Requesting suspension setup assessment

[Norm Peterson]

I figured out where some of the uneven steering is coming from. During high speed turns, I start to slide on my seat and find myself using the steering wheel to hold myself up, which makes it difficult to steer.

Try to relax as much as possible any muscles not involved with turning the steering wheel. Tension in other muscles can reduce the amount of weight you're putting in the seat and against the seat back, making the steering wheel having to pick up the slack. Make your body as close to a "sack of grain" as you can.


Norm

Sponsored

 

[BmacIL]

Quickfit Pro harness works great, btw. Allows you to easily drive with light hands.

 

[valentinoamoro]

Interesting.
I did four waves of chassis/suspension work so far. I did experience what you seem to have in the video, but it went away once I changed shocks and springs.

Wave 1 was front and rear sways with end links. No negative effects on ride.
Wave 2 was when I did a bunch of rear chassis bracing (in one install) - namely, vertical links with bearings, toe to knuckle, rear LCA, CB005, red diff inserts. The change to ride was immediate - I noticed a firm jounciness (similar to what you had in your video) at slow speeds on bumpy roads - kind of made the ride jiggly! It went away at velocity. It greatly reduced wheel hop and improved road feel though, the OEM configuration had a numb/floaty rear and disconnected front to rear transition. There was no increase in NVH.
Wave 3 was Steeda adjustable pro-actions (middle setting in rear, slightly firmer up front) and Gt350R springs along with Steeda camber plates in front and rear adjustable camber mounts (and trimmed FRPP bumpstops). And of course, alignment! The slow speed jiggle/harsh jounce totally went away. Wheel hop was purged.
Wave 4 was lightweight (20 pounds) wheels and better tires. The suspension response improved dramatically. The car just recovers faster on bumps, grips way better and feels like it lost 300-400 pounds on the nose.

Long story short, I felt the likely culprits on the bounciness/jounciness was the vertical links or the cradle lockout. I cant know for sure. Based on what you are seeing, it could have been the vert links although I am not sure why you experienced it and mine went away with shocks and springs. I do know though that the Steeda adjustables and 350 springs, when correctly calibrated purged all of that while allowing me to retain the zero wheel hop and much better rear road feel/response that those bearings and lockout provided.

P.S -
Next (wave 5) is my last suspension mod and is a minor tension link w bearings.

 

[Burkey]

At least vertical links are relatively cheaper and easier to install than dampers. If they don't help or help enough, I'll try the adjustable dampers. This is the first time I'm going all out on suspension mods, and finding that I do like a firm ride.

For the life of me I can’t see how swapping out the vertical links will or even could make a scrap of difference to the way your car handles bumps. That is NOT part of their function.

 

[Bull Run]

Long story short, I felt the likely culprits on the bounciness/jounciness was the vertical links or the cradle lockout. I cant know for sure. Based on what you are seeing, it could have been the vert links although I am not sure why you experienced it and mine went away with shocks and springs. I do know though that the Steeda adjustables and 350 springs, when correctly calibrated purged all of that while allowing me to retain the zero wheel hop and much better rear road feel/response that those bearings and lockout provided.

Thanks for the detailed breakdown of your upgrades.

Mike gave me a recommended alignment setting so that's my next step. The Firestone shop nearby where I usually go for alignments won't touch aftermarket stuff (e.g. camber plates, camber arms, adjustable toe links). Therefore, I ended up doing an eyeball alignment first so they can get the alignment within the factory specs. I'll need to find a shop that does performance alignments using aftermarket parts. Since I like to experiment, I'll likely swap over to Pro Action adjustables when the weather cools down and do further testing. Looking forward to the rest of your build!

 

[Bull Run]

For the life of me I can’t see how swapping out the vertical links will or even could make a scrap of difference to the way your car handles bumps. That is NOT part of their function.

Actually, the car handles the bumps (as felt on bridge expansion joints and speed dips) the same way before the swap. The improvement that I felt was for the general light unevenness found on the streets. Perhaps going all spherical bearings were too effective in reducing almost all deflection? My understanding is that VLs are mainly for preventing back and forth knuckle rotation but perhaps it also adds additional deflection reduction?

 

[Bull Run]

Try to relax as much as possible any muscles not involved with turning the steering wheel. Tension in other muscles can reduce the amount of weight you're putting in the seat and against the seat back, making the steering wheel having to pick up the slack. Make your body as close to a "sack of grain" as you can.

Putting the seat one notch upright helped. However, the leather seat is on the slippery side and it's hard to remain upright on hard turns even with a more relaxed stance. I'm thinking a seat with cloth or suede covers will help. Going over to my friend's place after work to try his seats out some more.

 

[wildcatgoal]

Non-Recaro cloth seats are much better than the leather seats on track. I slide right out of my leather seats on track -- at this point it's becoming dangerous as it's hard for me to control everything and also keep myself upright.

Tight AutoX course -- makes no difference, haha.

 

[wildcatgoal]

For the life of me I can’t see how swapping out the vertical links will or even could make a scrap of difference to the way your car handles bumps. That is NOT part of their function.

Vertical links stabilize the rear suspension geometry and contribute to compliance. Many, including me, report reduced inside wheel hop on a sharper turn after installing vertical links. As for handling BUMPS... yeah, not really their primary contribution.

I've had BMR spherical, Steeda Delrin, and now Steeda Poly vertical links. No objective difference in "handling bumps" really other than when I took out the BMR sphericals and put in Steeda Delrin, NVH reduced. Also my rear end was jittery in AutoX and under heavy breaking with the BMR sphericals. In drag racing, they make sense I've gathered, but I couldn't tell any difference between those and Steeda Delrin in my own limited drag racing (not my thing so...). Steeda Poly is my preference for road course and street. Worth noting, every other bushing on my IRS is either a spherical or poly/delrin upgrade.

I wasted a lot of money on vertical links... just get Steeda Poly if your road coursing or on the street, Delrin if you bias more toward drag racing. That's my take. Or just don't change them at all and spend money on things that matter more like a Steeda (or whomever) lower control arm bearing. That's the ticket.

You're mileage may very.

 

[Bull Run]

Recaros in GT350R felt a little snug on top sides of my back but felt like these type of seats will really hold me in place on tight turns. I ordered a pair of Corbeau A4 Wide seats with double locking seta brackets. Will post feedback here once they are installed and tested.

 

[Norm Peterson]

Putting the seat one notch upright helped. However, the leather seat is on the slippery side and it's hard to remain upright on hard turns even with a more relaxed stance.

It probably does take a little practice to get yourself to relax as fully as possible.


Norm

 

[Bull Run]

It probably does take a little practice to get yourself to relax as fully as possible.


Norm

For sure, I think that it'll be easier to be more relaxed once I install the seats that'll hold me in place.

 

[Norm Peterson]

I've also found a supplemental non-slacking lap belt worn over the OE 3-point to be of help once you go beyond about 0.8 lateral g's. This one was re-purposed from a car I used to own and just loops around the seat. The towel is there for picture purposes only.

Norm

 

[Coyote Red]

Once I got the BMR CB005 & 006 installed I feel no hop, Car is "flat" thru the twisty's. Progressive springs helped my center of gravity and wide sweeping turns. I have wore out two rear Bridgestone pole position 255/45/18's down to the wear bars in less than a year, 280 treadwear,AA traction. I am going to square setup, 255/18 Firehawk Indy 500's Monday.

 

[Eritas]

Once I got the BMR CB005 & 006 installed I feel no hop, Car is "flat" thru the twisty's. Progressive springs helped my center of gravity and wide sweeping turns. I have wore out two rear Bridgestone pole position 255/45/18's down to the wear bars in less than a year, 280 treadwear,AA traction. I am going to square setup, 255/18 Firehawk Indy 500's Monday.

You should like them. They are a lot better than the PP, but have pretty poor wet performance.

Sponsored