I have a 914-6 conversion. It has the rear parking brake shoes inside the rotor. Essentially a rotor/ caliper disc on the circumference, and a mini drum brake on the inside. One side is a little bit stuck on intermittently when I drive. I suspect the shoes weren’t put on correctly as some lack of retainer springs are allowing for the break shoes to shift inside the drum space. I’ll open that up again tonight to take a peak as to what might me missing.

Do the 914 six parking brakes share the same configuration / parts with the early 911’s? I need to reference a diagram for the correct brakes and likely buy a few miscellaneous springs/ retainers to keep the shoes from shifting.

Thanks in advance
Todd



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Hi Todd- No; the stock 914-6 has no brake shoes as a part of their system.

Thanks Michael.
Must have 911 brakes!
TY.

A PO has applied some type of conversion as the 914 & 911 dont share any rear suspension or brake parts. Pictures would help
It is somewhat common to change calipers on the 914 rear to eliminate the OE integrated P-brake of the /4 & /6 and to add vented rotors.
When doing so 911 shoe brake components are sometimes applied.

The 914-4, 914-6 and 916 do not use the 911 parking brake. However its not hard to add it. Use early 911 parking braking parts. The later one does not match the 4 bolt holes on our trailing arms.
Hardest part is welding a piece of angle iron to use as a stop.
http://www.914world.com/bbs2/index.php?sho...=4909&st=20
Tangerine Racing makes a nice cable adapter.
https://tangerineracing.com/shop/ols/produc...1-parking-brake
Following several threads I made a cable out of a couple of extra clutch cables before Tangerine had there adapters. The 911 parking brake works great and I have Boxster calipers front and rear on my car. Awesome braking.
Ben also has some cool pictures of the setup in his thread. http://www.914world.com/bbs2/index.php?sho...606&st=1260

@steve
@914werke
@cairo94507

Thanks for all the info. I’ll take a couple pictures when I get back on the lift with the rotor off.

The previous owner did convert to boxster /Brenbo brakes. 5 lug.
I think I recall him saying 911 trailing arms. Is that possible? I know they are reinforced for the GT style modification.

The 911 trailing arms are not compatible, but Vellios (RIP) used to modify the 914 trailing arm with the 911 trailing arm bearing housing to use the later bigger bearing and 911 parking brake.

Thanks Steve. Good to know. Todd

Phase.com has the needed information. The GT cars did have 911 e brakes. I just did the conversion but it was and still is kind of a mess.Click to view attachment

Why would a GT car intended for the race circuit, that went so far as to have a balsa wood deck lid for weight reduction, be fitted with 911 e-brake?

Read away


https://www.pbase.com/9146gt/my9146gt_rally..._brake_911_drum

Well, this is what the forensics determined. The picture speaks for itself. The question is where do I purchase a new backing plate that has the correct brake pad, separator chunk of metal and the opening for the parking brake tube and cable.

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Interesting. I’m wondering where I can buy a new backing plate. I can do the welding if I need to to create the bumper/ stop for the bottom end of the brake shoes.

If I am seeing the picture correctly, Someone welded the shoe anchor to the thin stamped steel backing plate?

The anchor needs to be welded to the trailing arm.

Sometimes people just scare the hell out of me Clearly had no idea of the forces involved.

GT homologation requirements. Cars had to be legal for road use.

Balsa reinforced fiberglass hood is legal for road use. Not having a parking brake is not legal for road use.

If you can weld you can probably repair the backing plate that is torn and maybe a little “bodywork” with a hammer and dolly to put things back where they belong.

Fabricate and weld a proper anchor block to the trailing arm.

If you want or need a new backing plate AutoAtlanta lists them, should be available through a dealer, or buy used.

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You have the wide SWB brake shoes on there and looks the same on the backing plates. I used the SWB backing plate which requires more work. The best match is 69-73 everything. Go on Auto Atlantas website and look at there parts diagrams and order accordingly. Your backing plate though really doesn’t need to be replaced. That contraption doesn’t do anything. You need to eliminate that spring on the cable

From what I see you need

New pins and springs for he existing brake shoes
Then a bracket welded in for the stop of the brake shoes(separated if you will)
And then reinstall.

Ok but the /6 from, which the GT was based, DID already come with a intagrated caliper parking brake ala /4 (with spacers) .....
Ive never bothered to weight the two solutions (if wieght was the reason for the change) but cant imaging the that was the motivating factor

There's a difference between a parking brake and an emergency brake. Without that angle iron welded to the trailing arm, you have a parking brake. If you pull the handle in an emergency at speed, the whole assembly will break loose and rotate on its axis. Check out how beefy the angle iron is on a 911 trailing arm.

@superhawk996

@Steve
@914world
@mb911
@cairo94507

Thanks everyone for all the information. Very useful as this is a new frontier for me.
Good point with the emergency vs parking brake. Looks like the po set it up for a parking brake for flat ground parking.

In summary
1. Spring delete . Remove spring in photo 2 permanently.
2. Remove the backing plate and repair it without the brake stop on it (delete item) Ugg. Looks like I need to remove the stub axle to remove the backing plate???.
3 Fabricate and fasten new brake shoe stop at location “C” in photo 3 ??? I should do both sides as the right side has the same stop mounted to the backing plate.
4. Install new brake shoe retainer / spring hardware.
5. Reassembly of parking brake mechanism/ cable.

Some day I’ll finally drive this car!!!

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By regulation (FMVSS 135 and ECE13) there is only a parking brake. It must hold the vehicle on a 20% grade. ECE 13 (European regulation) has a deceleration requirement of the parking brake as follows:

To check compliance with the requirement specified in paragraph 5.2.2.4. of this Regulation, a Type-0 test shall be carried out, with the engine disconnected, at an initial test speed of 30 km/h. The mean fully developed deceleration on application of the control of the parking brake system and the deceleration immediately before the vehicle stops, shall not be less than 1.5 m/s2. The test shall be carried out with the laden vehicle. The force exerted on the braking control device shall not exceed the specified values.

0.15g of deceleration from 30 kph (approx 14 mph) is hardly braking at all and shouldn’t be considered emergency braking.

But as pointed out by Steve - the system that someone “built” for your vehicle is not adequate to satisfy either of those requirements.

Same thing happened to me but the damage to parts was worse,luckily I was able to straighten the backing plate and weld it back together .
Purchased replacement parts Retro Automotive for a fair price and they even included 2 spare springs and shoe steady pins,great to deal with .
In another way I was lucky as the RH wasn't broken as the cable was made too long,the backing plate is simply not strong enough to support the load as the metal is too thin....even if it was this isn't the correct method.
I should have checked this but the PO did an otherwise good job of the conversion .

Regarding your situation - I’m sorry you have to rework this situation. Your assessment of FUBAR was spot on.

Yes, weld a beefy steel anchor to the trailing arm. Measure the dimensions you need - if I recall it needs to be about 40mm wide - a couple of mm clearance on each side between the anchor and the shoes. It should contact that center portion of the shoe along the center line of the shoe. Again as Steve correctly points out the anchor on the 911 is cast iron and it’s beefy - for a reason.

I wouldn’t make it out of anything less than 1/4” steel. 3/8” would be better.

Yes - do both sides only a matter of time before the other side fails in the same way. It will never fail at a convenient time. At least in my life experience, things always fail when it’s dark, raining or snowing, on the hottest day of the year, or when I need to be somewhere at a specific time. Usually, some combination of those at the same time.

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I will take a picture of mine shortly

This is me adding an extension on the car as the brake tab was placed wrong by me.Click to view attachment

This is the thread I used to build mine.
http://www.914world.com/bbs2/index.php?sho...88772&st=80
There are also some pictures of my setup. Wes V cut off a piece of thick angle iron and welded it to my trailing arms. Really nice guy "RIP" and did it for free. He had a nice little shop in his garage and was building a Subaru conversion. I heard he had a heart attack.

I used the Tangerine Racing kit which comes with hefty bent and drilled supports, pictures show the placement during conversion:

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A good weld onto the hub carrier and you're good to go; hopefully your backing plate can be "persuaded" back into shape?

- Tony

@superhawk996
@Steve
@914world
@mb911
@cairo94507
@porschetub
@retroracer

Thanks everybody for all the help
A couple of pictures worth a 1000 welds! I totally get what the standard should be and were to go from here.

I can see why the part on my car failed!!! Just a little under engineered I'd say...yikes. Failed on a sunny day, no traffic, 1/4 mile from home. WAY lucky! Smelled horrible though. Of course I thought the smell might be my new engine melting down.


I see a decent backing plate for $50 buck on ebay- since the circle section where the cable passes through my plate is so jacked, I think I'll just buy a replacement with some "character" .

Appreciate all the tribal knowledge.

That will require a new bearing just so you

Tony same here. I just welded the bracket on in the wrong spot so had to extend it

AFAIK the Factory GT's did not come with drums. The factory GT disc was not machined for a drum. Anything with a drum is a homebrew solution.

The 911 rear drum in hat is just an expedient solution to get to vented rear disks, larger rear calipers, retain a park brake, and avoid real 914/6 caliper prices

My thoughts are:
Enjoy a 914-6 with some ponies and torque that has plenty of braking and a reliable emergency/ parking brake. With the boxster/ Brenbo brakes and the hybrid drum/ disc, I think I’ve got a reasonable set up. Mimicking an original 914 six GT isn’t my goal. We’re all chasing different 914 pot of gold dreams right?

That said, I think there’s room for improvement on my the master cylinder. I’ve seen some folks go with a 23 mm. That a real thing?

Talked to Chris at Tangerine today who is always so generous with his time and experience. Time fabricate and weld up the brake shoe stops the right way.

“ experience” = knowledge I’ve gained just after I needed it.

No spacers on the Six calipers. The rear rotors were not vented, so no spacers needed. The pistons are a larger diameter than the -4 rear calipers, but that is pretty much the only difference.

I don't know if adding a spacer to fit over vented rotors would mess with the self-adjusting mechanism or the handbrake mechanism. It seems unlikely, as none of those parts are in the caliper seam, but sometimes non-obvious stuff causes issues.

--DD

914-6 GT calipers with vented rotors are easily made using stock six calipers and a set of rear M calipers. The M spacers and bolts move right over and perfectly duplicate the GT caliper. Eric has made me a couple sets.
The 912 M caliper from ‘69 uses a solid rotor. It just leaves out the spacer from the vented M caliper. I think some of the early 911T’s had solid rotors on back.

The 914-6 caliper is basically an M caliper with the handbrake. Same piston size.

@roundtwo Todd, I have the 23mm master cylinder in my car and have no regrets at all. But I have the 914-6 GT rear calipers and '88 Carrera front calipers and we removed the brake bias valve from the firewall. I am also running vented and drilled rotors all around, the fronts being 24mm.

Next time we see each other and have our cars, you can drive mine and see how you like the brakes.

@Cairo94507
Hey Michael,
I'll add the 23mm to the list. Seams as if the more I work on the car the longer the list becomes!
The day will come when you can take my 914 for an official brake test! Best to keep the boat anchor and 50 ft of chain in the passenger seat for now. Works as a parking and emergency brake.
Todd

Todd - They are never really finished. I suffer from the same syndrome of crossing one item off the "to do" list and adding two more. Cheers. Michael

I have boxster non S calipers front and rear with the 19mm master cylinder. No issues. It just depends how firm you want the pedal to be.
I’m also running a “T” instead of the stock rear regulator. I have slammed on the brakes in the rain and other situations and the front always lock up first.