Issue with rotor warpage on a 90 Q45.

[mattd1979]

I'm on my 3rd set of front rotors. The first set I replaced is what came on the car when I got it. I don't remember if the previous owners had them replaced or if they were the originals. I was told at the Nissan dealer where I worked at the time that they couldn't be turned any more because they were already at the minimum thickness and so I had driven it for another 30k like that until I replaced them with a set of premium rotors from NAPA. I proceeded to do the break in of the rotor and seating of the pads as per the service manual and the rotors were good for about a week. It hadn't rained any that week and I hadn't driven through any water. I started noticing the pulsating sensation as I applied the brakes when coming to a stop. I know that the ABS isn't where the pulsing is coming from because that is more like a vibration feel and the pulsing from ABS wouldn't gradually slow down with the speed of the car like that caused by warped rotors. I figured it was the fact that they were made in China and the steel wasn't very good. I ended up purchasing an OEM set from OrderInfinitiParts.com. This time the rotors lasted about 3 weeks before they were warped. I can't seem to figure out what the deal is with this. The brakes aren't dragging as if I'm riding the brakes causing the rotors to over heat and the car doesn't pull one way or another like you would feel when the brake calipers aren't fully releasing. Any ideas?

Thanks,
Matt

[OwnerCS]

Matt -

Check out the article and read about warping at the following link.

http://en.wikipedia.org/wiki/Disc_brake

Here's the article to read below..

http://www.stoptech.com/technical-suppo ... ther-myths

[Q451990]

Warped rotors are pretty common on the early Q, but not quite as quickly as you describe. Setting the rotors in a way that minimizes the runout with a dial gauge is a tedious process, but seems to work. I've yet to figure out a good way to hold the hubs in place while tightening the bolts.

Another option is to have the rotors turned on the car, so that you basically turn them in a way that matches the warped hubs better. There is also a shim system that can be used - but the name escapes me at the moment. It's somewhere in Q45Tech's old posts.

Heath

[paranoidjack]

Great article OwnerCS, it was a good read.

[maxnix]

Be sure to check hub run out before mounting new rotors. If not within specification, the rotor will not run true and it will suffer from uneven wear often interpreted as warpage.

I have only had good luck with the Brembo rotors, and prefer the drilled and plated Stillen Brembos.

[Lokim]

One thing many people don't do is clean off the hubs real good before installing the rotors. Get a nice, stiff wire brush, or better yet a wire wheel on a die grinder or high-speed drill and clean all the scale off the hub before installing the rotor. That stuff makes the rotor's mounting surface uneven, so even if you get the wheel torque right (also critical, as incorrect or uneven torque will warp rotors, too) the rotors will warp because the base they bolt to is all wavy with rust. The spec is 85 ft-lbs, BTW.

[maxnix]

This is true, and they can be painted also to retard the rust formation if you have the time.

[mattd1979]

I know it has been a while since I posted to this thread but I just wanted to update. I have since gone through two sets of slotted and drilled rotors that I got from PowerStop thinking that maybe the rotors were getting to hot and so I upgraded. That obviously didn't do any good. I narrowed the problem down to the left front wheel. I replaced the left front spindle/hub assembly thinking that the hub was warped. That didn't help. I then replaced the caliper with a rebuilt unit because I noticed that the caliper didn't seem to release as much as the passenger side did when I released the brakes and spun both wheels with the front on stands. Since the rotor had already been warped by the time I replaced the caliper I decided to get a rotor from a previous pair that I kept that was originally mounted on the right front and I mounted it on the left side. I wanted to see if replacing the caliper took care of the problem. There was a difference of night and day. That lasted about 4 days. Now it is doing it again. In the end I have replaced the entire left front wheel assembly and still have the problem with the rotor warping on that side. I haven't jacked the car back up to see if the left still is not releasing as far but if it isn't then maybe the braking equalizer valve which I think is in the ABS manifold is sticking slightly. Anybody else here ever run into this situation before?