13" wheels on standard Beetle discs

[Dan Dryden]

Has anyone managed to fit 13" wheels to the front of a beetle running standard sized discs?
What calipers have you used?

I'm trying to fit some 13" wheels to my 72 super beetle but having clearance problems with the standard calipers.
Standard discs are 280mm with a pad sweep area of 41mm.
The inner diameter of the wheels is 310mm, so I'm needing a caliper body which only protrudes by 10mm... Seems like I'm wanting something that doesn't exist.

How does H_Aich run 13" wheels on his race car?

[GS guy]

The Formula First guys use the VW OEM style calipers and discs with 13" wheels - check them out for fitting procedures.

[Dan Dryden]

Thanks for the heads up on that! I've just found this article about grinding the calipers to fit the 13" wheels.

http://www.formula-first.org/Technical/ ... lipers.htm

I've actually already ground an old seized ATE caliper to fit my application but was concerned about the amount of material I had to remove. It exposed the gasket slightly that sits between the claiper halves.
Perhaps the TRW ones used in the article are more tolerant to grinding....?

[Marc]

They're dealing with Aero steel rims. Are yours alloys? Those typically have a smaller bell I.D. The shape and backspace matter too...not likely that you'll be able to fit stock calipers without excessive grinding. You can take a little off of the rim, too, if legal liability's not a concern

[Marc]

Wilwood makes 4-piston Dynapro calipers for Hondas which fit inside most 13" rims, but you'd probably need to make some sort of adapter to mount them....also those cars have rotors which are ~15mm smaller than ours, so there's ~5/16" difference in potential clearance - those still might not work with some rims without cutting down the rotor O.D.
They're sold as a kit w/rotors for ~$500 so the calipers are probably ~$200 ea...

[Dan Dryden]

You're right about the steel wheels. I had just realised that myself and came back on here to raise the point... Only to see that you had already done so, Marc! Lol!
The problem with the standard beetle discs is that the central hub is large and the sweep area for the brake pads is pretty small.
I may have found a UK brake supplier called Hi Spec, who list a race caliper that would fit around my 280mm disc. It has no dust seals, so I'd have to keep them clean and well serviced. The only problem I can see is that the pad swept area is 43.5mm.... 2.5mm larger than is available on my disc.... I wonder if 2.5mm could be shaved from the bottom of the pads?.... Also my discs are 8mm thick, the site recommends a minimum of 10mm....
If not, I will look into another idea I had which involved using a steel hub from Pacific Parts and bolting a brake disc from another manufacturer with a suitably sized disc.

[Dan Dryden]

Link to caliper from Hi Spec:
http://www.hispeccalipers.co.uk/rs114280.html

[Marc]

...The only problem I can see is that the pad swept area is 43.5mm.... 2.5mm larger than is available on my disc.... I wonder if 2.5mm could be shaved from the bottom of the pads?.... Also my discs are 8mm thick, the site recommends a minimum of 10mm....

I would think so. I have the opposite problem on my trike's front brake, it has a Harley rotor and an aftermarket caliper that uses Honda Goldwing pads which sweep slightly further outboard...as they wear, a lip develops on the outer edge of the pads that rides on the periphery of the rotor, making an annoying/embarrassing squeal that only stops when the brake's applied. To prevent that I have to grind some away from the pads.
As far as the rotor thickness goes, it shouldn't hurt anything other than you'll be needing to replace the pads a little more frequently. It's not uncommon for the same caliper to be used on different rotor widths in conjunction with pads of corresponding thickness - for example, the MKI GTI Rabbits had thicker, vented rotors than the "normal" Bunnies and used the exact same caliper but had thinner/harder pads; same situation with many Honda motorcycle models. If Hi Spec designed their calipers to accept a pad with an industry-standard conformation (quite likely I would think), there'd be a good chance that you can find a compatible one that's a little thicker.

...I will look into another idea I had which involved using a steel hub from Pacific Parts and bolting a brake disc from another manufacturer with a suitably sized disc.

The Wilwood DPHA Honda setup I mentioned comes with 262mm bolt-on rotors (and there are slotted/drilled options available), with 4x100 PCD...doesn't look like the center would be quite big enough to redrill to 130mm: http://www.ebay.com/itm/WILWOOD-DPHA-FR ... rmvSB=true

I found the 4-piston Honda calipers for sale separately, my guess as to cost was pretty good: https://www.jhpusa.com/store/pc/viewPrd ... duct=12257

Several folks have said that they'd found other calipers which'd bolt directly to the VW spindles (been hoping one would chime in on this topic). IIRC, there are BMW, Volvo, and even Mopar-subcompact calipers which might bolt up, but I have no idea if any of those yields any better rim clearance.

Oh, and if someone should suggest trying the Girling calipers from a `74 'Ghia my advice would be to avoid them. Rare, prone to squealing, require oddball LH thread flex hose too IIRC)

[Dan Dryden]

Here's some pictures of where I am right now. Trial fitted and with the standard (scrap) ATE caliper (too) heavily ground.

[Piledriver]

I don't think its gonna make it with the alloy wheels unless you go with a turned down rotor and different calipers etc.
Most Wilwood calipers run long, narrow pads but probably won't like tiny rotors.
There are some mini-sprint calipers that may work, for thin rotors as well.
The ceramic coated aluminum rotors might work fine for an AX weapon. (not street driven)
For the back, consider inboard rotors.

A lot of folks running 13s just run drums for AX, plenty of stopping power with T3 rears and the right shoe friction material for AX, particularly with the huge braking "multiplication" from shorter tires..
A lot of places can put whatever friction material you like on your shoes.
(Think industrial)

[Dan Dryden]

To clear the ball joints, I need to use a 10mm spacer with these wheels.... Looks like I'll need wider front fenders too! Lol!

[Dan Dryden]

I don't think its gonna make it with the alloy wheels unless you go with a turned down rotor and different calipers etc.
Most Wilwood calipers run long, narrow pads but probably won't like tiny rotors.
There are some mini-sprint calipers that may work, for thin rotors as well.
The ceramic coated aluminum rotors might work fine for an AX weapon. (not street driven)
For the back, consider inboard rotors.

A lot of folks running 13s just run drums for AX, plenty of stopping power with T3 rears and the right shoe friction material for AX, particularly with the huge braking "multiplication" from shorter tires..
A lot of places can put whatever friction material you like on your shoes.
(Think industrial)

It will be a couple of weeks before I get the opportunity to take a ride over to Hi Spec brakes with my front wheel/hub assembly. I'm hoping they'll be willing to take a look and maybe even help me develop a setup that will work.

I plan on running pretty large spacers at the rear to fill my oversize fenders, so hoping the caliper will barely fall within the confines of the inner wheels.... Almost inboard!

Running drums is out of the question. I used to run a type 3 rear drum setup which was fine for street driving, but out on a race circuit they would suffer badly fade.

If Hi Spec cannot come up with a solution (at a reasonable price) using the standard beetle discs, I'll look into using discs and calipers from other cars that will offer me the clearance I need.

[Piledriver]

To clear the ball joints, I need to use a 10mm spacer with these wheels.... Looks like I'll need wider front fenders too! Lol!

Perhaps power steering as well...

[Dan Dryden]

To clear the ball joints, I need to use a 10mm spacer with these wheels.... Looks like I'll need wider front fenders too! Lol!

Perhaps power steering as well...

It will be fine!

I currently run 8.5"x18" wheels on the front of my beetle, so I'm expecting the steering to be lighter!
The front wheels I'm trying to fit are only 7"x13" and will have a lot less rolling mass...

...Plus, it's a good workout for my arms.

[Marc]

When our club adopted a spec McCreary tire that was harder than the Goodyears we'd been running, it was available in 23.5x10 15" or 13" and 20.5x9.5 13" versions - we switched to the smaller tire (changed gearing accordingly) because it heated up faster, yielding an advantage in the early laps. Our mid-engine car built to defend the inside groove against the front-wheelers used Standard Beetle drums in the front and GTI Rabbit front discs in the rear, and actually had more trouble with the discs overheating/fading/catching on fire...used semi-metallic linings we had custom-made at a local reline shop on the front.
Admittedly that was circle track and the brakes did get a chance to cool twice a lap, but on some short tracks where the fast way around was to keep the throttle wide open and set the chassis for the turns with left-foot braking there were nights when the front brakes were all that were left by the end of the feature, with the discs glowing nearly yellow-hot (narrowly avoided being black-flagged more than once). And that was with a front air dam and NO brake ductwork, just a small front grille.
...drums can work, and due to the increased leverage which Piledriver mentioned they can work well with short tires.

T-Bird body (original Daytona was short-lived) with 23.5" tires in Las Vegas: https://scontent.fsnc1-1.fna.fbcdn.net/ ... e=57AF330B

20.5" tires, season champ in 1990: https://scontent.fsnc1-1.fna.fbcdn.net/ ... e=57B67702

1989 Trophy Dash at the long-defunct Port Angeles "paperclip" track (#25 Daytona, still working the bugs out). FWD, Mid-engine, RWD, rear-engine - we had a little of everything in those days Won by Scirocco w/GTI engine, #2 was $$$ pro-built chassis with set-back Esslinger Ford (claimed 250+ HP), #21 2332cc 'Ghia...(we ran a stock-rocker 1775):

Teeny tires! Dry-sump tank had to be moved to the other side, the pump couldn't overcome the G-force this chassis was capable of.