Total noob tire-change question

[Want.FR-S]

Originally Posted by Scion FR-S

Thanks.

Anyone know if CT will torque the nuts to spec? From what I've read a lot of garages just use an air impact wrench and do no manual adjustment. These things seriously overtorque and can result in warped rotors giving you a pulsing feel when braking hard.

It depends. I think I saw once the tech actually use torque wrench to tighten the nut. Most of the time the tech just use air impact wrench to tight it with no adjustment.

I am not sure if overtorque the nut could result warped rotors. I have the warped rotors twice on an automatic car. I thought that was because with auto you always need to press brake during stopping so the rotor warp easily. On my manual daily now I do not get that problem.

[OrbitalEllipses]

"Warped" rotors are just pad deposits left on the rotor. It has more to do with proper bed in of pads than anything else.

[Sport-Tech]

Originally Posted by Want.FR-S

I am not sure if overtorque the nut could result warped rotors. I have the warped rotors twice on an automatic car. I thought that was because with auto you always need to press brake during stopping so the rotor warp easily. On my manual daily now I do not get that problem.

There was an article in the Toronto Star about that by an experienced mechanic, talking about disc warping from over-torquing. Impact wrenches have up to 350 lb/ft of torque, way too much. It causes a very rapid shimmying or stuttering feel as you brake hard.

[Brett]

Originally Posted by neutron256

Why would you need jack stands just to change wheels?

Always use jack stands. They take seconds to put in place. If jack fails, there is great potential to damage the car and yourself. Every time I think about not using them I think, "I'd miss my foot if it were gone." Then I take the 30 second to grab the stands and put them in.

Re Harbor Freight: my approach with them is to never use anything from them that my safety depends on. No safety glasses, no harnesses, and no jack stands.

Brett

[Brett]

Originally Posted by Want.FR-S

I am not sure if overtorque the nut could result warped rotors. I have the warped rotors twice on an automatic car. I thought that was because with auto you always need to press brake during stopping so the rotor warp easily. On my manual daily now I do not get that problem.

It will certainly result in lug nuts that are hard to remove by hand. Especially at night in the cold when it's raining on the side of the road on your way back from a date to your place. If someone else puts my tires on, I lift the car when get home, loosen with a huge breaker bar, and torque back to 80 lb-ft (spec for my car).

Brett

[Sport-Tech]

Originally Posted by Brett

It will certainly result in lug nuts that are hard to remove by hand. Especially at night in the cold when it's raining on the side of the road on your way back from a date to your place. If someone else puts my tires on, I lift the car when get home, loosen with a huge breaker bar, and torque back to 80 lb-ft (spec for my car).

I had to literally jump on the wrench to get the nuts to loosen the one time I had to change a blown tire (it was a cold night).

FYI: from the BRZ manual:

Tightening torque:
89 ft•lb

Looking at the manual, it appears there are special notches built into the side rails that are specifically fitted to the provided jack. Good news, it should make the provided jack adequately safe for using for winter tire changes. They do recommend use of blocks, but only call for jack stands if you are getting underneath the car.

[Want.FR-S]

Originally Posted by Scion FR-S

There was an article in the Toronto Star about that by an experienced mechanic, talking about disc warping from over-torquing. Impact wrenches have up to 350 lb/ft of torque, way too much. It causes a very rapid shimmying or stuttering feel as you brake hard.

I thought the rotor warping is on the disk ring side where the pad touch the disk, while the wheel is in contact of the *center* piece of the rotor. As I said before, I had to replace front brake disk due to warping twice. For the second time I specifically asked to see the warped rotor, and it happened on the ring side so you get this pulsation when braking. The center piece was intact.

In short, I am questioning whether that mechanic said is correct. Even though the impact torque wrench can have up to 350 lb-ft torque, that does not mean the lug can take it up to that level. If you over-torque, the lug would break into pieces first before your wheel or rotor is damaged.

[Khyron686]

Wheel shop should never use impact wrench to put the lugs on, ever. But they do.

I change both my cars at least 2 sometimes 4 times a year. It's a 15 min job - should be no problem doing that in a parking lot. They just don't want long repairs/oil and crap.

I also label the wheels with duct tape so I can rotate the front/back each time. Check air as well (have a compressor). Sometimes do oil if it's the right time. Save the dealer for the nasty stuff.

[Brett]

Originally Posted by Scion FR-S

I had to literally jump on the wrench to get the nuts to loosen the one time I had to change a blown tire (it was a cold night).

I usually have to jump on my breaker bar or use a cheater pipe the first time I take new tires off a car.

Brett

[Droopy]

What we do here for our regular cars and race car is:
1 we loosen them slighty (release the pressure, the pop at first, use the breaker bar)
2 jack the car up (one corner at a time, and on the reinforced point for jacking, and we have a 4 ton floor jack)
3 finish loosening the lugs and take them off
4 remove the wheel(sometimes if they havent been changed in a long time the rim will stick to the rotor, not safe but we knock on the tire to break it loose)
5 place the other wheel on
6 put the lugs on, hand tighten first then tighten in a star pattern (tip: you can actually spin the tire with the wrench on to speed up the process, but not very fast and only after you have put all the lugs on and hand tightend)
7 lower slowly to the ground and remove jack
8 torque then repeat for next wheel

the spinning the wheel only for about 3 of the lugs if you use this to take the lugs off

[Sport-Tech]

^ Thanks Droopy - copied for reference.

From Tire Rack on over-torquing:

Be careful because if you over-torque a wheel, you can strip a lug nut or hub, stretch or break a stud or bolt, and cause the wheel, brake rotor and/or brake drum to distort.