[h018871]

The company I got the bars from sent me the Hotchkis rear bar by mistake. So, I was able to measure all three rear bars.
My measurements were from the center of the bar for reference. Looks like the published OE and BMR measurements are made differently. Regardless of the numbers, the BMR stiffest, OE only and Hotchkis softest settings all use the same lever arm length.

[carguy55]

That cool info right there. How is the ride off track with upgraded bars in the middle position ?

[h018871]

On smooth-ish roads, no difference. If bumpy, it is stiffer but not harsh
I run around most of the time in touring mode

[kropscamaro16]

no tests on afe power bars?

[NickyRacerBoy]

Great info here.
All I can attribute to this thread is that I run Hotchkis front bar on middle hole and BMR rear on first (soft) hole and DSSV shocks along with Hoosiers R7 or A7 and my car has INSANE front grip! Car is so neutral too. I have absolute faith in the car

[TrackClub]

Originally Posted by NickyRacerBoy

Great info here.
All I can attribute to this thread is that I run Hotchkis front bar on middle hole and BMR rear on first (soft) hole and DSSV shocks along with Hoosiers R7 or A7 and my car has INSANE front grip! Car is so neutral too. I have absolute faith in the car

This!

[racerx8]

Originally Posted by NickyRacerBoy

Great info here.
All I can attribute to this thread is that I run Hotchkis front bar on middle hole and BMR rear on first (soft) hole and DSSV shocks along with Hoosiers R7 or A7 and my car has INSANE front grip! Car is so neutral too. I have absolute faith in the car

This is fact! My 1LE (stock MRC suspension w/Hotchkis & BMR as above) Hoosier A7, on APEX 19's. Thanks Nicky

[TheRealJA105]

Bushings lasted through the 4 days of the SCCA TT Nats. I am officially calling my fix a success!


I think i need to start trying some adjustments, everyone is recommending more front bar on Camaros and Vettes and I have the rear on stiffest and front on middle trying to get more oversteer. My car is definitely tail happy on corner exit (hard not to be with the supercharger), but still pushes on entry so I'm not sure what exactly to adjust in my setup.

[AustinTXracer]

I'm still on the stock bar F/R and I still like it this way so far with 295/305 SC3 setup. I'm a bit concerned about swapping out the stock bonded bushing bars for lubed poly bars because the bonded bushing bars actually add significant spring rate to the car. I haven't tested yet, but I'd guess they are adding 150lb/in at the end links which is probably at least 75lb/in at the wheels. I'm guessing you are seeing a bit more nosedive under braking once you swap the front bar unless you've swapped the factory springs out as well. Just an educated guess though. Curious if some GM engineers are around to shed light on the effects of bonded bushings.

[kropscamaro16]

Originally Posted by AustinTXracer

I'm still on the stock bar F/R and I still like it this way so far with 295/305 SC3 setup. I'm a bit concerned about swapping out the stock bonded bushing bars for lubed poly bars because the bonded bushing bars actually add significant spring rate to the car. I haven't tested yet, but I'd guess they are adding 150lb/in at the end links which is probably at least 75lb/in at the wheels. I'm guessing you are seeing a bit more nosedive under braking once you swap the front bar unless you've swapped the factory springs out as well. Just an educated guess though. Curious if some GM engineers are around to shed light on the effects of bonded bushings.

have you looked into trying out the yyz springs?

[Msquared]

Originally Posted by AustinTXracer

I'm still on the stock bar F/R and I still like it this way so far with 295/305 SC3 setup. I'm a bit concerned about swapping out the stock bonded bushing bars for lubed poly bars because the bonded bushing bars actually add significant spring rate to the car. I haven't tested yet, but I'd guess they are adding 150lb/in at the end links which is probably at least 75lb/in at the wheels. I'm guessing you are seeing a bit more nosedive under braking once you swap the front bar unless you've swapped the factory springs out as well. Just an educated guess though. Curious if some GM engineers are around to shed light on the effects of bonded bushings.

I strongly doubt the added rate from the front bar is anything close to 150lb/in at the end link. I haven't measure measured the length of the sway bar arms, but if they are 12" long then the arm is only being twisted 5 degrees in the bushing with 1" of travel. I bet you can move the end of the stock bar 1" with 15lbs of force, maybe less.

Also, the end links attach directly to the strut, so they are very close to a 1:1 motion ratio. So whatever the rate at the ends of the bars is will also be very close to the wheel rate.

[Mountain]

Originally Posted by TheRealJA105

Bushings lasted through the 4 days of the SCCA TT Nats. I am officially calling my fix a success!


I think i need to start trying some adjustments, everyone is recommending more front bar on Camaros and Vettes and I have the rear on stiffest and front on middle trying to get more oversteer. My car is definitely tail happy on corner exit (hard not to be with the supercharger), but still pushes on entry so I'm not sure what exactly to adjust in my setup.

I collected similar notes of people's setup at TT Nats. But what I did seem
to find is that most people didn't put much consideration into playing with the rear bar. I think it was Ed V. that told me he softened his front [Hotchkis] bar at one point, and it felt better, but his times were better with it stiffer. Not sure which hole, full-stiff or medium, he was fastest with.

I know Sam was of the opinion to mess with the rear as 1. the front doesn't really do anything bad stock and 2. to him, it seemed the rear of the car is what needed attention in calming it down. His comments were more in respect to the SS 1LE, but the SS suspension isn't that terribly far away from the 1LE. I tend to agree with him, especially after this weekend.

I've went from -1.5 camber in the rear to -1.7 this season and it didn't seem to really help all that much in calming the rear (if I go more, I begin to run out of toe adjustment). I have a FE3 bar I should've brought to Nats (I brought the wrong bar - rear Hotchkis, which goes the wrong direction of what I want to try).

[TrackClub]

Originally Posted by TheRealJA105

Bushings lasted through the 4 days of the SCCA TT Nats. I am officially calling my fix a success!


I think i need to start trying some adjustments, everyone is recommending more front bar on Camaros and Vettes and I have the rear on stiffest and front on middle trying to get more oversteer. My car is definitely tail happy on corner exit (hard not to be with the supercharger), but still pushes on entry so I'm not sure what exactly to adjust in my setup.

Good to hear on the bushings: congrats regarding your ingenuity and perseverance!

Regarding your set up:

1) It is extremely unorthodox to run a stiffer rear bar on a F engine car, especially one with an extra weight of a blower. I think this is causing you a F vs R roll stiffness imbalance on entry/mid corner and an obvious oversteer issue on exit (which costs you tons of time).

2) Looking at your recent NCM vid you proly lose at least 3-4 secs having to correct for oversteer on exits and delaying benefit of your supercharged power. Case in point, Provoste was 2 secs faster in a bone stock SS 1LE except for DTC60s. Sir Jackie Stewart once said: "The corner exit is far most important than the corner entry in terms of smoothness". Colin Braun repeats that most recently in my post "Best track advice ever" with more detailed advice. It is so obvious, yet i think too many of us focus on getting this extra tenth on entry and forget about principle #1: good exit that will pay fat dividents all the way til the next braking zone . If i were you, i would fix that issue first.

3) if you feel understeer on entry, then obviously your front is set up too stiff (yet i didnt see any corrections for understeer in your NCM vid, so perhaps it is mild?). Also, very clearly, your rear is too stiff. So...given the two comments above (and i know how fast Nicky Bobby is ) perhaps consider what they run bar set up wise, copy them, soften the bars and run them equally. Another fast guy, Ryephile runs the same set up as well if i recall correctly. Funny how marrying BMR sways with Hotchkis makes more sense than BMR only. Maybe BMR took a page from a Stang book, thinking a Camaro would benefit from a stiffer rear, but clearly it does not.

4) i see a wing on your mods list. Have you balanced it out in the front with a splitter/cannards/extractor hood/etc?

5) do the G3s just bolt on to your car, or do you have to use spacers? Changes in track width ratio F vs R can also change balance one way, or the other.

6) getting some toe out in F should lead to better turn ins (albeit i like my stock SS with 0).

7) if you subscribe to Ross Bentley's Speed Secret Weeklies (and if you dont, subscribe today!!!), you can download his FREE e book on set up. It is short and excellent. Truly excellent.

Last comment: i havent competed for years (except for iRacing in off seasons ). I just arrive and drive and have fun. Yet, i am still very competitive regarding my PBs. Ive been happy with my PBs in the last 3 yrs. Then 2020 happened and my usual season went to shit. But that gave me an opportunity to contemplate my driving and look for improvement opportunities. I had decided to really focus my limited outings on carrying brakes deeper than usual (even though i always trail brake anyway) and most importantly: releasing them very smoothly. I only did 5 days this season and ran only 2 venues. Result? I beat my PB on both and almost immediately:
1 sec on a 1:20+ track (from 1:19 to 1:18) and 2 secs on a 2:00+ track (from 1:59 to 1:57). Food for thought regarding old dogs learning new tricks

Cheers and best of luck!

PS Re posted suggestion to try YYZ springs...save your money (so sorry Krops!).

[h018871]

TrackClub, very nice write up / explanation

I like numbers, so.........
I put these together. For me it makes it much clearer what should happen and why. We're running different setups (springs/aero/tires/surface/pressures/etc), so a bar change for one person will not necessarily have the same results for another.

TheRealJA105 Considering sways only: you have ~ 23% rear bias over the stock FE4 setup

EDIT: you don't have the Hotchkis front bar and I corrected the bias chart