Which hub for 996TT brakes onto 88 Carrera?

[billjam]

I've had a full set of 996TT brakes gathering dust in my attic for years and I am looking at what is involved in fitting them to my 88 Carrera.
I can make my own caliper adapters, but I can see that different front hubs will definitely be required for mounting the discs.

Can someone who has done this conversion let me know which hubs will do the job?

[jetstar911]

PFFF, I'm in the same boat! I would like to know as well.

[175K911]

I got mine from Steve Timmons at InstantG. He custom fabs the hubs to use the 996TT rotors with the Carrera bearings and struts. Not sure he'd sell just the hubs though, but he does sell the full converstion package with the hubs and adapters. Several years of dedicated track use and never a single problem. And my BIL must have 100+ track days on the same setup on his 3.6 SC and never a problem.

But keep in mind that the 996TT brakes are heavily biased to the front. Anyone I know who's done the full conversion has front brake lockup challenges on the track. Many of us have run different pad combination front to rear, but my BIL and I both converted to the Fabcar dual MC brakes with different size master cylinders front and rear to correct the heavy front bias.

The good news is that the brakes are so understressed on a light 911 Carrera or SC that you can get several years of track use on a single set of rotors. And I've never boiled my brake fluid.

Early shaved 944(VW type) with spacer and caliper adapter. Yes on using Timmons for kit. Have it on my car and is an overkill!

[spuggy]

Originally Posted by 175K911

But keep in mind that the 996TT brakes are heavily biased to the front. Anyone I know who's done the full conversion has front brake lockup challenges on the track. Many of us have run different pad combination front to rear, but my BIL and I both converted to the Fabcar dual MC brakes with different size master cylinders front and rear to correct the heavy front bias.

The 996TT front to rear bias is 1.92:1 - and the 993TT is even worse, at 1.99:1. Which is just fine on a car with ABS...

The bias with the 996 N/A (aka Boxster S) calipers and rotors front/rear is 1.7-something (my figures say 1.72:1 hydraulic and 1.77:1 torque, factoring in the rotor sizes as well) - a lot better - and a bit of tweaking with grabbier rear pads improves that still further.

Although you can still push the front wheels along in a cloud of smoke if you hit the brakes from heavy boost without letting the front suspension settle, or really jump on them, I think this would work better for most folks who aren't running really hard at the track, or who don't want to go with dual master cylinders (which is obviously the superior set-up).

I was prepared to yank the booster and go with a SC/RS repro dual M/C set up if I had to, but I'm quite happy with how the bias worked out, with the Pagid Yellow/RS14 combination.

Originally Posted by 175K911

The good news is that the brakes are so understressed on a light 911 Carrera or SC that you can get several years of track use on a single set of rotors. And I've never boiled my brake fluid.

Exactly. Even 996 NA brakes seem very understressed on a ~2600 car driven primarily street/few track days, even with lots of HP on tap (modified turbo)... Main reason was the bias concern, but I didn't see the point of having bigger/heavier brakes than needed either...

The 996 front rotor volume, just calculating/comparing rotor dimensions and ignoring the hubs/non-swept area, are 96% of 930 front rotors (996TT fronts are 29% bigger, or 125% of 930's)..

I installed the 996 brakes a couple of years ago - I'm still on my first set of pads (something over half worn), can't find a lip on the front rotors and don't change the fluid after a track day (in fact, the fluid still looks fine after 3 track days, when I do change it)... That works for me...

For the OP, the kit from Instant-G includes everything needed except hard lines - hubs, new seals, bearings, adapters and all fasteners of the correct length/hardness. Just sayin'

[billjam]

Thanks for the feedback guys.
You have inadvertently confirmed what I suspected deep down - I really don't need 996TT brakes on a mostly street-driven Carrera!
I also have a set of Boxster calipers complete with mounting kit, so I think I will head in that direction instead.