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Cracked 3 spokes in 1 session on Enkei PF01's

dmichaels

Papa Smurf
547
30
CT
I've been good about inspecting wheels, tires, brake rotors and brake pads after every session this season, and today after the last (5th) session of the day at Palmer Motorsports Park in Mass, I discovered the below. Three spokes cracked through during the ~40 minute session. I felt the car was a bit off towards the end and pitted, but as I did a cool down lap, I clearly heard "clicking" which was in line with wheel rotations bouncing off the jersey barriers and such. I'm assuming it was the cracked spokes rubbing as the wheel flexed under load... anyways, anyone have luck getting these warranted? I've got several GT500 wheels with the same sized tires that I'll rotate in for tomorrow, but pretty amazed 3 spokes cracked so quickly.

Pic:
IWV8pC_fXJ86QNTzoScibQsAfb5YlafercVWU=w708-h943-no.jpg
 
How old are they, what tires are you running and do you rotate from front to back? Those were on the rear?

There have been cases of them cracking like that but we haven't seen any fail so they couldn't be driven on. They typically crack on the front with slicks. Some members have had them replaced under warranty if they weren't too old.

@cloud9
@Black Boss
@ArizonaBOSS
 

dmichaels

Papa Smurf
547
30
CT
NFSBOSS said:
How old are they, what tires are you running and do you rotate from front to back? Those were on the rear?

There have been cases of them cracking like that but we haven't seen any fail so they couldn't be driven on. They typically crack on the front with slicks. Some members have had them replaced under warranty if they weren't too old.

@cloud9
@Black Boss
@ArizonaBOSS

I've used them about 7 track days I think. 6 of those were with BFG-R1's, and one with Conti scrubs (today...).

Yes, the one that cracked was on the rear today, but they get rotated regularly.

I bought them from another member, but if I remember correctly, they were all lightly used.
 
Are wheel failures in general at the track attributable to wheel construction (forged vs cast vs rotary forged), light weight (not built robustly enough), or heat/stress (bouncing off curbs)? Or some combination of all three?
 

Grant 302

basic and well known psychic
SlowJim said:
Are wheel failures in general at the track attributable to wheel construction (forged vs cast vs rotary forged), light weight (not built robustly enough), or heat/stress (bouncing off curbs)? Or some combination of all three?

Great question. It has to be a combination of all three.
If it was only rotary forged issues, all of the Enkei and other brands like Forgestar would have the exact same issues. Ditto for the track use...we'd see the same problems in similar timeframes with other brands. If it was some sort of batch defect, they'd probably fail under normal street use. To my knowledge, that's not happening.

I think the main culprit is the amount of material and curvature in their 9.5" rim for the way some of us are using them...with slicks or R-comps at the track. I haven't seen all the pics, but I suspect all of them are failing in the roughly the same place. This points mostly to an issue with the material cross section and probably bending over shear since it is loosely curved there.
 

Wingrider

'11 GT500, 99% Track Car. Lots of mods & I coach
I'm certainly not defending the wheels, but I've lost count of the number of track days on my 9.5's and mine look ok. I just inspected them very closely before putting them on the car for 2 track days this week. I have had these about 2 years as a point of reference. I am moving to a set of the HRE's in 10.5/18 that I'm picking up @ Sonoma that I will swap in.

I have the black 9.5/18's and unsure what to do with them once I have the HRE's.
 
While the sky is not falling and the cracking is not systemic you won't know if they are going to crack until they crack. You should check them after each track session. The good news is they crack and we haven't seen any catastrophic failures with these wheels. They are good quality wheels but the stresses our heavy cars put on them appear to be too much for the 9.5.

I'll be selling m 9.5/10.5 set soon if anyone is interested.
 
1,022
97
Exp. Type
HPDE
Exp. Level
10-20 Years
Texas
NFSBOSS said:
While the sky is not falling and the cracking is not systemic you won't know if they are going to crack until they crack. You should check them after each track session. The good news is they crack and we haven't seen any catastrophic failures with these wheels. They are good quality wheels but the stresses our heavy cars put on them appear to be too much for the 9.5.

I'll be selling m 9.5/10.5 set soon if anyone is interested.

What is the offset of the 10.5's you are thinking about selling? I found out that I could run my Enkei 10.5's on the front too and go with a square setup on these, no spacer needed. They stick outside the fender slightly in the rear but I don't mind the extra track width. Anyway, shoot me a PM if you are serious about selling them with a price.

Adam
 
Wingrider said:
I'm certainly not defending the wheels, but I've lost count of the number of track days on my 9.5's and mine look ok. I just inspected them very closely before putting them on the car for 2 track days this week. I have had these about 2 years as a point of reference. I am moving to a set of the HRE's in 10.5/18 that I'm picking up @ Sonoma that I will swap in.

I have the black 9.5/18's and unsure what to do with them once I have the HRE's.
I have run well over a hundred track days on Enkei PF01s. I did have one spoke crack each on two 7 year old wheels that I replaced last year, but that was after a significant amount of track time and heavy abuse on curbing. I had another set that was less than 3 years old and they were in perfect condition. I would imagine that same duty cycle on other lightweight aluminum wheels may have produced the same result. We're stressing all the parts on these cars and critical items like wheels, brake pads, tires, rotors and suspension components should be regularly inspected between track events. Wheels, pads, tires and rotors should be inspected during track events. All of the parts on the car with enough duty cycle will eventually fail.
 

Grant 302

basic and well known psychic
cloud9 said:
We're I'm stressing all the parts on these cars and critical items like wheels, brake pads, tires, rotors and suspension components should be regularly inspected between track events. Wheels, pads, tires and rotors should be inspected during track events. All of themy parts on the car with enough duty cycle will eventually fail.

Fixed that for ya! ;)
 
3,696
3,585
3 letters.....

CCW

BTW "rotary forged" is not that much of an improvement over cast

https://trackmustangsonline.com/index.php?topic=9132.0
 
SlowJim said:
Are wheel failures in general at the track attributable to wheel construction (forged vs cast vs rotary forged), light weight (not built robustly enough), or heat/stress (bouncing off curbs)? Or some combination of all three?

Personally I wouldn't run a non-trueforged wheel (or legitimate race wheel) on the track - especially a brand with known cracks and failures. Too dicey - for me personally.

If I had to run a non-forged wheel I would see if the spokes are thin and highly bowed out....recipe for cracks in my opinion (again, just my opinion. happy to be corrected).
 
3,696
3,585
DG#56 said:
Personally I wouldn't run a non-trueforged wheel (or legitimate race wheel) on the track - especially a brand with known cracks and failures. Too dicey - for me personally.

If I had to run a non-forged wheel I would see if the spokes are thin and highly bowed out....recipe for cracks in my opinion (again, just my opinion. happy to be corrected).

Again, and no one pays me to say this BTW, the wheels we use are inspected every time they are mounted, in 5 years at Phoenix I have seen exactly 2 cracked wheels, both happened at the same time , on the same car, on the same side, those wheels were 3 years old and went through abuse like this..
qFrE6hnl.jpg

again, as stated in the link I posted on wheels, if you run on the street, cast are probably fine, rotary forged IMO is a sales gimmick, and forged for the track, any of those wheels will be fine IF you don't exceed the design parameters of that particular wheel. Out of necessity, at a race, I took a sledge hammer and a piece of wood, and beat a CCW back round again so we could use it, I would not do that to any other wheel. As far as easy to clean, it's hard to beat black anodized. When we were running IMSA and doing pit stops I was always deburring the area around the lug nuts , cleaning and inspecting them and touching them up with BBQ black for TV.
f2zhtzvl.jpg
 

ArizonaBOSS

Because racecar.
Moderator
8,545
2,376
Arizona, USA
Wisdom there. I'll probably go for CCWs on my next set(s) of wheels, but I'm hoping I can get at least two years use out of my 10.5 Enkeis. No issues since February and I've been on them hard every month since then.

Fingers crossed.
 

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