The good old days of rocker arms

[jabro1000]

Got yet another one for all of you much more savvy than myself Reynard owners out there...The good news is that with some much appreciated advice from Mr. Reynard aka Keith Averill, the Hewland/Reynard gearbox is back in its home, and everything with that process went pretty smooth. Was feeling pretty good about things, so naturally something terrible assumedly lurked just around the corner. Finished fabbing up the toe/alignment bars and bolted them up to the chassis to start to get a rough bead on our toe in/toe out handling questions, and WHAMMO, our next obstacle, challenge, discovery, or however you would refer to it, jumped right in our faces:

Dad: "Wow, that bar doesn't clear the left front tire by much Jeff."

Me:"No Dad, I knew it would be close, but it looks like we've got 3/8 to 1/2 and inch to play with, should be plenty for the small increments we'll be adjusting."

Dad:"Yeah, probably. We could always put some spacers behind the bar."

Me:"Yeah."

Dad:"Hey, why this right front is way farther back from the bar than the other tire?"

Me:"Sh%t"

We thought at first it may be a castor adjustment issue, looking more closely at things (in an admittedly rough and not terribly scientific fashion just yet) it appears as though there are some fabrication discrepencies between the right front and left front rocker arms. We obviously need to analyze the whole situation more closely, and (with the exception of the straightaway dartiness which we believe to be related to other issues) the car handles fine for my driving abilities at the moment. The question is though, given the apparent complexities of having these rockers arms fabricated, I would think that they would be difficult to duplicat exactly on the nuts every time without a real accurate jig. Is this a situation which others of you out there have encountered before, and if so what have you done about it?

[rickb99]

Hard to tell from those photos because if the change in angle. But the front of the right tire is sitting back about 1/4" further then the left tire.

[jabro1000]

I could argue with you about that too, but we've had enough of that today, want to save some for next time !

[Purple Frog]

Yes, almost all rockers that i know of are fabricated in jigs...

I studied your pictures a while. Realizing that earlier this week I was sold on the idea that we were looking at a hole in a gearbox cover... not.

1. It looks like you did a good job fabbing the alignment bar. But, after installing did you check that it is perpendicular with the center line of the car? To establish a centerline, I use the center of the Reynard gearbox casting for the rear, and the center of the chassis for the front. It helps to have a surveyors transit, or laser device, or a great eye...

2. You are sure both front tires are the same diameter? DaveW has taught me to be anal about measuring tire circumferences. I measure all tires, almost every session. Clean them with a heat gun, inflate to a control pressure (I use 20 psi), and measure with my tire tape. This is a very critical step at the start of any setup. Rarely with bias tires are they the same. Usually though you can get two within 1/8" - 1/4" circumference. Radials are very close. But you can be way off if you have tires from two differnt generations, e.g. a early 2007 Hoosier vs. a late 2007 Hoosier. Remember the number two rule of racing...

2a. Some high dollar teams do actually have a set of "setup" tires and wheels. They consist of sticker tires that were picked through until they had a matching set... A practice that is a bit outside my budget. But if you measure everytime, and record the measurements every time, it is not too hard to adjust accordingly.

3. If the bars are perpendicular with the centerline of the car, then measure back from the bar with a T-square to the center of the outside spherical bearing at the end of the rocker. That could tell you something. If left and right measure close to the same...then...Like you said... a large difference in castor left to right? That would explain the dartiness.

4. Also, make sure the front shear plate is installed on the Reynard casting correctly and centered. Measure from the centerline of the car to the center of the rocker pivots on that shearplate. Should be the same left to right. A badly machined shear plate with less than 1/16" differend left to right could cause that problem in your picture. Also try to establish that those outside pivots are on the same horizontal plane. If the shearplate is not horizontally correct it could be tweaking the rockers so that they are not pivoting on the same relative plane.

5. And yes, could be the two rockers were built by different shops and on different jigs, and are not mirror images of each other. Or one has be twanged a bit. That is usually when I send the two rockers to Pat Prince and beg him to please hurry (dream on ). But, if that is your problem, and with drivers school fast approaching, we'll just adjust the car as best we can and go have fun. I wouldn't be surprised if over half the formula cars in a regional race have different wheelbases left to right.


6. You didn't pull the alignment strings super tight on the left side of the car and just barely tight on the right side of the car, did you?

7. Damn, just noticed someting else! It appears in the picture that you have the car up on stands, not resting on it's own weight. Why didn't I see that earlier. If so, then the droop limiters would have to be adjusted perfectly , else one wheel may be in more droop than the other. Put the car on a level (semi-level) surface, make sure the steering is dead nuts centered, same pressure in both tires... then look at it again.

Take two margaritas and call me in the morning.

[jabro1000]

Thanks Dr. Frog! Let me first extend my gratitude for referring to the crude stack of assorted lumber scraps that the car is sitting on as a "stand". Actually the rear is up on a proper stand which I welded up Friday night, and hopefully the front one will roll off of the fabrication room floor tomorrow. We never got to fully checking for squareness with centerline with respect to the bars; actually, we spent a good deal of time strenuously debating back and forth about the proper way to find the centerline of the car, and looks like according to your guidelines, Dad wins. Will run through some of your suggestions tomorrow and see if things improve some. The whole sticker setup tires concept is beyond my budget and reality also, but fortunately my addition and substraction skills are pretty well polished . PS It was an anomolous 70 something degrees here today, and it was pretty amazing to me how much softer those old tires got even just sitting in those kind of temps. I have some new Hoosier's I'm going to get mounted up this week so it's a moot point, but it definitely makes me wonder how they would have done with better temps at the track.

[Purple Frog]

The center of the front should be the center of the casting, since it has the pivots for the rockers on its outer ends.
On a Reynard, if you think about it, the steel chassis so sort of immaterial. If you base alignment off of the transaxle and front casting you be tracking straight no matter how twisted, bent, tweaked, twanged the steel tubes are. Get the bars right and you can check alignment almost in a grassy paddock. Some old guys even use the alignment bars to set ride height (why crawl under the car?). It's possible if the bars go on the same way each time.
Finding the c/l and marking the alignment bars so they always go on centered is crucial. You want the strings the same distance out from the center on both sides. I like the strings to pass the wheels at axle level.

Remember, if my car isn't up on its 30" stands, then my front stand is a piece of 6" PVC.

[Brian]

For me, step one is the car on the floor, at ride height (with springs, or with blocks), and see if the chassis is square. I start with wheel base, and track width, and that's pretty much where you are at. Don't just focus on the upper rockers - find out where the lower a-arm is at as well. I would think that it's a real good possibility that the rocker mounts on the chassis might be tweaked in or out, causing the rocker angles to be off. Lord knows the rocker mounts on my T440 were tweaked!

If you think the rear of the car is straight, measure from a point on the rear upright to the front upper ball joint to see if one is truly farther forward relative to the rear suspension, not just your bar. With the length of the bar, any tiny discrepancy at the bar mounts will magnify to a large difference at wheel width, and there is no particular reason why the bar mount points are going to be ultra precision.

Oh, and use thinner string. I use 50 lb test fishing line that you can barely see.

Brian

[jabro1000]

As always, appreciate all of your help guys, and thanks for your patience in explaining things that are probably second nature to you by now. Spent the better part of six hours in the garage today measuring, stringing, lasering, eyeballing, and redoing all of the above and have come to several earthshattering conclusions:

1)I have a twenty year old car, and it's not exactly perfect (I strongly believe the rockers are a tiny bit different)

2)I am a mere human being, and I am not exactly perfect (Alignment bars are not exactly perp with centerline and need some more tinkering/reworking)

3)My garage is not Los Alamos, and will not be anytime in the forseeable future (Until I purchase an electron microscope I won't be able to lay out or read markings on the chassis or floor with an accuracy of +/- .001")

The best thing that came out of today is that I think I have the centerlines of the front and rear castings to within +/- 1/32", which brings me to my biggest conundrum concerning this whole setup thing at the moment. If you are laying out a mark on something metal you can scribe it, which with absolute perfect execution is probably accurate to +/- 1/64", and that's being pretty generous, but if in a situation where you have to layout a pencil mark on something (ie. the floor) the mark itself is 1/16" wide. Opinions seem to vary, but I am told that one highly recommended toe-in setting is 1/16". If I flub a measurement on this end by + 1/32" and on that end by -1/32" there goes my 1/16" right there. Exactly what types of measuring instruments are we using to get this degree of accuracy. Can't be a tape measure; Biggest dial caliper I can find is only 12" which won't get me where I need to be; Trammel bar??? (If so, anyone have a good source for where to get one?)

I am going to keep messing with the alignment bars and stringing the car and referencing perpendicularity (word?) with center until I feel things are closer to perfect before making any adjustments to the car. I know I could take it to a prep shop and have all of this done for me, but that won't do anything for me when I'm sitting in the paddock somewhere someday wanting to adjust the car on my own. Maybe the bottom line is that the car seems to drive OK right now, and I'm better off just taking it out and driving it til the wheels fall off just like it is?

[Brian]

I share your pain with old cars being a little funky sometimes. You just have to balance things out.

For castor I use a protractor level, either digital (my newest toy) or the old fashioned kind that you have to actually look at. for Camber I've been using a Pace bubble type gauge. for toe I have used a trammel bar for years. It isn't accurate but it is repeatable. It measures total toe, so if your recommendation is 1/16" per side, you would see a difference of 1/8" total.

You have the strings, though, and that's the better way to do toe. You simply make sure the strings are parallel to the car center line as best you can, and then measure in from the string to the wheel rim using a dial or digital caliper. that's where people measure to thousandths of an inch. Measuring to .001" using a string that's waving in the breeze, is probably .030" thick anyway, and to a wheel rim that probably has .020" of run-out is sillyness of another kind, but that's still the best way to measure toe.

But to your point. Measuring to these precise numbers implies that you know what the numbers should be. I'd say that at this point you don't know those numbers for you and your car. You have some guidelines. At this point in your learning curve, just making sure you a a bit of toe out on the front, a bit of toe in on the rear, some castor, a bit of camber, and go drive the car and see what it feels like. I honestly know a top level guy who has put a setup on a car by eye, not a string or digital anything in sight (on a level floor, though) and that car went out and ran pretty near lap records. So make sure there isn't something silly on there, and try it out!

edit: forgot about the marks. If you had grown up the child and grandchild of carpenters and such like I did, you'd know that if you are marking with a "wide" instrument, you can establish a convention of "center of line, left of line, or right of line" that can guide you. Not that framing houses or doing trim carpentry has a ton to do with race cars, but the fundamentals of accuracy are the same if you're measuring with wavelengths of light, or a thumbnail mark on a piece of wood.

Brian

[Purple Frog]

Do not fall into "paralysis by analysis"

Just get it close and drive it. It is a 20 year old Reynard. There is probably slop in places you don't even know are places yet. They are very forgiving cars and very fun to drive. Get things generally pointed the right way and have fun.

You'll get better over time with the setup science.

[kea]

If the result of what I see in your photo, is a different caster angle between both front wheels, that would have a big influence on the old darting issue we spoke about in the past!
Is the distance from the center mounting hole in the front beam, to the rocker pivot bearing center, the same for both sides? Is the front beam flat across the front, or is the right front side being pulled back? Or, just call me and we'll talk.
Keith
Averill Racing Stuff, Inc.

[rickb99]

Keith,

If it IS a difference in caster, that will WORRY me a little. You adjust that with the lower A-arms 'only' right? Depending upon the direction it needs to go, a couple of the rod ends are FULL in Hope it needs to go the other way.

IF we were eyeballing things correctly, YES the 'apparent' difference in that right A-arm does put the top ball joint further back. Wheather it's a manufacturing difference between the two or as you say, something pulling it we aren't sure unless Jeff has taken more measurements.

Jeff plans on calling you today or tomorrow about something else. Probably on his lunch break so he won't have a lot of time.

[kea]

Jeff called and I explained a few things to him.
Keith

[jabro1000]

Well, even if I never manage to win a race I will be able to rest assured that we have set the record for the worlds's slowest chassis alignment ! The good news is I think things are starting to come together a little bit with the whole thing; of course that opinion will probably change drastically the first time I brake for turn 2 and the back end whips around on me at 130 mph ... Spent mucho time getting the alignment bars dialed in just right and centerline of the car down to the gnat's earlobe, thanks for emphasizing the importance of that Frog; the time spent was well worth it. With the bars done correctly and the Longacre Camber/Castor gauge we decided to start taking some measurments to see where things were sitting. Measurments for toe and camber were all over the road, and we figured that knowing what to expect from the car as it sat, we might as well adjust some things and see if we couldn't really screw the whole deal up.

Before:

LF Toe 1/8" Out Camber -1.2 deg
RF Toe 1/16" In Camber -0.6 deg
LR Toe 1/8" In Camber -0.7 deg
RR Toe 1/32" In Camber -0.1 deg

Now:
LF Toe 1/16" In Camber -0.9 deg
RF Toe 1/16" In Camber -0.85 deg
LR Toe 1/8" In Camber -0.7 deg
RR Toe 1/8" In Camber -0.7 deg

We are hoping that these adjustments along with new tires and warmer temperatures make some measure of improvement in the dartiness of the car. It would seem that having one front wheel slightly toed in and the other slightly toed out could make the car a little unpredictable at times (Why yes, you can call me Einstein, thanks for asking!) Castor has us a little intimidated, and we debated the necessity of turnplates numerous times today, but decided that $600 is going to a lot of other things before we ever get to that. Breaking out Prepare to Win, Carroll states that chalk lines on the floor are "good enough for our purposes", so back out to the garage I went and laid out some lines on the floor. I may not be spot on with this one, and could see things changing 1/10th of a degree or two with some slightly more assiduous layout, but it looks like LF Castor (the side of the car which is closer to the bar in the pictures) is about +3.5 deg and RF Castor (side which is further away) is about +3.0 deg. So the quesions are (you knew they were coming ) is a .5 deg castor difference enough to equate to a 3/16" difference in the distance to the bar, and would said castor difference be enough to translate to dartiness on the straight at the track?

[Brian]

There are a lot of ways to measure castor. One really basic way is described in the DB1 setup guide on the Swift Register site. It involves measuring from a known point on the rear upright to the upper and lower balljoints at the front - the difference is an indication of the tilt of the front upright, hence the castor. It's probably more important to have them equal than set to some magic number, at first. I would probably drive it at 3 and 3.5 and see what it felt like. I usually set castor by looking down on the upright from directly overhead and adjusting by eye, then check with a level of some sort. I always figured that since I didn't know the exact number I wanted and I just wanted them to be the same, that would work out OK. I still think that until you're fine-tuning for a driver who knows what he/she wants and why, "some" castor is enough to get you started.

As far as the toe is concerned, 1/8" out on one side and 1/16" in on the other is exactly the same as 1/32" out on both sides with the steering wheel/rack off center by an imperceptible amount. It would probably work out just fine, although it's a tad less than some might recommend. Toe on the front is a total included angle, not two individual measurements. That's how the old Dunlop optical toe gauge works, and it's still a very good system to use, if fiddly, fragile, and it doesn't automatically set the steering wheel straight...

Remember that anything to do with front suspension/steering geometry is to a large degree self-correcting by the one part of the system that you can actually adjust on the fly - the nut behind the wheel!

[GeoffRain]

If you haven't already done it, you should invest an hour or two to do the bump steer - at least in the rear. Set up imporperly, rear bump will make the back end feel loose even when it isn't.

Also, watch that you don't go too heavy on the front camber. I did it "by eye" once after a minor shunt in qualifying. When I went out for the pace lap, the steering was "a little heavy". By lap 6, I didn't think I could hold the wheel any more. Unfortunately, I was leading and on my way to winning my first ever race, so wimping out was not an option. We did win that one. Had to rest my hands for 2 hours before I could drive the tow vehicle home!

[rickb99]

For those of you who followed this saga and the case of the darting around front end in the other thread and the screwy looking problem above, ALL of the advice taken and it solved the problems. Totally stable front end that he says goes where he points it. Using the scientific method, the only way to tell for sure if the 'darting nose' was a result of the improper alignment or, 33 degree temperatures and stone hard old tires would be to repeat those conditions. And, I really don't want to go through that!

Jeff had his first novice race this weekend. Did a nice job with no spins and no damage. The FC lap record at this track is held by Bob Gelles with a 1:25 in a newer VD. Jeff did a 1:33 in qualifying with the old Reynard. I thought that was pretty good for a first time novice. The rest of the story is his.

He did just BARELY made the race though. 7 minutes to 'release cars when ready' and it was a hysterical fire drill switching to rains and setting pressures (had to leave the two leaky rims over inflated till the last second) as the threatening down pour started. Then, push starter... Uhhh no go. Push starter agian.. Uhhh no go. Jeff strapped in saying it's okay dad if it doesn't start, it doesn't start.. It's okay dad... Meanwhile dad's wiggling wires switching switches, looking at lights, banging the dash. Finally removed side panel and sure enough an intermittant contact on the solenoid wire intermally. Got him going for the race and now to figure that problem out.

If it ain't one thing, it's that other thing.. Don't cha love it?

BTW: KEA, that is NOT your new starter with the wire problem.

BTW2: He ran the weekend on a nice set of Berget used Hoosier's

[kea]

Rickb99,
Glad to hear Jeff made it out and had a better time.
Sometimes oil (old engine leak?) will get inside of the starter solinoid and stick the piston enough, that it won't travel and make the internal connection. It's not very difficult to remove and inspect/clean, so if you don't find another reason for it's inactivity, try this.
Keith

[rickb99]

Will do Keith. I'm 99% sure it's a wire problem. When he hit the button there was absolutely NOTHING... not a hint of a click or any sound like the solenoid was 'trying'. Regardless of that, it's time to pull it and make sure we don't have a bigger issue as you say.

[Purple Frog]

If they started all the time, they wouldn't be Reynards.

I remember a race at Roebling Road a few years back where I believe 3 Reynards had to be push started within the 5 minute warning. The legendary "ceremonial push starting of the Reynards".

[jabro1000]

Thanks Frog, I'm glad we now have a formal way of determining that we have a bonified Reynard and not just some knockoff look-a-like . In all seriousness, thanks to everyone who has thus far taken the time to help us wade through our ignorance in trying to learn how to run this car. We have a long way to go obviously, but thanks to all of you the car felt much improved this time out. I had a great time when I took it out to the track day in March, but this time I had an absolute blast, and was comfortably able to push the car just a little harder every lap around the track (until it started pouring rain and hail 9 minutes before I went on track at which point I nearly wet my carbon-x in fear; every race in the rain at Pacific Raceways seems to result in mass carnage). I'm almost positve I could have got it into the 1:30's in the race if it had stayed dry. Can't hardly wait til the next one!

PS Special thanks to dad for performing the last minute miracle and getting the car going when I had written the whole thing off.