| Author | Message | ||
| BretM (Bretm)
Advanced Member Username: Bretm Post Number: 2968 Registered: 2-2001 |
I've been reading the thread for awhile and have to throw in my $.02. Not to discredit you at all Erin, but I think when something happens out of place we naturally attribute any new problem with that event, and become over concerned. When I had my Bridgestones on the 308 (I hated these tires, really hated them, like wanted to kill them quickly hated them) I used to lock up both fronts for about a month at least 3-4 times a week when braking and seeing how hard you could actually get it to stop immediately prior to lockup. They never really developed any wicked vibrations, etc. granted I replaced them after this month with Pirellis so I didn't have any really long term testing. The point of my rambling is just drive a bit and I bet it will go away. And yes, I'm sure there are those of you out there that can say you locked them up once and wrecked the tires, that a wobbling tire isn't good for the front end, etc. I was just stating my experience. | ||
| Donny Bridges (Wildcatfans)
Junior Member Username: Wildcatfans Post Number: 102 Registered: 9-2001 |
We miss ONE drive, and ALL the action. My opinion, if it is a "faint" wobble, rebalance to eliminate that possibility and keep driving. It'll probably get better with time as the tire wears. Sounds like we need to plan a nice long road trip. Just glad to hear you missed the guy. Tires are cheap in comparison. | ||
| Dan B. (Dan_the_man)
Junior Member Username: Dan_the_man Post Number: 67 Registered: 9-2002 |
Erin, You flat spottd the tires, rotate them to the back, burn them down some, rotate them back to the front and get it all ballanced. Dan | ||
| Lawrence Coppari (Lawrence)
Member Username: Lawrence Post Number: 406 Registered: 4-2002 |
It is difficult to warp a rotor in one stop at highway speeds. Moreover, if you locked the brakes and the wheels don't spin, no heat is generated at the rotor beyond the point when the wheels stopped rotation. Look at it this way. The brakes turn kinetic energy into heat. The kinetic energy is .5*m*v**2. For a 3500 pound car approximately 80% of the kinetic energy goes into the front rotors when stopping. That means each front rotor got about .5*3500*.80/32.2/2*(88)**2 = 168K ft-lbs of energy for a stop from 60 MPH. That is only 216 BTU. If a rotor weighs 12 lbs that is a temperature rise of only 141 degrees (specific heat of cast iron is 0.13 BTU/lbm-F). That is no big deal. In the above, the only things I'm guessing at is the weight of the rotor and 80% factor for braking. I'd say you flat spotted your tires or rotated them on their rims. | ||
| Robert (Rjklein4470)
Junior Member Username: Rjklein4470 Post Number: 205 Registered: 3-2002 |
Sounds like the roters got hot and warped | ||
| Francisco J. Quinones (Frankie)
Junior Member Username: Frankie Post Number: 77 Registered: 8-2002 |
It sounds as if you flat-spotted your fronts or maybe they just actually "shifted" or rotated on the rims moving them from where they originally were balanced.shaving and rebalancing may save you big $$ for a while. just my .02 good luck.  | ||
| William H (Countachxx)
Intermediate Member Username: Countachxx Post Number: 1575 Registered: 2-2001 |
Erin , your tires are most likely flat spotted, best cure is to buy new ones or depending on your budget, figure out which corner is worse & replace just that side or end. Good Luck | ||
| Kelly (Tifosi1)
Member Username: Tifosi1 Post Number: 496 Registered: 2-2002 |
E-man. I got money says your through a weight. Maybe on the inside where you cannot see it. I would get them balanced first. Then look into the shaving process. They can check the rounds ness of the tire while doing the ballance. MY 2 cents. The AC Cobra will not be invited back to our drives. | ||
| Bob Campen (Bob308gts)
Member Username: Bob308gts Post Number: 377 Registered: 9-2001 |
Tire Rack does tire shaving, check out their website, Tirerack.com | ||
| Erin Patrick Pierce (Fulmina)
Junior Member Username: Fulmina Post Number: 55 Registered: 3-2002 |
Thanks, guys. I now have a good idea of how to proceed. Magoo, the weight is still there, and I am sure the balance was perfect before the lock-up. Bringing it back to the people that sold it to me: Sounds good to me! I know the guys at the tire store fairly well and am confident that they would rebalance the tires for me. I will rule that out first. JRV, after I ensure the balance is correct I will call around about the shaving. I didn't know people did that. Thanks. Mike, James, Mike C: good points. To put caution before valor: I would rather leave them where they are than take a chance on rubbing. Thank you all for your insight on this. It is nice to have a place to turn to with so many experienced drivers willing to offer help. Oh, and one more thing: Randy, now that wasn't very nice. Are you the fellow that wants people to buy him a Ferrari? I noted your e-mail address underneath the large picture of you driving a stationary car (In your profile). Thanks for contributing--I'm sure everyone is as anxious for your input as I am. | ||
| Mike Charness (Mcharness)
Junior Member Username: Mcharness Post Number: 110 Registered: 8-2002 |
If you only flat spotted the fronts, you *can* move the rear tires to the stock front wheels. They'll fit just fine. You can put two new tires on the rear. Many 308 owners with 16 inch wheels have "upsized" their tires to 225/50's on the front and 245/45's on the rear. That's what I've done on my QV. | ||
| James Napolis (Napolis)
Junior Member Username: Napolis Post Number: 115 Registered: 10-2002 |
Dave and JVR are right are right. You can flat spot your tires on one lockup and it sounds like you did. You can't safely rotate smaller fronts with larger rears. Burning out the flat spot? Hard to do with a front tire and a very very bad idea. A tire trueing machine might help but one panic tire can easily destroy a tire. Assuming an equal road surface if your brakes are adjusted properly you should have flat spotted at least two if you were traveling in a straight line and more likely all four. | ||
| mike 308 (Concorde)
Junior Member Username: Concorde Post Number: 53 Registered: 8-2002 |
308/QVs (both US and Euro) have different size fronts and rears... not just the tires, but the rims also are slightly wider in the rear, so you can't (shouldn't) just rotate them. | ||
| David J. Smith (Darkhorse512)
Junior Member Username: Darkhorse512 Post Number: 54 Registered: 10-2002 |
and as for the street tread, I highly doubt you feel a flat spot. Speaking from "experience" and for Erin, you can and he did. | ||
| Randy (Schatten)
Member Username: Schatten Post Number: 477 Registered: 4-2001 |
Watch your tail gating maneuvers man! sheesh! and as for the street tread, I highly doubt you feel a flat spot. | ||
| magoo (Magoo)
Advanced Member Username: Magoo Post Number: 3581 Registered: 2-2001 |
Erin, I find it hard to believe that one lock up caused a "wobble" in your car. Maybe you just didn't notice it in the 400 miles you have put on the tires and they could have some runout or imbalance condition. Also maybe a wheel threw a weight. In any event take it back to whoever installed the tires, tell them you notice a wobble, don't tell them you locked them up, and have them do a runout check and a rebalance. | ||
| JRV (Jrvall)
Junior Member Username: Jrvall Post Number: 159 Registered: 11-2002 |
It's possible you might find a Truck Tire Co. near you that can shave the tires round again. Most truck recapping companies shave tires to 'true' them up. Also, Tire Rack used to shave the BFG tires for certian SCCA Racing Classes that required treaded tires, maybe they still do, worth a few calls. | ||
| Erin Patrick Pierce (Fulmina)
Junior Member Username: Fulmina Post Number: 54 Registered: 3-2002 |
Thanks for the insight, Dave. | ||
| Erin Patrick Pierce (Fulmina)
Junior Member Username: Fulmina Post Number: 53 Registered: 3-2002 |
I suppose it is possible that there is another reason for the wobble... it just feels like the tires. I guess they also could have been yanked out of line or something. I have never locked them up that badly before. The guy went from 90mph to a stop as fast as he could. Burn it off, eh? You are right, that does sound like fun. I wonder if I could rotate the tires to do that.... the back ones are a bit wider than the front. The back are 225 and the front 215. All my buddies with 308s are able to rotate, but my rims are different sizes in the front and back. (They appear stock. I have a QV Euro) Thanks for the ideas. | ||
| David J. Smith (Darkhorse512)
Junior Member Username: Darkhorse512 Post Number: 52 Registered: 10-2002 |
A lock up in the front followed by a vibration in the front? In racing they call them flat spots. There are contact patch sized sections on your tires that now have less grip than the rest of the tread. You may want to adjust your brake bias to favor the rear tires a little bit. Now that the circumference of your tires has this little imperfection in them, they will continue to vibrate and lock up under heavy braking on that flat spot making the vibration worse. I don't think your tires are dead. You can try to avoid emergency style braking and let natural tire wear even out the tread over time. | ||
| Taek-Ho Kwon (Stickanddice)
Junior Member Username: Stickanddice Post Number: 55 Registered: 11-2002 |
A panic stop in tires so new should not make that big of a difference in the tread. Are you sure that is what is making the car wobble? If you want to even out the tread again, just smoke the tires and that should do the trick. It can be fun too! | ||
| Kevin Marcus (Rumordude)
Junior Member Username: Rumordude Post Number: 107 Registered: 9-2001 |
Dude, were your tires warm or still wiping off a bit of the frosty morning chill? warm vs. cold makes huge difference. beyond slicks, i dont think you'd see much different from any other tire out there in terms of locking up the brakes. make sure you ease up, and steer away if you can! thats why i hate messing with people on the road - you never know if they are going to do stupid crap. on the track you can at least expect them to be "not quite as stupid." | ||
| Erin Patrick Pierce (Fulmina)
Junior Member Username: Fulmina Post Number: 52 Registered: 3-2002 |
Hello all. In order to narrowly miss a kit-AC Cobra (when he so unwisely decided he should pass traffic, then immediately slam his brakes!) I locked them up today... Now I'm riding like I wore off a bit too much of my tread whilst leaving those nice dark marks on the highway. I have a faint wobbling from 35-55 that is very unappealing to me. I also have just under 400 miles on my shiney-new P-Zeros! I wanted your opinions before I replace them. Is there another way to go about this? I know, I should have been a little lighter on the brakes-- perhaps even pumped them a bit, but I was a paint-coat away from having a very unattractive kit-car hood decoration and my foot wouldn't budge! Luckily, I did not hit the fellow. Any advice would be great. Regards, Erin |