Rear brake upgrade (again, lol), Or,how to get a vented rotor Options

[HalfMoon]

Cross-drilled are a waste of time for almost all cars. (Rotors with cast-in holes can be OK, and drilled can be OK for a track car that gets torn down and minutely inspected every event, but very much not for a street car.)

To manage heat problems, ducting air to the rotor and caliper can help immensely. I remember Chuck Forge had clamshells around the whole rotor that were fed by an air scoop pushing high-pressure cold air onto them. You couldn't see any of the rotor.

--DD

--DD

That's very good to know as the non-drilled vented rotors are a good deal less expensive.
Like the idea of ducting...the Sheridan body I have would make for a good duct opening just fore the rear wheels, no?

[HalfMoon]

Sooo, I reckon the Sebro 20mm will work allright
http://www.pmbperformance.com/catalog/item...576/9661559.htm
And using the stock caliper, from what I've read I'll have to have Eric cut em down a bit, then use a spacer for the caliper and a spacer betwix the rotor and the hub?
Um, and I have to re-drill a centering hole to, eh?
Have I missed anything?
Seems like an easy and cheap mod.

[mepstein]

On mine, i just shaved down the rotor diameter 2-3mm. I didnt need any spacers but I am using 911 hubs. If you are using a 4 hub, you can re drill holes for the set screw but its not needed. Once you put on the wheel and tighten the lug nuts, everything is held secure. Rotors wont "fall off" when you remove the wheels since the caliper holds them on.

[HalfMoon]

On mine, i just shaved down the rotor diameter 2-3mm. I didnt need any spacers but I am using 911 hubs. If you are using a 4 hub, you can re drill holes for the set screw but its not needed. Once you put on the wheel and tighten the lug nuts, everything is held secure. Rotors wont "fall off" when you remove the wheels since the caliper holds them on.

Thanks for chimming in on that. I had read a thread where someone claimed that they needed to drill and tap a new guide as they felt the spacer between the rotor and hub had compromised the ability for the rotor to self center. I had thought that kinda odd as the lug studs center the rotor....
Mebbe because you hadn't used the spacers, you didn't encounter that problem?
Either way, not difficult to solve.

[mepstein]

On mine, i just shaved down the rotor diameter 2-3mm. I didnt need any spacers but I am using 911 hubs. If you are using a 4 hub, you can re drill holes for the set screw but its not needed. Once you put on the wheel and tighten the lug nuts, everything is held secure. Rotors wont "fall off" when you remove the wheels since the caliper holds them on.

Thanks for chimming in on that. I had read a thread where someone claimed that they needed to drill and tap a new guide as they felt the spacer between the rotor and hub had compromised the ability for the rotor to self center. I had thought that kinda odd as the lug studs center the rotor....
Mebbe because you hadn't used the spacers, you didn't encounter that problem?
Either way, not difficult to solve.

Put on new rubber flex lines if you havent done them recently. Its so much easier to do now and they sure dont get better with age.

[HalfMoon]

On mine, i just shaved down the rotor diameter 2-3mm. I didnt need any spacers but I am using 911 hubs. If you are using a 4 hub, you can re drill holes for the set screw but its not needed. Once you put on the wheel and tighten the lug nuts, everything is held secure. Rotors wont "fall off" when you remove the wheels since the caliper holds them on.

Thanks for chimming in on that. I had read a thread where someone claimed that they needed to drill and tap a new guide as they felt the spacer between the rotor and hub had compromised the ability for the rotor to self center. I had thought that kinda odd as the lug studs center the rotor....
Mebbe because you hadn't used the spacers, you didn't encounter that problem?
Either way, not difficult to solve.

Put on new rubber flex lines if you havent done them recently. Its so much easier to do now and they sure dont get better with age.

Chuckle. Way ahead of ya Bro! I just finished up a total brake rebuild and included the rubber lines.
This vented rear idea is kinda after the fact :-(
At least when I go to crack open the calipers for the spacer they'll be freshly rebuilt, eh? Less than a hundred miles!
And I just now got em well bedded :-(

[bdstone914]

The 6 vented calipers are always an option. I'll check to see if I have a set Eric did up for me.

I didn't see rear vented 6 rotors at PMB's site?
Confused.

6's did not have vented rear rotors. They are 911 rotors.
What calipers and rotors are used up front? That is where most of the braking happens.

[HalfMoon]

The 6 vented calipers are always an option. I'll check to see if I have a set Eric did up for me.

I didn't see rear vented 6 rotors at PMB's site?
Confused.

6's did not have vented rear rotors. They are 911 rotors.
What calipers and rotors are used up front? That is where most of the braking happens.

That's what I thought too. Poster to thread must have been thinking about fronts.

As to my front calipers and rotors, per earlier post in thread, 911 SC

We're not addressing braking power or balance per se (in this thread) but rather rear brake cooling capability in a car who will see track time where repeated high speed braking will occur at a track where 914's have a history of rear brake fading.
And judging from what I'm reading and researching, the 911 vented rear using the stock 914 caliper seems to be a cost effective solution. It'll remain to be seen if the 914 caliper will suffice using a rotor that doesn't overheat and boil the fluid...

[Mikey914]

I have a 1 or 2 sets in the shop but haven't got back in to check. I think that one was built for vented rotors as I had Eric do up a few in this configuration. I do know I can have them built up if they are not currently in that configuration, but I do need to check (I'm thinking I have one that is already set up.
Mark

[mgphoto]

The bolts are the issue, I believe. Hardware is 7 mm fasteners with strength grade of 10 or 11.
Early/4 rear calipers have Ribe fasteners '73 and up are standard bolt heads.
Late calipers have upper and lower bleeders, only one on early cars.
Can't speak of/6 never played.
Mike

[HalfMoon]

The bolts are the issue, I believe. Hardware is 7 mm fasteners with strength grade of 10 or 11.
Early/4 rear calipers have Ribe fasteners '73 and up are standard bolt heads.
Late calipers have upper and lower bleeders, only one on early cars.
Can't speak of/6 never played.
Mike

My car is named Lil Bastard. From my profile picture you can see why.
No purist here. I'll toss the Ribe's (I have the earlier style on my 73) and git some high grade Allen's.
I s'pose Eric will have the caliper spacers.

[Mark Henry]

The 6 vented calipers are always an option. I'll check to see if I have a set Eric did up for me.

I didn't see rear vented 6 rotors at PMB's site?
Confused.

6's did not have vented rear rotors. They are 911 rotors.
What calipers and rotors are used up front? That is where most of the braking happens.

(IMG:style_emoticons/default/agree.gif) V-calipers use the 911 rotor. They also must be cut down, at least they do on the /4 V-calipers.

[mepstein]

The 6 vented calipers are always an option. I'll check to see if I have a set Eric did up for me.

I didn't see rear vented 6 rotors at PMB's site?
Confused.

6's did not have vented rear rotors. They are 911 rotors.
What calipers and rotors are used up front? That is where most of the braking happens.

(IMG:style_emoticons/default/agree.gif) V-calipers use the 911 rotor. They also must be cut down, at least they do on the /4 V-calipers.

Yes, just like when you use a 914-6 rotor/914-4 caliper on a 5 lug conversion.

[914Sixer]

914-6 GT cars had vented rotors. They were special made rotors. They have a 911 part number. I do not have the parts number right off hand though. Years back they were in stock in Porsche Germany.

[mepstein]

914-6 GT cars had vented rotors. They were special made rotors. They have a 911 part number. I do not have the parts number right off hand though. Years back they were in stock in Porsche Germany.

Eric Shea had once quoted ~$250 for the pair (old quote), but they fit 914-6 GT calipers. They might still be too large diameter for v calipers.

[mgphoto]

901.352.041.12
Rear disc - 2

According to the 914/6GT spare parts list.
Mike

[Chris914n6]

(IMG:style_emoticons/default/agree.gif) V-calipers use the 911 rotor. They also must be cut down, at least they do on the /4 V-calipers.

Need to ask... what are the V calipers? Stock 914 rears or something else?

[mepstein]

(IMG:style_emoticons/default/agree.gif) V-calipers use the 911 rotor. They also must be cut down, at least they do on the /4 V-calipers.

Need to ask... what are the V calipers? Stock 914 rears or something else?

Eric makes/made 914-4 calipers with a spacer for vented rotors.

[mgphoto]

(IMG:style_emoticons/default/agree.gif) V-calipers use the 911 rotor. They also must be cut down, at least they do on the /4 V-calipers.

Need to ask... what are the V calipers? Stock 914 rears or something else?

V'ed calipers have a spacer to widen the gap for the disc to run through, wider gap allows wider vented rotor. Because of the calipers size the outer edge of the vented SC disc must be cut down for the rotor to fit without hitting the caliper.
Mike
Both /4 and /6 rear calipers can be v'ed. 914/6 v'ed become 914/6GT and Ferrari Dino calipers.

[larryM]

always a fascinating discussion

- must be 300 ideas about this on the internet with more permutations than my old brain can handle

to further upset the cart - see the recent Pelican brakes advert for Part # 911-352-907-00-PMB set of the "M" style calipers showing 914 style e-brake levers - would be a helluva deal if true

http://www.pelicanparts.com/More_Info/911-...SVSVSI=357.htm#