Luke Skaff Past and current projects…

Third Generation GM F-Body Brake Upgrade – Making a Hub (6/9)

On my setup I am using 88-96 corvette C4-HD (13 inch) brakes which requires a larger offset hub (the heavy duty, HD, hub).  The C4 HD 13-inch front rotors have a large offset (rotor inside hat to rotor rear surface), in order to fit the caliper bracket and caliper in between the spindle and the rotor you need a large offset hub to push the rotor out further. To achieve this larger offset you will need to create a hub with a larger offset by starting with a rotor that has a larger offset like the 88-92 F-body 1LE rotor. I have done this below, another option is to turn down a stock rotor and use spacers.  I do not recommend the spacer method as it will put more load on the front bearing.  One benifit of the HD hub over the standard hub is the front wheel bearing is larger then the standard thirdgen rotor.

Brake upgrades using 88-96 corvette C4 Non-HD 12-inch (with C4 rear rotor), LS1 F-body, and corvette C5 & C6 setups you can machine down the factory 82-92 F-body rotor into a hub in the same process seen below.

You can take a set of rotors to just about any local machine shop and they can do it for you.  All you need is a lathe.  Make sure to bring the new rotor with you so they can check fitment.

1) Since it is very hard to find someone with a used set of 1LE rotors I started with a brand new set.

GM Third Generation F-Body Stock 1LE Rotor

2) Spray on a penetrating oil (eg. PB Blaster) on the studs and let it sit for 15 min or so.  Use a press to remove the studs or tap them out with a hammer.

3) Now you need to cut the rotor off the hub to prepare it for machining on a lathe.  I used a angle grinder, which is a simple but effective way of doing it.
  

4) The hubs need to be machined on a lathe to take off the extra material so they will fit inside the hat of the rotor.  Also this step is needed to make them round and balanced.  For C4 and C4 HD upgraded take the hub down to a 5.95 inches diameter.  For other setups just bring the new rotor you are going to use into the machine shop with you and tell them to machine it down until it fits into the hat of the rotor.

For LS1 rotors and some C5 & C6 rotors there is an inner lip cast into the inside of the rotor hat.  The hubs need a taper cut into them to clearance the this lip in the rotor.  If you do not account for this the inside of the rotor hat will not sit flush against the hub.  This is easy to do while the hubs are on the lathe.  Below is a picture of a standard Thirdgen rotor turned into a hub to clearance a 12" LS1 rotor, note the lip \ tapper on the front face of the hub.  The LS1 hub is turned down to a diameter of 5.87 inches, C5 and C6 setups should be similar but may be able to accommodate a larger diameter hub.

5) Here is a final picture of the HD hubs after they have been prepped with a coat of por-15 and are ready to go on the car.

Page created: January 2006
Page content last updated: October 2011