How to DIY Some Basic Car Maintenece

[Accumulator]

Swanicyouth (and anybody else...)- You use anti-sieze on the wheel lug nuts/bolts? If so, how do you adjust the torque specs for "wet vs. dry"?

[Swanicyouth]

Swanicyouth (and anybody else...)- You use anti-sieze on the wheel lug nuts/bolts? If so, how do you adjust the torque specs for "wet vs. dry"?

I use it - or I use caliper grease. BMWs use lugs that have the studs built into them. But it`s very necessary to lube up the rotor hub to wheel area - as the wheels themselves commonly seize to the hub on the spindle. The wheels can be next to impossible to get off the hubs after a while. Probably my frequent wheel cleaning doesn`t help.

But, I just use the regular torque spec. I never had a wheel fall off - so it seems OK.


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[Accumulator]

Swanicyouth- Yeah, I too use a thin coating between the hub and wheel, having had to get serious with some new-to-me vehicles that hadn`t been treated that way.

The issue with wet/dry torque values is that when you use anti-seize/etc. you need to *lower* the torque lest you overtighten things. It`s one of theose topics where, uhm.....opinions vary and guys on both sides of the argument think they know it all. I generally lower the setting on the torque wrencha bit, and like you I figure I`m OK as I`ve never had any problems even though some of those "internet experts" think I`m still going too tight.

[Woob]

Nice, BMW`s are fun to work on.

[Swanicyouth]

My Findings Regarding Pedal Pulsation and Brake "Judder"

So, I`ve owned multiple BMWs, and after a while - all of them have suffered from some degree of pedal pulsation, braking harshness, and brake judder. Nothing bad - and probably nothing a "normal" car driver would notice. In the past, I haven`t worried too much about it I`d just hang new rotors when I replaced the pads and the problem would go away for quite a while. However, the BMW in question has M drilled rotors that cost $500+ a set... It`s time for a permanent diagnosis and solution.

Interestingly enough, I`ve been using non-metallic (first organic / later ceramic) brake pads on all these cars. First thing I always did when purchasing a BMW was remove the dusty stock pads and replace them with low dust pads. Years ago, this mean using "organic" or asbestos type pads - today it means using ceramic pads. These type of pads are noted for being more "rotor friendly" than semi-metallic pads. So, they shouldn`t be causing an issue - right?

These cars have always been driven with care. Since my experience tells me these cars are sensitive to pedal pulsation and braking roughness, I have always tried to using the brakes quite gently - "babied" the brakes. Conventional wisdom tells us pedal pulsation is caused by "warped" rotors that have excessive lateral runout. Shimmy of the steering wheel while braking also tends to point to the front rotors - assuming the suspension on the vehicle is tight and the wheels are fairly in balance.

It`s commonly believed that rotors become warped from being overheated. The problem is, I`ve never come close to overheating the rotors on any of my vehicles. There is also another school of thought that says most pedal pulsation is caused not by warped rotors, but by brake pad deposits that have become embedded in the rotors. Obviously - replacing the rotors is a fix (possibly temporary) for either situation.

It`s not uncommon for someone to experience this braking issue and take their car in for service. The most common fix is to replace the pads & rotors. Problem is fixed...Or is it? It`s also not uncommon for the problem to return. I`ve seen dealers put 5 and 6 sets of rotors and pads on cars under warranty to fix pedal pulsation. New cars have been bought back by manufacturers in the Lemon Law due to pedal pulsation issues. While pad/rotor replacement fixes the problem temporarily, it seems to return for some drivers in a matter of weeks or months. So, why do some people have an issue with this and some don`t on the same car? Why do some people go through multiple sets of new pads and rotors - only to have the problem fixed temporarily? What is the root cause of this?

Three well written articles on is subject are linked below:

http://www.centricparts.com/files/te...rakeJudder.pdf

What Causes Brake Pulsation? | Power Stop

Racing pad selection and brake pad deposit - RacingBrake.com

First thing one needs to do is check the front end and balance/trueness of wheels. But, assuming the issue is being caused by something in the front end - this would not explain why many have had temporary fixes by replacing pads and rotors. All things being the same, if the pulsation is caused by something amiss in the front end - replacing/machining rotors and hanging pads should not improve the problem. But, any damaged or worn parts in the front end will need to be replaced first.

After checking the front end, you need to pull the wheels and check the front rotors for excessive lateral runout. To do this, you will need a mounted dial indicator. The procedure is quite simple - you just mount the dial indicator, zero it, and spin the rotor with the needle tip contacting the rotor.





If your rotors are slotted/drilled - you will have to stick to the inner/outer perimeter of the rotor to get an accurate reading. The holes/slots will make the gauge jump excessively when the measuring pin hits them.

As I suspected, my rotors have virtually no lateral runout. The runout reading was < 0.001". I`m not sure if BMW has an official "runout spec"...But, my experience tell me that once rotors reach about 0.004" of lateral runout - pedal pulsation may become a problem (depending on vehicle).

So, what gives? No runout. Good front end. No diagnosable issue... Well, once everything else proved to be good, you have to look at pad deposits on the rotors. You likely won`t be able to visibly see them - but you sure can feel something amiss when you hit the brakes. The above articles tell use that pad deposits are responsible for most pedal pulsation - not rotor warpage.

Quite frankly - I`m not (wasn`t) a believer. I`m from the old school with semi-metallic pads and warped rotors. But, since the "fix" is free - I decided to give it a shot. What is the fix? The fix involves warming your brakes up to operating temperature and making several (~10) panic stops from 60mph to 5mph (right before ABS kicks in), while letting the brakes cool a little bit in between. After that, you drive normally around trying not to stop to let the brakes cool. So, this is what I set out to do.

Another fix is to sand the rotor surfaces rotor down with garnet paper the. Clean them well with Brake Kleen. Garnet paper is old school "sand paper" that is used for wood working that doesn`t have certain metals in it. Regular sand paper is not recommended to attempt to resurface rotors, as the metals in it can actually embed themselves in the rotors, possibly creating hot spots while braking - making braking roughness worse. I was skipping the garnet paper step - but will do it next time I have the calipers off.

After I buttoned it up - I realized it was going to be sort of hard to find an area to do these "panic stops" without getting killed or getting arrested. Basically, the highway is out unless it`s 3am and your the only one on it. So, I went out to where there was a bunch of farms and stuff and started beating (gasp!) on my brakes. I probably did 15 panic stops. The pedal started to feel "different" - maybe a bit spongy at first. My wheels were filthy and trashed afterwards. Oddly, there seemed to be a bit of grease slung out onto the wheel. Not sure where it came from - nothing is leaking.

Now, I`m the biggest skeptic when it comes to stuff like this and the first person to call BS. But, it actually worked. The slight pedal pulsation that was so annoying was 98% gone. I mean it was a marked difference. I was quite stunned - as this went against my gut feeling - which is usually right. So, after going through this and my experience with brakes in general; I`ve come up with a few THEORIES:

1. Performance type cars today that are experiencing pedal pulsation likely have a pad deposit issue.

2. Rotor deposits are more likely from "rotor friendly" ceramic / low dust pads - since these pads don`t have the aggressiveness (or abrasive friction) of the older semi-metallic like pads to self-clean the deposits off the rotor(s).

3. Most new cars that have had multiple rotor/pad replacements under warranty due to "warped rotors"; only to have the issue return - likely have pad deposit issues. Obviously, new rotors have no deposits - so the issue is temporarily fixed. However, since the driver`s driving habits have not changed - the issue will return in weeks to months.

4. "Babying" brakes (especially on performance cars) is probably a big contributor to this phenomena. Occasional aggressive use of the brakes actually helps to clean the deposits off the rotors. Performance cars braking systems are designed to run hotter, cool better, and take more abuse. If the brakes are "babied" the rotors may never get hot enough for the pads to self clean the deposits off the rotors via abrasive friction.

5. Pad deposit issues are less likely if you keep the more aggressive / factory dust-maker BMW pads. This makes sense, as the more aggressive pads clean the rotors better / easier (more dust) and likely just generally run hotter. This also makes sense as to why is issue has not been caught by engineering. Although, pad deposits can occurs with factory pads which is likely due to driving habits.

6. Ceramic pads tend to work more by adherent friction (leaves layer on rotor) than abrasive friction (like sanding) opposed to semi-metallics which are likely vice-versa at normal operating temperature (hence more dust - but less deposits)

**** One practice I am now avoiding, which I learned from the above articles, is keeping my foot tightly on the brake at stop lights. Apparently, this is a big cause of pad deposits. At the stop light, when the rotor is hot - and brakes are held on with a lot of force - pad deposits can occur from transferring friction material to the rotor unevenly. So, it is recommended to just keep your foot on the brake as light as possible to keep the vehicle from moving. Something I used to do the opposite of.

I`m really curious of others` experiences with pedal pulsation, the fixes, and what you think of my "theories".

[Ronkh]

My son`s 335 has had 3 sets of rotors/pads
Still pulsing

He is getting worried since he has 42 k on the clock now, and is thinking of getting rid of it since after warranty
bmw stands for breaks my wallet

[Swanicyouth]

My son`s 335 has had 3 sets of rotors/pads
Still pulsing

He is getting worried since he has 42 k on the clock now, and is thinking of getting rid of it since after warranty
bmw stands for breaks my wallet

Ron, are they factory pads????

This is an important question I`ve found in my research. Are they low dust pads????

Have him try the the method I`ve outlined above, which can also be found in Stop Techs website. I`m telling you - I almost crapped my pants when it worked.


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[Ronkh]

Ron, are they factory pads????

This is an important question I`ve found in my research. Are they low dust pads????

Have him try the the method I`ve outlined above, which can also be found in Stop Techs website. I`m telling you - I almost crapped my pants when it worked.


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Yep they are. They keep telling him he has warped rotors?

I will let him know about the pads. Thanks

[Billy Jack]

I`ve always subscribed to the GM method of rotor prep (which the flat-rate guys never do) and rotors seem to last forever for me.
First, after knocking off any rust around the perimeter, I give them a good soap and water scrubbing. Once dried, the surfaces get a D/A sanding with 120-150 grit paper, including the hub mating surface. One more soap and water wash and they`re almost ready. Final important step before install is to also sand any rust off the hub and give it a light painting with anti-seize. The wheel mating surface also gets a bit of anti-seize, as well as the wheel stud threads and the lug nut cones. I`ve been accused of anti-seize abuse, but I`ve never broken a wheel stud in over 40 years of wrenching and never had to hammer the wheels off any of my own cars.
Once it`s all back together, I subscribe to the 30-30-30 theory. That is 30 stops from 30 mph, with 30 seconds of cool down between stops. IMO, driving technique also contributes to rotor longevity. Pittsburgh is all hilly terrain and I`d rather make a few hard stabs at the brake pedal rather than riding it lightly all the way down the hill.
Also, I never use the e-brake on an auto trans vehicle unless absolutely necessary and even then only lightly. I used to test transmissions when I worked for GM and never saw a park mechanism fail. However, I`ve seen many folks who habitually stomp or yank hard on the e-brake need rotors almost every brake job.


Bill

[Accumulator]

swanicyouth- Yes indeed, agree completely, with one exception- with one vehicle I have the "low dust"/ceramic pads tend to cause me *less* trouble in this regard and my more aggressively dusting (and performing) pads caused more trouble. I finally gave up on running fancy aftermarket pads on my old Tahoe in favor of the GM ceramics, and sure enough, no more trouble. Sure did increase my braking distances though and I can understand somebody taking me to task over that.

And yeah, the info on the StopTech website is great.

That whole "overheated rotor warping" thing is, I suspect, usually said by people who haven`t actually monitored their rotor temps.

Billy Jack- I use the parking brake on my automatic cars now and then just to keep things working OK. On one of our Audis we never used it (but I did inspect things regularly, no visible trouble) and then my wife put it on and it froze solid, wouldn`t release. Fortunately she was at our Audi dealer when it happened (talk about luck).

[Dogfather]

I want to replace the front end links on my Subaru.
Can I do this with the car on the ground (or ramps) or do I have to use jack stands?
Or does it even matter?
Thanks

[RDKC]

If you`re referring to the stabilizer bar end links than I`ve known people to do them on the ground. However, I would prefer to do it in the air with the tire off for space.

Swanicyouth, those are probably some of the most detailed how-to`s that I have seen. You did a great job, absolutely fantastic.

Just a couple things I did not notice though...

1. Chock your wheels when you work on a car, especially when you jack it off the ground. I have seen mistakes be made and vehicles roll off the jacks/stands. An extra bit of safety that takes a few seconds but could save your life.

2. Regarding the coolant flush. If you want to flush the system with water and not remove drain plugs it`s still possible to do and get the proper dilution ratio for the coolant. Simply drain the system, fill with distilled water, and let the vehicle run to operating temperature. Repeat again and drain the system. Once drained, use concentrated coolant instead of prediluted. If you have a 6 gallon capacity, simply add 3 gallons of concentrated coolant and fill the remainder of the system with distilled water. You don`t want to run the vehicle too long on just water for a few reasons and the main concern being you are removing the lubrication from your water pump. I prefer coolant flushes using the proper chemicals to help remove any scaling, rust, etc. that has built up in the system. Just my $0.02 though.