Projects:
Overview
Porsche Engine Conversion
Front & Rear Disc Brake Conversion
Hydraulic Clutch Conversion
Fuchs Wheel Conversion
Rack & Pinion Conversion
930 3.3 Turbo Engine Swap
RC10 VW Bus
VW Type 2 Fuchs wheel conversion
by Harold Williams
July 2011

When I decided to switch to Fuchs wheels I wanted to retain my current disk brake set up. I used a 912 hub which is 1/2" narrower than a 911 hub. This would allow a wider wheel/tire combination. I also used a 912 front rotor due to the dimensions being very close to the stock '71 VW disk. This allows the use of the stock VW caliper or Wilwood caliper using the stock mounting location, with the option of changing to a bigger rotor/caliper combination. The 912 disk didn't require any modifications to work with the Wilwood caliper I'm currently using. The disk may need to be turned down to work with the VW caliper. The V.W. rotor is approximately 10.750" vs the 912 rotor at 11.125".

I test fit a few different wheel/tire combinations. The widest was a Fuchs 3 pc. wheel measuring 8" x 17" w/245/35/17 tires. The backspacing is 5.5". This combination fits in the front wheel well with a slight rubbing on the inside if the wheel is turned full lock. At this time I'm going back and forth between Fuchs 7" x 16" w/205/50/16's Toyo T1R tires and Fuchs 7" x 15" w/215/55/15 Michelin TB15 tires.

Below is a description of the modifications made to the 912 hub. An aluminum spacer was made to fit between the hub and disk to locate the disk in the stock V.W. disk location. This allows the use of the stock caliper, or a Wilwood caliper, which is pretty much a direct swap out. The dimensions below worked for my application, they should be considered a starting point.

Hub modifications: The inner & outer bearings needed to be moved out to compensate for the bus spindle being longer than the 911 spindle. I made 2 spacers that were inserted between the bearing seat and bearing. The front spacer is .225" thick, 1.625" i.d. and 1.780 o.d. The rear spacer is .200" thick, 2.050" i.d. and 2.310" o.d. These were a snug fit, but not a press fit. The rear of the hub was also enlarged to 2.560" to accept a stock VW bus bearing seal. The rotor mounting surface was flycut.

Spacer: 1.250" overall thickness. Recess to fit the hub, .225" deep x 4.210" i.d. Extension to fit disk, .265" high x 4.220" o.d. Spacer thickness .950". Drill 5- 8.5mm holes for bolts. Allen head bolts measuring 8mm x 50mm with 2 washers and lock nuts were used.

Parts listPrices (paid in 2009)
Porsche 912 front hubs (used)$70.00 pr.
Porsche Inner wheel bearings17.00 pr.
Porsche outer wheel bearings13.50 pr.
VW rear seal
912 solid rotor (.050" thick) 100.00 pr.
dusk caps milled from billet aluminum20.00 pr.
1 1/2" x 6" aluminum spacers to relocate rotor100.00 pr.

Rear hub seal to try: SKF-38/62/10 HMSA7V

For the rear I'm currently using a H&R 5/8" thick 112mm to 130mm wheel adapter. Wheels and tires are Fuchs 3 pc 8" x 17" w/245/35/17's. The backspacing is 5.5". I rolled the rear fender using a baseball bat to clear the tire. A Fuchs 8" x 16" from a '86 944 turbo (1 yr. only) would also work. This wheel has an approximate backspacing of 5.5" vs. a 911 8" x 16" which has a 4 7/8" back spacing. I'm in the process of trying a few different things to avoid using the wheel adapter, as well as fitting a wider wheel/tire combination.

VW rear hub modification
by Harold Williams
August 2011

In order to avoid using a wheel adapter, which i had been up to this point, I decided to modify the stock VW 5 x 112mm rear hub of my 1968 Crewcab to the Porsche 5x130mm bolt pattern. For some reason the hub has a "V" notch. To fill it, I cut a 1/8" wide x 3/16" deep groove in the notch. A piece of 1/8" thick steel was inserted into the notch and welded on both sides. The holes for the drum retaining screws were also welded. I used a 5x112mm to 5x130mm wheel adapter bolted to the hub to locate the Porsche bolt pattern. The holes are 14mm to accept either Porsche or after market studs. The old studs were cut flush and left in place. To give the wheel some extra support I made a hub centric ring 2.815" o.d. dia. x .500" high and welded it to the hub. The ring was slightly larger than the final dimension, then turned it down to the finish size after it was welded. The hub was turned down to a 6.195" o.d. diameter to fit inside the rotor. I used 77mm studs to allow the use of a spacer if needed. To compensate for the longer studs I drilled out the end of the Porsche aluminum lug nuts.

Since I planned on retaining the Wilwood calipers from the first disk brake conversion I chose a Boxster rotor (#986-352-401-04-MS) which is dimensionally close to the Audi rotor I was using with that set up. The o.d.diameter was turned down from 11.640" (291mm) to 11.125" to enable the caliper to clear the bolts on the 3 pc. wheels I was using. This probably wouldn't be necessary using 17" diameter wheels. The inside of the rotor was rubbing the trailing arm so a 1/16" aluminum spacer was used between the hub and rotor for clearance. The caliper bracket was made from 3/16" thick aluminum plate similar to the previous one. The "S" shape on the top section of the bracket allows the caliper to set into the bracket.

To fit the fatest tire in the wheel well, heavy duty spring plates replaced the Sway-a-way adjustable spring plates. The wheels are set up with 1 degree negative camber and 0 toe. I stretched/flared the fenders approximately 5/8" using a 1 1/2" diameter aluminum pipe. There is about 1/8" clearance between the inside of the fender and the tire side wall. The current wheels are 3pc Fuchs centers with 16" BBS 5.5 inner and 3.0 outer rims making the rim 8.5" wide. Tires are Toyo T1R 245/45/16's measuring 9" wide at the side wall.

The rotor-face-to-rotor-face distance is approximately 55 9/16" vs 58 3/4" using the '86 aluminum 944 trailing arms. A stock '86 944 turbo 8x16" Fuchs wheel (one year only) should clear the fender. The 944 8" x 16" has approximately 5.5" of back spacing vs 4 7/8" back spacing of a 911 8" x 16" Fuchs wheel. A 225 or 245/45/16" should also work.

Parts list    (prices paid in 2011)
used V.W. rear hubs    $40.00
Boxster rotors    90.00
aluminum plate    50.00
misc. supplies    30.00
72mm wheel studs    60.00
H.D. spring plates & bushings    215.00


click on photo to enlarge

  • rear hub front

  • rear bracket

  • rotor

  • rotor and caliper

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Overview   |   Porsche Engine Conversion   |   Front & Rear Disc Brake Conversion
Hydraulic Clutch Conversion   |   Fuchs wheel conversion
Rack & Pinion Conversion   |   RC10 VW Bus



Related site: The DP935 Registry

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