Base line setup that came on my SR8 - odd to say the least.

I don't have a radical but I am interested.  I set up my racecar with scales and know a few things.   Spring rates don't mean anything unless you have context like the off road trucks.  Chassis frequency gives you an instant relative stiffness across anything with wheels.  There is a chart in the mechanics section in the resource on this site.  It tells you the spring rate for the SR8 at the frequency you want.  In the most simple form lowest frequency for slow tracks big bumps rain.  High frequency fast tracks, dry conditions, very smooth track. 

I don't think you can set anything until you balance the car on your scales.  The manual has baseline settings for rideheight, shocks.  You need to ballast the car as raced with 50% of the fuel load.  disconnect the sways, put hot presures in the tires which is 32psi on 2013 sr8 on dunlops.  Then set the rideheight to factory.  Then tweek each corner to scale the car.  Radical is the only manufacturer I have seen who wants the LF and RF close +-22lbs at the expense of 50% cross.  I have not scaled a radical but I think you should be able to get 50% cross and near perfect LF and RF corner weights.  I think the weird LR you have might be someone scaling the car from only 1 corner.   You can do that but you screw up your rideheight.  Bad RH will make an aerocar undriveable because the air going under an aerocar is critical to your grip and overall balance. 

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Posted by: Richard Kosar

Hey Charlie - as this forum grows you may want to add sections for things such as suspension setup, engine, trans, etc..  Also where's a "preview post" button so we can check our work before handing in our homework (posting)?

I have to ask:  
When adjusting shocks, do you go from fully closed (clockwise until seated) or fully open?  In the motocross world we go from fully closed (seated) out.  So it's "X clicks out".

The settings I took off the car today are:
Front:
Rebound - CLOSED!!!  Huh?   Who runs on the fully closed setting???  This may be why the front end was so stiff and searching - it was packing!
HSC (high speed compression) - 11 out
LSC (low speed compression) - 13 out

Rear:
Rebound - 21 out
HSC - 18 out
LSC - 8 out

I've not figured out what springs are on the car - they're grey on all four corners.  I need to find out what rate they are, though.  It looks like the rears may have tender springs on them - they are orange with flat coils.  The lightly preloaded spring actually shows a bit of space in-between the coils.  I know in the manual it mentions spring frequencies - argh... I'm an off roader.  Give me a spring rate and a preload number.  Never did follow that frequency thing...

Preload is odd.

Front:
Left 46mm  Right 47mm
Rear:
Left 44mm  Right 33mm  (huh???) - this is the one that the tender(?) has some space between the coils.

I've put a level across different points on the car and I can't find a common number.  It appears to have about .2 degrees of twist in the chassis - still not positive on this, though, as it may be the jack heights and some other factors causing this.  I'll get the car back on the floor and then start looking at what's level or not.  Once on the ground I'll start measuring camber and caster - have a set of turn plates already so that's a bonus.

I have a set of scales heading this way so I'll be able to get a reading on that.  I'm curious as to what the weight will be with me in the car and that funky right rear preload setting.

I need to make a set of alignment bars that attach to the chassis and I'll start getting measurements for toe and such.

So, does anyone have some base settings that they can share?  I'm sure that they are fairly close across the board (within 4-5 clicks on shocks, similar spring rates, etc.)  I'd like to be able to compare what you guys are running and what's on this car just to get a base line.

Thanks in advance for any input.

Great idea Richard.  I created a new section as requested and moved your post to it.  Regarding "preview"  Unfortunately this software doesn't have that function.  But you can make a post and then edit it if you want to make changes.

Regarding your technical question, I was going to point you to the Mechanics manual like Carl (FatBillyBob) did....and by the way Carl is being modest when he says "he knows a few things about race car set up".  He knows A LOT about race care set up.  

Charley

Charlie - thanks for the new section.  I’ve owned an off road forum (minibuggy.net) for the past 6ish years (it was dropped into my lap) and have found that you’ll add as the forum grows. It makes things easier for the members to navigate. I’ll speak up on occasion if you don’t care.  I have to laugh - had to go back and see if I’d posted this thread as it wasn’t in the section I put it in.

Carl - thank you!  I’ll have to go read up on spring frequency.  I read a bit about it a while back but it was more road oriented so I didn’t wrap my head around it. Your description is a perfect way of putting it.

I've looked at the page in the manual and need to cross reference what springs are on the car.

Aero - this is a new world. What you say makes all sorts of sense. My experience says “raise ride height, soften springs” but you mentioning aero throws a whole new aspect into it and I’ll be a sponge for anything you wanna throw my way.

I had an eye opening experience at Buttonwillow regarding aero as I was playing with the two GT4 Porsches.  I got up behind the one that was doing the video through Riverside and I felt the front of the car suddenly get light in the steering.  As I moved back out from behind him into clean(er) air I could feel the car stick back down to the track - heard the F1 announcers talking about loosing aero in my pea brain.  It was an interesting moment and I was quite tickled that I noticed it, especially since I have such minimal seat time in the car.

Regarding scales - I’ll go about getting things set up weight bias wise as the manual states. I’m quite curious to see where it is as it sits now.  I’m sure it’s not correct.  11mm of preload difference on a shock that only has 3” of stroke is quite a drastic difference compared to my world of 13” stroke shocks.

My plan over the winter is to get as much track time at Arizona Motorsports Park (AMP) as possible. I’m already fairly familiar with the place to using it to learn and dial in this Radical should be a good plan.

My scales arrived this afternoon and the car's ready to go other than the bodywork being on it.

So this afternoon I loosened all the damper settings to fully open, (forgot to put the tires to hot pressure - will remember to do this), disconnected the sway bars and started playing with spring preloads.

Here's what I had with me in the car on my first measurement:

Started spinning springs and got the front end spot on once:

Then started trying to dial in the back and this is where I left it this evening:

Trying to get my head around which spring to add preload to and which one to remove it from has been a bit of a challenge.  I've been taking pictures of each change but I'm not keeping track of the change(s) on paper.  Tomorrow I'll put pen to paper and start tracking the movements.  Trying to get that 70 lb difference across the back out is a good learning experience.

I am correct in that I want my weight in the driver's seat as I do the settings, right?  I'm getting good at climbing in and out. (:

There are two plastic anchor points on the crash structure, I use them for my string bar, they line up perfectly. I'm am pretty sure that's what they are for. 

Thank you Graeme, I’ve noticed those pieces.

I plan on making a set of string bars next.

Talked to James and Bill at Spring Mountain today.  I was able to get a lot of good base line setup info.

Some of the settings on my car were close to what I've been given, some were a bit off.

Front camber should be -2.5 degrees.  Mine was right side -2.0, left side -1.5
Rear camber should be -1.5 degrees.  Mine was right side -1.5, left side -.75

My drop heights were way off too.  The car was absolutely slammed to the ground - about 20mm more than needed.  I'm now at the recommended 68mm front, 81 rear (this gives me a recommended 13mm of rake).

Shock settings weren't very close either  They are now (all out from seated, fully closed):
Front LSC 12, HSC 35, Rebound 4  - I find the stiff front rebound interesting.
Rear LSC 10, HSC 35, Rebound 22

Cross weight at the front with me in it is equal at 19.7% each side at 327 lbs 
Rear is more left weighted (542 left, 470 right) but I've been informed that's the way these are and it's all right.
Car weighs 1664 with me in it (not sure exactly how much fuel is in it - 2/3rds tank maybe?)

I need to make a jig for toe tomorrow.  Changing my camber definitely changed toe in the front.

Was told to have 1mm toe out up front and 3mm toe in in the rear or 2mm toe in if I like a slightly looser rear end.

Question - Do you measure toe from the center line of the car to the wheel or is it from center line of wheel to center line of wheel?  I've seen it done both ways and as sensitive as these sound to be to changes, if I get it the wrong way, I'll be either half way there or have twice as much as needed.  I'm kind of under the impression it's off the center line.  (does this make sense?)

I'm moving along!  Going to Arizona Motorsports Park on Saturday to see what the changes have done.

I center my strings using a similar point on the chassis side to side at the front, then at the back. Then go back and forth until it's perfect. Effectively, to the center of the car. The problem with using the hub as many recommend, is that camber changes will change the dimension from the hub to the centerline of the car. It might not matter because its such a small amount, but that's my perfectionist coming out. 

Things I have noted, front camber will change toe, but not the other way. Rear: toe will change camber, but not the other way.  

make a good drop height bar, but make note of tire height from the bar to the top of the scales.  

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Wow!  I got much better balance on my 3500lb corvette converted to racecar.   I would hope you could get near perfect with a light purpose built racecar. 

Your front weights look great but your cross weight is 52% way off.    You want to:

1-make sure you have a flat floor use bucket of water trick

2-disconnect sways

3-tires to hot pressure

4-alignment settings close to equal left and right

5-1/2 the fuel load  so drain your tank add what you need for slosh like 2gallons then maybe 5gallons more total 7 gallons (that assumes 10gallons for 30-40min race...total guess on my part)

6- sit on a scale fully equipped helmet etc and in driving position with feet on another scale.  put weights in your drivers seat matching the butt scale.  put weight in footwell matching the foot scale

7- set car to factory ride height

8- you need roll off platforms or greased slip plates under the scales to release the stichion of your suspension. 

All this is super important to have any meaningful results or you are wasting your time.

now start scaling the car but make small adjustments in the direction you want at 3 corners not just 1 so that your rideheight does not go to hell in one corner.  This is especially important on cars with aero.

Great information! One day I'll be referring back to this page.

How do you figure cross weights - for that matter, what is cross weight?

Looks like I’ll be tossing a couple of bags of bird seed and some billet blocks into the seat and and floor and rechecking things today.

At least I was on the right track as far as spring adjustment and not trying to get results with one spring.

Posted by: K-fab

How do you figure cross weights - for that matter, what is cross weight?

Looks like I’ll be tossing a couple of bags of bird seed and some billet blocks into the seat and and floor and rechecking things today.

At least I was on the right track as far as spring adjustment and not trying to get results with one spring.444

cross weight is RF + LR / total weight   you want 50% cross so your car turns left as well as it does right.  you want RF = LF for best braking.  Unless you can move weight around the car it is difficult to achieve so you compromise.  Radical base setup is LF RF delta 22lbs if I remember correctly and makes no rec for cross weight. 

Thank you, fbf.

I went back and redid my camber settings after reading your post.  I put two bags of bird seed and a bag of water softener salt in the seat (140 lbs) and 20 lbs. of billet aluminum in the footwell and rechecked my camber.  Interesting that everything was off by about .5 degrees in the same direction.  Damn, these things are touchy!  I’ll mess with the cross weighting this week.  I’m starting to understand spring changes.  They affect across the chassis diagonally and, to a point, both the other corners.  I’m still not sure how to get 70 lbs of rear differential spread about all four corners.

One other thing I forgot to mention was I put the OEM spec front sway bar back in when I was putting it back to “stock”.

Rear end was twitchy today. I spun twice.  Once was cold tires and too abrupt with throttle input (snapping off) and other was getting a bit deep under braking into the corner than I should have (should have just dropped two wheels off and kept going ? ).  Regardless, the rear end is loose compared to the previous setup.

I read a bit of the tuning info in the manuals and it mentions stiffer front sway bar to make the rear end plant better.  Hmmm....  Thinking the stiffer one may have been the correct choice?

btw, I don’t know spring rates - none of them were still marked.

Cheated sound check this morning.  While doing sound check I short shifted and kept the revs below 6k.  

Got a pass point by during my second session at the sound check point and broke the 96db limit by 5.  Crap.  Got black flagged and my day was done.  

My “loud” mufflers arrived yesterday and I didn’t have time to install - will have to cut the mid pipes and weld the muffler section in place. Pix to come.  I think I need to repack the main mufflers too.  I will defeat the 96db limit at AMP!  Heck, even at the expense of 10-15 hp I’m good - the Radical needs to be quiet. Any hp that I choke out will not be missed.  Lol 

Fortunately my student wanted me to drive a session so I still got to play - I had no idea how fun a 1999 Miata is! What a hoot!  Massive chassis movement - felt like I was in our Polaris RZR - but what a blast being able to feel each wheel grip via throttle, brake and steering.  They drift so easily and predictably it was an absolute blast to drive. The guy that owns it, 20 year old, first time on a track, kept saying “Wow! I had no idea it could do this!”  Yeah, neither did I! ?

It’s been a great day.