RSAErick

I recently completed a brake and suspension upgrade, and I wanted to share the experience. There were a number of challenges; but with the help of many, none were insurmountable. Special thanks to Steve Weiner and Bill Verberg for their personal guidance throughout. I am very appreciative of everyone that I have learned from here - truly amazing and generous people here. I am anxious to contribute something to this community, but I doubt that I will ever be able to give as much as I have taken.

Anyway, as background information, here is how the project unfolded, and the logic (or lack thereof) that I used to determine the outcome:

Initial Observation: Front and rear brake calipers were in need of repair, due to the caliper piston boots being torn.
- Option: Brake caliper rebuild
- Slippery Slope: Instead of investing the money into rebuilding the 964 calipers, I would invest the money into 993TT (red) or 928GTS (black) big brakes. Bigger brake pads would be more resistant to heat from track driving, and would last longer - saving money in the long run. Of note, the proper big brake upgrade combo for the 964 is 993TT (or 928GTS) front calipers and 993NB rear calipers.


BUT, once my decision was made to upgrade the brake system (rather than repair it), I came to several realizations which illuminate how the slippery slope works:

Realization #1: The 964 master cylinder is not designed for the fluid requirements of the 993 big brake calipers, and may not provide the firmness desired for track use.
- Solution: 993 master cylinder
- Slippery slope: The 993 master cylinder requires the use of the 993 brake booster. Also, the 993 master cylinder only accommodates 12mm brake line fittings, whereas the 964 uses 10mm fittings.

Realization #2: The 993TT/928GTS front calipers do not fit directly on a 964 wheel carrier
- Option: Purchase adapters to fit the big brakes to the 964 wheel carrier
- Slippery Slope: Use 993 wheel carrier
- Super Slippery Slope: Use 993RS/EVO wheel carrier - which also gives you the added benefit of eliminating the bump steer problems that are experienced when the 964 is lowered to RS (or below) ride height.

Realization #3: 964 Ball Joints and 964 Tie-Rods do not fit 993 wheel carriers
- Option: Use 993 Ball joints and 993 tie-rods
- Slippery slope: Use 993 or 993RS Tie-Rods
- Super Slippery Slope: Use 993RSR Tie-Rods, which have no rubber.


993 Ball Joint (left) vs. 964 Ball Joint (right):




Here is what I believe to be a complete parts list for the Big Brake and EVO upright upgrade. Please contact me if you would like this spreadsheet sent to you:






Of course (as usual), I encountered several major (and unanticipated) challenges during the process....

Challenge #1:
Removing 964 front wheel hub from 964 wheel carrier: To begin with, the hub is attached with a 32mm bolt/nut that is tightened to >300 ft-lbs. I recommend leaving the wheel carrier attached to the ball joint/tie-rod/shocks, as this will help support the unit during forceful measures. The use of a 1/2"-drive breaker bar failed. I was finally able to remove it with a Snap-On 18V impact driver. But it wasn't easy! Second, the wheel hub is pressed into the wheel bearing. I was able (with guidance) to remove the hub using a slide hammer attached to the wheel studs. This also took a lot of force.

Also, the 993 wheel bearing will need to be pressed into the 993 or EVO wheel carrier; and then the 964 hub will then need to be pressed into the 993 or EVO wheel bearing and carrier assembly. I had my local shop perform this job.

Here is a picture of me using a slide hammer to remove the 964 wheel hub from the original wheel bearing/carrier:




Challenge #2:
The 993 master cylinder accepts 12mm fittings, whereas the 964 brake lines use 10mm fittings. There are some discussions about using 10mm to 12mm adapters. However, I chose to have my local Porsche shop (Redmond European) cut, bend, and flare new 4.75mm brake lines using 10mm fittings on the 964 side, and Fedhill 12mmx1.0 fittings on the 993 master cylinder side. Here are the fittings that work:
http://store.fedhillusa.com/m63.aspx


Challenge #3
The 993 brake booster will not fit into the 964 bearing bracket. It is too large. I was able to use a die grinder to bore out the inside diameter of the 964 bearing bracket to accommodate the larger booster end. The 964 bearing bracket is made of aluminum, so use the correct grind tool for this softer metal. And, because the pieces fit together slightly differently, I needed to adjust the brake pedal to depress the brake light switch at rest - otherwise, the brake lights were always on.

The next two pictures show the differences between the 964 and 993 brake booster:






Here is a picture of the new 993 brake booster overlaid with the 964 bearing bracket that it needs to fit into:




Here is a picture of the inside of the 964 bearing bracket after increasing the inside diameter by die-grinding:




This is a picture of the brake light switch and pedal adjustment point - located under the wooden floor board. After the 993 components were reconnected, I needed to adjust, so that the brake light switch was depressed when the brake pedal is not depressed:




Challenge #4:
As pointed out by Oleg (perelet), the knurled screw on the 964 control arm is smaller than the 993 version. Likewise, the 993 ball joint, which fits the EVO upright perfectly, has a larger mounting hole for the control arm knurled screw than the 964 version. Please see the following thread for details: https://rennlist.com/forums/964-foru...carrier-3.html

After consideration to using 993 control arms, or to adapt a 993 knurled screw to the 964 control arms, I chose to mount the 993 ball joint to the 964 control arm without adaptation. I am hoping that the torque of the mounting nut and caster eccentric are sufficient to hold the ball joint in place. However, I am very open to discussion about the wisdom of this decision.

Here is Oleg's picture of the 964 knurled screw with the 993 ball joint:



Challenge #5:
The Porsche Motorsports 993RSR tie-rods (top) are significantly longer than the 964 tie-rods. At the minimum adjusted length, the RSR tie-rods were too long when attached to the 964 manual steering rack and Evo uprights, resulting in unacceptable toe-in. The solution was to cut the threaded portion of the tie-rods on both the steering rack side and on the wheel carrier side, so that they could be threaded in far enough to get proper toe alignment. Also of note, the 993RSR tie-rods adjust in a different fashion that the 964 tie-rods (bottom), because they are 2-piece, rather than 3-piece. Also, keep in mind that the 993 tie-rods use a different bellows/rubber boot, and the 964 version will not fit the 993 tie-rods.




Proportioning Valve
I also decided to remove the internal components of the brake proportioning valve, since it was reported that this would provide less front bias than was designed for a street 964:




Here is the finished product (front):




I have three track days with the new setup, and can confirm that the bump-steer issues have been dramatically improved with the EVO uprights; and I am now running with a lower ride height. And the big brakes feel very solid and have vicious bite. But the braking stability and tracking is also much better; although there were so many changes made that I don't know which changes are primarily responsible - suspension, alignment, and ride height were also changed, in addition to EVO uprights and big brakes. Also impressive, the brake pad wear has dropped dramatically.

If you plan to embark on this upgrade, I hope that some of this info will help.

Best of luck!

geordie

Erick,

Great write up and information.

Thank you

Babalouie

Not so much of "slippery slope" as "slippery cliff"

sc

Props to you Erick! No doubt this write up will be a great resource to many. Thanks and cheers!

GeorgeK

Is it the angle of the picture, or is the bridge line on the caliper out of its recess and dangerously close to the brake disc?

That said, beautiful setup!

ghhally

Erick,

thanks for confiming that parts sitting in my garage, will finally fit
my car once rebuild starts.

Not wanting to touch the 964 parts, I also picked up the bracket for the brake booster / master cylinder.

How did you solve the 12 to 10 mm brake line connections?

RicardoD

Great post and reference for others. Your Rennlist Karma is high now.

Laker

Nice job Eric, thanks for documenting it all

KaiB

Wahoo Erick....on the road with your project, well done!

As time wears on, you'll most certainly notice your brake upgrades. For heat dissapaation alone the job was worth it, but as you begin to really push the car - you'll see.

Can't wait for the next update, tehe....

RSAErick

Thanks guys! I appreciate the comments and feedback. Anyway, now that I'm back in town, I wanted to answer some of the questions...

I hope not! I'll have the wheels off tonight or tomorrow, and will inspect. I did not remove or modify the bridge line at all, since the orientation of the bleed lines on the 928GTS calipers appeared to be the same as the 964. However, I've read that the feed and bleed lines may need to be reconfigured for 964 adaptation... now I'm concerned that something may be incorrect.



Yes, purchasing the 993 bearing bracket (rather than modifying the 964 bracket) would be a good solution also, I suppose. I was trying to be 'frugal' as I was sliding down the slippery cliff.

For the 12mm to 10mm brake line adaptation, I had 2 new brake lines cut and bent to the approximate dimensions as the previous 2 lines; and purchased 12mm x 1.0 threaded fittings for a 4.75mm brake line from Fedhill (http://store.fedhillusa.com/m63.aspx). The new lines were flared with the standard 10mm fittings on the side that attaches to the 964 brake system; and 12mm fittings on the 993 master cylinder side. Although the hard brake lines are a bit hard to route correctly by not-so-gentle 'massaging', it worked perfectly, and is a very clean adaptation.

Bill Verburg

Nice job! Nice write up!!

race911

And people think the 964 and 993 are basically the same............

Now some may see why I decided to just leave RSA #1 alone to race in stock class. (I had a bunch of stuff laying around that was destined for my '92 C4 that I had previously time trialed, but even with the hydraulic assist brakes I quickly realized it was not going to be a simple bolt on.)

RSAErick

True. Doing this properly is not a completely straightforward adaptation. At least not for an amateur, such as myself. Considerations for race classes may complicate the decision process; however, I do not have plans to race this car - merely to 'optimize' it for my use. I have been reminded several times during this process that everything is a compromise; and I see that very clearly now.

swftiii

I did almost the same thing this year and have my first track day with the new brakes this weekend. I'm using Porsche cross drilled rotors, but have the same setup after that, but without the 993 uprights.

Can't wait!

Skip

RSAErick

I temporarily disconnected the sway bar to install the booster. After that, the 993 booster fit well.

Let us know if that does the trick for you. Best of luck!