Is there a difference in hub "width"?

cstreit · cstreit's Garage

Gang,

I got most of my VCI modified 964 brake calipers installed but ran into difficulty getting the right rear caliper on. The brake disc was spaced out about 4mm.

Upon further inspection I noticed that while the hub on the left side looks like this... (Notice the TABS on the center of the hub)

The right side looks like this... No tabs..

So any ideas? Is the hub just not pressed in right? Is it from a different model that had a wider offset?

Is it worth replacing myself considering the amount of work it takes to press, pound, heat/cool these things myself...? Is there another way?

cstreit · cstreit's Garage

FYI, here's a shot of the front... I know the calipers are cruddy, but I could paint them and they'd look like hell after 3 laps on the track...

Bill Verburg · Bill Verburg's Garage

The tabs were added some time in the mid 70's to center the wheel on the hub. You have an early hub w/o the hubcentric feature on one side and a later hub on the other. I think that you have answered yor own question. If the rotors are fully seated then there is a difference in the hubs. This would help explain why some people have had to shim calipers on big brake upgrades while others have not. Have you updated to the alloy arms? If not this would be a good time to do so. Other wise swap out the offending hub.

cstreit · cstreit's Garage

I have updated to the aluminum arms... So looks like I need to back-date the right hub. Darn! Lots of persuasion and I'm not sure I'm up to the job...

KTL · 03-26-2002, 10:17 AM

Chris,

How did your old M caliper rotors mount to the hub? Same way, no? Just slip them onto the hub and that's it, right?

Why would the new 944T rotors suddenly cause a problem? I would think if the new rotors were an incorrect sizing for your application, both rotors would not fit properly. That of course assumes that everything fit properly prior to the brake upgrade and that assumption must be correct since I saw video of you burning up the track with your car!

Maybe one of the new calipers is machined incorrectly?

Just some guesses on my part.

Good luck

Tyson Schmidt · 03-26-2002, 10:33 AM

The hub without the snout is a pre-'74 hub made for the narrower rear wheel bearing. The other is a '74 and later hub. Yes, they are 5mm different. The flat hub will stick out 5mm farther, due to less of a machined area for the bearing.

KTL · 03-26-2002, 10:38 AM

Thanks Tyson.

Now, what I would like to know is how the heck was Chris' car set up before with the old calipers?

The mystery continues.........

katigbr · 03-26-2002, 01:47 PM

I also upgraded my trailing arms to the aluminum but kept my old hubs. Am I going to have problems? I haven't run the car yet but hearing that the bearings are different has got me worried. I noticed that when I installed the driveshafts that the cotter pin hole was around 5mm deeper than I remembered it but put off worrying about it until later. It all becomes clear now....

Can I use the old hubs with new arms? It sounds like I would be running on less bearing surface (same as old). Is there anything regarding using old hubs with new trailing arms that I need to worry about? Can I just drill new holes for the cotter pins without compromising the shaft strength?

Regards,
Rick