Changing the Rear Brake Pads on a 1994 Q45 - Can I do it?

[AlabamaDan]

Hello everyone,

I could use some advice. When I purchased my Q45 six months ago, the previous owner stated that the brake pads had recently been replaced at Just for Brakes or someplace like that.

So, now out of the blue I heard the sound of brake pads going out, then the next day the msg comes up on the dash that my pads are worn. I guess it could be the guy lied, only changed front pads, or that the aftermarket pads wore out quickly. Either way, I guess I've gotta change 'em.

I've changed disc brakes on muscle cars and found a 1994 Sentra to be no more difficult. Just take your time and remember how it came apart. Oh! and only do one side at a time!

Is it any different on the Q45? I understand that I need factory pads in order to have the sensor for replacement. I haven't looked, so I don't even know if the rear brakes are drum or not. Are they drum brakes with all those springs? Do I need any special tools?

I'm hoping this is something I can order parts for and fix in my garage at home. Can y'all give me some advice?

Thanks,Danny

[maxnix]

Do you have a dial indicator that reads 1/10,000ths of an inch accurately? How about a lathe?

Always a good idea to check and usually turn the rotors to return to OEM specifications.

[DAEDALUS]

Disk brakes front and rear. Probably tighter tolerances that what you've worked on before, but the principles are the same. You can short the sensor wire to clear the message. Nothing like new factory pads though, on top of new factory shims and hardware.

[qship96]

agree!replace the shims and all hardware,learned the hard,noisey way! and order the hardware kit in advance,as my 2 local dealers no longer even STOCK them,and they were not even in stock from joe,for the fronts!

[AlabamaDan]

Always a good idea to check and usually turn the rotors to return to OEM specifications.

I usually just check over the rotors to insure that they are still smooth. If they need turning I thought I could carry them somewhere. Hopefully, they won't need turning.

...the principles are the same. You can short the sensor wire to clear the message...

Won't the message clear itself once I change the pads, and now the shims? I was in hopes the principles were the same. I can still use wood blocks and a c-clamp to push the piston back right?

[AlabamaDan]

How long do you have once the pads are down so far that the sensor msg comes on?

[Q45tech]

Maybe a 500 miles from the first moment the message comes on.The rotors warp fairly easily and need retrueing at least once between pad replacements say a 12,000 miles on rear as the average pad life on rears is 25k. [but that depends on driver and local applications per mile].

[AlabamaDan]

Q45tech! Glad you chimed in. This is fairly simple right? Anything I should watch out for?

[AlabamaDan]

I found a very extensive write up on brakes in a previous thread, which by the way I found from Q45.org.

http://nicoclub.com/zerothread...+pump

Many thanks to tangalora for taking time to start this. (I wonder what ever happen to the pics to go along with all the steps.) Between Tangalora, Q45tech, Q451990, and everyone else who contributed.

Many posts discussed using the caliper to measure "run-out." Now I've never done this before. Can someone explain what we're doing, why we do it, and how to measure it? After we measure it and find it outside 0.0028 how do we correct it? All this has me confused and losing self confidence.

[911/Q45]

The pad swap itself is easy, don't be discouraged. For the perfect job, you check the runout with a dial indicator and resurface or replace the rotor if it's out of spec. Runout is the "wobble" you get from a warped rotor.

[elwesso]

Probably the best thing to do is to go ahead and replace the pads, and then take it to a shop to turn the rotors..

Always best to minimize the time that the car is in the shop, so they have less things to screw up on, as well as the amount of reduction in your back pocket.....

[Chally]

If you have NO brake pulsations, you can get away with just a pad change. It is fairly easy & when you see it, it's fairly self explanitary.I've found that my front discs are the ones that warp the easiest as they take a lot more of the effort. If you machine the rears, make sure they don't machine them any thinner than 8mm. Here, down under, the discs aren't allowed to get below the 8mm minimum during the pad life.Go do it.

[Q45tech]

Unfortunately the rotors share the load based on rotor mass [weight] and warp at equal times.

The Q uses a little more [5%-10%] rear brake than most RWD due to less [%] weight transfer due to long wheel base and relatively low center of gravity and agressive ABS software coupled with viscous LSD........because they can ----- to achieve great for then stopping distances.

Careful about using different front pads.........as the rears are the same but there are various oem front pads that have different friction curves.

A less agressive [less dusty longer wearing] front pad will throw more stress on the rear so the rears wear out faster than the front..........the ABS covers up any changes and makes things seem ok when they are not.

Unfortunately the orginal U90 brake pad has be superceeded with the U91/U93.

[Q45tech]

Brake pedal pulsations are damped by the ABS system so they are not the first indicator...........a slight quiver in the streering wheel at 60-70 mph shows up first [often confused with or in combination with tire wheel imbalances] that increases as brakes are applied lightly is the first sign of out of spec rotors.

Rear rotors are felt in the seat as a tiny fore aft movement during light braking that just gets worse. Again in combination with tire wheel problems a seat vibration can occur at 60-70 mph.

Most drivers are not very sensitive to the nuiances of braking.

[qship96]

qtech,you often mention front pad options as u90,u91,u93-the last 2 sets of pads i have installed were u92-never hear you mention the u92-whats the deal with these? friction stamped FF

[AlabamaDan]

I just ordered the parts from Joe! I'll clean up the garage this weekend and hopefully get the pads changed next weekend. Wish me luck!

[maxnix]

Unfortunately the rotors share the load based on rotor mass [weight] and warp at equal times.

This is my experience also. It is whether you want the job done easy, or the job done correctly.

Pull the rotors while you have it apart and get them turned. Don't forget the high temperature lubrication on the pins and adjust your parking drums while you have it apart.

[aaronl]

For the least runout shouldn't the rotors be turned on the car?aaron

[maxnix]

Not if the hubs are true (measure them) and uncorroded.

It's usually done on car so a cheap customer who doesn't want to pay the necessary labor costs will be satisfied for a few thousand miles. Turning on car will disguise worn or misaligned hub carrier, bearings, etc.

[Q451990]

Gotta tell you... I spent hours with a dial gauge, new Stillen (Bradi/brembo) drilled rotors, getting the runout perfect. Just like every other time, they felt great at first and then eventually warped in 3-5K miles. In my experience the second time after having the rotors turned seems to hold longer before notable warping. It's a constant battle.

I don't even know if I could find a shop to minimize runout here in Columbia if I wanted to pay someone to do it - so I wouln't rule out replacing my own brakes just because of not being able to measure runout. You'll get a job that's at least as good as your average dealership tech. if you use OEM parts and lubricate everything properly per the FSM.

Heath

[AlabamaDan]

Thinking more about beauty while I'm doing this, I thought I'd paint some of the components down there. I don't think they'll show through the BBS wheels too much - unless you're a car freak like us - but I thought I'd do it anyway. Anyone else tried to dress up things down there?

[Q45tech]

Q451990 is correct a sensitive driver with note that even perfection [minimal runout in spec or better] rarely lasts beyond 5,000-6,000 miles.

The cars weight and the rotors light weight just don't compute.

Every Q I've tested had excessive hub runout after 100k, the hub runout gets multiplied by the ratio of hub to rotor diameter, so if oem rotor spec is 0.0028 the hub must be < 0.0013".

The usual problem is installing a decent trued rotor on a warped hub making the just trued rotor wrong when installed.

[squeefoo]

Gotta tell you... I spent hours with a dial gauge, new Stillen (Bradi/brembo) drilled rotors, getting the runout perfect. Just like every other time, they felt great at first and then eventually warped in 3-5K miles. In my experience the second time after having the rotors turned seems to hold longer before notable warping. It's a constant battle.

Heath

Agreed. Thought I could cheat a little W/300zx brakes (28mm vs 32mm?) since they were a little thicker. I haven't taken anything apart yet since the first turning (he took off.030), it's got a little wiggle now after about 3k; but it will be parked again for the winter so I can weigh the rotors and see if that was a mistake. My Dad has bone stock brakes all around, and they haven't warped in 110k just pads and fluid changes. I have't bothered to paint anything w/ piepans, but I've seen alot of specialty paints just for brakes. Just wire brush, degrease, wipe off and blast away.2 .

[Jesda]

After dumping OEM pads and switching to cheap pads, rotor warping was no longer a problem. Brake dust became an issue however, and I'm sure stopping distances were slightly longer. In day to day driving, there's no noticeable difference. The cheap pads even feel "grippier"

-Jesda

[halfoffautoparts]

How do I adjust the parking drum brakes while I have the brakes apart? Also, if I don't get the OEM pads, is the pad wear sensor just unplugged and forgotten about ?

[tangalora]

I found a write up on brakes in a previous thread ...http://nicoclub.com/zerothread...+pumpn ... uel+pump(I wonder what happened to the pics to go along with all the steps.)Can someone explain what we're doing, why we do it, and how to measure it?

I just checked; the pictures are there.Try resetting your forum cookies to see the photos.That comprehensive brake howto was a NICO team effort, each person pitching in. It would be a shame to waste all that effort.

If it helps, normally, I don't see the pictures either until I go to the "user cp" at the top of the NICO web page and reset my cookies (for whatever reason). Most times the first reset doesn't take and I have to do it twice. Sometimes I have to login in again when I try to re-view the thread (dunno why). Eventually, sometimes after a few passes at those two steps, the photos come back (at least they do for me).

In those photos, they show what dial gauge to purchase and how to use it (courtesy of the NICO team).

If you still can't see the photos, I can email you the 12-page PDF I just made of that brake job thread. Since I'm probably the lowest common denominator, whatever I can do, you can do better & faster (armed with this information).

[Jesda]

Thats my new wallpaper!!!!!

[elwesso]

That could be one of the coolest pictures ive seen......!!

I think it may take a place over the law and order "Fred" picture...

Tangalora, you are GOLDEN!!!!! :

[tangalora]

Thanks guys ... The photo is way off topic so I'll be brief on that.

I wanted to convey the Nico team spirit to the original poster so I annotated a stock Infiniti racing photo with the avatars of those who've helped me. If we really wanna do it professionally, we could gather all the avatars (hundreds?), convert them to GIF89, transparize the backgrounds, and then they'd be much prettier superimposed on almost any team-spirit photo.

The Nico team does make any collage more interesting.

Back on topic for the original poster: -If you can see the photo above, then you should see the brake-pad pics.-If not, try that control-panel reset-cookies suggestion (it works for me).

Q: If the previous owner replaced the brakes, why is "brakes worn" lit?A: Brakes wear differentially; maybe only one axle set was replaced.

Q: Day 1 I hear sound of brakes wearing out; day 2 "brakes worn" lights?A: These two events may not likely be related (except coincidentally).

The warning light remains for hundreds of miles before the friction material is actually worn off sufficient for metal-on-metal contact.

I've personally driven hundreds (I forget how many, maybe 500 as Dennis said) after the warning light lit and I still had plenty (relatively speaking) of friction material left. The pads do wear unevenly though, so, it's possible one side is touching the disk while the other side holds the sensor. Also, the sensors are only on one pad out of four for each axle, so, you could hear one side hit on day 1 and then wear out the other side (with the sensor) on day 2. Since my sensor was plastic about 10mm in diameter, I doubt you'd hear it contacting the disk.

Q: Is this something I can order parts for and fix in my garage?A: Absolutely. The brake thread shows all soft & hard tools needed.

Q: I need factory pads in order to have the sensor for replacement?A: Nope. Aftermarket pads come with splice'able sensors.

Use factory pads & parts (from Joe) for different reasons (please see thread). http://www.everythingnissan.com (www.everythingnissan.com).

Q: Are Q45 brakes any more difficult than a muscle car or Sentra?A: Yup. Easy. Proof you can do it is that even I can do it.

While a Q45 brake job is relatively easy, there are a few tricks (such as imobilizing the front rotors and spnning the rear rotors to check runout) and FSM diagram booboos (like mis-splaced rear shims); so again, see the brake thread for the complete detail. That's why we wrote it.

Q: Should I replace the hardware?A: Do as qship96 says; get the hardware/grease kit from Joe.

In my situation, as the brake-thread photos show, my hardware kit was mangled beyond use. Using new hardware makes the job actually easier as the metal springs won't be warped hindering the new-pad insertion & motion.

Q: I usually just check over the rotors to insure that they are still smooth?A:Me too. I use my long fingernails and a dime as "precision" sensors.

In my humble opinion, far too many rotors are turned (see automobile articles in the thread backing up that supposition). Nothing wrong with turning rotors, mind you, except that most that are turned don't need to be turned. I think a groove can be 60 thousands before it needs to be put on a lathe (according to the referenced articles). That's thicker than a dime (if I remember correctly). Runout is a different story and should be checked with a dial gauge as shown in the articles.

Q: Won't the message clear itself once I change the pads?A: Yes. It will clear itself when you replace the sensor.The OEM sensor is much nicer than the Raybestos aftermarket sensor in that it's a complete wire that just plugs properly into the harness connector. The Raybestos aftermarket sensor splices into the wires and therefore may be error prone over time. Either way (I've done both), the message instantly clears itself up (unless you did the wrong axle, which happened to me as described in the brake thread).

Q: I can still use wood blocks and a c-clamp to push the piston back right?A: Why bother? Use a caliper spreader.When you remove the worn pads, the pistons will be all the way out. Push them back with a caliper spreader (I got mine at a local auto store for a few bucks). The caliper spreader (which remains in place while you do the brake job) keeps everything clean while you disturb all that brake dust & also prevents the kids from accidentally popping the pistons out by pumping the brakes when you go inside to bake some cookies or something.

Q: After we measure runout outside 0.0028 how do we correct it? A: Dennis explained it. We'd use thin shims behind the rotor.

However, I do understand your runout testing concerns. Here's my advice (for what it's worth). As Dennis mentioned (if I remember correctly), he checks runout and that takes him a long time. It took the longest time for me too. Here's a little secret. Most people, I think, do NOT check runout. So, you can do a pretty good job w/o that one test. Up to you, of course. It is better to check runout. But, I wonder if the local guys at Brakes-R-Us actually check runout? Does anyone have experience with this? Do the local brake shops take the time to check runout? Or do they just turn or replace rotors and consider the runout fine by default?

Q: Should I match the front/rear pads as Dennis suggests?A: Absolutely!

Notice Dennis' post above which says to match the pads. According to tests quoted in the brake thread, differences between stopping power were huge when there was a mismatch. Given that Joe sells pads at about the same price as aftermarket (in my case, anyway); and given Joe sells them cheaper that you can get the same pads for at the local dealership; and given Joe's OEM pads come with the correct sensor harness connector so there's no splicing needed; and given that you need Joe's hardware kit (if you can get it) anyway; and given that Joe's pads are to OEM specs (albeit perhaps not the original Q45 OEM specs), and given you still have hundreds of miles before a sensor trip turns into scraping metal (at least in my experience) ... blah, blah, bloah, I don't see any good rationale for NOT using Joe's OEM pads & hardware.

Q: How do I adjust the rear parking drum brakes?A: I never got that far so others will have to pitch in here.

The procedure for checking & adjusting the parking brake is on page BR-27 of the 1990 Q45 Factory Shop Manual (FSM), diagram SBR003B. A quick scan of that chapter reveals a shoe spreader (like all drum brakes) adjuster at the base of the drum and a front & rear parking-brake cable. There appear to be two length adjusters on each end of the rear cable (I didn't see any adjuster on the front cable, but, I may have missed it as the diagram is puny).

"]Q: If I don't get the OEM pads, is the pad wear sensor just unplugged?A: Dunno. Someone mentioned you might need to short the wires first.

DISCLAIMER: My only claim to any of the answers above is that I've read the FSM & done a brake job following NICO help every step of the way. I am NOT trained or qualified otherwise to answer any question above so take everything I suggest with a grain of salt.

[AlabamaDan]

Ok everyone, I'm going to do it Sunday. I've got my garage cleaned out and all my tools loaded into my new toolbox . I received the pads and hardware kits from Joe, I bought a caliper spreader.

Armed with my FSM and NICO printouts, I'm going in. It's been years since I've worked on cars. Used t do it all the time in high school, but that was so long ago. This will be the first thing I've ever done to my Q.

Sure hope I don't screw the pooch.

Thanks for all your help.