New rotors installation
New rotors installation
It's time. There's slight vibration on the steering wheel during braking from >50mph. 98K on my 97q45. Rotors were turned at 72K. Front pads have 6mm left, rears 7mm. I'm leaning to get a new rotors and pads instead or trueing again. The question: is it DYI job or I still need to turn new rotors to make it into specs even if stick with OEM parts?
You won't know if the rotors are OK as mounted unless you index them. After suffering with frequent resurfacing I broke down and bought a gauge. After fooling around for about an hour per side (first time, etc.) I got runout to within spec on a pair of Powerstops that had just been done after developing vibration at about 7,000 miles.
Great results. Smooth braking from 80 . Now at 6,000 miles, and still as smooth as the day I finished.
Great results. Smooth braking from 80 . Now at 6,000 miles, and still as smooth as the day I finished.
Measure the runout at each of the five possible positions, and install at the one with the least runout. It makes a big difference. I only did the fronts, because the back is a lot more trouble, as it requires a helper to move the opposite wheel. If I can rope someone into this bit of lunacy I will do the backs.
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Q45tech
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- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Just measure the max runout postion and select the correct Brake Align shim [0.003" or 0.006" correction] then if need be you can spend the hour selecting which position is better.
I can usually get 0.001" on 2 tries with the shims.
Many times you really need to change bearings and hubs to get oem spec after 100,000 miles of use or so.Setting perfectly can double the time between warps or when you have to do it again!
I can usually get 0.001" on 2 tries with the shims.
Many times you really need to change bearings and hubs to get oem spec after 100,000 miles of use or so.Setting perfectly can double the time between warps or when you have to do it again!
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szh
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Unfortunately, no longer a Nissan or Infiniti, but continuing here at NICO! - Location: San Jose, CA
My usual dumb questions of the day (so what else is new from me! 
):
How and where is the runout measured? Along the edge of the rotor or perpendicular to the rotor face somewhere? In other words,is it a thickness variation issue or a diameter variation issue when the wheel is turning?
If a diameter variation, how does this minute amount of offset mass affect the cars braking? Heck, out of balance tires would be a bigger deal!
So, how exactly does the shim work in the correct scenario above - does it sit around the hub (braced by the lugs, I suppose) and move the rotor a tiny bit in the plane of the rotor? Or does the shim actually tilt the plane of the rotor a tiny amount?
Thanks for any education you can give me!
Z
):How and where is the runout measured? Along the edge of the rotor or perpendicular to the rotor face somewhere? In other words,is it a thickness variation issue or a diameter variation issue when the wheel is turning?
If a diameter variation, how does this minute amount of offset mass affect the cars braking? Heck, out of balance tires would be a bigger deal!
So, how exactly does the shim work in the correct scenario above - does it sit around the hub (braced by the lugs, I suppose) and move the rotor a tiny bit in the plane of the rotor? Or does the shim actually tilt the plane of the rotor a tiny amount?
Thanks for any education you can give me!
Z
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Q451990
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Good question... I've been playing with my new dial indicator and thinking about the best way to pull this off. Those shims would be nice!
My other concern is trying to figure out the best way to index the cross drilled rotors - hopefully there's a good spot it can track all the way around (so the pin doesn't drop into a hole!). Obviously it can be done since I think Dennis is still using PowerStop, at least on one axle.
Heath
My other concern is trying to figure out the best way to index the cross drilled rotors - hopefully there's a good spot it can track all the way around (so the pin doesn't drop into a hole!). Obviously it can be done since I think Dennis is still using PowerStop, at least on one axle.
Heath
You guys might want to look into "laminated shims". They're somewhat off-the-shelf, as there are government and mil-specs that control them and to which they can be purchased from machine shops and aerospace suppliers. They can be machined like regular aluminum sheets, and are made up of .002" thick aluminum plies that are stuck together. You could get a .1" thick piece, machine a lug stud-sized hole in it, and then peel it into several pieces, down to the thickness you need.
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Q45tech
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- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
T3 doesn't use the Brake Align Shims because customers won't pay for the process. It is rarer and rarer to see someone who wants the best and can afford to pay the cost.Adding 2 hours at $70 hour is $140 plus $80 or $220 more for a perfection brake job. Actually pays for itself since you double the time between rotor warps..........not to mention the more pleasurable miles.
The BA shims are tapered.........very hard to duplicate for $20
I have 4 that I got as a sample. Against their advice I have reused them twice. Slowly I am in the process of replacing my wheel bearings and hubs.......half way there. [RF and LR done].
The BA shims are tapered.........very hard to duplicate for $20
I have 4 that I got as a sample. Against their advice I have reused them twice. Slowly I am in the process of replacing my wheel bearings and hubs.......half way there. [RF and LR done].
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
They come in 0.003", 0.006", and 0.009" but using anything over 0.006" means you really need to do some hard part replacements...........4 of each of the smaller thicknesses.....about a $100 worth.
Since te shim is making up for the hub error you can leave the shim on the hub retrue the rotor and replace it back exactly in the same position [same lug to same hole] and get nearly the same result......once or twice without going thru all the measuring and selection...........the hubs deform and bend slowly over 50-100k.
Rust corrosion on inside of rotor cap and on hub gets amplified.....6" hub vs 11" rotor to edge...........thinking of it the taper on a 0.003" correction shim is a little more than half what it's trying to correct............trig!
Since te shim is making up for the hub error you can leave the shim on the hub retrue the rotor and replace it back exactly in the same position [same lug to same hole] and get nearly the same result......once or twice without going thru all the measuring and selection...........the hubs deform and bend slowly over 50-100k.
Rust corrosion on inside of rotor cap and on hub gets amplified.....6" hub vs 11" rotor to edge...........thinking of it the taper on a 0.003" correction shim is a little more than half what it's trying to correct............trig!