AXers and racers: VERY IMPORTANT! [Check Hub Bolts if driven hard]

[Krazed Kanary]

I have had both front hubs loosen significantly and potentially dangerously, so beware and check before and after each event.
First one was discovered a week ago when I took the car in for an alignmnent and to correct an ABS warning, service traction control and service ESC warning. The tech did a scan which indicated to check the left front sensor. Checking the sensor it popped out of the hub into his hand. They didn't have one on hand, so he glued it back in with some weatherstripping cement temporarily until they could order a new one. That turned off the warnings. All seemed good, until he tried to set the front camber and it would not go beyond -1.9* on the left. We both knew that wasn't right, so more checking was begun. With the front jacked up he grabbed the tire and was able to shake it in and out 3/8" at the top. Checked the pass side and it was tight. Bad bearing was the diagnosis, and since the bearing and hub was a sealed unit the entire hub would need replacing. We were to race the next day, so a consult was made with the dealership manager (we are sponsored by the dealership) and he ordered the tech to remove a hub from a brand new GXP from stock to replace mine. I watched as he removed the new one, it was held on by the caliper and 3 bolts thru the rear of the upright. When he went to remove the defective one on my car I noticed the bolts came out a lot easier than they did off the new car, but didn't give it much thought until today. We ran in a two day event this weekend, and when changing back to the street tires after the event this afternoon, I checked the front for looseness and found the pass side hub was now nearly as loose as the driver's side had been the weekend before! I then remembered the easily removed bolts on the other side, so I grabbed a 15mm wrench and checked the mounting bolts. All three were loose between a 1/4 and a full turn!!! I tightened them all and remounted the wheel and it was now tight.

I would suggest that everyone using race tires and/or AXing check the hubs for free play with the wheel jacked up every time you change tires, and routinely retorque those 3 mounting bolts. I suspect it is differential expansion between the aluminum upright and the steel bolts with the extra side loads exerted that are causing the bolts to loosen. I plan to put some locktite red on each bolt and retorque them tomorrow. The rear uses the very same hubs and mounting method, so I will check the torque on those bolts as well. Besides the change in alignment and kicking out the ABS sensor, should you run around with the hubs loose, it could damage the upright and caliper as well as possibly allowing the wheel to come off, potentially resulting in a life threatening accident. BE AWARE and TAKE CARE!

[snaponbob]

Oh CRAP!!!!!!!!!!!!!!!!!!!!!!!!!!!

Thanks for the details. I read your first notice about this and checked Streak. All is tight. BUT, I am thinking that Lok-Tite and a torque wrench are indicated.

[Daywalker]

Thanks for the heads up, I will be checking all of mine this week.

[sodamninsane]

wow... sounds like time for some safety wire / cotter pins / nylocks... thats one part I'd hate to have fall off at 100+mph... did you feel any vibration in the wheel? Usually you can hear loose hubs / bad bearings thunking around up front...

[Krazed Kanary]

Originally Posted by sodamninsane wow... sounds like time for some safety wire / cotter pins / nylocks... thats one part I'd hate to have fall off at 100+mph... did you feel any vibration in the wheel? Usually you can hear loose hubs / bad bearings thunking around up front...

No vibration or noise so there is no warning at least not with early looseness. The only indication is with the wheel jacked up if you grab the top of the tire and shake it in and out hard it moves. A tight hub wil not have any free play. I don't know if a loose rear hub would show the same symptoms, since it has the axle in the center, so I'll check them with a wrench. The bolts go into threaded holes in the hubs (no nuts) so locktite and/or safety wire thru the heads may be the only options other than regular checking. Lock washers won't work, they would just eat into the aluminum upright. There are bolts on the market that have nylon inserts in the threaded portion, that may also be an option if they come in the right size.
I need to do more research.
Anothe option may be adding a hardened flat washer under the bolt heads for the bolt to tighten aginst.

[salstice]

Could you post some pics of the bolts in question. You gave a good description, but a pic is worth a thousand words. Thanks!

[93AS]

This whole thing is a little disturbing.... if the bolts are loosening due to the bolted joint flexing (likely) no amount of safety wire/loctite will cure that issue.

Eric

[solsticeclampe]

Originally Posted by 93AS This whole thing is a little disturbing.... if the bolts are loosening due to the bolted joint flexing (likely) no amount of safety wire/loctite will cure that issue. Eric

Glad I saw this post. I've started a list of Beware Alerts and this ones new. I have my dealer go over things I know or have heard have been poblematic. After reading a header install here. When I went in for service I asked them to check my manifold bolt torque because the member doing his header had mentioned how lose the bolts were when he started. They checked mine and they were not torqued down and asked me was I smelling exhaust. No Sir, I have just been hearing from fellow solsters about stuff like this. Now their prepared when I come in and checking for whats on my record + new stuff like this and always my differential and diff support brackets. Thanks for this good
POST! SOUNDS LIKE A RECALL IN THE MAKING. Maybe they'll change it all if it is uncureable and put some non-rusting rotors back on it while their at it!

[SolsticeMan]

First off - everyone relax.

This seems like a serious issue, but if you look at the potential modes of indication, you will get exactly what you saw: eventually, the sensor ring will break and you will set ESC and ABS codes. This is WAY before the hub starts to come apart.

In fact, I bet these bolts could come a heckuva ways out and the hub would still be retained - it will rub like a bunofasitch on stuff, but the system will still be retained by the brake calipers... and eventually it may work it's way out to the point where it WILL start having steering play, or wearing out your brakes, making the toe REALLY wacky, but the hub itself is retained within the knuckle by a good inch. For it to 'come apart' would mean it has to work all the way out along the center hole in the knuckle - and so long as you have a caliper on the wheel, that just ain't gonna happen.


Second - don't just "torque" the joint with a wrench and turn it like you are he-man-master-of-the-universe.

Take a close look at the joint - you are torquing a STEEL bolt into an ALUMINUM knuckle. If you get overzealous with torqing it down, you will either

a) break the bolt (not very likely - prolly a hi-grade bolt) or
b) strip the F*C& out of the threaded holes in your knuckle (extrememly likely!).

Either way - you end up with having to buy a new knuckle. Prolly talking $150 just for the part. IF you can get one, that is...


The service manual (according to my local dealership) says 115 Nm or 85 ft lb for the three bolts. I wouldn't torque a single foot-lb more than that, but that's just me.

I've got a question e-mail sent out to a few of my sources, but I suspect if you've seen it, K.Kanary, others have too. I have heard that assembling the joint with loctite may be the key, but that may be old info.

93AS - depending on the situation, sometimes all it takes is a bit of loctite. It isn't always joint flex that causes bolts to loosen. Sometimes heat cycling plays a MUCH larger part in it than we ever suspected - especially when we are talking aluminum and steel or forged iron sandwiched parts.


K.Kanary - how long have you run your car on these hubs? How many events? Have you ever taken the car on a racecourse like Watkins Glen, or is it all AX? Is the only way you checked it by shaking the wheel?

Here's my - it's free advice, so prolly worth what you've paid to read it, but here goes...


Get a paint pen http://www.durablesupply.com/unipainmar.html and mark your bolts when you assemble them. Then, a simple visual inspection after every race will tell you if they have loosened. If they have turned, even the thickness of a paint pen mark, then you need to re-assemble and tighten them.

When I actively race, EVERY suspension bolt gets properly torqued, critical ones loctite blue, and most that see heat get some loctite red. Then, they got marked, and inspected usually after every weekend, or after every 5 races (including qualifying sessions).

Of course, there were the hi-take-apart exceptions, like the caliper bolts (which I have never seen loosen on the cars I drove IF properly installed), and a handful of others that I developed a list of along the way. I even had a list of bolts that required replacement after so many disassembles, including the big-azz hub nut, and the clevis bracket cam bolts (on strut suspension) that only took so many reassemblies before they needed new cams.

Makes for a bitch disassembling, but unlike many others that I ran with back in the day, I never had any of the bolts come loose. I never used an inch of safety wire.

(THE USE OF LOCTITE IS EXCEPTING, OF COURSE, LUG NUTS - DON'T LOCTITE THOSE, PLEASE!!!! YOU'LL BE IN FOR A WORLD OF HURT IF YOU DO).


My guess is that if we are racing Solstices/SKYs, and looks like even AXing, you should at minimum disassemble and reassemble the hub bolts with some loctite, properly torque, mark with a paint pen/marker, and monitor them. My guess (if it were me, and what I'll prolly do if I AX my own GXP when I get one) is loctite red, but that's me - your actual mileage may vary.

We'll see what our collective sources say over the next few days...

[fastmike]

This has been an issue with all the Solsti' that are running R tires.
I think we went over it a long time ago.
Dasto was the first to have it happen I think.
The black ZOK(Kevin Dietz's) had it happen during the Pro finale last year.
I just slightly overtightened the bolts and neither my car or Kevin's have had this re-occur.
FM

[Dasto]

Originally Posted by fastmike This has been an issue with all the Solsti' that are running R tires. I think we went over it a long time ago. Dasto was the first to have it happen I think. The black ZOK(Kevin Dietz's) had it happen during the Pro finale last year. I just slightly overtightened the bolts and neither my car or Kevin's have had this re-occur. FM

FastMike is correct! I discovered it early on since I have had my car since December 2005. I passed the word around back in early 2006 IIRC. Anyway, I used loctite and check them occasionally. They have never budged since the original problem. I do not have Antilock brakes and therefore no speed sensors. I had no warning until the brakes starting making unusual noise coming off course. Jacked the car up and found the problem. One bolt was already completely missing!
Dan

[alcyon73]

If this problem surfaces after several AX's with sticky tires, I can't help but wonder if it is likely to become a problem after several thousand miles of street driving.

I'm also wondering if anyone has simply tried tourqing the bolts to spec and then watch it to see if it comes back. I'm sort of thinking that maybe they were not torqued to spec by GM in the first place... but since AXer's like to nut & bolt a lot, it seems unlikely that it is just a simple matter of shipping cars with loose hardware and more likely is a problem that is likely to surface on a lot of cars over time.

I've been doing a little AX , but with the stock tires. Now I'm wondering if it is going to be a good idea to jack the car and check the bolts after every ax...

Me

[SolsticeMan]

Originally Posted by alcyon73 If this problem surfaces after several AX's with sticky tires, I can't help but wonder if it is likely to become a problem after several thousand miles of street driving. I'm also wondering if anyone has simply tried tourqing the bolts to spec and then watch it to see if it comes back. I'm sort of thinking that maybe they were not torqued to spec by GM in the first place... but since AXer's like to nut & bolt a lot, it seems unlikely that it is just a simple matter of shipping cars with loose hardware and more likely is a problem that is likely to surface on a lot of cars over time. I've been doing a little AX , but with the stock tires. Now I'm wondering if it is going to be a good idea to jack the car and check the bolts after every ax... Me

It IS a good idea to mark and check them, alcyon73.

Personally, It's my humble opinion that most times, bolts or fasteners like this have a torque retention feature (by varying the thread depth, or making areas of the thread slightly out of round). If you just re-tighten them, it might not have the same amount of retention. Personally, I'd loctite them if you are AXing.

I'm fairly certain that 1) they are torqued properly before leaving the assembly plant, and 2) normal driving won't loosen them. As of several months ago (last info I had), only people who are club racing or AXing have seen this.

[Krazed Kanary]

We have close to 300 AX runs on race tires on our car. We do not track the car but it is also used as a daily driver.
First I don't think it would be telling tales out of school to say I received a call today from someone I believe to be a senior engineer with GM after I called to report my findings.
His first reaction was that I must have previously removed the hubs. It took some time to convince him that I had not removed them prior to them loosening and in fact until the dealer tech replaced the first one I didn't even know they came apart like that, and NO ONE but myself or someone under my direct observation/supervision has ever touched my car. I stay right with the car while anything is done that I don't do personally from alignments to mounting my tires. I am very anal that way. Prior to last week, a wrench has never touched those bolts. He stated that mine was the first case they were aware of the hub bolts loosening on a production car that had not had the hubs removed prior.
He suggested using locktite red and torquing the bolts.
He also said not to check the bolts for looseness by attempting to tighten them. Only check by visual inspection and by shaking the top of the wheel while jacked off the ground.
I think Solsticeman's suggestion to mark the bolts and check for the marks to having moved is an excellent idea! I will use it after applying the locktite red.
One correction I would make tho is that the bolts do not thread into the aluminum upright, they pass thru the upright and thread into the steel hub.
It was not my intent to start a panic, only to report what happened and suggest everyone who AX or races their car check their hubs for any sign of loosness. I don't think it is a major safety issue/concern for street driven cars that do not see the severe cornering forces nor do I think the wheel could come completely off.

[93AS]

Originally Posted by SolsticeMan 93AS - depending on the situation, sometimes all it takes is a bit of loctite. It isn't always joint flex that causes bolts to loosen. Sometimes heat cycling plays a MUCH larger part in it than we ever suspected - especially when we are talking aluminum and steel or forged iron sandwiched parts.

Heat cycling can also cause joint flex.... if the joint is flexing enough to reduce bolt clamp load enough to loosen bolts that's a serious joint failure.... loctite will not fix the issue only eliminate bolt loosening as an indicator.

Eric