What all is involved if I want to put vented rotors on the rear of my factory 6? Can I just purchase the rotors, spacers, pins and bolt it all together?

Jeff

For an original 914/6 caliper, just find some scrap 911 rear calipers with the spacers. Just transfer the spacers, bolts and seals over. If you look closely you will find the outer castings are the same. For a 914/4 rear caliper you need some custom machined spacers. The best source of the longer bolts are from the scrap 911 caliper. The pins can be a problem because the 914 pins are different, and there are no longer ones I know of. They may need to be fabbed. The spreaders would be 911 parts.

Thanks for the quick response! Should I take the rotor from a 911 also, should the rotor and caliper be from the same year/model 911?

OK, so since I have the original 6 caliper then this is a very easy thing to do, right?

Jeff

I think the rotor to get is the early style, not SC which is thicker. You will also need to have spacers made to move the rotor out into the center of the caliper (about 5mm). Yes, the 914/6 caliper mod is relatively easy. I think matching the year of the caliper and rotor may work. I have not had late calipers mated to the thicker rotors in my hands to see if there are differences in the spacers.

Does anyone have photos of this?? It doesn't look like the inside of the rotor is any further out in the photo so what do the spacers look like and where do they go? It looks like if you just put the spacers in the calipers it will bring the outside edge out to match the thicker rotor. BWTFDIK

Jeff

hilow jeff,

have a look at this site ->

http://www.phoenixhobbies.com/html/brakes.html

It seems to me that the spacers from a 911 caliper will not fit without any modification ...


Benno

Jeff,

The spacer needed to center caliper over rotor is simple. Just use a appropriate thickness flat washer between caliper and where it mounts to trailing arm to center. The caliper mounting bolts (2) will secure. Hope that was clear.

Note: centering the caliper is easier than trying to relocate the rotor. Just mount the rotor and secure with two mounting screws. Mount caliper and you will be able to measure exactly how far off you are from center. This is the washer thickness needed.

If this did not make sence, let me know and I'll pull a wheel for pictures.


John

well, that's the way it looks at first blush, the the spacer is referenced to the center of the disk even though it mounts the same old place...

i've seen people who have done it (somehow) by mounting the calipers farther inboard but it looked to me like there's not enough room and the calipers will hit the trailing arm. when i did this done (i donno where the spacers came from, i think they were custom in those days) i spaced the disk outboard.

3mm (standard 1/8" aluminum sheet) is enough. it looke just like a really skinny wheel spacer - 5x130 holes for the lugs, big around as the hub. slide in on the hub, slide on the disk, ta da.

it also give you that smug satisfaction that you have increased your rear track 1/4" and nobody can tell by looking :-) ...

The spacer looks like a spacer used between the rotor and rim, but its OD is sized to the inside of the rotor. There was a GT rotor that would fit properly, but I think it is unobtanium. I would rather not space the caliper either. Note that the standard setup includes the spacing effect of the rain shield mount bracket between the caliper and the trailing arm. Removing the bracket reduces the thickness of spacer required.

Could you measure the length of bolts required to assemble the caliper with the spacers. I forget the length needed. The bloody things are 7mm bolts and the long lengths are nearly impossible to find. The 7mm stuff is nearly impossible to find. I have made spacers for the 914/4 calipers, but to use them I need longer bolts. Actually, the long bolt can be used as the short bolt in the new setup. It is just the one bolt I have to source.

DaveP

hi dave,

actually I'm considering the same conversion of a pair of /4 calipers, but i have no clue how to make the needed spacers .

could you send some pictures of your spacers (between the two halves) ?

Benno

I've home-made the spacers before on a -4 rear caliper...
I've also just bought M911 calipers and stolen the spacer to vent a 914 front...

Its not that big of a deal either way.
split your rear caliper in half. trace out the face pattern... measure the spacer on a 911... buy stock of the same size, or slightly thicker... cut out the spacer.... drill the bolt holes and fluid passage... take it to a machine shop and have the faces cut perfect... also have the macine shop cut a square shoulder into the fluid passages for the seal... buy new seals... buy a core vented (911) caliper to steal the longer bolts and hardware from... bolt it all together.

I had to custom make some pins for the pads...

you'll have about 50bucks and a couple of hours into it.. just as well rebuild the whole caliper while your there... the breaking improvement is negligible...

I'd take pictures but I sold mine after I realized it just added sprung weight and didn't really help with braking... I've since moved a 914 front caliper to the back and run it with and with out vented rotors...

brant

i have to go to the storage facility today to pull out my 6" Fuchs for sale (hint, plug, hint, nudge, nudge, wink, wink...) and i'll pull a caliper off the car. i can get measurements of the pins, too, if you want ...

Rich,

Just measure the shank length of the longest bolt. I just keep forgetting what it is.

DaveP

sorry 'bout the delay - busy, busy -- and limited access hours at the storage facility ...

anyway !

the 'outer' (shorter) bolts are 2,570"
int 'inner' (longer) bolts are 2,735"

i guess that'd make the outers 65mm,
the inners 70mm

if i ever noticed before, i'd forgot - the pins have two clip retention holes - it looks like they might be 911 caliper pins with a redrilled clip hole. or maybe not - they're simple enough (and mine are just cheap mild steel) that they could have been made to order, and whoever drilled the clip hole just got it wrong once. i do notice that the top and botom pins have different clip locations ...

Just FYI.. the 9146 caliper and 914/4 caliper halves are not the same. The 6 caliper half has a much bigger piston.

My favorite combo is SC vented rears with 911M calipers and 944 Turbo fronts.

I gave up trying to understand why people want vented rear rotors now I just shut up and sell them what they ask for.


B

are they 16s??? if so, i might be interested

Andy

Just guessing here, but I dont think you want 15x6's or even 16X6's for that fact.


B

they were 15's, and they have been sold... sorry.

their sale financed a set of 15" 7's & 8's -- i'm trying to stay reasonably "period correct" with the RS look on the 911.

i'll burn through the tires that came on the new wheels at the Hershey AX, and put on a set of DE tires - probably Toyo RA-1. eventually the plan is to mount slicks - 8" front, 9" rear...

i can use 6x16 as a core to get 8x16 and 9x16 made out of them ...

Andy

That's a 4 caliper.

Jeff has 6 calipers, which is why I'm guessing Brad mentioned...

Brad, et al, are correct. The 914/4 is a much smaller caliper. The 914/6 pads do not fit in the 914/4. In fact the 914/6 rear pads are the same as the 914/4 fronts up to 72.

DaveP