasn't taken the wrong way. I sincerely mean it - to my knowledge I've not witnessed any of your advice on this forum being incorrect. As such I personally don't feel post count has anything to do with discussions on the forum.

As far as the suggestions on the rack we'll have to run what we've got now and see what it does. Right now the steering uses the forward most hole on the arm because that gave a better angle to the upper control arm. Static, that is, straight ahead geometry seems to be good but whilst turning through a small angle I'm not sure about. Also not sure how much turning will be needed on track either but we'll definitely pay close attention to it.

All this recent setup on the car has really got me thinking about the Z. For the last few years we've adjusted it by seat of the pants feel and laptimes, no scales and so on. Just tire temps, air pressures, toe plates, and a camber gauge. We're going to scale it and do our best to set it up next weekend as we've got the first points race the first weekend of March. But with the Z, being a stock car class, we are not allowed to make real changes to the suspension. The suspension is as given from the factory and you do the best with springs, shocks, and camber plates to make the most of it. I'm sort of scared of what we'll find!

Ron

jac mac · Feb 16, 2010

Re: T70 Spyder Track Day Outing #2 Planned

Nah, no problems here, my hide is to old n thick to notice any barbs on a fence or otherwise. The post thing was just me & numbers & the coincidence at the time..

I think you will find the lola a pleasure to adjust etc while sorting as compared to your other cars... rather than changing something on the Z-car where improvements can be hard to define with all its compliant bushings & flexy pressed steel suspension links ( we or more correctly, some of my fellow kiwis used to cut the heads off three inch nails & punch a couple of dozen into each rubber bush, just below the surface, to compress the rubber & therefore reduce the compliance of the bush), you should now be able to notice relatively small adjustment changes for better or worse.... however, be aware that with such solid linkage etc & some parts operating at conflicting angles you can on occasions create a 'bind' in suspension movement... simple way to check that is remove the spring/shock unit & sway/anti roll bar and check for full up/down movement of the upright concerned- @ front try it on both lock extremes as well- do that & you should keep out of trouble....

Just for the fun of it & while the white stuff is still around, deliberately spin the car while testing so you know what your in for..preferably with plenty of run off area

As an aside to this, many moons ago I was asked to build a full floating 9" rear end for a very well known ex Cologne Capri that had been repowered with a C*** engine, the existing Atlas? diff had shorn off the carrier brg on the Ring Gear side twice in succession & was obviously not up to the job, now the diff was a 4 link setup & we were very careful to mount the diff exactly as per the original lest we stuffed up the geometry & excellent handling of the car. After fabricating the housing etc I trial fitted it in the car & checked for full & free movement etc, the crew chief was on hand & we noticed what seemed to be excessive play in the upper front LH rod end, ...soooo we removed the arm to check it & found it had been ' doctored' with a piece of heater hose to replace the ball.... chucked a new rod end in and tried again.... with that 'new' rod end the diff housing travel was now limited to about two inches up/down when any angle of roll was simulated.... lesson learned & old 'fugly rubber' rubber rod end refitted..... never built a four link since, always three bars or versions thereoff.... had we not tried the 'empty' housing first we might never have noticed it & introduced an ongoing problem to that car.... sometimes you have to do it wrong to learn how to do it right..

flatchat · Feb 16, 2010

Re: T70 Spyder Track Day Outing #2 Planned

This is what I've done --- hopefully will be able to test drive it this w'end
-- may have to take some shims out to raise the rack a bit

T70 Spyder Track Day Outing #2 Completed

Ron Earp

EGLITOM

Ron Earp

Ron Earp

flatchat(Chris)

Fran Hall RCR

Ron Earp

flatchat(Chris)

Jac Mac

Ron Earp

Jeff Young

Jac Mac

Ron Earp

Jeff Young

Ron Earp

Jac Mac

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Ron Earp

Jac Mac

flatchat(Chris)

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