18" Falkens too tall?

Rjscharer · #1 (**permalink**) 09-07-2014, 01:04 PM

My new Backdraft with 85 miles got a spider crack over the passenger's
rear wheel well after a short ride. The folks in Florida are doing the right
thing without hesitation. A friend of mine in Wilton,Ct told me he suffered
the same thing last year on the other side. His dealer took the Falkens
off and put Nittos on. The problem never came back after repairs. It appears
the profile of the Falkens is too tall and leads to bottoming out. Needless to
say, I am asking for this tire swap from Boynton.Why do the glass and paint
repair if this is going to happen again.is anyone else aware of this problem?
Thanks

Jeff Frigo · #2 (**permalink**) 09-07-2014, 03:00 PM

18" Wheels on a cobra??? PLease

Grey 65 · #3 (**permalink**) 09-07-2014, 03:01 PM

This has nothing to do with the tires. The ride height on the front and the rear of the car is adjustable. If your tires impact the body of the car you need either stiffer springs (not the correct fix) or you need the ride height adjusted (correct fix). You could always just put 13" wheels and tires on it and eliminate the problem this way also.

The problem was created when Backdraft reduced the backspacing on the rear wheels but kept the wheel width the same, thus pushing the entire wheel outboard. Crawl underneath and you will see you have over 1 inch of clearance between the backside of the wheel/tire and the shock mount. Therefor one must run the rear of the car higher to keep the same tire to body clearance as the old 18x11 wheels had since the wheel is now much closer to the body than it was before.

Kevin....

Cashburn · #4 (**permalink**) 09-07-2014, 03:10 PM

Kevin,
It's the tire size in this case. I don't have the Falken specs at hand but the profile they put on are too tall for the limits of the suspension adjustment. However you have made a good point, it's probably amplified by the backspace change I have no explanation for.

Grey 65 · #5 (**permalink**) 09-07-2014, 03:36 PM

Quote:

Originally Posted by Cashburn

Kevin,
It's the tire size in this case. I don't have the Falken specs at hand but the profile they put on are too tall for the limits of the suspension adjustment. However you have made a good point, it's probably amplified by the backspace change I have no explanation for.

Sorry Jay, I didn't realize Florida was putting Falkin Azenis 295/40/18's (27.2" Tall) on cars.... almost 2" taller than the 315/30/18's (25.5" Tall) version of the same tire. I should have looked to see what size they were putting on the cars, I had assumed it was the 315's...

I will be switching out my tiny 17x10.5's for a pair of 18x12's this winter. Vintage Wheels will be making them to the offset I provide them. Then I can properly run 335/30/18 BFG Rivals.

Kevin....

Cashburn · #6 (**permalink**) 09-07-2014, 03:54 PM

Yeah <shakes head> you'd never imagine it. Good call on the other wheel option.

Mark Brye · #7 (**permalink**) 09-07-2014, 03:57 PM

I will be switching out my tiny 17x10.5's for a pair of 18x12's this winter. Vintage Wheels will be making them to the offset I provide them. Then I can properly run 335/30/18 BFG Rivals.

Kevin....[/quote]

Vintage made a set of 17x8 and 17x11's for me a couple years ago. They were the Shelby American Racing Style wheels. He even made the fronts so that they cleared my Wilwood brakes without having to use different front pegs. They turned out great but it took a while. First set the wheel pin holes were off a little but he fixed it.

RT3_1350 · #8 (**permalink**) 09-07-2014, 06:53 PM

After reading thread and inspecting mine I have nearly 1 inch less clearance from the rear tire (295/40/18) up to the fender edge on driver side than the passenger yet the distance from the frame to the garage floor on each side is exactly the same. Figure the fiberglass body mould is not perfectly symmetrical? Anyway wondering if hitting a decent road bump is going to do damage.
How can a person tell if the suspension is cranked up all the way?

Cashburn · #9 (**permalink**) 09-07-2014, 08:16 PM

Quote:

Originally Posted by RT3_1350

After reading thread and inspecting mine I have nearly 1 inch less clearance from the rear tire (295/40/18) up to the fender edge on driver side than the passenger yet the distance from the frame to the garage floor on each side is exactly the same. Figure the fiberglass body mould is not perfectly symmetrical? Anyway wondering if hitting a decent road bump is going to do damage.
How can a person tell if the suspension is cranked up all the way?

Your shock will be at its limit. The KYBs afford more height adjustment if needed.

jimbo01 · #10 (**permalink**) 09-08-2014, 03:52 PM

As I discussed with my friend from St Augustine. I just spent a month trying to find tires for the new 18" wheels I just purchased. After sending back 2 sets of Pirelli tires which were made in 2012 and finding that was the latest production date. (They don't want to tell you that) Jay is correct in that the back offset is wrong on the new wheels but they want admit that in Boca.
The best solution for me was a set of Michelin 315's and 245's. After installing them the ride is excellent and no vibration and not 2 years old either. I don't race the car so I was looking or ride and drive ability. I have the ride height set at 2 fingers clearance front and rear according to Backdraft.

Cashburn · #11 (**permalink**) 09-08-2014, 07:06 PM

We can still stuff 335 Nittos in, we just have to mod the control arm and increase negative camber. We've tried the BFG Rivals and 1 car was great and the other car took a lot of wear in to smooth out. Have a car now we are trying Bridgestones, but they are 19" and my calendar says 2014, sorry Jeffo...

Mark Brye · #12 (**permalink**) 09-09-2014, 07:25 PM

Jay, what mod are you doing on the control arm? Are you just elongating the hubs upper control arm bolt holes a little on the inside to bring the tire in more? Then using an adjustable lower control arm to bring the entire wheel inboard with the added negative camber?

Rjscharer · #13 (**permalink**) 11-20-2014, 02:28 PM

Well,here we go again. My saga continues. My new car was returned to me the third week
in October after having the spider crack repaired by Boynton. The car has gone about
30 miles since then. Guess what folks! Went out today to wax the car for a weekend
show and the crack is back again. They had my car for 5 weeks, repainting the rear passenger fender and the trunk lid. I have asked for a new car. Having a new $63k car
that will have been painted three times in three areas that do not match up color wise is more then I can take. What do you think? PS...they insisted on keeping the 18" Falkins. Car
has a total of 140 miles on it.

427BDR · #14 (**permalink**) 11-20-2014, 02:41 PM

wow, I'm so sorry to read this, what an awful experience. how were the cracks actually repaired? sounds like they did a minor patch and repaint but the structural cracks were obviously never properly repaired if they came back after only 30 miles.

and what tires did they replace them with? I assume you're not running the Falkins and running something with a smaller overall diameter, yes? as reference I have the Pilot sports and they are about an inch smaller in OD vs the Falkins. (but they are wider and required modifications to the rear suspension to get them to properly fit without ridiculous camber). The 18" Pilots have about the same OD as the previous 17" Nittos while the 18" Falkens are much taller as you unfortunately learned.

At this point I think you deserve a new car, or at the very least can they pull the body off, strip the paint and properly repair the cracks and then repaint the entire body so it is uniform? That may work if done properly (and faster turn around).

Good luck, hopefully you get this sorted to your standards

Rjscharer · #15 (**permalink**) 11-20-2014, 03:36 PM

Hi...thanks for the reply. When the picked up the car for repair, I asked in writing that they
replace the Falkins with Nittos. I learned from these postings that the profile of the Falkins
is too tall. They refused to change the tires out. They told me they had delivered 200 cars
with the Falkins with no problems. Well, they have a problem now.
Rich

eedeutsch · #16 (**permalink**) 11-20-2014, 04:29 PM

Get rid of the Gabriel shocks, they are junk. Replace them with KYB 343144. This change will certainly help. I have the Flalken's on mine
and when I changed to the KYB's, no more bottoming out.

RT3_1350 · #17 (**permalink**) 11-20-2014, 04:29 PM

Rich
Am indeed sorry to hear that you are going through this.
Custom Cars should compensate you for their mistake in setting up the car wrong to start with and for the time without your car. After reading your first message I quickly adjusted my driver side rear suspension to make the body clearance the same on both sides. I have the same tires as you and feared the same issue might happen. Suggest you confirm the body clearance is the same on both sides before you take it back.
Mark

Rjscharer · #18 (**permalink**) 11-21-2014, 07:20 AM

Looks like things will work out. Frank from Boynton just called to say they have
started to build me a new car. Happy with the solution and very glad they were
accomidating. New car is British Racing green,no stripes, tan interior.

427BDR · #19 (**permalink**) 11-21-2014, 07:30 AM

Glad it worked out!

cbreez · #20 (**permalink**) 11-21-2014, 08:53 AM

Quote:

Originally Posted by eedeutsch

Get rid of the Gabriel shocks, they are junk. Replace them with KYB 343144. This change will certainly help. I have the Flalken's on mine
and when I changed to the KYB's, no more bottoming out.

Why would that help? Help what exactly?
Shocks have no effect on a suspension "bottoming out", spring rates and clearances do...shocks have no effect on spring rate.

You discredit Gabriel shocks. Do you know the dampening rates on either the Gabriel's or the KYB's? Please share with us.