nsogiba

Like a hot dog down a hallway!

tungstenfoot

I found one of the front upper spherical bearings on my LG GT2's was waayy too stiff, could hardly move it w leverage. I tried some lube to no avail. So instead of articulating through its range of motion, it was transmitting some side loads to the upper mount causing some looseness and premature wear to the upper mounting hardware spacer. I got a hold of Anthony at LG Motorsports and since the bearing is replaceable by removing a retaining ring and press, we agreed to try a new bearing. LG promptly sent me replacements, and I was able to replace w no issue. A smart design and excellent customer service, Thank you LG Motorsports !
So all back together now, just changing fluids today. Will start alignment when tires are back from mounting

LG Motorsports

Hi Gang,

My thoughts on Delrin vs Spherical bearings.

Keep in mind that delrin bushings in the suspension only allow motion in a single axis where spherical bearings do allow some anti dive as well.

Plus Delrin has to rely on the contact between the bushing/sleeve where the bolt goes through. the friction area is very large and that friction is increased exponentially as they are asked to do more work. (Braking and acceleration )

Delrin is 100 times better than the stock sloppy rubber but to be precise with your suspension and its function, sperical bearings are the way to go.

To show how bad the Rubber is, we did a video on the dyno that shows the wheel and the A arm bushing movement under acceleration forces.

The same happens to the front A arms when braking. imagine the tire grip that pulls the lower A arm and tire toward the back of the car (holding the car back while braking)

Delrin will tend to bind on its bushings under both Braking and Acceleration. This binding does not show up on the bench.

This in known as "Hysteresis Loss" or just plain binding that the car's suspension has to overcome before it can do its job. The same forces -fore-aft come into play all the time.

Delrin has huge Dynamic Friction induced under both Braking, and acceleration.

IN the past, we only used Delrin when the rules specifically banned "Spherical Bearings"

Also, I see the alignment numbers showing "Toe In" at both ends of the car. We NEVER run toe in at the front. NEVER. The car will not turn easily with toe in. Toe out lets the inside wheel seek a tighter radius quicker and you will see and feel "quicker" steering. PLUS toe out gives the driver more confidence by eliminating any twitchy feel on turn in.

I hope I can answer any questions here or you can contact me directly at LG Motorsports for technical advice that we learned through the years of racing and winning.

Thanks

Lou Gigliotti
LG Motorsports

tungstenfoot

^^cool vid. Yeah OE rubber isnt doing an aging cars handling much good.
The braking forces you describe are exactly what toasted my front OE rubber bushes from the control arms.
No plans to toe-in the front, if anything I will toe OUT. Ive always run zero toe front but will see how toe out feels and monitor tire wear, especially if i put some miles on street.

Here are my targets for now, any comments much appreciated. Just targets for now and will adjust based on how the car feels:

All w 18" OE speedline wheels (front & rear): Rival S 275/35-18 front & 315/30-18 rear. Toe Distances measured to wheel edge.

Rake, measured from jacking points: .5" +/-.1" (rear high). I have measured from wheelbase before but jacking pts seems to be common ref point

Front toe: Zero to 1/8" total out (18" wheel)
Front Camber: -1.5 to -1.8 deg per wheel
Front Caster: +7.5
Its my understanding that "less caster leads" so may try and shoot for .3- .5 degree less on driver side for road crown
Rear Camber: -1.0 to -1.2 deg per wheel
Rear toe: 1/8" total in (18" wheel), 1/16" in per side

LG Motorsports

I am assuming this is a track set up. if so, then:

Rake = Good. Raise or lower either end to add or subtract grip.
>>> Raise one end will reduce grip at that end,
>>> Lower one end will add grip at that end.
you can use rake to balance the car if springs or sway bar changes are not available.

Front Toe = Good. That is where I would start also.

Rear toe = ok. We usually start at "3/16th total toe in" at the rear then " tune the car with toe and rake to balance it.

Front Camber depends upon the tire.
Pirelli or Hosier tires can need 2.5 to 3 degrees at the front.

Rear camber, 1.5 to 2 degrees is a good starting point then use tire temps to finalize the setting, same for the front, use tire temps to finalize the camber setting. Plus use the wear at the outer edge to see that the entire tire is making contact and being used to the max.

caster should be the same both sides. A race track can be crowned in either direction depending upon the corner. Caster is just "camber gain" so if you are out of camber adjustment and need more then add caster

BUT know that more caster = harder steering pressure needed. (today's power steering can over come that very easily.

Have fun at the track!!

Lou Gigliotti
LG Motorsports

tungstenfoot

Im back at it this weekend. Its on scales now and I've nailed 50 % cross weight BUT i cant get a 1/2" of rake. Right now i am 1/4".

To be clear, when referring to "jacking points" for ride height measurements, are these where the pucks go under each side (near doors) ?

If so, ive got work to do... let me know

6speedsteve

Yes, hope this helps.

https://www.corvetteforum.com/forums...uspension.html

I also have the trim height tool for the Z & D specs but is some what involved to use, car needs to be on a lift or high off the ground.

I just checked mine with the pucks installed, I can twist mine so they are snug to the frame & I run 1" wheel well height difference front to rear, which I know is not proper measurement etiquette, but my rear puck is 1/4" higher than the front.

tungstenfoot

Ive been at it since 11am and man am I beat. I either need a lift or hubstands, im getting too old for this crap! ... up and under the car all damn day, gets old.

I am still at +1/4" rake as measured at the jacking pucks (fwd and aft on door sills). The rear is looking alittle high, which i dont like...but ive got it balanced for now at 50% cross. For rake, I think im fighting the fact my rear tires are ever so slightly smaller diameter than fronts. I dont want to drop the front too much either, so I decided to leave it for now. i really need to drive it on my setup and re-measure.

I then started adjusting camber w AMT lower control arm plates. I had originally started at S2 at all four corners but i needed to adjust 3 corners to even out camber. For example, My driver side rear at S2 was only getting .9 deg so I needed to goto more aggressive S1. Let me tell ya, there is absolutely no way to get more than S1 position on my car at the rear w Vansteel Delrin bushings. There is NO flex to get more, unless you were to enlarge or slot the rear mount because it pivots there. The S2 position at passenger rear gave me -2 deg.

So its not consistent, Don't expect to get even results, every car is different and your results may vary. As it sits now...
Im gonna finish setting toe tomorrow and take it for a quick spin, drive in and recheck everything. I am borrowing a friends caster gage and turn plates tomorrow too. I feel like my budget DIY camber gage may be giving inconsistent values or the car needs to settle. will see whats up tomorrow, beer time!!

tungstenfoot

AutoX and Road review of Delrin bushing setup:
Rival S 275/35-18 fronts set to 31 psi and rear 315/30-18 at 28psi.
Lg GT2 shocks set at 6 clicks front, 4 at rear
Height to fenders approx 26-7/8" front, 27-3/4" rear
1/8" total toe OUT front
Front: -1.5 camber, +7.5 caster
1/8" total toe IN rear
Rear: -1.2 camber
At AutoX the car was fast. I ran CAM-S and ended up winning my class! I also did well compared to the rest of the street tire prepared & mod classes. #43 Here: http://wny-scca.com/live/
...Makes me wonder what can be done on slicks!

With Delrin bushings, Turn in is immediate and i feel alot more feedback through the wheel. I can also read the rear end better because its less vague, no more waiting and wondering what will happen. There was one late apex right hander that could be Trail braked and was really impressed w how i could set the car and toggle the rear slip through this turn w steering and brake. Once pointed i could really put the power down too.
Im not sure if the added rear tire width or how the alignment settings are now locked down w Delrin bushings (probably both) but man I have traction! Just a great feeling of accomplishment, im so happy w these changes. The car has ALOT more in it too because i dont feel like i put a complete good run together.
Post event review of tires show i could use some more front camber. So i increased from -1.5 deg to -2deg, based on front edge wear (thanks Lou!). This was an easy read because my tires were brand new before the event. I then had to reset caster and toe to my previous setting. Drove it today and It feels even quicker, i just love how it turns in now, just point and it goes!

Street review: sharp edges, pot holes and expansion joints are definitely a bit sharper in the cockpit. If you hit something nasty, it was a thud w rubber bushes, now w delrin it can be a mild crash and You can hear it in the dash. This was on a really bad road.
Now most are gonna say NVH this and that and i get it... but for me, i could care less. Why do you want to hit potholes and drive your corvette on such crap roads anyway, why do you want to drive a corvette on **** roads AND be comfortable? I live near buffalo, NY trust me our back roads after a long winter are complete crap, you dont WANT to drive these roads.
On normal roads (not perfect roads) the car rides and drives perfectly fine, yes, i can feel the road more and I do feel irregularities but on normal roads i call that better feedback. The Highway is totally fine too, no bad behaviors. On complete crap roads its definitely noticable, but those are not roads i want to be on at all.

Icing on the cake: Wheel hop is gone! and the delrin bushings are completely silent so far (only 200 miles) If you cant tell, Im super stoked w how it drives now, i cant wait to drive it again👍🏻👍🏻

oneandgone

Great thread, thank you! I've been looking at these as well and I think you just sold me on them. I'll keep checking back as it will be a while before I'm to that point, will see what your long term impression is.

tungstenfoot

just to check in on how all is going... ive got about 1200 miles on my setup, including 2 more autoX's. All is well and really enjoying this new setup. I'm currently undefeated in regional CAM class scca events i've entered, and everything is exactly as stated above. Totally silent, alignment is locked. I checked tread depth across the tires yesterday and all 4 are even at 6/32". Only slightly more wear on rear inner treads, closer to 5/32", but thats expected w rwd and 405 whp : )

BmoreRnsDeep

Do you drive to and from events? If so how is the street ride effected?
Thanks.

tungstenfoot

Yes, I drive to all events. Sunday's event was in Erie, PA about 1 hour drive from me. As stated above, the sharp edges at bridge expansion joints and broken pavement edges are where its noticeable. The 90W near Silvercreek is like this, the road is crap tho in desperate need of repair... all that said, for me its not bad at all and the benefits of turn in, response, feedback, no wheel hop, maintaining my alignment (and more easily setting it)... all far out weigh any NVH. In fact, the Z06 on Delrin bushings and coilovers drives with way better compliance and better NVH than my Subaru STi with rubber bushing and coilovers ever did. Its definitely a compromise, but then again when I first got this car I thought it drove like a Cadillac and was surprised this was considered the corvette "track model". Its all relative, subjective and depends on what you want to do with the car. hope this helps

oneandgone

I cannot wait to do this mod. Chances are it's going to be a while though, I'd like to do it alongside either drop spindles or coil overs. I'm leaning towards the spindles because I'm not sure I want to have to spend the time getting the coil overs set up just right.

6speedsteve

I have drop spindles on my car & are worth the money, there are some minor assembly issues, but not too complicated to correct, and I will also be installing a set of Ridetech coilovers this winter as well, which should be a challenging install to get right with the drop spindles.

oneandgone

What kind of assembly issues?

6speedsteve

I am heading to work so I will post pictures & details when I get home after work, I don't have the pictures I need on my work computer.

BmoreRnsDeep

I understand that the rubber arms help insulate the suspension on the street due to their movement i guess. Would it be of any benefit to have mono ***** on the arms on the street? Would it really be unbearably harsh or would the suspension work better and actually handle road irregularities more efficiently?
Thanks,
Zach

6speedsteve

I decided I do not want hijack Tungsten's thread by posting about my spindle issues, I will start another thread & give you the link, this way I can get more pictures this weekend when my rear tires are off the car, I took some front photos with car at ride height & they came out better than I thought they would.

bfit

Turn in quicker, on the road I personally don't know why you would stray far from stock setting.
if you are taking about road racing, you will need toe out on the front.
How much depends on your caster/camber setting and your ability to drive.