mikymu

Hey guys, give Rich a call and he will get you the right replacement bolts. He just ordered a set for me and it's on it's way

Cheers

Mike

dbratten

When I put in new SKF hubs several years ago I found it easiest to remove the entire knuckle as it is only the two ball joints and one tire rod to take it off. They popped right off with a hit of a hammer. It's not worth fighting them on the car.

FWIW, I reinstalled the hub bolts with red Loctite and they have never come loose. Also, I often change pads and rotors and reuse the caliper bolts but only torque them to 110 pounds. They have also never come loose. An air wrench makes short work of all of this.

--Dan

Bill Dearborn

When I replace or swap front wheel bearings I just pop the lower ball joint loose so the stud lowers in the knuckle which gives me plenty of room to get to the bottom bolt. I have never removed the knuckle from the car as it is very easy to replace the bearing with just the bottom ball joint stud loosened. My service manual doesn't indicate the bearing bolts need to be replaced and I am still using the ones that were installed in the factory. I have GMPP so when a bearing goes bad I have the dealer replace it and the mechanic reused the bolts. I carry a spare bearing to the track and if something goes wrong I can swap it into place until I get home and then I reinstall the bad bearing and take the car to the dealer. That way I don't have to keep paying for new bearings.

Bill

mikymu

Good suggestion Bill. That's one thing I LOVE about our cars - parts are dirt cheap - compare with Porsche. Totally make sense to carry spare parts and that's what I do now days

trackboss

Hardbar used to sell a replacement bolt kit that was much nicer than the factory torx bolts. Not sure if they still do, but it's pretty simple to measure the size of the factory bolts if you have them out and order up some similar replacements with 12pt heads and nylocs. They are re-usable.

RX-Ben

That kit was not cost effective and thankfully is no longer available.
Get two boxes of these (12.9 allen cap screws, M12 x 1.75 x 60mm, partially threaded) - http://www.mcmaster.com/#90128a302/=udr4e4
And then two sets of these (1/2" nord locks) - http://www.mcmaster.com/#91074a133/=udr5ib
1/3 the price of the hardbar setup, with parts left over.
And the black 12pts rusted quickly and were a pita to remove once rusted.

ratt_finkel

I hate to be the first one to mention this. But is there any possibility the braking issue is driving style related?

I know on my c6 that before switching to a more aggressive rear pad, that the heavy front brake bias would make extreme braking maneuvers freak out the ABS.

mikymu

It's always a possibility but I tried going easy with brake pressure (almost went off track), slight harder with modulation in mid braking and of course standing on it with all my might. It just kept on engaging ABS. I also mix match rear pads with OEM and more aggressive endless W007 and did nothing.

I came from a background of GT3 Cup as shown below and it has no power brake and no ABS. If you get braking wrong and lock up the tires then it's an expensive $2K rubber tax. Took me a while to learn and got really comfortable with the Flinstones brakes after 2-3 track events and no lock up after that so I would say I know a thing or two about brake modulation but there is always room for improvement

ratt_finkel

Well then you should have no problem with the driving aspect LOL

I found that switching to a rear pad that was say, one notch less aggressive than the front did wonders for ABS issues.

Likes others have said though. Shocks can do some funny things. And you may just be a compression **** away from fixing this issue. Though I suspect there may be a deeper rooted issue here.

redtopz

Mikymu, have you tried pulling the abs fuse and see what happens? You might be going around in circles and simply have a faulty abs module. I've been there. Otherwise, I would run similar brake compounds front to rear. I use Hawk 70 in front and 60 in back. I also have a proportioning valve for the rear line to the master cylinder which I dialed in with the abs disabled. It's possible your bias is way off or your shocks are too stiff, but it doesn't look right in your videos how often the abs is kicking in and locking up the front tires. That looks like a faulty abs system to me. I would pull the fuse and see if you still lock up the brakes as easily. You might be surprised.

mikymu

I too wonder if shocks are too firm but I have soften it to only 4 clicks compression and rebound from full soft - max is about 20 clicks. Not sure if one or two clicks soft will be enough to change braking dynamic but you never know. The car will feel like a boat lol

That's a very good suggestion Bill but if ABS module is faulty then I should have same issue with iron rotor but it's not. I barely have any lock up with iron rotors once tire warm up and the car is planted under hard braking. The only area I experience brief lock up running iron rotor is the downhill entrance into East from West where the weight of the car shift to the front ....

ratt_finkel

Have you done a back to back test? It's possible the module has gone bad since then.

Also, it you have a broken compression adjuster. You may be running more compression than you think. Are you sure you are 4 clicks from soft and not 4 clicks from hard?

I know I've made brain farts like that.

Might also be worthwhile having one of your esteemed colleagues taking a lap or two in your car to get their input.

RichieRichZ06

Dan, they are referring to the upper and lower ball joint nuts. According to GM, anytime they list an angle in the torque specs it is a one time use only.

dbratten

Thanks, Richie, for the clarification. Now that makes sense. From the video it looks like you were having a lot of fun that day.

--Dan

RichieRichZ06

I was having a lot of fun that day. The car was working, I was feeling good (although a little hung over from the partying we did Thursday night) and I picked up on the new configuration quickly.

mikymu

Yes, shocks are not 4 clicks from firm and recently checked

all this talk about lock up made me go back and review my video log and this is what I found

• stock shock, leaf spring R6, and CCM with stock pads - No lock up
• Ohlins coilover 14 clicks firm, sphericals, R6, CCM with stock pads - No lock up
• Ohlins coilover 14 clicks firm, sphericals, R6, CCM with endless ME20 - No lock up
• Ohlins coilover 14 clicks firm, sphericals, Continental GT-O slicks, CCM with stock pads - ABS engaged at most brake zones with lock up

Video below is the first time I ran the Conti GT-O slick which has a larger front tire and I experienced significant over steer with the set up and also had to lower front end by about 3/16" ride height. So I think larger front tire diameter may have throw off ABS - funny how I have very little lock up with iron rotors with the same tire ....



Ah Ha!! Now we now why you were so damn fast. You were running ethanol

Werks

[QUOTE=mikymu;1588162812]Yes, shocks are not 4 clicks from firm and recently checked

all this talk about lock up made me go back and review my video log and this is what I found

• stock shock, leaf spring R6, and CCM with stock pads - No lock up
• Ohlins coilover 14 clicks firm, sphericals, R6, CCM with stock pads - No lock up
• Ohlins coilover 14 clicks firm, sphericals, R6, CCM with endless ME20 - No lock up
• Ohlins coilover 14 clicks firm, sphericals, Continental GT-O slicks, CCM with stock pads - ABS engaged at most brake zones with lock up

Video below is the first time I ran the Conti GT-O slick which has a larger front tire and I experienced significant over steer with the set up and also had to lower front end by about 3/16" ride height. So I think larger front tire diameter may have throw off ABS - funny how I have very little lock up with iron rotors with the same tire ....





[QUOTE]

The only problem with the assumption on the front tire size causing the issue is that I'm running the exact same year/model of Z06, front & rear wheel width, tire type & sizes and we both run together and I do not have the ABS issue. As I mentioned to you before I think that the issue is probably going to boil down to damping (settings on your shocks) or as I mentioned you might want to have Rich check to see if you have a different ABS programing version or something like that which can possibly be flashed or updated (I never though about pulling the fuse to see if the ABS module was malfunctioning as others have mentioned). Last time we were sitting around in the pits I also noticed that your car while lowered, looks like it has nearly no rake in it, which I think can also be an issue. I'm running around 3/4" rake in my car, so that might be something that you want to take a look at too.

Next time we are out together I'll let you take my car out for a session so that you can see what it feels like and compare it to what you are seeing with your brakes.

mikymu

Thanks Ron

I know we were running the same tires but other than tires our cars are set up differently as you have noted. To minimize variable I just look at how my car's brake behave with different setup in the past 2 years and it was obvious that the brakes start locking up and engaging ABS when I start using the Conti slicks. Not sure how much I want to play with it since it's alot of work switching tires and brakes pads when I know iron rotor eliminate the issue regardless of tires. If those caliper bolts are not so damn difficult to remove I may entertain taking CCM on and off and try different tire combination at next track event to figure out the issue ... or just pull the damn ABS fuse lol

As far as rake goes, the rear of the car go through about 1/2" to 3/4" ride height change with fuel load variation and I ran the car at full fuel to fumes on the track and the brake behavior was no different so I don't think it is why my ABS is acting up as of late