DerHase's 2019 GTI Rabbit Edition: HPDE shenanigans

[DerHase]

Maybe look into MSS Kits springs if money isn't too much of a concern. I installed mine at 1/2 way in the height adjustment when I installed mine and the car was about 1/4" higher than stock. Lol.

Thanks but that kit is nowhere near worth the money. It’s almost 2x the price of a Ground Control kit which comes with Eibach springs instead of some of questionable quality, and much nicer adjusters that also help eliminate bind due to the control arm angle changing vs the upper spring seat. If the MSS function as a true dual rate (would need to see the springs at ride height) then the effective spring rate is probably an order of magnitude softer than stock until the tender spring is fully compressed, at which point the larger spring rate fully takes over. It also looks to be a very good likelihood of coil bind but I can’t say for sure without seeing them installed and taking measurements. Just based off of prior experience fabricating coilovers and piecing together stuff using Koni road race cartridges and spending $1000s testing out springs.

I don’t have any real need for the front to be adjusted, but having rear adjusters and being able to throw a 300-350lb spring in the rear might be a nice option. If I wanted to do this absolutely as cheaply as possible, I’d buy a pair of BC rear adjusters for $90 and some Eibach or Hypercoil springs and be out no more than $250 for everything.

Someone else recently found the 034 RS3 lowering springs work well on a MK7 wagon, so that’s another interesting option. Very little drop, more spring rate.


All that said I threw the shocks on yesterday - holy shit these things are good. Going to do the offset camber bushings today, I wanted to drive around a bit before to assess the feeling of the shocks alone. The car should have come with these stock. Soaks up all the little imperfections but keeps the body better controlled entering a turn. 10/10 recommend.

 

[scrllock]

Thanks but that kit is nowhere near worth the money. It’s almost 2x the price of a Ground Control kit which comes with Eibach springs instead of some of questionable quality, and much nicer adjusters that also help eliminate bind due to the control arm angle changing vs the upper spring seat. If the MSS function as a true dual rate (would need to see the springs at ride height) then the effective spring rate is probably an order of magnitude softer than stock until the tender spring is fully compressed, at which point the larger spring rate fully takes over. It also looks to be a very good likelihood of coil bind but I can’t say for sure without seeing them installed and taking measurements. Just based off of prior experience fabricating coilovers and piecing together stuff using Koni road race cartridges and spending $1000s testing out springs.

I don’t have any real need for the front to be adjusted, but having rear adjusters and being able to throw a 300-350lb spring in the rear might be a nice option. If I wanted to do this absolutely as cheaply as possible, I’d buy a pair of BC rear adjusters for $90 and some Eibach or Hypercoil springs and be out no more than $250 for everything.

Someone else recently found the 034 RS3 lowering springs work well on a MK7 wagon, so that’s another interesting option. Very little drop, more spring rate.


All that said I threw the shocks on yesterday - holy shit these things are good. Going to do the offset camber bushings today, I wanted to drive around a bit before to assess the feeling of the shocks alone. The car should have come with these stock. Soaks up all the little imperfections but keeps the body better controlled entering a turn. 10/10 recommend.

You know MSS springs are good because the 'track influencers' still push them and MSS refuses to publish spring rates.

Didn't someone fit the PSi rear adjuster to a mk7? It's pricey compared to what you get with the full GC kit but looks nice.

https://www.performanceshock.com/product/psi-raceline-audi-ttrsvw-mk56-rear-weight-jacks-rh-adjust/

 

[dwvw]

MSS Springs are made by Eibach as well. I don't track my car (drag racing only) But haven't experienced any negative effects on them. If I didn't find a good used set I wouldn't have bought them, but a local guy was selling them for half price as he couldn't get rid of a popping sound with them, they are quiet on my car. I just wanted something that I could adjust amount of lowering that worked good with DCC.

 

[DerHase]

MSS Springs are made by Eibach as well. I don't track my car (drag racing only) But haven't experienced any negative effects on them. If I didn't find a good used set I wouldn't have bought them, but a local guy was selling them for half price as he couldn't get rid of a popping sound with them, they are quiet on my car. I just wanted something that I could adjust amount of lowering that worked good with DCC.

(Edit: Didn't realize the springs were made by Eibach, so that's at least good.)

Are one of the two springs fully compressed at static ride height though? Because if not then you have a ridiculously soft spring rate (which I'm sure works great for drag racing at least up front, rear might be debatable). Or if literally all you care about is the ride height then sure.

When you are compressing two springs in series, there is a formula (below) needed to get the actual effective combined rate. That rate does not change until one of the two springs is fully coil bound (or if you have a physical blocker/locking collar which is common for offroad 4x4 applications, at which point the direct rate of the non-coil-bound spring is the only thing at play).

Even if you stack two 500lb springs on each other, you only end up with a 250lb actual rate until one is coil bound. This works great in offroad applications, but with the amount of wheel travel we have to work with, I don't see it working well at all. Dual spring setups on track cars generally involve a VERY light tender or helper spring that is 100% fully "blocked" at ride height to make up for the fact that the much higher rate springs normally in play just don't extend very far. Drop off a 2in "cliff" and a 1000lb spring on the front corner of our cars would normally only be compressed ~1in so it won't be able to fully extend to cushion the blow and the car has to just drop back to earth with no tire pressed against the ground for a split second. There is debate as to the effectiveness of this stuff even among top amateur racers.

The formula for dual rate springs is

(A * B) / (A + B)

Where
A = Spring 1
B = Spring 2
The order you do it in doesn't matter.

 

[DerHase]

Got the Koni SAs installed and drove around a bit - these things are awesome! Reminded me a bit(!) like the first time I drove an STR prepped S2000 on a $10k set of Motons. Controlled body roll but effectively removes almost all the surface imperfections you feel on the stock shocks. They seem to have more compression and more low speed rebound, with less high speed rebound.

Then today I got the offset LCA bushings installed. I managed to pull the driver side LCA without touching the subframe at all. Unbolt the DSG torque mount, pry trans forward, slip out/in the bolt. Whoever said you need to drop the subframe has never worked flat rate May be a different deal for AWD or if you have stiffer engine/trans mounts.

Still need to set toe - currently sitting with 10mm of toe out after my initial estimated change of the tie rods while it was still in the air (1.5 turns on each side was not sufficient). Should be able to fix that tomorrow and drive it a bit to get an impression of how it’ll be.

 

[dwvw]

I'll see if I can get a pic. I'm not sure if one spring is fully compressed at ride height. It's possible. Like I said, I don't track my car. The Iroz MK7 that went 9's used them so I figured they's be ok for me. I wouldn't pay retail for them though.

 

[DerHase]

Ran the TSCC Points Event #2 autocross yesterday so here's a summary of that:

Changes since last time:
-Superpro camber bushings on the forward LCA (replaced the Powerflex bushings I'd previously installed), maxed out of course. Zero front toe.
-255/40 + 245/40R17 reverse staggered V730s (previously 245 all around)
-Koni Special Active shocks

For starters I drove like CRAP. 4hrs of sleep, I had my son with me, missed an opportunity to eat lunch before my runs since I was running around helping novices and I just never felt it. Was a really fun course, just wish I was a bit better mentally/physically prepared. I still managed fastest STH run, but I had no chance of beating Tim Aro (who is a top level national competitor for the record). I think with better driving I could have knocked off a low 40 or high 39 sec run, but I don't see any chance of doing a 38.5xx to beat Tim.

Now with all the typical racer excuses out of the way:

Observations on the car:

• The shocks are awesome. The rear was far more planted and definitely improved in overall grip moreso than the front IMO. Will require playing with higher tire pressures out back I was on my way to doing that, but my last run really needed to be a clean one so I erred on the side of caution since my driving was craptastic anyway. Also need to consider playing with adding stiffer rear springs as @xXDavidCXx recommended.
• The 255s up front I'm not sure if they really bite notably harder. Considering I also added camber, and better shocks, I was kind of hoping for more. I ran them at 29psi all around. 31 up front was tried and didn't seem to have as much bite.
• Since adding the shocks, the front bar feels more "free" if that makes any sense. I noticed this driving on the street but wanted to see if it held true when driving harder. I think that they make a big difference in helping to damp the added bar rate as well. It feels less "springy" as you pass the 0 lateral G mark transitioning from left to right or visa versa. Hard to explain, not sure that there's any data that would be able to pinpoint it either. Best I can think is that it doesn't feel like it wants to "stick" on center, the body motion is more smooth in transition I guess?
• I don't think using LC is any faster... The main benefit is that it rapidly lowers your IATs sitting on the start line. @mrmatto You can see this in the video above. It drops from 154F down to 138F in about 5 sec sitting on the launch control.

Here's the squiggly lines from my least-slow run:


Honestly the overall numbers seem ok. It doesn't "feel" like it really corners that well. I think it's because my idea of handling comes from auto-xing a 2200lb car for so long The GTI feels much more numb by comparison. But the throttle pedal actually does things so that more than makes up for it

That said - it's not a truly valid comparison with the camber change, running at a different site, AND new shocks - BUT the overall peak to peak lateral Gs are almost exactly identical from PE1 vs PE2 data. The both have peaks up to 1.250-1.295 lateral Gs, and if you highlight the peaks where the input is held, they average out to 1.05ish Gs. I somewhat wonder if the 245s are actually faster...


Results:

Finished 3rd overall in the ST bump class (all ST* cars run against each other on PAX):


15th/113 overall in PAX:


And was 26th in raw time for the record (of 113 total timed entries).


My son Levi came along and is finally big enough to ride along so had fun hopping in a few cars. His favorite was a buddy's Skyline. And not related to the auto-x, but the day prior we took the dogs to a local outdoor brewery. They had so much fun that the little bastards tried to jump in as I was packing for the auto-x event later that night

Edit: on a side note I was also having a "12v battery low" warning - even though battery was replaced last year (and coded correctly). Made a separate post about that saga here since I finally figured it out. Battery tested good, but has diminished capacity. I think it happened due to a bullshit charging mode on my CTEK charger. Basically don't use the recondition mode on an AGM battery. Ever.
https://www.golfmk7.com/forums/inde...ad-if-you-have-a-ctek-battery-charger.422526/

 

[xXDavidCXx]

I'd really caution you on your observation of tire pressures tested at 29 and 31.

I don't know anyone who currently runs that low of a hot or cold pressure that low.

Next time try 35 and 40. The front of the car is heavy and the tires need more psi to support that weight in heavy braking and cornering.

Also, what is the wheel width up front? 245s may be better.

I also have not tried the 730s so my psi recommendation is on what I know about RE-71R/RS/660s/

 

[mrmatto]

Good intercooler data . thanks.

FWIW, I run my V730s (255/40r17 on 17x8.5) at 33 psi in the front at autocross. I might try 32 psi, but I chalked the sidewalls and was getting close to the rollover limit at 33 psi. Depends on the surface, camber, and wheel width, of course. I’m at around -1.5-1.6 for front camber.

 

[scrllock]

I'd really caution you on your observation of tire pressures tested at 29 and 31.

I don't know anyone who currently runs that low of a hot or cold pressure that low.

Next time try 35 and 40. The front of the car is heavy and the tires need more psi to support that weight in heavy braking and cornering.

Also, what is the wheel width up front? 245s may be better.

I also have not tried the 730s so my psi recommendation is on what I know about RE-71R/RS/660s/

cross-discussion was happening here: https://www.golfmk7.com/forums/inde...ective-2018-gti-se.421428/page-2#post-7959598

most of the guys I've seen running mid-high 20's for hot psi are lighter rwd chassis. though there were some guys claiming to run 28-29 hot with mk6/7 GTI.
IIRC tony is on stock springs.

I have a track day this weekend, I might try 30-31 hot but 34-35 was wearing well last season before the suspension overhaul.

 

[DerHase]

I'd really caution you on your observation of tire pressures tested at 29 and 31.

I don't know anyone who currently runs that low of a hot or cold pressure that low.

Next time try 35 and 40. The front of the car is heavy and the tires need more psi to support that weight in heavy braking and cornering.

Also, what is the wheel width up front? 245s may be better.

I also have not tried the 730s so my psi recommendation is on what I know about RE-71R/RS/660s/

Yeah these are way different than RT660. I'm on a 17x9. My sidewall rollover is more than acceptable.

Good intercooler data . thanks.

FWIW, I run my V730s (255/40r17 on 17x8.5) at 33 psi in the front at autocross. I might try 32 psi, but I chalked the sidewalls and was getting close to the rollover limit at 33 psi. Depends on the surface, camber, and wheel width, of course. I’m at around -1.5-1.6 for front camber.

That's probably about right when you factor in the following:

• 17x9 vs 17x8.5
• -2.6ish deg vs -1.5/1.6
• 26mm FSB vs stock

This is just the pressure that seems to be working best for *my* car.

cross-discussion was happening here: https://www.golfmk7.com/forums/inde...ective-2018-gti-se.421428/page-2#post-7959598

most of the guys I've seen running mid-high 20's for hot psi are lighter rwd chassis. though there were some guys claiming to run 28-29 hot with mk6/7 GTI.
IIRC tony is on stock springs.

I have a track day this weekend, I might try 30-31 hot but 34-35 was wearing well last season before the suspension overhaul.

Yeah everything I've found has pointed towards WAY lower pressures on lighter cars:

27psi hot on S2000:
https://grassrootsmotorsports.com/forum/grm/kumho-v730-tire-pressure-recommendations/198557/page1/
https://www.s2ki.com/forums/wheels-tires-56/kumho-ecsta-v730-1205904/

23 to 25psi on a Miata on track:
https://forum.miata.net/vb/showthread.php?t=748585

28psi hot on S550 Mustang:
https://www.mustang6g.com/forums/threads/kumho-v730-305-30-19.185957/

I couldn't find anything else for FWD strut cars, but across the board the pressures are way lower. And my sidewall rollover (lack of) seems to indicate no problems.

 

[MonkeyMD]

I'm running 35 F & 38 R or up to 36 F 41 R on grippier surface.

Even my "pro" codriver liked & was faster with 35 38 than 33 36 that we ran 1st 3 runs

 

[DerHase]

I'm running 35 F & 38 R or up to 36 F 41 R on grippier surface.

Even my "pro" codriver liked & was faster with 35 38 than 33 36 that we ran 1st 3 runs

Yeah I don't know. Will be making big sweeping changes at VIR for science to figure it out. Yours may be slightly different with 18 vs my 17s. Generally more pressure is needed with less sidewall anyway, but that's a huge difference.

Rollover is definitely not a concern whatsoever though.

 

[scrllock]

Yeah I don't know. Will be making big sweeping changes at VIR for science to figure it out. Yours may be slightly different with 18 vs my 17s. Generally more pressure is needed with less sidewall anyway, but that's a huge difference.

Rollover is definitely not a concern whatsoever though.

Those look very similar to the wear on my 245/40/18s running 35 hot

 

[MonkeyMD]

Yeah I don't know. Will be making big sweeping changes at VIR for science to figure it out. Yours may be slightly different with 18 vs my 17s. Generally more pressure is needed with less sidewall anyway, but that's a huge difference.

Rollover is definitely not a concern whatsoever though.

Mine are actually 17 too. 255/40R17 na 9" wheel with -2.4 camber up front 1.6 R