32 replies to this topic

[Alberto]

I recently finished a fresh setup on my car and wanted some input.  I've only corner balanced 3-4 cars over the last 10 years so I'm a noob.

The car is a 1990 1.6. 

Driver (me) is about 205 lbs in suit, helmet and HNR.

 

Here is where I netted out with me in the car, ~1 gallon of gas, cool suit cooler with water in the pass seat area and the car on hub stands (so no wheels):

 

LF: 600 lbs        RF: 552 lbs

LR: 568 lbs        RR: 519 lbs

 

Left:         1171 lbs     52.3%

Rear:       1085 lbs     48.4%

X RF/LR  1120 lbs      50.0%

Right:      1069 lbs      47.7%

 

I set camber at -3.3 front, -2.9 rear.  Toe was 1-1.5 mm in on each side in the rear and 1-1.5 mm out up front. 

I forgot to check ride height on the ground but I was mostly checking to ensure that I had a minimum of finger or so of space between the shock and bumpstop.  I didn't when I started.

 

Yes, I did level each of the scales and then leveled them to the RF which was the highest spot in my garage.

 

Any input is appreciated.  Thanks!

[Jamz14]

Put the wheels back on, load the drivers seat with you weight, set ride height and start again.

That would be my input.

[Ron Alan]

Very important note...how hard you drive the car will determine your set up! If you come in with a line of rubber...adjust!

[FTodaro]

This will be controversial, but i do not like hub stands. I could not reproduce the same camber  numbers going from stands to tires on the same alignment. So i use tires on the car with air pressure set at the hot temps you run on your tires. 

Also agree, I set ride hight first as that will impact final camber.

 

I always like to check or set up the car before I have uncompressed the suspension. So if i jack up the car, i will jack it up on the control arms, as when i have uncompressed the suspension, i am not confident it settles to the same place as it would if it had been run on track. I may be wrong but that is how i do it to try and get the most accurate and reproducible results.

[Alberto]

I intend to recheck with wheels and my weight later.  Wanted to get some input before I put the wheels on since it is so much easier to adjust while on the hub stands. 

 

Interesting comment on the camber...  I'll make sure to recheck that with the wheels on the car.

Thanks.

[Jamz14]

I agree with Frank, depending on the hub stands. Why go through all the fine tuning work on the stands just to have to start over with the wheels on? Do your hub stands weight exactly the same as your wheels? How can you cross your car if they don't? The stands affect camber and therefore affect toe. But if you like doing it twice.......

Are you setting up with your driver weight in the drivers seat?

[Jamz14]

Easier usually means inaccurate when it comes to setup.

[Alberto]

Thanks but not looking to get into a debate about hub stands right now...

[Jamz14]

Nor I. Was trying to be helpful, and to ensure that the setup that you wanted was the one that was actually on the car. And, you mentioned that the Hub stands affecting camber was interesting. So I thought you were actually interested.

[Alberto]

Fair enough.

 

One of the things that I was curious about whether I should attempt to decrease some weight on the left or attempt to get more weight onto the RR.

[Jamz14]

Fair enough.

 

One of the things that I was curious about whether I should attempt to decrease some weight on the left or attempt to get more weight onto the RR.

Without getting into everything one could consider with moving weight around; as long as I wasn't moving too far away from my desired height when adjusting any of the corners to dial in my cross......... I'd leave it alone and wouldn't worry about it.

[Bench Racer]

IMHJ, if when using tires or jack stands and the numbers can't be duplicated, eliminate the issue and use what you'd normally use at the track. KIS principle. Didn't want to use the second S insinuating anything.

[FTodaro]

Fair enough.

 

One of the things that I was curious about whether I should attempt to decrease some weight on the left or attempt to get more weight onto the RR.

Depending on the amount of cross your running there is nothing you can do in the set up that effectively puts more wt on the rr. You can try to put stuff on the rr like cool suit or fire suppression but with the cross we run the RR is going to be light.

Some people smarter than me work on trying to balance out the wt more between the right and left, I do not focus on that, again I could be wrong but i focus on getting Ride height right, cross right and camber right the wt on the wheels is what it is.

 

That is just me.

[MazdaSteve]

Sway bars disconnected?

[Ron Alan]

Many factors go into a set up but because I know you Alberto, I know your car, I know the tracks you drive and I know the tires you drive...here is my advice. Cross at 50-50.3, front camber at 3.0-3.2, Rear camber 3.2-3.4(.2 higher than front), 1/8" total toe out in front. 1/16" total toe in in rear. Ride height equal front to rear(no rake)and error on the side of a little higher than to low(Maybe 4.5" off pinch weld or 3/4" from shock top to bump...assuming you have fatcats). After all this is done re-connect your swaybar link(you should have disconnected 1 side when you started) once the car is back under full load. Soft/soft on your car! This is the hole furthest from the 90 degree bend!

 

As mentioned by others...getting weight to specific corners should not be a concern. Weight forward or rearward is more important depending on how the car handles in general. Lots of little ways to move this around if you need to...to many to go into here.

 

Once you get back on track with your new set-up here is the 1 piece of advice I will give you...as you go back to the throttle at turn in and your car starts to rotate...TRUST that it will only rotate so far as it loads and you are on to the next corner pedal to the metal!

[Tom Sager]

Depending on the amount of cross your running there is nothing you can do in the set up that effectively puts more wt on the rr. You can try to put stuff on the rr like cool suit or fire suppression but with the cross we run the RR is going to be light.

Some people smarter than me work on trying to balance out the wt more between the right and left, I do not focus on that, again I could be wrong but i focus on getting Ride height right, cross right and camber right the wt on the wheels is what it is.

 

That is just me.

 

I think that is most of us. 

 

Working to get the LF and RF closer to equal isn't a bad thing on tracks where you run a little more than 50% cross. 

[Alberto]

Thanks gents.

 

Let me give you guys some background.  The car started the setup process at ~47 or 48% cross weight RF / LR with the standard camber and toe settings that most of us run.  The handling balance had been inconsistent and I wanted to address this as part of this setup.  On right hand corners, like T3 and T5A at Thunderhill, I couldn't put the power down b/c the rear would kick out.  The car was also difficult to transition from T3 into T4 and which is a quick transition and into T6 which is the beginning of a long straightish bit of full throttle. 

 

One of the first things I checked once on the scales with the car was weighted was how much space I had between the top of the shock and the bottom of the Fat Cat bump stops.  I had less space on the driver side rear.  I think it was less than Frank's finger but I don't think Frank ever gave us precise measurements on that appendage so I can only approximate.  I could barely get my finger in there to touch the shock shaft. (Get your mind out of the gutter).  Because of this I started my setup by raising the rear a few rounds until I had enough space there.  Because of all that ^^, I was curious whether I had lighted the rear too much.  Spoiler alert - Testing showed that I had indeed raised the rear too much.

 

After this, I did the same to the front.  Generally speaking, the fronts seem to have a wee bit more space "at ride height" to fit fingers and other appendages than the rears do.

 

Depending on the amount of cross your running there is nothing you can do in the set up that effectively puts more wt on the rr.

<snip>

i focus on getting Ride height right, cross right and camber right the wt on the wheels is what it is.

 

Yes and no.  At the end of the day, I wound up right around 50% cross weight.  However, before my last adjustment I was at something like 49.5 or .7 cross%.  In order to achieve 50%, I could have decreased the ride height on the driver's side front (LF) or the passenger side rear (RR).  I chose to do the driver front since I was concerned about running out of shock travel in the rear and that skewed the Left / Right weight from 52%L to 52.3%L.  Does that matter?  I don't really know.  Hence the thread. Mathematically / theoretically, it might.  Then again, the car has soft rubber suspension bushings so I'm not sure how precise to set my standards.

 

 

 

Many factors go into a set up but because I know you Alberto, I know your car, I know the tracks you drive and I know the tires you drive...here is my advice. Cross at 50-50.3, front camber at 3.0-3.2, Rear camber 3.2-3.4(.2 higher than front), 1/8" total toe out in front. 1/16" total toe in in rear. Ride height equal front to rear(no rake)and error on the side of a little higher than to low(Maybe 4.5" off pinch weld or 3/4" from shock top to bump...assuming you have fatcats). After all this is done re-connect your swaybar link(you should have disconnected 1 side when you started) once the car is back under full load. Soft/soft on your car! This is the hole furthest from the 90 degree bend!

 

As mentioned by others...getting weight to specific corners should not be a concern. Weight forward or rearward is more important depending on how the car handles in general. Lots of little ways to move this around if you need to...to many to go into here.

 

Once you get back on track with your new set-up here is the 1 piece of advice I will give you...as you go back to the throttle at turn in and your car starts to rotate...TRUST that it will only rotate so far as it loads and you are on to the next corner pedal to the metal!

 

those camber and toe specs are close to what I've been running except rear camber. 

 

So why more rear camber compared to front?  I'm going to google the theoretical behind camber settings but what is your experienced opinion behind that?  Drago says a few tenths less rear camber in another thread... 

 

Also, I think you meant to say 3/8" not 3/4" from shock top to bump...

 

 

Anyway....

 

I did a test day this weekend at Thunderhill on Saturday.  The first session was a clusterfuck since I had forgotten that Toyo RRs like lower pressures than the old RA1s.  Once I figured that out and targeted 34 PSI hot, I attempted some testing.

 

At the end of the day, I wound up with the the rear 2 rounds lower and the driver front 1/4 turn up and set the rear bar to full soft and the car was better.  I had started out with the rear bar set with one side to medium.  I had originally set the rear camber to -2.7 when on the scales and I had more understeer than I used to have.  I'm wondering if increasing the rear camber to -3.x like Ron mention will help that or whether I should set one or both ends of the sway bar to medium...

 

It was a fun day.  Nice to be on track again after 16 months. I'm going to recheck things this weekend.

[FTodaro]

I would let you measure my finger but that is proprietary.

 

You should have more shock travel clearance in the front vs rear and Generally I and many others are running the cars lower these days to achieve camber. You can get into those bump stops a wee bit with out getting tossed off he track. Your car is lighter than mine so you may be able to press it a bit lower.

[Steve Scheifler]

There seem to be some issues with your measurements and some assumptions, if I understand the above post.

You can’t shift overall L/R or F/R weight by adjusting ride height, so where you mention raising the rear a few turns made the back too light, something is amiss, unless you mean it felt too light on the track in terms of rotation/oversteer, which would be due to the impact of rake on handling, not static scale weights. Perhaps you know this but I’m just going by your words.

Similarly you mentioned the final adjustment moving overall L/R by 0.3. Again, theoretically not possible. That indicates a problem with the car binding up somewhere or not settling correctly. As you say, rubber bushings etc so a few tenths shift in any direction is not unusual and if you want to be precise you need to learn to overcome that by jouncing and rolling the car to get repeatable results. And of course if overall L/R or F/R is off then so is your cross.

You questioned whether going from -2.7 to -3.0 might reduce understeer. No, that’s backwards. Assuming that -2.7 isn’t already max or too much then -3.0 will increase contact patch on the loaded side, increasing grip and therefore increase understeer.

But in order of importance in terms of things likely to have a large negative impact on handling (as you have described it), I would rank everything else discussed above far more likely than a few tenths cross weight. And I know you don’t want to debate doing setup on hub stands vs wheels & tires, but IMO that’s the first thing I would correct.

I’ve never seen you drive or even where you finish or how your lap times compare, so don’t take this personally, but for someone not at the very pointy end of a deep field a few tenths cross weight will have little or no impact. I suspect that quite often what even they are experiencing is more the result of getting slightly more or less into the bumpstops rather than a few tenths of weight shift alone. (That was dramatically clear with the factory parts which were like hockey pucks after the first eighth inch.) Perhaps once you establish your own baseline it doesn’t really matter whether the change in handling is the tiny cross-weight shift or other factors, you learn what change has what impact even if you don’t fully understand the mechanics, but I think it could if you find youself making bigger changes to accommodate a particular track, like the bumps at Sebring.

[davew]

How you do an allignment is less important than consistent methods. But you must follow a couple of basics.

 

Platform  or floor must be level.

Driver weight in car.

Specific amount of fuel in car. Always the same.

Cool suit etc must be in as raced condition.

 

After you have those things factered out of the equation you can start work. If any of these basic things are missing, the data is worthless.

 

Ride height is extremely important. If you don't do ride height all other data is worthless.

 

Adjusting spring collars will NOT move weight LR or FR within the perameters we live with. Yes jacking the car up 6 inches will move weight. But that is not withing our perameters.

 

You do not mention caster, did you forget to measure that also?

 

Your toe numbers are misleading. Are you using toe plates or strings that measure off the wheels. Toe plates will give you about a 30% higher toe reading than strings.

 

Set a baseline properly. Then see what happens. If your baseline is off, or your data is incomplete, all your results are only as smart as the butt you are using to adjust the car.

 

Dave