3pc Rim PSA: Check your rim bolts

AFM744 · 08:30 AM

I have been totally checked out for the last 6mos with lots and lots of messy personal stuff. But my car has been running FANTASTIC. However, I had one of my Kinesis K57s disassemble itself on southbound 17 the other day. At first I noticed "Hmmm, feels like a flat" so I got off the freeway quick. Further inspection revealed FIFTEEN of the forty rim bolts were snapped off. Out comes the AAA card. One quick trip to the local fastener wholesaler for 12.9 grade bolts, a teardown and rebuild, and it's back on the ground. But I will probably rebuild it again with proper replacement (shanked) bolts.

In other news, the car finally went on the dyno. I was at 034 Motorsports (Audi tuner) discussing some new projects I'll be prototyping for them and they coaxed me to let them strap 'er down to the rollers.
It was 95F, they have NO fans to put out back, and my intercooler was too hot to touch, but my car put down 354whp on 10psi and straight donkey-piss CA 91. That's the most HP they've ever seen from CIS on their dyno, so I'm happy until I get back to my EFI conversion. On that note I will LIVE in this damn car before I sell it, so sooner or later I will get back to my EFI conversion.

flat6pilot · flat6pilot's Garage

What sort of EFI system will you be using?

AFM744 · 11:53 AM

I currently have a large box on the shelf containing:
Carrera manifold, rails, etc
TEC3r ECU, DFUs, etc
GT3582R

I need the following to commence conversion:
GT2 Lightweight Flywheel (60-2 reluctor ring)
GT2 pressure plate, drive plate
modded brackets and intake for GT35R
Fuel Injectors (probably Siemens 60#)
secondary plug wires
A F***ing Job.

Jim Dorociak · 09-20-2009, 07:48 AM

So what size bolts were used on your Kinesis wheels - I restored several sets of Supercups and they were M6. Which is a small bolt. I drilled my wheels for M7 and put in a larger size bolt. I think it is very typical that these small bolts break. Speedline, Techart, OZ and RH wheels are built with M7 bolts so I feel that is the Industry standard. I like to use stainless steel as they do not rust and require no maintenance to keep looking good. Jim

911nut · 911nut's Garage

Quote:

Originally Posted by AFM744

I need the following to commence conversion:
GT2 Lightweight Flywheel (46-2 reluctor ring)

Over on Rennlist there's a lot of pros and cons around using a lightweight flywheel on a Turbo car. The con is that a lightweight flywheel will make every gear feel like 1st gear; the engine ends up at the red line so quickly that the turbo really doesn't spool up.
It's interesting to note that the factory only used the lighter RS pressure plate on the 1993 Turbo S. The flywheel itself was still the stock dual mass one.

Reaper930 · 09-20-2009, 12:23 PM

Also note on a lightweight flywheel you might have to raise your idle. On mine, the flywheel is so light, that when I clutch it from anything over 3k rpm it would stall out easily as it couldn't hold the idle when dropping so quick. Thus the problem was fixed with a higher idle which gives more room to fall before reaching 0 RPM.

JohnJL · 09-20-2009, 02:39 PM

I have mixed feelings about the lightweight flywheel.

It has made idle and paddock tuning a bear (when combined with other variables.)

On the other hand the motor spools up extra-quick, I have trouble shifting quickly enough when TPS = 100%. Even on only 10 psi through a G50 asnd LSD I can break traction in third.

I used the same intake you are planning on. I ended up cutting and turning it.

AFM744 · 09-21-2009, 06:28 AM

Quote:

Originally Posted by Jim Dorociak

...I like to use stainless steel as they do not rust and require no maintenance to keep looking good. Jim

But stainless bolts are about half as strong as 12.9 alloy steel bolts. I agree stainless is far more appealing for aesthetics and maintenance, ... if I were drilling out to M7 I'd definitely go stainless.

AFM744 · 09-21-2009, 06:44 AM

Re: all comments about LWFW, I agree they are polarizing. However I installed a LWFW on my last turbo car and miss that snappy throttle response. I just rode in a great R-Grouppe replica the other day with a 3.2 motor, and was taken by how snappy the motor revved. I HATE how my motor revs with CIS and DMFW, it down-shifts rev-matches like a damned Kenworth compared to so many cars I have driven.
There are common misconceptions about LWFW. A stock, heavy DMFW does enable easier and more aggressive launch "out'a the hole" because you can spin that big thing up and it'll store and transfer energy to get you off the line. However, I will trade that for crisp, immediate up- and downshifts. I cannot concede to the comment that a LWFW will prevent boost. Boost is made by loading the engine and creating combustion energy. A big single turbo sometimes cannot spool up fast enough through first gear. I know my car gets through first gear pretty damn quick, IF it doesn't just light 'em off and bounce the rev limiter. ...or my clutch (stock, original 93k) just says "No way dude" and asphyxiates everyone.

Jim Dorociak · 09-21-2009, 06:53 AM

The stainless steel bolts I use are specifically manufactured for 3 piece wheels and are 10.9 hardness and will not rust for 25 years. Jim

AFM744 · 09-21-2009, 06:58 AM

Jim, where'dya git 'em?

full quack · 09-21-2009, 11:28 AM

Is that 25 years from the day of manufacture? Or do they just turn into a pumpkin at midnight when there time is up?

Sorry couldn't resist....
Mark

Jim Dorociak · 09-21-2009, 11:49 AM

Thanks for the laugh about the bolts after 25 years, not sure I will be around to see what happens after than period. Jim

A930Rocket · 09-21-2009, 01:33 PM

The bolts will be there, but the wheels will be long gone...

Reaper930 · 09-22-2009, 06:19 AM

Amen to that - although its hard to live with, its like that Red Headed Slut I keep talking about - She tries to kill you everytime you take her out but is oh so rewarding to experience. I refuse to go back to a stock or heavier flywheel even if it makes the car more driveable...its just not worth the trade off with a sluggish feel.

Quote:

Originally Posted by AFM744

Re: all comments about LWFW, I agree they are polarizing. However I installed a LWFW on my last turbo car and miss that snappy throttle response. I just rode in a great R-Grouppe replica the other day with a 3.2 motor, and was taken by how snappy the motor revved. I HATE how my motor revs with CIS and DMFW, it down-shifts rev-matches like a damned Kenworth compared to so many cars I have driven.
There are common misconceptions about LWFW. A stock, heavy DMFW does enable easier and more aggressive launch "out'a the hole" because you can spin that big thing up and it'll store and transfer energy to get you off the line. However, I will trade that for crisp, immediate up- and downshifts. I cannot concede to the comment that a LWFW will prevent boost. Boost is made by loading the engine and creating combustion energy. A big single turbo sometimes cannot spool up fast enough through first gear. I know my car gets through first gear pretty damn quick, IF it doesn't just light 'em off and bounce the rev limiter. ...or my clutch (stock, original 93k) just says "No way dude" and asphyxiates everyone.

Rob 930 · 08:07 AM

On the subject of Kinesis wheel failures, I had one fail too, a couple of weeks ago. I have a 78 930 track car with Kinesis K27 9.5 and 11 by 17 wheels, with Nitto NT-01 tires. I rebuilt the wheels in 2002, and had the centers powder coated. I replaced all the hardware (40 bolts and nuts per wheel) with new chromed bolts from Kinesis (which is now out of business). At that time, I got counseled by them on the procedure, which included torquing the bolts to the recommended 16 ft-lb, and I used their approved silicone sealant for the joint. I retorqued the bolts a few weeks after rebuild, after a brief run-in period on the street. But I never checked the wheel bolt torque since then, which I probably should have done. However, I haven't used the car that much since then; it probably has 1500 miles on it since the rebuild and about 6 track days.

On the track, fortunately at a low speed (about 50 mph), the car snap spun counterclockwise in a fairly straight section of track. The right right tire had suddenly gone flat. Because the rear tires are so large (315/35), when the right rear went flat, it rubbed on the inner fender well, acting like a big brake. Hence the spin. Fortunately, no harm was done to the car, other than the tire, a slightly scraped outer rim flange (which has been replaced), and some rubber tire deposits on the wheel well. As a precaution, I'm going to replace one of the forward-going oil lines which also got a bit rubbed.

Inspection of the wheel showed that 8 of the 40 bolts on the rim perimeter had broken off. A few other nuts were loose to the touch. Others still were not "loose" but had much less than 16 ft-lb torque.

Geek mode "on"

As one who analyzes failures for a living, I took a very good look at the wheel bolt fractures. They all failed in fatigue, which suggests that they came loose (lost their preload) and went into cyclic bending (which never happens if their preload is maintained). Their failure had nothing to do with being "too weak." They just lost their preload and became loaded in a way that was unintended and unfavorable. There was also evidence of abrasion under the nuts on the aluminum wheel flange, indicating that they had been "working" for a period of time, and had probably been below their prescribed torque for a while. A picture of the bolt fracture surface, below, shows beach marks (or striations), that show the progression of a crack across the bolt diameter. They look like waves in a pond. The fact that the fatigue crack propagated almost all the way across the bolts suggests that the bolts are not particularly highly stressed when in service. Had they been highly stressed, you would expect to see a large zone of "final fracture" where the fatigue crack ends and the the remainder of the bolt cross section failed from overload. Instead, the fatigue crack extended across almost the entire face of the bolt before fracture occurred. One more observation -- the bolts did not appear to have flaws or defects that created initiation points for the crack to form. The cracks seemed to start at the thread roots, which is an unavoidable and normal stress concentration in a threaded fastener.

Geek mode "off"

What this means is that the bolts and wheel sections are not defectively designed or manufactured; they're plenty strong. The bolts simply came loose and failed in fatigue, just as would happen to the five wheel studs if you don't keep your lug nuts tight. I think the fact that I had the centers powder coated was a big factor. The perimeter bolts clamp together this "sandwich" that includes the powder-coated wheel center; the coating is thick and soft -- and it probably oozed and relaxed over time with heat and load. Hence the originally torqued rim perimeter bolts likely lost their torque over time and I failed to notice that it was happening. Had I a) not powder coated the wheels and/or b) retorqued the wheel perimeter bolts periodically I probably would not have had this problem. It would probably have been a good idea to keep the powder coating off the clamped joint surface (or to clean it off before assembly).

I checked the other wheels and found a couple other bolts that were down a bit in torque. Out of caution, I'm replacing all the hardware in my right rear wheel and will be watching those torque levels from here on.

Rob

Jim Dorociak · 09-30-2009, 08:15 AM

Me personally feel 16 ft lbs is too low, not that I torque much more than that, but I like to torque to 18-20 ft lbs, and use loctite on each nut when assembling. Some of the wheels I restore I do not put paint or powdercoating on the back flange of the wheel center and actuall clear coat after the wheel is assembled so I a not bitting into soft paint or powdercoating. Not all nuts have the seriations which chews up the metal. I have now switched to a non seriation nut.

I have disassembled wheels that were done by other people only to find most nuts had become finger tight.- scary thought even if there are 40 bolts holding wheel together. Jim

AFM744 · 09-30-2009, 08:15 AM

Rob, that is almost exactly how my wheel failed too. My wheels were reassembled by Kinesis after being painted some years ago (I've since stripped the paint). The center painting (or stripping) does seem to be a factor doesn't it? But if so then why did Kinesis condone this modification to my car's previous owner?

16ft/lbs!!?!?!?

Holy-hell that sounds loose for something undergoing such chronic vibration, heat and stress cycles. All my wheels' bolts were pretty sloppy, and I torqued them up quite a bit; 26ft/lbs actually as suggested by the local wheel shop.

JFairman · 09-30-2009, 08:29 AM

It's not always a good idea to put silicone sealer glue on the mating surfaces when assembling 3 piece wheels because sometimes it won't all squeeze out even if you are fast and get the wheel together and torque all the bolts before the silicone starts to set up and dry.

If you don't believe that then take the wheel apart a day or so afterwards and you will see a thin layer of silicone between the parts and that means those parts never came all the way together the way they should.

Not everyone does it this way but it works for me... I put a very thin layer of hylomar gasket sealer on the mating surfaces. Hylomar is the consistancy of grease and it never thickens up or dries so it will squeeze out when you torque down the nuts on the back side of the wheel bolts.
Then wipe off the squeezed out hylomar around the perimeter with laquer thinner. This will take it all off and leave clean aluminum at the seam where the wheel halves came together.

The seam has a small recess so now spread a bead of silicone sealer along that seam and then wipe your finger along it just like you would after caulking a seam in a house to smooth the caulking.
Wiping the seam with a finger will force the silicone all the way into the surface of the seam and leave a smooth surface and will look like nice if you don't keep smearing it over and over trying to make it look smoother as the silicone starts to dry and skin over on the surface.

You could skip the hylomar step and the wheels will probably hold air fine with the silicone applied after the wheels are assembled dry, but I like to do it for added insurance against air leaks anyway.
The hylomar will also keep water from wicking into the seam when driving in the rain or washing the car and causing corrosion in between the wheel halves and on the threads of the bolts down the road.

Rob 930 · 09-30-2009, 02:41 PM

Guys,

For the Kinesis wheels, I'd be very hesitant to torque beyond 16 ft-lb without knowing exactly what type of bolt is being used. If these are M6 bolts, then 16 ft-lb is at the top of the acceptable scale, even for Grade 12.9 bolts. To overtorque them risks yielding (or failing) the bolts, which would not be good.

Also, I don't think this is a case where Loctite would help. Loctite keeps the nut from rotating on the bolt, which is useful for some settings. But here, the loss of torque was most likely not from nut rotation, but from joint relaxation, so the Loctite won't prevent that. To make matters worse, if you want to re-torque the bolts periodically, which I plan to do, the Loctite will prevent an accurate re-torque.

For joint sealant, Kinesis recommends only a very specific brand, called Shin-Etsu Silicone 1 component RTV. Standard RTV silicone sealant is not to be used (though I'm not sure why). And according to Kinesis, sealant is not to be put between the mating surfaces of the wheel halves -- those surfaces are to be sanitarily cleaned and the wheel bolted together and torqued. After assembly, a bead of sealant goes in the groove around the joint. Thinking about it, I'd never want to have any kind of compliant layer between the mating surfaces that may compromise the joint clamping torque. As it was, my wheels held air perfectly for 7 years until I the bolts broke due to torque loss.

I think the moral here is to simply be careful with powder coat and paint (i.e. avoid it or remove it from mating surfaces), check the bolt torques periodically, and don't over torque them. These are great wheels -- very light and strong -- but they have to be maintained properly (which unfortunately I didn't pay enough attention to).

Rob