1303 Brakes

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H2OSB
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1303 Brakes

Post by H2OSB » Sat Jul 08, 2017 11:49 am

I would like to start a thread for disc brake upgrades using info from those who have real world experience or know enough to make a substantial contribution such that this thread could become a stickie.

I've been doing a lot of research today because, oddly, I still don't know for certain what brakes I want to run on my Super Beetle. I had planned to run a full 944 set up front and rear with 911 M calipers on the front to get better balance, however, I've decided fitting the 944 spindles safely (and the work thus required to do so) is more than I want to deal with in both time and money spent.

I would really like to run some version of 914 brakes on the front...at least rotors because they both bolt on out of the box, and I own a set already :) For the rear, I still plan to use the 944 brake apparatus because I REALLY like the 944 parking brake system, and, I have all the parts for the conversion. I have discovered the early 912 rear rotors fit over the 944 parking brake shoes in the same fashion, so I will use them with a different caliper.

After talking to Lanner Khan about this quite a bit (I'm pretty sure I drive him crazy), I am going to run front disc brake conversion brackets such as these from Topline http://toplineparts.com/brakes/disc-bra ... -0989.html with a secondary bracket to adapt radial mount Wilwood calipers over early 914 front rotors. There are a lot of detailed reasons for this based upon rotor width and other dimensions that I won't go into here. Along those same lines, I will use the same radial mount Wilwood calipers on the rear, with caliper adapters albeit with smaller pistons.

I know there are tons of folks who have successfully adapted some kind of Porsche brakes to their cars, but I am absolutely anti-bling, and want what is lightest and most effective brakes without being ultra expensive. My car will not be a show car, however, I will use it for autocrossing, so I do want a bit more stopping power than the typical Ghia front/aftermarket rear conversions provide, though not too much more is required. My engine is going to either be a 1911 or 2056 T4 conversion, so somewhere betwixt 100-130hp.

All this said, I would have loved to have some effective and clever OE type bolt on set up to get the braking power I want (i.e. the Old Euro Talbot Horizon calipers were a bolt on to Ghia (and 1302S/1303S) spindles and gave 48mm pistons).

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Piledriver
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Re: 1303 Brakes

Post by Piledriver » Sun Jul 09, 2017 2:02 am

Watch your brake bias, might want to run various combinations through the free calculator at https://brakepower.com.

The "default" rear caliper with parking brake is the Mk4 setup which from memory has a single floating 38mm piston, which effectively makes it two 38mm pistons as it's a double acting floater.
Try to score the aluminum version.

The tires will be the ultimate limiting factor in any case.

Note:If you plan on an adjustable rear bias/limiter valve, the rears should be almost same piston area as front, simply so you have something to turn down, at least on an ACVW. This is due to the extreme rear heavy weight bias.

If there was no weight transfer, you'd need much larger brakes on the back... If the CG gets low enough that becomes almost true.

On my square, 1G braking calls out between 54-58% front bias, depending on CG.
I went with 54% and ended up swapping 944T front calipers on the back for more area.
I do have slightly less grabby Mintex red pads out back, still have not felt a need to install the bias valve.

My setup is Wilwoods w/ 1.25"x4 pistons up front, and 2x40+2x36 (944T front) Brembos out back.
On a Bug the std rears 2x30 and 2x28 would probably work better as a T1 is taller.

Yes, my rear calipers are actually bigger area than my fronts, but the brake pads even things out.
Running PFC14 pads up front, Mintex red out back. The Pagids had too much grab out back.
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H2OSB
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Re: 1303 Brakes

Post by H2OSB » Sun Jul 09, 2017 5:52 pm

Pile, as always, you offer great advice. I really hadn't wanted to run an adjustable proportioning valve, but am now reconsidering. They aren't very expensive, all things considered so I will likely have one in the end.

My entire brake plan is based around sound engineering, in that an aircooled VW had an almost identical weight distribution to the SWB 911s. They had 48mm front piston calipers and 38mm rear. Thus, when I had planned to use 944 brakes, I had the stock size 36mm rears (single pistons...but act the same a dual opposed pistons) and I exchanged the 54mm piston 944 singles for 911 M calipers with 48mm dual pistons (believe it or not, the M calipers bolt on in place of the 944 calipers, AND are centered over the 944 rotor).

However, now that I've decided I will go back 1303 spindles to re-acquire the factory geometry (alas, I'm still lowering the car, so......), I have to rethink a few things.

I will not consider using the typical disc brake conversions offered by many because I've already determined I want a bit more braking than those kits provide. The conversion kits come with 40mm piston Ghia calipers. I'd like to stick with the 911 formula of 48f/38r. The Wilwood calipers I choose are close to the Porsche sizes, albeit in inches. Also, I would like to go with solid rotors for the small weight savings they provide. I do not believe vented rotors are necessary for the "modest" maximum power I could end up with.

I could have custom hubs made, either from scratch or from modded 944 hubs (or turned down and re-drilled Beetle brake drums). There is also the possibility of repurposing the hub portion the the newish hub/rotors being produced by Cbperformance. I had a chance to get a good look at them at the most recent Sacramento Bug-O-Rama, and I'm pretty sure a set of SWB 911/912 solid front rotors, as well as any of later 911 rotors that bolt to the back side of the hub could be redrilled to work with those hubs.

That said, I have a brand new set of 914 front rotors from an earlier brake upgrade attempt on my son's 1303 that will work fine for my needs. Most don't know, but I've confirmed personally, 914 rotors as well as those from a 924 fit directly on a Super Beetle spindle without even changing to different bearings.

As an aside, if a person was ok with the 4x108 bolt pattern, 924 front rotors could be used in a brake upgrade with a matching rear brake conversion made by turning a 924 rear drum down into a hub for some 4 lug Audi rear rotor and Golf/Passat calipers with a custom adapter, although that's along the lines of reinventing the wheel. There are a couple of really cool 4 lug Audi wheel choices the should fit under a Beetle fender, and would make an interesting twist on German Look concept. Be aware, however, it is impossible to redrill a 4x108 bolt pattern to 5x130 without many partial hole overlaps, so 924 rotors can not be used to get the Porsche PCD.

I could go on forever.
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Re: 1303 Brakes

Post by Piledriver » Sun Jul 09, 2017 7:30 pm

Do note the "SWB" part of the early 911s, your beetle is significantly longer wheelbase, and that matters...
(run it through the calculator to see how much)

Yes, the 914/4 and even T3 rotors are for std BJ spindles, T3 lates are same as early 914, early T3 same as Ghia.
(or perhaps it was the other way around)
LATE 914/4 rotors are same as late, or all(?) 411/412s. (deeper offset)

The rotor offset varies by vary by year/application though.
If you are welding on a caliper mount, get whatever is easy to find.

Do consider the hubcentric size, as well as rotor centering if using a composite rotor (Any 2 piece)

The late VW hubcentric size was IIRC 83mm, those can be easily turned down to Porsche 73.ish mm, although you could fairly easily make up some "hubcentric" dust caps (with internal oring seal) for the more common non-hubcentric rotors.
Plastic hub adapter rings seem to be aviailable in almost any std size to ~anything larger.
If you run hubcentric spacers, the 944 front dust caps may fit those, so you may be able to skip the VW dust cap entirely.
(although you may need to drill a square hole for the speedo drive)

Don't rely on the bolts/studs for wheel centering, it makes a noticeable difference front and rear.
I even turned my rear T3 hubs to take a press-on aluminum hubcentric ring.
(the 944T stuff was already hubcentric and rotor-centering, so needed no mods when I went there)

Also note that CB sells 914 rear rotors in a 5x130 pattern, effectively rear 914/6 replacements.
On an actual 914 they center on the hub internally IIRC.
Last edited by Piledriver on Sun Jul 09, 2017 8:09 pm, edited 2 times in total.
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Jadewombat
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Re: 1303 Brakes

Post by Jadewombat » Sun Jul 09, 2017 8:07 pm

I would stay away from 914 rear brakes. I adapted them on my friend's '69 ghia some 15+ years ago and we were very scientific about doing some braking distance testing before and after the swap from 60mph and the rear disks DID improve braking by reducing it a distance of 10ft., however the amount of work involved to grind down T3 hubs, weld up brackets, fit those little 914 calipers, and by today's standards with the allen key adjustment "centering" you need to do of the pads/calipers--it's a pretty hokey setup.

I did 924T brakes all around on my '73 1303. These brakes were phenomenal! I had welded in some plates on the front lower control arms to accept a Golf ball-joint and used a CNC drop-down pedal cluster with a balance-bar (individual MCs) because I didn't like "limiting" effect of a proportioning valve. That car was stripped down and the bias wound up being near 50-50 F-R. On a rabbit GTI, yeah it's probably 80-20 F-R. On my bug, no. I had a slightly more than stock engine in that car and drove the piss out of it in autoX. The pedal felt as solid as a Mercedes. The ONLY thing I didn't like is even as much bite as those tiny rear shoes had inside those rear rotors--a set of 30+ year old parking brakes from a 924T/944 make a weird sound and move a hair when you engage it (it's a semi-common problem).

I never tried it, but I like the idea of a set of 924 brakes adapted to a 1303. Easy, no ball joint adapting needing at the front and the rears bolt-up as easy as pie.

You said your on a budget H2O. Honestly, a set of decent used 924 or 944 brakes is worth well more than the new knockoff stuff sold. Those huge vented 944 rotors and calipers are nice to have, are they needed on a bug even with an engine 2X stock...hmm, debatable, but probably not. You can get away with a nice set of 924 stuff and have slots cut in the rotors and have a world of selection of cheap, very lightweight 14" 924 and Audi rims at your disposal.

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Re: 1303 Brakes

Post by Piledriver » Sun Jul 09, 2017 8:17 pm

You should probably decide on wheels before buying absolutely anything else.
Also agree the 924 brakes should be about free and work well, at least for the front.
(if you like the wheel/tire choices, decent 14" tires are like finding hens teeth these days)

5x112 might be a better choice...

Agree on not using the 914 calipers, they suck when they work right.
(venting clearance is set manually and is critical, and needs reset periodically if you want useful rear brakes, 914 rear calipers are not self adjusting, I think the new engineer got that task, along with the 914 trip odometer....)

OTOH with the MK4 rear 38mm calipers, they are pretty stout, and the parking brake action is very strong.
Also self adjusting if you use the parking brake as a good German should. (at every stoplight)

On a lowered bug, the 40mm Ghia fronts are probably a very good match to the 38mm Mk4 rears.
Might need a proportioning valve, I didn't but I was running larger BMW 2002Ti (40mmx4) fronts.
BTW, they might bolt on, and work well on a Bug.
They were a little too much for my T3 with the Mk4 rears, but a bug is taller.

I scored a nice set of staggered Forged Fuch (manholes) in 16x6/16X8 with the right offsets for $200.
16s seem a bit iffy for great AX tires though, limited sizes....
But they look and fit great on a T3. I really need to break down and have them polished.

The only downside is they completely hide the brakes.
I'm fine with that, makes it less obvious. (the 245s out back kinda ruin the stealth effect tho)

Note than any 924>968 had a 50/50 weight distribution so needed much more front bias.
Same was true for a SWB 911, not from weigh bias but due to the short wheelbase.
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H2OSB
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Re: 1303 Brakes

Post by H2OSB » Mon Jul 10, 2017 12:10 am

I will say, Steve Carter, with his first AeroLook early Super Beetle had late T3/T4 brakes with their 42mm pistons over 914 rotors on the front along with typical 944 rears with 36mm pistons over vented rotors and said they stopped great and were well balanced.

I don't know what to do. I want do it once and right. Light and effective...and relatively cheap. But then, don't we all.

I originally wanted to use the late 914 rotors due to their hubcentricity, but the offset was greater than the early rotors and I was trying to make them work on 924 spindles (making caliper brackets ended up being too difficult because 924 rotors are FAR smaller than 914 rotors thus the "ears" are closer to the spindle so the deeper offset wouldn't have mattered anyway...if that makes sense). The long and short of it is I have a pair of non-hubcentric rotors that I can re-drill and I'm too cheap to not use them.

I do like the some of the Audi wheels, particularly the "Sport" wheels that came on the Audi 90 verts, but I'm already committed to 5x130.

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Re: 1303 Brakes

Post by Piledriver » Mon Jul 10, 2017 11:19 am

The area for a pair of 42mm calipers (2 calipers, total of 4 pistons or 2 floaters) is 8.58 sq cm.
In a 4 piston caliper, that slots the area in between 4x1.12" and 4x1.25"

2x48s are effectively just a tad smaller piston area than 4x1.380s

Unfortunately the piston size selection of Wilwoods Dynalites and other small calipers is not great, but a few offer 1.25" pistons.

914 front calipers would work well, but they also make great door stops. (heavy)
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raygreenwood
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Re: 1303 Brakes

Post by raygreenwood » Mon Jul 10, 2017 7:14 pm

Use the late 412 rotor. It was the same as late 914 rotor.
It goes like this:
VW 411 rotor fits VW 411 from 1968 to August of 1972. It also fits the 914 to August of 1972. It also fits the VW type 3 FROM 1971 onward to the end of production.

The 412 rotor FROM August of 1972 also fits 914 FROM August of 1972. This is the LATE rotor with the wider caliper, thicker brake pad and deeper hat/dish as mentioned.

The reason for this UPGRADE....really has nothing to do with caliper or pad thickness upgrades. Thats just a nice by product.

The EARLY rotor is inferior to the LATE rotor. You will notice that the late rotor has a "hub-centric" cuff around the spindle nut cap. This is to strengthen the rotor because the earlier rotor FLEXED heavily in cornering on cars with wider tires and more weight.

To combat the misalignment and piston/seal wear issues the early caliper had...the type 3 and type 4 cars had the caliper with the guide pin and clutch inside of the piston.

I would not base what you are doing around the earlier rotor. Ray

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Re: 1303 Brakes

Post by Piledriver » Mon Jul 10, 2017 9:17 pm

I can confirm early 914/411 rotor is used on the late T3s, late offset was too deep, hit the spindle backing plate.
It would probably do the same on a T1.
The late 914 spindle was a little longer. (still BJ)

I had a new set of late 914 rotors, didn't fit the late T3.
They fit my 74 914 fine of course.

I used a worn pair of late 914 factory rotors for my front hubs tho, with hats, plasma cut down and drilled and studded 5x130.
Sadly I had to cut down the hubcentric bit to 71.5mm(?) for the Porsche hubcentric size, so it lost some stiffness, didn't know about that tidbit, might have done it different.

The CB 6061T6 aluminum hubs with bolt on rotors are probably the best fix, and you are not stuck with the rotors or std offset if the backside is plain as reported.(save for the reported 5 x 4.25" pattern CB uses for their rotors with the funky cast in cutouts) I just wish we had some photos...
These are the "early" offset to match T1/T3 and Ghia, and from CBs pics and the description of the backside, its a pretty solid hunk of aluminum... They are not hubcentric tho, I would turn up some thick alloy dustcaps to fix that.
The price has gone up on these?...
http://www.cbperformance.com/product-p/4182.htm

I'd be curious if their plain $20 "wide 5 replacement rotor" would fit those, drilled and slotted makes for cracked rotors in hard use, although they look great. (I don't dare harass Maryanne any more than I have)

Wilwood has a variety of hat mounts for backside hub attachment, and as its just a circle of aluminum or steel custom would be relatively cheap to mount ~any bolt on rotor out there.

I'm still eyeing these 2" thick 5x130<>5x130 spacers and 914 rear wheel bearings... to become hubs.
Just need a hunk of CrMo tube the right ID/OD to become an axle... That and a pair of T1 flywheel bolts to hold them on.(and the tap to match)

Porsche uses those or very similar dual row sealed bearings on all 4 corners of everything they make from the 90s to date.
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Re: 1303 Brakes

Post by burls » Mon Jul 31, 2017 10:11 pm

Has anyone put Subaru brakes all round and had success
71 superbug Subaru Outback cross

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