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Old April 29th 2010, 16:06
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Post 993 Turbo Front Brake Upgrade - Part I

by Sandeep Syan

People may be asking....Why would you want to put brakes that are capable of generating 2000 hp of braking force onto a beetle that is capable of maybe 120 mph at the most ? There are systems available from various manufactures that will increase the braking capacity of the humble beetle to levels that are quite satisfactory for most.

I for one, have greater expectations from my beetle than most will have.

In the past, I have had the chance to enjoy the thrill of racing a 125cc shifter kart competetively. I placed well in the races I competed in...but as the race progressed, the kart never stopped as good as it did in the first few laps...due to the solid rotor, single piston caliper braking system I had. I then tried a friends kart for one race and was blown away by the braking power the kart had towards the end of the race...allowing me to drive more aggressively. No wonder.....the system consisted of vented, cross-drilled rotors with dual piston calipers.

Using this as a learning experience and, as I plan on racing my beetle on the weekends...I though, why not go for the best I can afford. After researching the various brake upgrades out there and their cost, I finally gathered the parts I needed for my 993 Twin Turbo front brake conversion.

This conversion is different than the rest because it requires NO MACHINING of the hubs. The only machining required is making some bearing spacers.

The parts list includes:

(2) front hubs from a 1987 944 Turbo, part # 951.341.605.03R, Porsche
(2) 944 Turbo inner bearings, part # L68149, SKF
(2) inner bearing races, part # L68111, SKF
(2) 944 Turbo outer bearings, part # M12648, SKF
(2) outer bearing races, part # xxxx, SKF
(2) inner grease seals, part # DFS 45x62x10 979.809.NBR, Kaco Radia-Wellendichtring
(2) CB Performance cast dropped spindles for disk brakes
(2) 993 Turbo front 2 pc rotors, 322mm x 32mm, part # 993.351.046.10 right, 993.351.046.10 left
(2) custom machined aluminum rotor hats to give the correct offset to the rotor while using the 993 rotor on the 951 hub that we have the parts, lets get on with it !!


Here are some images of the rotors and custom aluminum hats. The hats are needed to give the correct spacing between the rotor and spindle as you shall see in later pictures.


Step 1

Here is the back view of the CB Performance dropped disk brake spindle. I've already tapped the bottom hole for M12 x 1.25 bolt (12mm metric bolt). It should be noted that this spindle is mounted upside down on my workbench to make fitting the parts easier. I've already cut off the top caliper mounting ear because it interferes with the 'Big Red' caliper. I suggest you fit the rotors first and then worry about modifying the caliper mounting points on the spindle. You will also need to make a bracket to fit the caliper to the spindle.


Step 2

Here is a view of the bearing spacers....starting from the left, Grease seal spacer, Inner bearing spacer. In this picture, I haven't yet installed the outer bearing spacer. I can't give you specific measurements on the spacers because when I went to the Porsche dealership to get new bearings and seals, there were 2 different sizes of bearings I could get. No Idea why....but I went with the bigger size of the two. I had the spacers machined with an 'interference fit'...which means that they had to be heated a bit to get them to expand and then they were pressed on to the spindle to insure they would not move.


Step 3

Next step is to fit the bearing races that come with the bearings to the hubs and then install the bearings with grease into the hubs. Install the hub onto the spindle and then tighten up the retaining nut so its snug. Pic 3 shows the spacing between the stock hub and spindle.


Step 4

The next step is to bolt the aluminum adapter hats to the rotors. This procedure has been covered in detail on the web so I will not cover it here. Then you can secure the rotor to the hub using the 2 small screws that come with the hub. The last pic shows the clearence between the rotor and spindle with the adapter hat.



For my application I am using 18 x 8.5 Cup 2's with Pirelli P Zero Assymetrico 235/35/ZR on the front and 18 x 10.0 Cup 2's with 265/35/ZR on the rear. Here's what the 322mm x 32mm rotors look like with the front wheels.

This conversion increases your total width per side by 7/8" (22mm). The CB dropped spindles are 1/4" (6.35mm) wider over stock spindles so if you were to use stock ball joint spindles, the conversion would increase the total width per side by 5/8" (16mm).

With my 18 x 8.5 Cup 2's on the front, at full lock to the right, the inside of the tire rubs on the lower bottom trailing arm and full lock the other way, rubs on the lower inside fenderwell, close to the heater channel on the pan. I hope to take care of this by adjusting the steering stops. If that does not work than a little bit of clearencing with the grinder might be in order.

Another view of the rotors behind the wheels. Part II - Fitting the 'Big Reds' to the spindle assembly coming soon ! This upcoming article will detail how I made the bracket to attach the caliper to the spindle. If you have any questions about this article, drop me an email and I will answer any questions you might have.

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