Suspension modeling

[bfury5]

Here is the correct chart showing body roll vs estimated camber.

Notice how soon the outside tire goes positive.

View attachment 198015

So based on this, if someone was theoretically lowered 3" (which is a ton), they'd need 2.7deg of static camber in order to "allow" for 3deg of body roll?

edit: That seems pretty reasonable actually. A 1.5-2" drop means that ~3deg of negative camber would easily allow you ~3.5deg of body roll before you lose contact patch

 

[w124_karl]

Just checking to see if I’m reading this right. Is this chart including camber changes as a result of suspension compression?

Either way, it seems like a stiff front bar is worth some testing on a stock ride height car (like SCCA GS). I’ve been taking grip away from the rear to get the car to “work,“ where maybe adding grip to the front is what we need to be talking about instead.

 

[xXDavidCXx]

Just checking to see if I’m reading this right. Is this chart including camber changes as a result of suspension compression?

Either way, it seems like a stiff front bar is worth some testing on a stock ride height car (like SCCA GS). I’ve been taking grip away from the rear to get the car to “work,“ where maybe adding grip to the front is what we need to be talking about instead.

I think it’s definitely worth looking into.

Use toe out in the rear for more rotation, if needed.

 

[xXDavidCXx]

So based on this, if someone was theoretically lowered 3" (which is a ton), they'd need 2.7deg of static camber in order to "allow" for 3deg of body roll?

edit: That seems pretty reasonable actually. A 1.5-2" drop means that ~3deg of negative camber would easily allow you ~3.5deg of body roll before you lose contact patch

Correct, except maybe I didn’t mention, but the starting camber is -0.5, so I think the static camber requirement is -3.5 degrees.

 

[jmason]

Caster (or is it kingpin inclination?) will effect camber. Obviously its effect is a function of steering wheel angle. Can you factor in caster into your calculations?

 

[xXDavidCXx]

Caster (or is it kingpin inclination?) will effect camber. Obviously its effect is a function of steering wheel angle. Can you factor in caster into your calculations?

Not with this simple web modeling system.

I'll have to dive into my pay program to do that, will take a while.

 

[Mini7]

Correct, except maybe I did

Correct, except maybe I didn’t mention, but the starting camber is -0.5, so I think the static camber requirement is -3.5 degrees.

Ran -2.5 front camber at the track and IMHO it was not enough. Added CSS swivels and got to -3.4 after the alignment was complete. This setup felt much better in conjunction with my increased rear spring rate. I will need to look for my notes on ride height. Front is stockish, rear ended higher than stock.

TCR racecar is at -4 on 11k front springs as a reference point.

 

[w124_karl]

I think it’s definitely worth looking into.

Use toe out in the rear for more rotation, if needed.

Any thoughts on how the addition of more front bar might affect the VAQ diff? Personally, I suspect the car is far too nose heavy for that to make much difference - I can't really imagine it picking the inside front wheel up off the ground, unless I'm about to turtle it.

Rear toe out might be something settable at the event. Been a very long time since I street drove a car with rear toe out, so I don't remember if that's annoying.

I suspect coilovers and spring rates and all that stuff are a way better answer, but there's no way I'm prepping this particular car for STH. I've seen a well built STH Audi TT can do, and unless someone like Tom O'Gorman was driving the GTI, it's going to lose.

 

[xXDavidCXx]

Any thoughts on how the addition of more front bar might affect the VAQ diff? Personally, I suspect the car is far too nose heavy for that to make much difference - I can't really imagine it picking the inside front wheel up off the ground, unless I'm about to turtle it.

Rear toe out might be something settable at the event. Been a very long time since I street drove a car with rear toe out, so I don't remember if that's annoying.

I suspect coilovers and spring rates and all that stuff are a way better answer, but there's no way I'm prepping this particular car for STH. I've seen a well built STH Audi TT can do, and unless someone like Tom O'Gorman was driving the GTI, it's going to lose.

The VAQ is reactive and if one wheel is in the air, then would probably sense the "slip" and send power to the wheel on the ground.

As for tire lift, I'll let you all speculate about this photo.

2019 Solo Nationals, stock springs/shocks. Hotchkis FSB on stiff, 034 rear bar, probably on stiff.

 

[theDoktor]

Just checking to see if I’m reading this right. Is this chart including camber changes as a result of suspension compression?

Either way, it seems like a stiff front bar is worth some testing on a stock ride height car (like SCCA GS). I’ve been taking grip away from the rear to get the car to “work,“ where maybe adding grip to the front is what we need to be talking about instead.

My thoughts exactly. I picked-up a 26mm H&R fsb from Strano & acquired all the single-use OEM hardware to make the change. Gonna replace the rear 034 bar with the stock bar and play with rear toe. Years ago I was pretty competitive with Randy Probst at Nationals going this route, both of us in Rabbits. Worth trying, anyway.

 

[xXDavidCXx]

Just checking to see if I’m reading this right. Is this chart including camber changes as a result of suspension compression?

Either way, it seems like a stiff front bar is worth some testing on a stock ride height car (like SCCA GS). I’ve been taking grip away from the rear to get the car to “work,“ where maybe adding grip to the front is what we need to be talking about instead.

To clarify, I did not test for compression, this is body roll at roughly the same ride height. two different ride heights.

 

[w124_karl]

Interesting photo for sure. I’m inclined to agree with what you said about the VAQ not knowing the difference, and just doing it’s thing.

@theDoktor - did you have to pick and choose all your single use hardware, or does someone sell a kit? I bought a kit from DAP when I put the KONIs on, and it came with some extra stuff. Not the end of the world, they’ll get used if I ever have to replace the brakes.

I‘d also be interested to know why that particular bar, if you don’t mind sharing. Lots of options, and if I’m pulling the subframe and then getting the car aligned yet again, I’d like to only do it once.

I think maybe the GS stuff should move to some other thread though. If there’s not a ”GS a alternate setups to beat the Civics” thread, maybe there should be.

 

[burgerkong]

Ran -2.5 front camber at the track and IMHO it was not enough. Added CSS swivels and got to -3.4 after the alignment was complete. This setup felt much better in conjunction with my increased rear spring rate. I will need to look for my notes on ride height. Front is stockish, rear ended higher than stock.

TCR racecar is at -4 on 11k front springs as a reference point.

View attachment 198067

That's actually pretty good, how did you get the -2.5 to start, 034 plates? Too bad CSS knuckles have exploded in price otherwise I would've gotten them...

 

[theDoktor]

Interesting photo for sure. I’m inclined to agree with what you said about the VAQ not knowing the difference, and just doing it’s thing.

@theDoktor - did you have to pick and choose all your single use hardware, or does someone sell a kit? I bought a kit from DAP when I put the KONIs on, and it came with some extra stuff. Not the end of the world, they’ll get used if I ever have to replace the brakes.

I‘d also be interested to know why that particular bar, if you don’t mind sharing. Lots of options, and if I’m pulling the subframe and then getting the car aligned yet again, I’d like to only do it once.

I think maybe the GS stuff should move to some other thread though. If there’s not a ”GS a alternate setups to beat the Civics” thread, maybe there should be.

I had to pick & choose all my hardware. The Koni Sport replacement was the easiest- just bought the latest versions of the front strut bearings & new top mounts for the rears. The front bar replacement is another thing as far as the hardware. I used the factory shop manual to determine what was involved for the front bar replacement, which included lowering of the subframe. Every piece of hardware that gets touched is single use, stretch-to-torque type and must be replaced. I made a list of what I needed, went to my local dealers website for the parts list, and ordered all the hardware. I must say that this dealer Parts Department was great to work with (Towne VW/Audi, Buffalo, NY). I went this route after reviewing the installation kits from DAP & I believe, ECS.

I chose that particular bar size after decades of experience autocrossing, including 6 Nationals, in a variety of classes (Most were Stock classes.) and after having a long conversation with Mark Strano. My personal experience and my driving style tells me that, for me at least, with the Golf chassis in Stock class, the key is getting the front to stick without excessive roll-over onto the sidewall without going into terminal understeer. The front springs are too soft for Stock class autocrossing and the OEM front bar is too small a diameter. Legally you can't do anything about the springs, but a bigger front bar is helpful, up to a point. I believe the 26mm bar is close to that limit. I was hoping to find one of the smaller, in-between size front bars that Strano used to sell, but it is no longer available. Still looking though! I can work with the rear of the car thru shock settings, alignment tweaks & tire pressure.

There was a thread devoted to the GS setup, but it seems to have gone dead. I agree- we ought to break out the GS prep stuff from the STH prep thread, although I find it quite informative and helpful. Here's the link to that thread I mentioned: https://www.golfmk7.com/forums/index.php?threads/2019-g-street-nationals-dashboard.370935/ I have a top level Nationals competitor locally in a Civic, so I know and can tune to that that level of competition. Helps that he is a friend, too.

 

[Mini7]

That's actually pretty good, how did you get the -2.5 to start, 034 plates? Too bad CSS knuckles have exploded in price otherwise I would've gotten them...

SuperPro 018k LCA
Vorshlag Camber/Caster plates to get -2.5
CSS swivels to get to -3.5