Popeye Loc: LifIno

Excessive can break the lug in half. Been there, done that. CRAP!!

Manglesphoto Loc: 70 miles south of St.Louis

Kewl, thank you very much

olsonsview

Torque sticks are good and a torque wrench is best, "IF" they are tested periodically. That is the caveat with either device. Accurate test benches are not easily available. With repeated use, either device can fail. In another life I was an ASE Master auto mechanic. So have plenty of real life experience. The wheel loosening and/or falling off was due to lug nuts run up by hand and never tightened at all! Even the best mechanics are human and can get distracted then forget where he left off I suppose?

al13

I always use Discount Tires when purchasing new tires. They use the pneumatic torque wrench to set the wheels in place and then hand torque each lug nut using the old standby torque wrench. I have been using them for the past ten years and watch then repeat the same on every car they work on. They look up the proper torque for the specific car 5hey are working on. Very rare in today’s times. Over torque can definitely warp rotors.

TriX Loc: Raleigh, NC

This idea has been around for a long time, but knowing how the disc is actually mounted I don’t see how. The studs (if the car uses lug nuts) or threaded holes (if the car uses studs) aren’t part of the disc - ther are allached to the hub which either rides on the spindle of a RWD car or attached to the outer CV joint on FWD/AWD cars. The “top hat” portion of the disc slides over the studs and is sandwiched between between the hub (which is a flat surface) and the wheel, so once the studs or nuts are tightened, the disc is flat against the hub. Unless the hub (which is is cast) isn’t flat, there’s nothing to warp the disc, at least that’s how it appears to me. Think of it as 3 flat metal plates or castings held togather by 5 bolts and nuts. No matter how tight to tighten the nuts, right up to failure, there is no force to warp any of the plates - just pulling them tighter togather.

home brewer Loc: Fort Wayne, Indiana

too much torque stretches the bolt too much and the bolt could yield; if the bolt exceeds ultimate strength it could fail and you may end up with wheel and tire leaving the car

eugenehinds

I believe this is correct therefore the practice of cross tightening is a waste of time, Measuring the stretch on bolts is the means of determining how tight is the head on our nuclear reactors, Torque not measured. an 8 inch bolt 8 ft long should be about .070 inches longer after tightening if my memory is correct. Here cross/sequence tightening is a must.

rustfarmer

Only some cars have rotors mounted as you describe. Some older models have the studs mounted to the rotors by a process known as "Squedging", where the lugs are positioned into the rotor and then a special tool is used to crush the bottom inner shoulder of the lug to lock it into the rotor. The lug is also splined into the rotor to prevent it turning. These rotors can definitely be warped or even stress cracked by overtorque.

TriX Loc: Raleigh, NC

True enough, but that is a MUCH older design. Most modern vehicles, including Toyotas, which are the subject of this thread, have the studs pressed into the hubs. In any event, think about the mechanics involved. You have two cast pieces of metal being pulled togather by bolts/studs. If both pieces are flat and touching, how can you distort the flat surfaces by pulling them together harder? It doesn’t matter whether bolts pass through two holes or are mounted to one casting, because the cast surfaces are touching - you can’t distort the rotor without distorting the wheel, and you can’t do that because there’s no immovable third surface separated from the other two to pull against. If the wheel only touched the disk in the center, and the rotor was unsupported where the studs are mounted, then I can see it, but that’s not the case.

I know this is old conventional car wisdom and originated after a disc warped after a wheel change, but it’s likely the disc was warped from excessive heat, sloppy machining when turning rotors, excessive rotor wear below minimum specs, driving through water with a hot disc, etc. and just coincidence. BUT if my thinking is incorrect, point out the flaw in my logic and I’ll reconsider.

Manglesphoto Loc: 70 miles south of St.Louis

Bingo!!!!

Kraken Loc: Barry's Bay

Lefty loosie righty tightie.

rustfarmer

I guess my love for cars is for the older ones. Most of these have wheels that are not flat on their backsides. Even a small warp to the rotors can make them rub the pads and cause them to crystalize, ruining the pads and reducing brake effectiveness. Guess for me it's moot, as I hate disc brakes anyway.

TriX Loc: Raleigh, NC

Understood, but not sure why you would hate discs. Regarding warped rotors crystallizing pads, not sure I understand. If a rotor is warped it just “knocks” the pad away from the disc when the high spot goes by, and since there is no return spring, there’s nothing to push the bad back against the disc. What you do get, is slightly longer brake travel (as you have to push the pad back to the disc to close the gap that was created) and of course, a pulsing pedal. Sounds like as you said, you’re working on older cars, most of which had solid discs which were more likely to warp than modern vented discs which are more efficient at dissipating heat. Also, with modern ceramic pads (which also don’t produce black dust), crystallizing at high heat doesn’t seem to be much of an issue.

Cheers

rustfarmer

I can make a list of my reasons to dislike (hate is too harsh I guess) discs. Calipers get hot to easily and boil fluid. Rotors are heavier than drums. Any wheel bearing looseness makes rotors wobble and crystallize pads (no, they do not just get pushed back--the seals make them return). Drums dissipate heat better and wheel cylinders are not as likely to boil fluid. Drums can be turned as needed several times while most shops today replace rotors at every pad change. Drums stop just as well as discs, contrary to the hype. (If you can lock the wheel, and control how much this happens how can discs be any better? Drums keep water away from inner parts. Probably twenty more reasons, but time for breakfast.

TriX Loc: Raleigh, NC

Well... it’s no accident that all modern cars and race cars where performance is ultra important have discs. You’re conveniently forgetting brake fade, which has gotten to be more of an issue as cars have gotten heavier. Remember that as discs get hot, they expand toward the pads, while drums expand away. I take some of your points (I’m not sure about weight, but I suspect you’re correct), but have to disagree with others.

First, I don’t know anyone who believes that drums disappate heat better than vented disks - there’s more surface area exposed to the air (the back side of drums are enclosed with zero air flow, and there is no cross drilling or vents possible).
Second, while brake fluid boiling can be an issue with discs, that has been pretty much eliminated with modern silicon fluid. If you watch race cars with their discs glowing cherry red or orange, they are not losing braking by boiling fluid.
Third, I disagree that the seals push the pads back to any degree. When I change pads, I depress the pistons and they stay put - the seal bends slightly backwards, but it is not enough pressure to overcome the friction of the pistons in their bores.
Fourth, pads crystallizing is old news - I never see it with modern pads
Fifth, discs do not need to be changed with every set of pads UNLESS you let the pads wear out and score the discs. I am on my third set of front pads after 125K miles, and using the original rotors, which are fine. You can also turn disks, just like drums, but it is often unsatisfactory (probably due to the non-precision nature of the turning machine). Shops change them to make more $ the majority of the time - depends on the hardness of the rotors and the pads, the thickness of the outer ridge and the wear limit that the manufacturer specs on the rotors.
Sixth, there shouldn’t be any bearing wobble or run out if the wheel bearing are in good shape, and if they’re not, you have way bigger potential problems than your brakes.

Anyone that thinks drums stop as well as discs has not done much racing. It may be true the first couple of hard stops where either can lock the wheels, but head down a long mountain or make repeated high speed braking on a track, and you’ll quickly find out what brake fade is all about. I used to enjoy the SCCA sedan class racing at VIR and road Atlanta between the 289 Mustangs, Yenko stingers and Sunbeam Tigers vs BMWs and Minis. At the beginning of the race, it was all about power, and the big engined rear drum brake cars led the field, but after a few laps when brake fade caught up with them, the Minis and BMWs walked away. As every racer knows, you can only go as fast as you can stop. And did I mention that discs are much more linear in turns of pedal pressure vs braking and much easier to modulate? We were campaigning a Datsun 280Z with solid rotor discs on the front and rear drums. We tried everything including velvatouch metallic linings on the back, but rear brake fade killed us some number of laps in. Not only could we not lock the rears, even if we had wanted to (we didn’t), but it screwed up the front/rear brake balance. We finally spent the $ for the 4 vented disc conversion package from Datsun competition parts, which made an amazing difference.

I grew up with drum brakes, including a Sprite that we had to swap sides and change the trailing shoe design to leading shoe to get it to stop, and I am not sorry to see drums go.