Rear brakes? upgrade while I have it apart? Options

[PatrickB]

Had a 1974 914 2 litre car for about 4 years now. Heard a grind this week, pulled the right rear wheel off. long story short I need a caliper and a rotor. Looking to source locally if I can, already saw what Pelican has on their site. I've called a local auto parts store and they are trying to see what they can track down. Called the local Porsche dealer too, haven't heard back from either yet. Want to autocross the car this weekend, and I'm north of the border so shipping from the states takes time.

Question is, is there an upgrade that is a bolt on? I read something on the pelican site about BMW 320i, but I think they were referring to the front. They also referred to some Volvo parts... Do the calipers bolt on, or is there mods to do it? the BMW parts might be easier to source...

Another option: What's involved in going 911 sized parts on the back? Car already has 16x10 5 bolt wheels on the back, 16x9 five bolt on the front... spacers bolted on the back, drilled rotors on the front. I think it has enough brakes for what I do with the car, but more never hurts!

[GeorgeRud]

Contact Eric at PMB. He'll know if you have any options other than the stock brake caliper.

[mepstein]

You don't have much choice for bigger brakes (if you want to keep your parking brake) unless you spend some big bucks. Either 914-6 calipers and rotors - $2k or 911 parking brake and M calipers $1k + and more labor. But then, It's not a good thing to go big on the back without matching the front.
I would fix/replace what you have. PMB is the right place.

[steuspeed]

I'm rebuilding my rears right now. Watch this video from PMB Performance. It was a huge help! The job is turning out much bigger than I thought it was going to be. I can see how turn key calipers from PMB would be worth every penny now.

https://youtu.be/dm_DnizKOZM?t=5

[PatrickB]

You don't have much choice for bigger brakes (if you want to keep your parking brake) unless you spend some big bucks. Either 914-6 calipers and rotors - $2k or 911 parking brake and M calipers $1k + and more labor. But then, It's not a good thing to go big on the back without matching the front.
I would fix/replace what you have. PMB is the right place.

Probably what's going to happen... but the lack of parking brakes wouldn't bother me. Got something else in mind? Do the front calipers bolt on same as the rear? If they'll fit the BMW parts would...

[Chris914n6]

I had the BMW calipers on the rear with the 911 front susp swap. Needed a spacer (washer) to center it on the rotor. Were pretty cheap as rebuilds from the local Foreign auto parts store & now RockAuto. Went back to stock for the parking brake.

Someone can correct me but I thought front calipers fit too. I wouldn't do it long term but in a crunch it's an option. Do both sides though as I'm sure the piston bore is larger. Will need new hard lines bent -- Autozone has all the tubes & fittings & tool.

Might need the 19mm m/c, I think the 17mm comes close to bottoming out.

If that car still has the V8 I'd look seriously into doing the 911 front susp swap for the vented rotors.

[ConeDodger]

OMG I hate the word upgrade the way it's thrown around with our cars.

You want balance. It's already been suggested that you call Eric and the boys at PMB. I agree. He'll know what you need for balance. Don't want the back end of that pretty car trading places with the front.

[PatrickB]

The V8 came out before I bought the car, was a 360 dodge. Currently has a 2 litre with twin carbs. believe it or not that's all steel, no fiberglass.
I have other plans for a driveline, already bought an adaptor plate and flywheel from KEP. Maybe next winter.

[GeorgeRud]

I see you have 5 bolt wheels on the car. Do you have redrilled rotors or has the car already been converted to 911 front brakes? Since the front brakes do most of the work, I'd concentrate on those more than trying to swap the rear calipers for something different.

You can simply get some 911 front struts and calipers that will increase the capacity. I used some Carrera struts and have plenty stopping power for my conversion car.

[tomeric914]

OMG I hate the word upgrade the way it's thrown around with our cars.

It's JC Whitney marketing! Higher top speed! Lower ET! Better gas mileage! Upgraded performance!

Get a pair of rebuilt rear calipers from Eric at PMB and move on.

[Andyrew]

I've debated throwing 320i calipers on my rear or 914 front's, but my rotors are vented and I dont know if the caliper spacer I have on my current rear 914 calipers will work.

I want to do this when I put 944 turbo brakes up front.

[tomeric914]

I've debated throwing 320i calipers on my rear or 914 front's, but my rotors are vented and I dont know if the caliper spacer I have on my current rear 914 calipers will work.

Why? The 320i caliper piston size is considerably larger which means your bias will change. The only thing this (cough, cough) "upgrade" will do is potentially allow you to lock the rears up before the fronts. It will also require more pedal travel if a larger master cylinder isn't fitted.

Stock 914 fronts have 42mm pistons
Stock 914 rears have 33mm pistons

320i and 911 fronts have 48mm pistons

https://members.rennlist.com/1976c38/brakes.htm

[Mark Henry]

If you want stock-ish , but vented rotors you can do the Vcalipers.
Widened stock calipers to accept vented rotors, proper balance and e-brake.

[Dave_Darling]

I don't think anything's going to get you back on the road for this weekend's event.

As you can see, the general consensus is that brake upgrades need to be very carefully considered. It's easy to spend a whole lot of money and get no measurable improvement--and not that hard to spend lots of money and wind up with worse performance than you started with!!

So, are there any specific deficiencies in the current brakes that need to be addressed? Other than the grinding and/or parts being worn out. If not, sticking with what you have should work just fine.

--DD

[Andyrew]

I've debated throwing 320i calipers on my rear or 914 front's, but my rotors are vented and I dont know if the caliper spacer I have on my current rear 914 calipers will work.

Why? The 320i caliper piston size is considerably larger which means your bias will change. The only thing this (cough, cough) "upgrade" will do is potentially allow you to lock the rears up before the fronts. It will also require more pedal travel if a larger master cylinder isn't fitted.

Stock 914 fronts have 42mm pistons
Stock 914 rears have 33mm pistons

320i and 911 fronts have 48mm pistons

https://members.rennlist.com/1976c38/brakes.htm

Because I have 944 turbo front calipers going up front.... which are 38/36mm piston sizes in replacement to my current 48mm 911 A calipers.

By my calculations this is the total piston areas. Looks like a 914 front caliper in the rear would probably do the trick pretty nicely. I can fine tune the stopping power with less agressive pads if I need.


914 stock 914 current 914 planned
Front 42 48 38/36
Rear 33 33 42
F area 1385 1810 2152
R area 855 855 1385
F/R Ratio 62% 47% 64%


Anyone have some good 914 front calipers (IMG:style_emoticons/default/smile.gif)

[mlindner]

Pm sent, Best, Mark

[PatrickB]

Thanks guys, my biggest concern was availability around here. I was considering other options in case I couldn't get stock calipers... rare as hen's teeth up here. the local Porsche dealer put me on to a local rebuilder that they use, I called him and he has parts for my calipers. I'll be up and running, but not for this weekend.

My kid wants me to take my winter beater to the autocross instead, '92 jetta with a twisted up 1.9 AAZ. Car is way faster than the 914 in a straight line, might try it just for fun.

[PatrickB]

I see you have 5 bolt wheels on the car. Do you have redrilled rotors or has the car already been converted to 911 front brakes? Since the front brakes do most of the work, I'd concentrate on those more than trying to swap the rear calipers for something different.

You can simply get some 911 front struts and calipers that will increase the capacity. I used some Carrera struts and have plenty stopping power for my conversion car.

Drilled on the front, spacers on the back. thought about the 911 stuff but it's huge dollars up here, might happen someday but not right now. other things to worry about first.

[Mark Henry]

Where in Canada are you? Looks like Ontario plates but it's hard to tell.

[PatrickB]

Where in Canada are you? Looks like Ontario plates but it's hard to tell.

You guessed it, middle of triangle London/Windsor/Sarnia. Bought it from a body guy near Essex about 4 years ago, he got bored with the car.