TheSamba.com :: View topic - Inside diameter of wheels

Wed Feb 24, 2010 12:59 pm

I'm putting big brakes on my van and the calipers "just" hit my 16" MBZ wheels. I've seen pictures of bigger brakes with 16" audi wheels. Can anyone confirm that the ID of the audi wheels is bigger than the MBZ wheels. I understand that is a gross generalization.
I can get the wheels to fit, but there is a rub mark on the rim and there is zero clearance for mud/rocks/debris.
New wheels will really not cost any money in the end.

Wed Feb 24, 2010 1:41 pm

My Mercedes S500 wheels (16x7.5 ET46) measure between 15.25 and 15.50 inches. The larger is on the ouside edge. There is a step about parallel to the mounting surface which is significantly smaller and hard to measure at the moment.

Wed Feb 24, 2010 8:05 pm

r39o wrote: My Mercedes S500 wheels (16x7.5 ET46) measure between 15.25 and 15.50 inches. The larger is on the ouside edge. There is a step about parallel to the mounting surface which is significantly smaller and hard to measure at the moment.

That smaller edge is were the brake caliper makes contact. I also have s500 wheels of the same dimension. That ledge measures 14.187" for anybody's future reference.
I made an accurate measuring tool. I'm going to look at some Audi wheels this weekend and hope for the best.

Wed Feb 24, 2010 8:56 pm

That "smaller edge" is called a drop center. All wheels have it, but its location on the barrel varies from one wheel to the next. Its purpose is to give the tire bead someplace to tuck into while mounting the tire to the wheel. What brakes are you trying to install these wheels over? I just put Porsche/Brembo 4 piston calipers and 13" rotors on my van (http://www.thesamba.com/vw/forum/viewtopic.php?t=401048) and they clear (barely) my 16x7.5" ET 37 (+8mm spacer) Audi S6 Avus wheels because the drop center is located right behind the spokes. If the drop center were located anywhere else the wheel wouldn't clear.

I hope that sheds some light on what to look for in a wheel that will work with your application.

Wed Feb 24, 2010 10:43 pm

I'm doing this brake upgrade:

http://www.thesamba.com/vw/forum/viewtopic.php?t=331312

So far, everything bolts together nicely...except the wheels rub. They bolt on, but they rub.

I also need ET 46 wheels or something close. The way I did the rears, I locked myself into spacers.

Thu Feb 25, 2010 2:31 am

Can you change your ET some more to clear?

Thu Feb 25, 2010 10:56 am

r39o wrote: Can you change your ET some more to clear?

Not an option. I would need to move the wheel out a solid 3/4" to get out of the drop center and I've already got 17mm worth of spacers.

Thu Feb 25, 2010 6:54 pm

I think your choice of 16" wheels is going to be very limited with that setup. The G60 is a large caliper, and in order to keep the flexing under control Girling had to beef up the spine, which makes the caliper body very bulky. It fit behind a 15" wheel in its factory application, but the use of a 312mm A8 rotor will space that caliper so far out that its bulky spine will cause clearance issues.

The two main reasons I went with the Brembo 4 piston caliper was stiffness (which manifests itself in better pedal feel and modulation in every day driving) and compactness. It sits down and around the rotor, allowing a larger S8 332x32mm rotor to fit with better clearance behind many (but not all) 16" wheels.

I hate to say this, but you may have better luck with wheel choices by going 17" or larger. Or...since you're in the Seattle area we can try to arrange a time to test fit my wheels on your brakes. I'm considering going to a 17" or even (shudder) 18" and if I do I'd be willing to sell you my wheels for a good deal (they're a bit haggard).

Fri Feb 26, 2010 10:19 am

buildyourown wrote: I'm doing this brake upgrade:

http://www.thesamba.com/vw/forum/viewtopic.php?t=331312

So far, everything bolts together nicely...except the wheels rub. They bolt on, but they rub.

I also need ET 46 wheels or something close. The way I did the rears, I locked myself into spacers.

Can you grind any metal off the caliper to make them fit? I am about to start the same brake upgrade and don't want to end up with the same problem. Going to 288mm rotors would solve it, but that means a redesigned bracket.

Paul

Fri Feb 26, 2010 10:52 am

Franklinstower wrote:

Can you grind any metal off the caliper to make them fit? I am about to start the same brake upgrade and don't want to end up with the same problem. Going to 288mm rotors would solve it, but that means a redesigned bracket.

Paul

I've been through just about all possible solutions at this point.
I have removed some material from the caliper. Enough to remove the "Girling" stamp. That's about all I'm comfortable with.

You really need a bare minimum of 14.375 ID on your wheel at the mounting face to clear. That is with very little clearance.

Options so far:
Upsize wheels - crap choice since I have $600 in new tires and 17" tire options suck
Find rare 16" wheel that fits - also tough since nobody has documented ID of wheels
Use a different caliper - I've got $300 in G60s and they are modified so my resale will suck
Smaller rotor - 288mm is the next size down in Audi. I can turn mine but then they aren't balanced any more. Still need to remake adapters.
If you go to a 288, then you have a Small Car kit and are only saving $140.
In retro-spec, the G60 caliper is a poor choice for a 16" wheel big brake kit. For the same money and trouble, I could have used Loogy's Mustang calipers and ended up with bigger brakes to boot.

Fri Feb 26, 2010 11:08 am

K this discussion is happenign in two threads, r39o what is the inside diameter of those wheels at the mounting face? ET?

Fri Feb 26, 2010 11:15 am

Sounds like the g60 is a beefy caliper and a good candidate, it is the 312mm rotor that is the issue. Must be why most kits use the 288 rotor - should fit any 16" wheel.

Fri Feb 26, 2010 1:02 pm

The inside diameter (measure straight across from the hub/wheel mounitng surface) of the Mercedes forged CLK320 wheels is 361mm (14.21") and the inside diameter of the 16x7 ET45 AUDI wheels that I test fitted onto my other van is 359.5mm (14.15").

Fri Feb 26, 2010 2:11 pm

loogy wrote: The inside diameter (measure straight across from the hub/wheel mounitng surface) of the Mercedes forged CLK320 wheels is 361mm (14.21")
And the CLK steel winter wheels 16x7 ET37 measure a hair bigger.. almost 14.4.. but there is a weld flange that is at the plane intersect of mounting surface to rim.
The dim shrinks to 14.15 or so at that point and outboard of the mounting plane.
There are welds at that joint that may result in less clearance than 14.4 but not less than 14.15"

Fri Feb 26, 2010 3:25 pm

So the Ding 16" S6 wheels would fit the G60 setup & remember the intent was to make a cheap BIG brake kit, not a cheap almost big brake kit.

Fri Feb 26, 2010 6:33 pm

BlackDogVan wrote: So the Ding 16" S6 wheels would fit the G60 setup & remember the intent was to make a cheap BIG brake kit, not a cheap almost big brake kit.

They might fit, but that hasn't been confirmed yet. Yes, the G60s came from the factory hidden behind S6 Avus wheels, but they were clamping on 288mm rotors, not 312.

I just thought of something...you might want to look into the single 57mm piston caliper that replaced the G60 on the 1989 Audi 200 quattros. Its more compact and inherently stiffer than the G60, so it doesn't need to be as bulky. You may gain the bit of clearance you need while benefiting from a slightly firmer, easier to modulate pedal because of the 3mm smaller piston bore and stiffer caliper body. I *think* the two calipers are interchangeable, meaning either would work with the bracket in this kit, but I'm operating on VERY distant memory here, so I could be wrong...but might be worth a look see.

Fri Feb 26, 2010 6:58 pm

Franklinstower wrote: Sounds like the g60 is a beefy caliper and a good candidate, it is the 312mm rotor that is the issue. Must be why most kits use the 288 rotor - should fit any 16" wheel.

Its actually the other way around. The G60 is a very soft, flexy caliper because of its bulk and high torque capabilities. To try and counteract that, Girling beefed up the spine, but they could only go so far without making the caliper impossibly big and heavy (its already quite a boat anchor). In contrast, the Brembo caliper I use in my kit is quite stiff and very compact axially, allowing a 345mm rotor while maintaining good clearance on many 16" wheels.

But I understand this kit is all about BIG brakes on a budget, and my cost on the Brembos is more than this entire kit, so budget it's not! And I understand the decision to go with the G60, despite my pooh poohing of that caliper its still one of the most powerful floating calipers Audi has ever used (short of the HP2 found on 2000-2002 2.7t powered Audis...which like the G60 was also replaced with a 57mm single piston caliper), and they're cheap. Most 5000/S4/S6/V8 owners who eschew the G60 in favor of a stiffer opposed piston caliper would be happy to give away their old calipers as it would save them the effort of throwing them out. I've personally thrown away probably a dozen G60 calipers...now I wish I had kept them!

Fri Feb 26, 2010 7:16 pm

Dingchowping wrote:
They might fit, but that hasn't been confirmed yet. Yes, the G60s came from the factory hidden behind S6 Avus wheels, but they were clamping on 288mm rotors, not 312.

Lots of Audis used that combo. I have yet to find a vehicle that came with the combo I have. (G60, 312mm, 16")

Quote: I just thought of something...you might want to look into the single 57mm piston caliper that replaced the G60 on the 1989 Audi 200 quattros.

This occurred to me also. But I think your models are wrong. According to Rock Auto, the 200 used the G60 caliper. The 80s and 90s used the G54.

What's a better combo:
305mm rotor and G60
312mm rotor and G54

I'm leaning towards the G60 since it won't cost me any more money and it's the devil I know at this point.

Edit: Your right, I missed the "Ate" part

Fri Feb 26, 2010 7:31 pm

buildyourown wrote:

This occurred to me also. But I think your models are wrong. According to Rock Auto, the 200 used the G60 caliper. The 80s and 90s used the G54.

What's a better combo:
305mm rotor and G60
312mm rotor and G54

I'm leaning towards the G60 since it won't cost me any more money and it's the devil I know at this point.

Nope. I got 'em right. I'm referring to the Ate 57mm caliper, not the 54...that's way too small. The 5000 Turbo quattro used the G60, the 10v Turbo 200's used the single piston G57, and the 20v Turbo 200 and V8 used the internal caliper "UFO" brakes that were later retrofitted to G60s as used on the 5ktq due to rotor warpage issues. The S4/S6 continued with the G60 setup in the US, dumbed down from the European brake system that used larger rotors (not sure how big) and 4 pot calipers.

You'll definitely want to stick with the G60s vs. the G54. The latter is way too small to be compatible with the Vanagon braking system.

Fri Feb 26, 2010 7:56 pm

I saw these HP2's on CL today. So Ding, what do you know about them?

http://seattle.craigslist.org/est/pts/1609211200.html

Did Audi still use the 288 rotor with those? How about mounting, similar to the rest of the calipers: G54; G57; G60 etc.

Also Mercedes had a lot of 300 mm rotors that came on 500's and others. but I don't know how they were offset compared the audi rotors.

I just measured two sets of audi rims I have in the garage - one was 356mm (14.01) and the other was 362mm (14.25). Both measurements were at the smallest diameter near the mounting surface.