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DerHase

Autocross Champion
Location
Hampton Roads, VA
Car(s)
2019 GTI Rabbit
Low grip situations = car won't roll as much = don't need as much roll stiffness.

My FSB on stiff in the rain is definitely not ideal, but on 200TW tires in the dry it's faster. You'll also notice even on 200TW tires they need to have some heat in them before the front starts to feel right.

Same thing as if you have some real high spring rates though. But sway bars are easier to make a quick change for the conditions if necessary.
 
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meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
jay745,

I agree...but I'll give a stiffer rear bar a go...maybe I'll find a lurid 4 wheel drift in my future. Can't wait for summer!

ZuMBLe, right, and who knows, I may have wished for a larger front bar after installing the Wavetrac...that's the struggle with finding balance on the street. Ideally, this car should be a track car...fewer compromises.
 

meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
Low grip situations = car won't roll ass much = don't need as much roll stiffness.

My FSB on stiff in the rain is definitely not ideal, but on 200TW tires in the dry it's faster. You'll also notice even on 200TW tires they need to have some heat in them before the front starts to feel right.

Same thing as if you have some real high spring rates though. But sway bars are easier to make a quick change for the conditions if necessary.
...the rates are 70N/mm front and rear...I don't know what the motion ratio in the rear is, I suspect that I could up the rear rate with little trouble and leave the RSB alone...I may try to increase damping in the rear just a click or two...maybe that will help stiffen the rear roll rate just enough alleviate my complaint. But the more likely reality is that I just need to learn to how to drive this setup...the LSD's engagement point is still a bit fuzzy to me...but if all were perfect, we might be bored!
 
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DerHase

Autocross Champion
Location
Hampton Roads, VA
Car(s)
2019 GTI Rabbit
...the rates are 70nm front and rear...I don't know what the motion ratio in the rear is, I suspect that I could up the rear rate with little trouble and leave the RSB alone...I may try to increase damping in the rear just a click or two...maybe that will help stiffen the rear roll rate just enough alleviate my complaint. But the more likely reality is that I just need to learn to how to drive this setup...the LSD's engagement point is still a bit fuzzy to me...but if all were perfect, we might be bored!

You need more rear bar. Your spring rates are way wrong. Rear motion ratio is severely reduced vs front. @xXDavidCXx has several posts about it. I think a 550-600ish rear spring out back is really needed for properly matching a front 400lb (70n/mm) spring but he can chime in with the specifics.

The bandaid would be as much rear bar as you can find.

Increasing damping doesn't help balance mid corner. It just increases or throws away grip on corner entry and/or exit.

Adjust shocks only to affect the car in transition, adjust springs or bars for stead state grip.
 

meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
@meb58 What kind spring rate and bar do you have in the rear?
Ohlin Road and Track kit inlcude 70N/m front and rear...the RSB is an 25.4 034 bar set on the softer setting. I do not know what the motion ratio is for the rear mulit-link, but the effective rate is for sure less than the front.
 

meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
You need more rear bar. Your spring rates are way wrong. Rear motion ratio is severely reduced vs front. @xXDavidCXx has several posts about it. I think a 550-600ish rear spring out back is really needed for properly matching a front 400lb (70n/mm) spring but he can chime in with the specifics.

The bandaid would be as much rear bar as you can find.

Increasing damping doesn't help balance mid corner. It just increases or throws away grip on corner entry and/or exit.

Adjust shocks only to affect the car in transition, adjust springs or bars for stead state grip.
Yea, my comment about adjusting the dampers was a "what if" question to myself, but it's a fundamentally flawed approach - thank you keeping me on track, no pun. I can easily up the rear rates through Ohlin...but adjusting the RSB is pretty easy...unfortunately, I could not break the RSB upper endlink bolts free while laying on the ground - car on ramps. So VW will do this Tuesday.

Is my math wrong? 70N/mm = 619 in lbs? MY MATH WAS WRONG! Should be 400in/lb

If it matters...toe is zero front and rear, static front camber 1.3 deg neg, (dunno what the actual camber gain is for 9deg pos caster - just lazy) rear camber 1.5 deg neg...I might have liked a bit less neg camber in the rear...but it's likely not a bad setting for very faster sweepers/turns. Ride height is 4-6mm lower than stock...or ~1/4"
 
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xXDavidCXx

Autocross Champion
Location
AZ
Car(s)
2017 GTI SE DSG
Ohlin Road and Track kit inlcude 70N/m front and rear...the RSB is an 25.4 034 bar set on the softer setting. I do not know what the motion ratio is for the rear mulit-link, but the effective rate is for sure less than the front.
The rear is about 50% of the front.
 

meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
Replying to myself...70N/mm is ~400 in lbs. I can't read early in the morning. If the rear motion ratio is in the .68 range, the effective rear spring rate is 272 in lbs...I might take a stab at a 525-550in lb rear spring rate = ~350 effective rate...should still be within the damper's working range. This is also a pretty easy replacement...I'll check with Ohlin Monday.
 
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xXDavidCXx

Autocross Champion
Location
AZ
Car(s)
2017 GTI SE DSG
Yea, my comment about adjusting the dampers was a "what if" question to myself, but it's a fundamentally flawed approach - thank you keeping me on track, no pun. I can easily up the rear rates through Ohlin...but adjusting the RSB is pretty easy...unfortunately, I could not break the RSB upper endlink bolts free while laying on the ground - car on ramps. So VW will do this Tuesday.

Is my math wrong? 70N/m = 619 in lbs?

If it matters...toe is zero front and rear, static front camber 1.3 deg neg, (dunno what the actual camber gain is for 9deg pos caster - just lazy) rear camber 1.5 deg neg...I might have liked a bit less neg camber in the rear...but it's likely not a bad setting for very faster sweepers/turns. Ride height is 4-6mm lower than stock...or ~1/4"
Don't buy springs from Ohlins.

Get NASCAR style bench stock from Hypercoil directly.

I've run 400/650 and 650/1000 and many in between on Ohlins R&T.
 

xXDavidCXx

Autocross Champion
Location
AZ
Car(s)
2017 GTI SE DSG
Replying to myself...70N/m is ~400 in lbs. I can't read early in the morning. If the rear motion ratio is in the .68 range, the effective rear spring rate is 272 in lbs...I might take a stab at a 525-550in lb rear spring rate = ~350 effective rate...should still be within the damper's working range. This is also a pretty easy replacement...I'll check with Ohlin Monday.
The exact number I calculated was .56 rear motion ratio.

Also, you don't have enough camber for what you are doing/asking from the car. Fix this first.
 

meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
Don't buy springs from Ohlins.

Get NASCAR style bench stock from Hypercoil directly.

I've run 400/650 and 650/1000 and many in between on Ohlins R&T.
Thank you for that suggestion...Hypercoil has a great reputation. Aside from my LSD learning curve, higher rear rates may help me to adjust the car a bit more...I'm old and have become accustomed to trailing the throttle a bit into a turn, then gently applying power to help straighten out the car...at this point in the turn, I expected the LSD to help pull the car through the turn. But I am screwing up the entry (with the new bigger FSB ) and I'm still learning to work with the Wavetrac.

The static camber was a guess...I really need to find the amount of camber gain with 9 deg pos caster.
 

xXDavidCXx

Autocross Champion
Location
AZ
Car(s)
2017 GTI SE DSG
Front static camber is pretty mild at 1.3 deg neg. but the Ohlin/Vorshlag plates are set to their max positive caster ( set that way from Oline, so I ran with it ). Positive caster is now ~9deg...so perhaps the increase in front roll stiffness isn't allowing enough camber compensation...dunno...it's a work in progress.
Oh by the way, the camber curve up front does not give negative camber under compression, it starts to go positive real quick which is why we need so much negative static camber, and more roll stiffness.

See this thread for a detailed explanation. https://www.golfmk7.com/forums/index.php?threads/suspension-modeling.380313/
 

meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
Oh by the way, the camber curve up front does not give negative camber under compression, it starts to go positive real quick which is why we need so much negative static camber, and more roll stiffness.

See this thread for a detailed explanation. https://www.golfmk7.com/forums/index.php?threads/suspension-modeling.380313/
Understood...but the added caster does add to dynamic camber...still, what is 9 degrees of positive caster? 1.5 more than stock? I had 2.5 degree static neg camber with the GC plates...but no added caster with that kit. Twas a pretty good DD and track trade-off.
 

meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
I used this diagram long ago in my past to help explain geometry to others...I simply haven't dived into the particulars of this car because it has been a pure DD until this past fall. I cannot find all of my work from my 2005 Mini JCW...last car that I tracked every week.
 

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meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
Still trying to find a great alignment shop near me in the Hudson Valley...:( I went to the University of Arizona for college...I see that you are from AZ. That was in 1979.
 
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