Plastic Fantastic 2

SuperBuickGuy · Aug 27, 2021

drove it today.... I may have to set compression to a stiffer setting. It also can feel loose in the rear (twitchy?) to the point I checked all the mount and adjustment points to see if something came loose...

learnin' any input would be great.

phantomjock · Aug 29, 2021

Need a little more detail...

Loose [in rear]:

Straight line - Instability
One wheel bump
Hard Braking
Sloppy/slow to take a set in corner
Good turn-In, then washes out
and, more

These are all Problem>Solution based entries in Carroll Smith's Engineer in your Pocket

It's about $20 from A-Z and pdfs can be found online too.
I'll look up a few possible answers while you wait..

It's gonna rain here (Ida)

Cheers - Jim

SuperBuickGuy · Aug 29, 2021

phantomjock said:
Need a little more detail...

Loose [in rear]:

Straight line - Instability

One wheel bump

Hard Braking

Sloppy/slow to take a set in corner

Good turn-In, then washes out

and, more

These are all Problem>Solution based entries in Carroll Smith's Engineer in your Pocket

It's about $20 from A-Z and pdfs can be found online too.
I'll look up a few possible answers while you wait..

It's gonna rain here (Ida)

Cheers - Jim

*check tightness of all bolts.... also, get full instructions. the QA1 steering adjust rod - it goes to a bolt that threads into the knuckle. They provide 1 washer but don't say which side it belongs - it goes on the inside or, the opposite of the way I'll install it every first time..... :clobbered:

Also need to revisit the spring settings up front, back to a bit of a rub under light, right turn....

and rotated the shock adjust to 9 (out of 11)... seems to handle well, so we will see.... I have Jeep work to do next then I can focus back on this

bobs77vet · Aug 30, 2021

SuperBuickGuy said:
drove it today.... I may have to set compression to a stiffer setting. It also can feel loose in the rear (twitchy?) to the point I checked all the mount and adjustment points to see if something came loose...

learnin' any input would be great.

that sounds like a rear alignment issue. when it travels up and down there is no jerky movements is there? are you using poly bushings in the trailing arms?

I read once that the poly bushings in the trailing arms actually impact the alignment since they dont compress at all during there range of travel

SuperBuickGuy · Aug 30, 2021

bobs77vet said:
SuperBuickGuy said:

drove it today.... I may have to set compression to a stiffer setting. It also can feel loose in the rear (twitchy?) to the point I checked all the mount and adjustment points to see if something came loose...

learnin' any input would be great.

Click to expand...

that sounds like a rear alignment issue. when it travels up and down there is no jerky movements is there? are you using poly bushings in the trailing arms?

I read once that the poly bushings in the trailing arms actually impact the alignment since they dont compress at all during there range of travel

washer placed on the wrong side was the issue this time. Drove it yesterday and it handled fine - granted, there was no hooning but no wiggle either.

SuperBuickGuy · Sep 11, 2021

would handling improve, stay the same, or be worse if I swapped to 18x10 and 18x12 for my C3 .... right now it's 18x9.5 and 19x12

phantomjock · Sep 12, 2021

I'll take a stab at it - but this is just cursory. I found a couple of SAE articles - but not a member - so didn't download them.

I have "invested" in a square setup. The wheels are 15x10, the tires are Pirelli P-Zero (275/695/15). I specifically went to a square setup as it will (should) give neutral handle - from a wheel and tire input. All other "habits" (good or bad) will be from the chassis and suspension setup. So, my choice is made. As I have no time in the car yet, I can't comment. I expect I'll keep it square as I can move wheel/tires front to rear and get another session or two out of them. My testing plan is to get the car done and run some sessions without the body, and sort chassis and suspension (Exo-Vette). Then, add the body and aero and see what works/doesn't.

Back to your Question:
Your setup is already staggered. With bigger rear tires than front - you gain traction from the rear - great on corner exit and the rush down the straight. But, you could get loose with too much power. Your alternative retains the stagger setup, so I can imagine (guess) the handling may be similar, barring any change in ride height. I did a quick run of the wheel diameters and found little to no change in the roll center between 18 and 19 inches - note I kept the same tire width 275/45 on each run. I'll send you a copy of the excel spreadsheet I used. You can play with it and see what happens - it just one axle at a time - not a full car analysis.

I wonder if any iRacing gamers might have any inputs - so to speak? Know any?

Cheers - Jim

SuperBuickGuy · Sep 13, 2021

Well, I did it.edited didn't buy a kit because I don't care about my floor AND the driveshaft wouldn't work anyway....edited

I got the TKX with the 2.87 first gear and .68 overdrive. that does mean I need to do something about the race RedZone lifters - but I think I have a plan - I'll call tomorrow to double check but I think I can get the rebuilt to the street spec (not the race spec which is causing my lower oil pressure at idle). While this won't be a DD it might actually be capable of driving to autox next year.

In that vein, Oct 11 is the last of the season for us, then I'll start getting it ready for Las Vegas Optima next year. Just wheels - and I think I have a pretty good idea of what I can do - C5 Z06 fronts, C6 GS rears.... thus my question about wheels and square, I can only get an 18" wheel - but I'll go ahead and step up to 200 tw tires for next year....

In that vein, I'm driving to SEMA (mostly because I can) this year, so I may try to get there a couple days early and get some track training the day before SEMA starts....

SuperBuickGuy · Sep 17, 2021

pretty distraction

box opened

SuperBuickGuy · Sep 18, 2021

Forgestar F14

opinions? watch out for....?

I may have found a reasonable deal on take offs - 18" wheels, which means different rear tires .... but I'll probably simply buy all 4....

bazza6977 · Oct 13, 2021

SuperBuickGuy said:
1 'down' 3 to go... one thing I did realize is I'll not be gluing the door post in place... where the skin is level with the flare has quite a gap in the middle of the door/flare.... ah well, fiberglass makes a good gap filler

I'm at this point with my flares from the same place , I have the same problem with a gap in the middle , by gap I mean its sitting out from the door pillar , about 1/4 of an inch on passenger side and wider on the drivers side . If I push hard it will close in , but it takes too much force and I think there could be problems later . I too have an aftermarket new tail light panel(not CIC) so lining up all 3 to fit well in the back leaves me with this . The top part of my flare panels are just overhanging the door gap as well , but its seems the only way at this point .I haven't glued anything yet.

Just interested in seeing what you ended up doing to get yours on.

SuperBuickGuy · Oct 14, 2021

bazza6977 said:
SuperBuickGuy said:

1 'down' 3 to go... one thing I did realize is I'll not be gluing the door post in place... where the skin is level with the flare has quite a gap in the middle of the door/flare.... ah well, fiberglass makes a good gap filler

Click to expand...

I'm at this point with my flares from the same place , I have the same problem with a gap in the middle , by gap I mean its sitting out from the door pillar , about 1/4 of an inch on passenger side and wider on the drivers side . If I push hard it will close in , but it takes too much force and I think there could be problems later . I too have an aftermarket new tail light panel(not CIC) so lining up all 3 to fit well in the back leaves me with this . The top part of my flare panels are just overhanging the door gap as well , but its seems the only way at this point .I haven't glued anything yet.

Just interested in seeing what you ended up doing to get yours on.

it wasn't easy. Do you have the wheels you plan on running on the car? everything lines up off that - because the flares are pretty thin, you can use heat to get it to relax enough to move. Outside of that, I had to cut the flare from the rest of the fender and move it forward on the front to get everything to line up. If you're having too much trouble getting the curve right, you may have to section the flare to get it right..... also, contacting Josh at CIC for tips is available.... while I have some annoyance at my situation, I think he does his best and is quite helpful

bazza6977 · Oct 15, 2021

SuperBuickGuy said:
it wasn't easy. Do you have the wheels you plan on running on the car? everything lines up off that - because the flares are pretty thin, you can use heat to get it to relax enough to move. Outside of that, I had to cut the flare from the rest of the fender and move it forward on the front to get everything to line up. If you're having too much trouble getting the curve right, you may have to section the flare to get it right..... also, contacting Josh at CIC for tips is available.... while I have some annoyance at my situation, I think he does his best and is quite helpful

Well , I have the rear tyres and a device called a "wheel fit " which is an adjustable bracket which clamps onto the tyre and is bolted to the hub , but is adjustable . (so you can get the right backspace and offset you need ). I haven't got wheels yet as I still have to do this to the front.

Anyway the tyres fit really nice on the back as is. Only worry for me is suspension travel (settle) between now and when its all back together .My suspension is unloaded now so I set it at full low (transverse spring at rear ) I have a heavy rated new one coming from Vansteel soon , I got it shortened and its supposed to be about 480lb . Motor ,g/box ,doors (loaded) , empty fuel tank are on the car now.

I tried a heat gun on the offcuts , but I think I overdone it in a too small an area . It just fractured everything as I tried to bend . I will play around a bit with that again on some wider off cuts . Thanks for the advice .

SuperBuickGuy · Oct 15, 2021

bazza6977 said:
SuperBuickGuy said:

it wasn't easy. Do you have the wheels you plan on running on the car? everything lines up off that - because the flares are pretty thin, you can use heat to get it to relax enough to move. Outside of that, I had to cut the flare from the rest of the fender and move it forward on the front to get everything to line up. If you're having too much trouble getting the curve right, you may have to section the flare to get it right..... also, contacting Josh at CIC for tips is available.... while I have some annoyance at my situation, I think he does his best and is quite helpful

Click to expand...

Well , I have the rear tyres and a device called a "wheel fit " which is an adjustable bracket which clamps onto the tyre and is bolted to the hub , but is adjustable . (so you can get the right backspace and offset you need ). I haven't got wheels yet as I still have to do this to the front.

Anyway the tyres fit really nice on the back as is. Only worry for me is suspension travel (settle) between now and when its all back together .My suspension is unloaded now so I set it at full low (transverse spring at rear ) I have a heavy rated new one coming from Vansteel soon , I got it shortened and its supposed to be about 480lb . Motor ,g/box ,doors (loaded) , empty fuel tank are on the car now.

I tried a heat gun on the offcuts , but I think I overdone it in a too small an area . It just fractured everything as I tried to bend . I will play around a bit with that again on some wider off cuts . Thanks for the advice .

Fiberglass (or glass for that matter) never stops moving, granted, it's slow - but heat and time does let gravity affect it. I'm not sure I'd use a heat gun, I used a radiant heat dish and let it 'cook' for awhile.... probably never got above 100* but it did move.

but keep in mind, I didn't have to move it much, I was more concerned that it relaxed into the shape I screwed it into.... I use sheet metal zip screws to hold it in place then aim my radiant heat dishes at them for a day. Once 'done' I could remove the screws and it'd hold its shape.

bazza6977 · Oct 17, 2021

SuperBuickGuy said:
bazza6977 said:

SuperBuickGuy said:

it wasn't easy. Do you have the wheels you plan on running on the car? everything lines up off that - because the flares are pretty thin, you can use heat to get it to relax enough to move. Outside of that, I had to cut the flare from the rest of the fender and move it forward on the front to get everything to line up. If you're having too much trouble getting the curve right, you may have to section the flare to get it right..... also, contacting Josh at CIC for tips is available.... while I have some annoyance at my situation, I think he does his best and is quite helpful

Click to expand...

Well , I have the rear tyres and a device called a "wheel fit " which is an adjustable bracket which clamps onto the tyre and is bolted to the hub , but is adjustable . (so you can get the right backspace and offset you need ). I haven't got wheels yet as I still have to do this to the front.

Anyway the tyres fit really nice on the back as is. Only worry for me is suspension travel (settle) between now and when its all back together .My suspension is unloaded now so I set it at full low (transverse spring at rear ) I have a heavy rated new one coming from Vansteel soon , I got it shortened and its supposed to be about 480lb . Motor ,g/box ,doors (loaded) , empty fuel tank are on the car now.

I tried a heat gun on the offcuts , but I think I overdone it in a too small an area . It just fractured everything as I tried to bend . I will play around a bit with that again on some wider off cuts . Thanks for the advice .

Click to expand...

Fiberglass (or glass for that matter) never stops moving, granted, it's slow - but heat and time does let gravity affect it. I'm not sure I'd use a heat gun, I used a radiant heat dish and let it 'cook' for awhile.... probably never got above 100* but it did move.

but keep in mind, I didn't have to move it much, I was more concerned that it relaxed into the shape I screwed it into.... I use sheet metal zip screws to hold it in place then aim my radiant heat dishes at them for a day. Once 'done' I could remove the screws and it'd hold its shape.

If the radiant heat dish is like what they use in a paint booth ,I might be able to borrow one and see how I go on some off cuts first . Thanks for the tips .