Porsche Brake Conversions

Update: May 2011

I get a lot of questions everyday regarding 944 brake conversions. I figured I’d put together an outline that covers the fitment of Porsche 944 brakes onto your T1’s. This is by no means the final word, there is tons of info on the web. Your best bet is www.germanlook.net. I’ll add pics as I get a chance. I use many of short forms (because I’m lazy), so this may help you understand:

1302- Super beetle, straight windshield, 3-bolt struts

1303 – Super beetle, curved windshield, 2-bolt struts

BJ- Ball Joint, 66+ T1’s

IRS- Independent rear suspension, in reference to 69+ T1’s (North America).

LP- Link pin, reference to front suspension 65- T1’s.

KG- Karmann Ghia

MC – Master cylinder

NA- Normally aspirated

T1 – Type 1, reference to beetle 1200, 1300, 1500, 1600, 1302, 1303.

T2- Type 2, Bus.

T- Turbo

If you are fed up of seeing the same KG front disk and stock rear drum on your dub, then the 944 brake systems may be the solution. So how do you get the brakes on your car?

Rear: We’ll start here since it’s the easiest. There are basically three varieties of 944 rear brake setups.

1) Early NA (83-85).

The caliper is sliding steel (ATE) axial mount with a ventilated disk (290mmx20.4mm).Early NA’s had steel IRS arms which are exactly the same as IRS T1’s. Some people claim that the 944 arms are internally reinforced whereas the T1’s are not. I’ve never had the nerve to chop one up to find out. You can put the whole arm on your T1, but you will have to replace the 944 pivot bushing with a suitable T1 one. I personally think the 944 arm is the same as T1, so I see no point to putting on the whole arm. If you want the 944 rear brakes, you will need the 944 backing plate (BP). The 944 BP bolts onto the T1 IRS arms in the same position as the T1 drum BP’s. The 944 BP’s have caliper-mounting ears incorporated into them. You will also need the 944 hubs, disks, calipers, brake shoes (for ebrake) and hardware. You can also install the 944 spring plates (although not required, as the T1 spring plates will also work) as they allow some adjustability of camber/height ( camber/toe adjustability only works with 944 arm because they have an additional hole machined that T1 arms are lacking). You can use the 944 stub axle if you wish, since if afford the use of the larger 100mm joints (as opposed to 90mm T1 joints). To make use of the complete 944 axle assembly (axle shaft and 2-100mm joints), you will need type 181 (thing) transmission output stubs on your T1 transmission since they allow the use of the 100mm joint. You can also machine the shoulder on one side of a T1 axle is you want to use the 100mm joint at the wheel side but a 90mm on the transmission side (100mm joint is wider than 90mm). If you have a 901 transmission, then use the 911 output stubs (100mm) and you can bolt the whole 944 axle assembly in place. There is a small issue of interfacing the T1 e-brake cable to the 944 e-brake hardware. See products for the required pieces. The stock early 944 setup comes with spacers and long studs.  With spacers the offset increase is 43.5mm per side. The spacers can be removed and shorter studs installed (studs from 86+rear or 83-85 fronts).  The spacers are 21mm so without them this nets 22.5mm offset increase per side. There you go, 944 rear disks!

2) Early turbo’s ( 85.5? and 86) have cast aluminum arms.

These arms can be differentiated from the later arms by having a bump-stop location cast into the arm. The caliper is a fixed aluminum unit (4-piston Brembo) axial mount and the rotor is ventilated and measures 299mmx24mm. The whole rear setup will increase your track about 44mm/side versus stock T1 drums. Please note that there are some early aluminum small offset (44mm) arms out there with the NA brakes(290×20.4 rotor and sliding ATE caliper). To put the aluminum arms onto your dub you will need everything from the 944; trailing arms out, spring plates and axles. The caliper mounting ears are cast into the arm, so they are not separable as above (1). Basically change the pivot bushing (to T1) and spring plates (to 944) and bolt them on. You cannot use your stock T1 spring plates because the bolt pitch differs. You’ll have the same issues as (1) with the ebrake. With these 944 stub axles, you will have to use the larger 944/T2 CV joints (100mm). These (aluminum) 944 stub axles are not interchangeable with the early 944’s, or T1 parts. The axle length is also much longer (about 21.5″) than the early 944/T1 axle(about 16″). Use the thing output stubs if you are using a T1 transmission, or 911 output stubs with a 901 transmission.

3) Late 944’s also have cast aluminum arms, but will increase your offset by 62mm-74mm per side. If the arm does not have a bump-stop location, it’s probably a late offset arm. They have the same caliper/rotor as (2), and everything else also applies. Also, the functional difference between the 87+ arms and 86 arms is the wheel hub, so a 86 hub can be installed into these arms to minimize the offset increase.

So what about Turbo brakes on a bug without the aluminum arm? You can use the turbo rotor (86 only) (299×24) and 4 piston brembo on the early (85.5 and earlier) removable backing plate. The rotor and caliper will bolt on, and you will have to shim the caliper (3mm) a little laterally to center it over the rotor. Use longer bolts for safety if you use the shims. See our product listings for the Turbo hardware kit (longer bolts and shims). If you use a Boxster S (986S) rotor (200-2008), you will not have to shim with the 4 piston 944 rear caliper.

Incidentally, you can also use 993 rear brakes (caliper and rotor) on the same early (85.5 and earlier) backing plate/caliper mount. The caliper will require a shim of about 3mm to center it over the rotor. 996 and later calipers can also be adapter to either the 86T or 986S rotor via radial adapters, see our product listings.

Front:

Unfortunately, the fronts are not so easily fitted onto your T1. Here’s where we get interesting. Lots of possibilities here. Let’s take a look at the 944 offerings first:

a) Early 944 NA (83-86). Steel sliding (ATE) axial mount with a ventilated disk (282mmx20.4mm). The rotor mounts from the rear of the hub and is fixed by 5 M8×25 screws. The hub is aluminum (PN: 477.405.605D).

b)Early 944T (85?-86). Fixed Brembo axial mount caliper with ventilated 299mmx28mm rotor. The rotor attaches from the rear of the hub like in (a). The hubs are different however because of the distance between the rotor mounting face and the wheel mounting face. The T hubs (PN: 951.351.605.00) are narrower in that dimension than the NA’s.

c)Late NA (87-89). Marketed as the 944S. Steel sliding (ATE) axial mount with a ventilated disk (282mmx20.4mm). The rotor mounts to the front of the hub similar to most modern vehicles. The caliper is exactly the same as (a), but the rotor differs. The hub is aluminum (PN: 951.341.605.3R).

d) Middle T (87-88) and 89-91 S2. Same caliper as (b), same hub as (c), but the rotor mounts to the front of the hub and measures 299mmx28mm.

e) Late T (89-91) AND 88 Turbo S. Same hub as (c), but radial mount Brembo caliper and bigger 304mmx32mm rotor.

Mounting:

There are three general possibilities to mount these front brakes to your T1. 1302/1303 have three choices, while only #2 apply to BJ/LP cars.

#1) Take the whole 944 spindle. This only applies to 1303’s. The 944 spindle will interchange with your 1303 spindle. This applies to the early 944 NA spindles (rotor mounted to hub from behind). The stock 1303 strut (and early 944) has a 20mm wide tang and 58mm hole pitch. The later (86+) 944 spindles have a 18mm tang width and 63mm hole pitch, and therefore will not be compatible with the 1303 struts.You will need special lower ball joints (17mm for 944 vs 15mm for stock 1303) available from european sources. If you have a 1302, then change your suspension (struts, spindles, lower control arms) to 1303 components. By using the 944 spindles, you have all required mounting points for the calipers/hubs etc. Your dub will be 944 from the spindle out. There may be an issue with the speedometer cable, as some 944 spindles are not machined for the cable. The tie rod mounting location may need reversing, easy to do with the current availability of the ‘bump-steer’ bushings.  Also the tie-rod will have to be longer since the 944 steering arm on the spindle is straight, whereas the 1303 steering arm curves in towards the center of the car.  The 1302/1303 tie rod ends will work with the 944 spindles. Overall, you will have to source everything from a 944, spindle out to perform this conversion. There is an offset increase of about 20mm (?) per side. The 944 spindle will also give you alot of positive camber, but you maybe able to remedy this situation with aftermarket camber adjustment bolt that afford greater adjustment.

#2) Modify 944 parts. Because the 944 hubs do not have the same bearings as T1’s, the 944 hubs can be modified to take regular T1’s bearings. The hubs also require narrowing. The spindle will require machining to mount a caliper bracket. Ideally, a mounting bracket would bolt into the stock drum-brake-backing-plate mounting locations of your T1 spindle. The 944 hubs are ‘fat’ at the inner bearing area, so they are too large to allow a bolt on caliper bracket. The mounting fasteners would interfere with the hub. The rear (inner) portion of the hubs have to be machined to be perpendicular with the spindle axis, and then a fabricated bracket can bolt onto the back of the spindle. You will have to source 944 calipers, hubs and rotors, then get the hubs and spindles machined. Offset increase can be minimized to about 3.5mm per side, depending on the hub machining.

Master Cylinders:

In general, the single piston caliper require the 944 MC, while the 4 piston brembo’s can get away with the stock 19mm dual circuit MC’s. Regardless of chassis origin (ie, 951, 985, 993,996 etc), most of the Porsche calipers use similar sized pistons in their calipers. The listing below deals with the 944 setups, but can be extended to cover most of the Porsche based brakes setups (4 piston calipers). For the 944 setups, we recommend the following master cylinders:

944NA: Use the 944 master cylinder (23/19mm). There is no provision for the brake light switch, so put a tee on the rear circuit and plumb in the switch (make sure the terminals face down so that you don’t trap any air). Remove the resevoir bottle from the 944MC, and use the line fittings and rubber grommets from your stock VW MC. That way you can connect to your stock VW resevoir. (Note, original German line fittings are too small for the 944MC, use the ones on the aftermarket Brazilian VW MC’s.)

• For beam suspension T1’s, the 944 MC bolts up. You need longer bolts and nuts (M8×55) because the 944 MC is not threaded in the mounting holes like a VW one. You have to shorten your pushrod a little (about 13mm) and you’re set.
• For 1302’s/1303’s the stock vw MC bolts up at and angle to the chassis, and bolting in the 944 MC will make it sit at an angle. VDubEngineering manufactures a MC adaptor kit that includes the adaptor, all hardware and the required longer pushrod.
• For T2’s, VdubEngineering manufactures a MC adaptor that allows the use of the stock T2 pushrod.

944T/986/986S/993: VdubEngineering has had good success using the stock dual curcuit (19mm) MC for all brembo (4 caliper) brake setups. The pedal is good and because of the small diameter, you can generate high line pressures with minimal pedal force.

• For T1’s, use the stock dual circuit 19mm MC. If the pedal is not to your liking, then change to the 944 MC.
• For T2’s, use the 944MC because it fits easily and the higher pedal ratio of the T2 allows higher line pressures with the a minimal amount of pedal effort.

Brake Lines:

Some line fabrication may be required due to the difference in the outlet ports of the 944 braking components. Use 3/16″ (5mm) steel brake with M10×1 bubble flare ends. Beam cars can reuse use VW disk caliper rubber hoses in the front. Super beetles will require a longer steel line between the strut and caliper, while retaining the stock length flex line. In the rear, you willl have to fabricate new metal lines from flex hose to the caliper.

Wheels:

The offset increase of Porsche based brake systems is typically beneficially because of the deep ET’s of Porsche wheels. Here are general guidelines:

17×7et52 wheels will fit with 2″ narrowed beams and Porsche brakes in T1’s.  In the rear, longaxle/IRS cars will fit upto a 7″ wheel.  For early offset wheels (Fuchs, Burners) and Porsche brakes, longaxle/IRS rear suspension will lead to fender fouling, so shortaxle is best. Superbeetles will take 17×7’s at all 4 corners with 1302 suspension and Porsche brakes, but the added width of 1303 suspension may require wider fenders or narrow offset brake conversions.  Please email with your specifics for guidance.