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4.0T A8 front rotors/pads tools

Old 10-09-2018, 08:17 AM
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Default 4.0T A8 front rotors/pads tools

Any special tools for doing the front brake rotors and pads? I think the one video on youtube specifies a 9mm long hex bolt, which isn't a problem. I have the service manual but it doesn't indicated bolt/nut sizes. I don't want to put it on jacks and pull the wheels off only find I'm missing some odd sized socket or something lol.

Thanks!
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Old 10-09-2018, 09:00 AM
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Hmmm...

Audi says you are supposed to replace the removed bolts for any caliper bracket to hub bolt ups--whether front or rear. Those bolts typically get pulled whenever rotors come off. Many indies probably don't, but it is per (real) manual and Audi + VW documentation for a lot of years now. Some think bolts are single use/stretch type, but in this case I think it is their corrosion treatment. Big picture, not expensive so I replace these days. In turn, that tells you what size they are, since they are in hand first. There is also a tiny T-xx screw that holds rotor to hub. I always replace those, since they can corrode and then have to be drilled out when car gets older. Pretty common post on D3 board as far as the practical experience as they age. Less than $1.00 each; and yet less if part of a discounted dealer parts order.

Can you post a picture of your front calipers? Or, describe them per following sentences. I want to see if they are the Brembo type like S8 (w/ slightly smaller rotors), or the simpler semi floating two piston ones used on the 4.2 and the 3.0T. If they have a pad retainer clip on the outside (where you can see them through the wheel spokes) with some logo on it, those are the simpler ones. If the side is solid and chunky, those are the Brembo's. Depending on answer there (or if someone else w/ A8 4.0T knows), there may be more pointers. The "9mm hex" reference sounds like the simpler ones, but not sure if that is actually what is on your car. There is a fair amount of confusion in prior threads--and some parts listings--so want to be sure. Not too hard either way, but the set ups and then which bolts and such vary.

FWIW to plan scope of work, the torques on the caliper to hub bolts are pretty high. Thus, from experience I typically need to be under car with a big torque wench to get them, as opposed to trying to do it with wrench turned backwards coming in from the wheel and fender area. On the "simpler" calipers you don't have to pull the bracket when you do pads only, but you typically do when changing rotors. On the Brembo type, the bracket always stays with caliper, so those should be pulled at the hub bolts in all cases.

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Old 10-09-2018, 09:17 AM
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Originally Posted by MP4.2+6.0 View Post
Hmmm...

Audi says you are supposed to replace the removed bolts. Many indies probably don't, but it is per (real) manual and Audi + VW documentation for a lot of years now. Some think bolts are single use/stretch type, but in this case I think it is their corrosion treatment. Big picture, not expensive so I replace these days. In turn, that tells you what size they are, since they are in hand first.

Be sure BTW you are removing the calipers at the hub bolt up point. Some of the amateur video or posts out there may suggest removing at the caliper to bracket point, but that is a definite no no per both Audi and Brembo. Those bolts also are not sold, and the tool is an oddball (sold on eBay via China). f why get messed up, caliper assembly is done. Make sure too you are looking at the "right" instructions. "9mm hex" has me thinking maybe that is for the "other" type that uses a more conventional large bracket to which the caliper bolt, and in turn is the semi floating more basic caliper. I think the A8 4.0T's have the Brembo calipers like the S8's. Those are not the same as the older 4.2's or the 3.0T's AFAIK. Which ever it is, it is not particularly difficult, but you need to know which specific brakes are on your car and then have the proper instructions for that set up. The torques on the caliper to hub bolts are pretty high, so from experience I typically need to be under car with a big torque wench to get it, as opposed to trying to do it with wrench turned backwards coming in from the wheel and fender area.

What is your plan on the anti vibration pad/piston discs? Again, I'm thinking you have the later/bigger caliper set up. Some try to reuse, others replace. $200ish a set of 12 for the Brembo's. Dealer only, so not cheap--as much as the pads.
I haven't taken the wheels off before, they use bolts as opposed to studs with lug nuts?
Edit: answered this with a quick google search. I'll probably just replace these as you said.

The service manual I have agrees with your second point:

It then says to unbolt the brake carrier and pull the caliper and carrier away as one. My general rule of thumb anyways is if the bolt looks expensive/odd...it probably isn't meant to be removed lol.

As far as the anti vibration pads you mentioned, do you mean the brake pad shims indicated below? It says "Always use new shims".


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Old 10-09-2018, 09:32 AM
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I also just noticed there's a couple options for the calipers/rotors in this manual:
1LL/1LJ/1LP
1LN/1LX
1LW

The 1LW are the ceramic brakes, any idea what the other two correspond to? Looking up the caliper/rotor part number was no help. My guess is short wheel base vs long wheel base?

​​​​​​​
Edit: Answered this as well, lol.

Last edited by sushistrip; 10-09-2018 at 09:38 AM.
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Old 10-09-2018, 09:37 AM
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I edited my reply realizing answer itself may not be right--it goes back to the confusion of what the actual brake set up is on a 4.0T A8. On the S7 with the same 4.0T as the A8, it is same as S8, but on A8 4.0T it may be cost reduced.

See revised reply below and then answer the "which calipers" question for further tips. On product codes (called PR codes), they are on the build sticker and you can look there. Or, post a pic of it and I can decipher--either in car maintenance manual if selling dealer did his job, or really buried in spare tire area.

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Old 10-09-2018, 09:51 AM
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On another question you had, yes all Audi's use lug bolts, not nuts w/ studs. Has been that way since my 73 first one. Sometimes I use a screw in stud tool to help align wheel and avoid it dropping suddenly onto caliper--wheels are in 65-70 pound range. Like this, as one of many examples sold. At least my D3 tool kit that came w/ car had a plastic version of it. I prefer metal. M14 x1.5 is the relevant spec:

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Old 10-09-2018, 09:55 AM
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I will snap some pics of my calipers when I get home this evening. You are correct, those are allldata diagrams. I trust the manual well enough, if there are differences between model years or trims it calls them out

I will be doing rotors along with pads because I have some gnarly wheel shake when I get on the brakes at highways speeds, definitely warped rotors.

I did see the torx bolt in the manual, you think the rotors come with that or do I need to purchase separately?
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Old 10-09-2018, 10:47 AM
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Originally Posted by sushistrip View Post
I will snap some pics of my calipers when I get home this evening. You are correct, those are allldata diagrams. I trust the manual well enough, if there are differences between model years or trims it calls them out

I will be doing rotors along with pads because I have some gnarly wheel shake when I get on the brakes at highways speeds, definitely warped rotors.

I did see the torx bolt in the manual, you think the rotors come with that or do I need to purchase separately?
Little torx is a separate piece part.

Wheel shake on braking is often rotors. But, NOT always, and specific to A8/S8. Can also be worn upper control arm bushings in front. Max stress on those seems to occur on braking and then things move around a bit. Had that on my D3 where I chased a minor vibration that was more pronounced on braking. It turned out to be the upper control arm bushing issue. You don't say miles, but typically some wear may be there by 50-80K even with the OE/OES parts. Inner front tire wear that you would often guess is an alignment issue can be another sign of upper bushing issues, particularly when you have some braking vibration.
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Old 10-09-2018, 10:57 AM
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Originally Posted by MP4.2+6.0 View Post
Little torx is a separate piece part.

Wheel shake on braking is often rotors. But, NOT always, and specific to A8/S8. Can also be worn upper control arm bushings in front. Max stress on those seems to occur on braking and then things move around a bit. Had that on my D3 where I chased a minor vibration that was more pronounced on braking. It turned out to be the upper control arm bushing issue.. You don't say miles, but typically some wear may be there by 50-80K even with the OE/OES parts. Inner front tire wear that you would often guess is an alignment issue can be another sign of upper bushing issues, particularly when you have some braking vibration.
I'm at 124k miles, so I wouldn't doubt the bushings could use some love. The vibration is most noticeable on initial braking, and only above 50mph or so. There is also a slight pulsing at lower speeds coming to a stop. Can the bushings be replaced or does the whole arm need to be replaced?

Edit: I see the arm and bushing sold separately, also alldata has a procedure replacing bushings, so I assume I don't need to replace the entire arm.

Last edited by sushistrip; 10-09-2018 at 11:19 AM.
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Old 10-09-2018, 11:37 AM
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Originally Posted by sushistrip View Post
I'm at 124k miles, so I wouldn't doubt the bushings could use some love. The vibration is most noticeable on initial braking, and only above 50mph or so. There is also a slight pulsing at lower speeds coming to a stop. Can the bushings be replaced or does the whole arm need to be replaced?
At 124K miles, you probably do have bushing issues unless they were already done, and even then only if dealer or OE level parts. I went through two OE sets by those miles on my D3. OES on D3 was Lemfoerder. Probably still true for D4. On D3 even dealer sold bushings separately, which were marked as Lemfoerder. Having just looked, they aren't broken out on the D4 ETKA parts diagram though, so may not be available. RM European currently has D4 Lemforder upper arms in $80 range, each. Takes 4 separate ones in total. A very good price for OE/OES. If you can find bushings, you then need a press to install them, or need to find a machine shop or mechanic to do it. (Meyle is junk BTW as far as I'm concerned, if you look at their site).

Given your miles, I would be replacing upper control arms before rotors, unless repair history says arms/bushings were done in last 50K miles. You can also unbolt the upper pinch bolt that holds them in on ball joint side and then do a careful inspection. Hard to get a true sense when they are bolted fully in place, but the deep cracks become obvious when you can move them around from tie rod end. If yours are literally torn out, that is the final stage of complete failure and then easy to see. Lots of creaking in suspension is another sign, plus the front inner tire wear. If you do control arms, also do sway bar end links. Known wear issue, even more so on D4 and in some cases by 50K. D3 got closer to 100K on those. Still do rotors of course if they are worn below min spec.--at your miles absent extraordinary non stop highway driving, they probably have already been replaced at least once before. Control arm job typically leads to an alignment BTW, especially if one was done in recent timeframe on worn bushings.

...you probably need to be taking off a wheel for more inspection given the various items...

Last edited by MP4.2+6.0; 10-09-2018 at 11:42 AM.
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