vanwyk4257

Do I need to change my master cylinder along with the brake upgrade for additional volume or is the stock '83 master cylinder capable of working with the Brembo S4 brakes?

I also have an extra set of S4 calipers, front and rear, in good shape (painted red by PO) that I am selling for $600 obo plus shipping.

Thanks!

cdbtx

No need to change the master cylinder.


Chuck

83 Kiln Red 928S (With S4 Suspension and brakes)

Pfunde

Mike, maybee i'm insterested in tha calibers, just one question - will they fit on my 78' ( with modefications - whatever is needed ).....

:-) Pfunde

vanwyk4257

Pfunde, go look at 928 Specialist's website, they sell kits to do this. You can buy adapters and hardware kits to mount these directly to your '78 spindles in the front and I think you simply use spacers in the rear with the new rotors. You can email me at mvanwyk@sbcglobal.net and I'll send you some pics if you are interested. Thanks!

Chuck,
Thanks for the advice on the master cylinder, that's what I was hoping to hear!

rjtw

Hi Chuck, Mike,
I have an '83 also and am curious... what else is involved in the upgrade? Do you have to change spindles etc.? Do you have to do anything to maintain proper fore/aft brake balance? I have to change rotors soon anyway -- if the upgrade is not much more work it might be a good chance.

Also, Chuck, how well has the upgrade worked for you? I think the brakes on my car are generally adequate, though they can start to fade under hard use. On the other hand I haven't been convinced that S4 brakes are much better, just because the few S4's I have driven seem to have a more mushy brake feel than my car. How do the upgraded brakes on yours compare to the originals?

DR

>I have an '83 also and am curious... what else is involved in the upgrade?

FYI, I have in my hand the prototypes for our new Bolt On Big Brake adapters for the 82 thru early 86 (80 Euro S and up) that DOES NOT require a front spindle change! With these we now have bolt on adapters for all year models to allow you to bolt on the Big Brakes without out any spindle changes etc.!!

Pricing will be under $200 for the adapter set. Testing has already started and as soon as I am happy with the setup and have some in stock I will formally announce them.

rjtw

Dave, sorry for my ignorance, but what is the "Big Brake" system (e.g. does it correspond to a stock 928 setup such as S4 or GTS), and will it fit with S4 wheels? Does it require fore/aft balance changes?
Thanks!
Rick

DR

Hi Rick,

>Dave, sorry for my ignorance, but what is the "Big Brake" system (e.g. does >it correspond to a stock 928 setup such as S4 or GTS),

Yes, adding S4 or GTS brakes to an eariler 928.

> and will it fit with S4 wheels?

S4 will, GTS type will not.

>Does it require fore/aft balance changes

No, but if you want to change you front/rear balance we can supply different rear brake regulators.

cdbtx

Rick,

I can't say enough about the upgrade, probably the single best thing I've ever done to the car. The entire suspension on mine is S4 now, added the hard bushing, and Bilstein/Eibach package, then S4 brake upgrade was a simple bolt on. It's like driving a new car..

Chuck


83 Kiln Red 928S

vanwyk4257

I will be doing the entire suspension upgrade as well, but I'm sure DR will do very well with the adapter for the '82-E86 cars. I plan to probably upgrade to stiffer springs and replace most of the bushings prior to installation as well. Once installed it will all get professionally aligned and corner-balanced to get ready for next year's track season!

2V4V

You don't HAVE to change the vacuum booster, but it is a different ratio for the later cars.

If you do update the booster, you MUST upgrade to a later model brake pedal, or at least, grind the stop off the early one. (ask me how I know...)

Greg

vanwyk4257

Greg, Thanks for the tip! I'm going to try it as is and see how it does on the track and street before I change all of that. What's the difference in the ratios on the later cars, is it more or less rear bias?

2V4V

Mike,

Don't have my data with me, and don't trust my memory that much. I'll try to post it tomorrow.

Not using the later booster/MC/etc. shouldn't really pose any issues.

Hope all is well is Grand Rapids, used to live there when I was a kid.

Greg

vanwyk4257

What part of GR? It's a great town, I grew up here and moved back after being away for a while in Iowa and Arizona. The winter weather and potholes are no fun, but we have Gingerman and Grattan raceway both within an hour so it's not too bad!

2V4V

Mike,

The difference in the Vac Booster ratio should probably not matter a lot. The main difference between the pre-84 and the post 86.5 brake hydraulics is/are the brake force regulators.

Pre 84 cars have 2, one for each of the rear wheels. Later cars have just one, that covers both rear wheels (no longer 'dual-diagonal' braking circuits).

The manual does a good job explaining thus "Until pressure rises to the switchover point, the same overpressure is applied to the input and output sides of the braking-force regulator.As the pressure in the input side rises further, the output overpressure (rear-axle overpressure) is reduced."

Pre 84 MY cars use either 55 bar or 33 bar switchover points, with one reg per dual diagonal circuit. 84-86.5 cars use a single 33 bar switchover for the rear axle. 86.5+ cars (the ones with the 4 piston calipers up front) are setup also with a single set at 18 bar switchover.

I used to live in SE. 2435 Richards Drive. Went to Breton Downs for kindergarten. Haven't been up in 20 years, though next time I'm up in Coldwater MI, I might take a little time and cruise up to the old hood, as it were. Go eat at Bill Knapps, or Granny's or something (if they even still exist...).

HTH,

Greg