Current thinking on better brakes for 1973 T?

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911hillclimber
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Current thinking on better brakes for 1973 T?

Post by 911hillclimber »

Always need better brakes for my 73T which is modified.
By 'better' I mean improved stopping for the same pedal effort.

The car has 3.5" front struts, 3" rear caliper mounts and A type iron calipers on the front.
Stock '73 vented and drilled discs all round, stock master cylinder and aeroquip hoses.

Pad are the excellent French Carbone, noisey but the most effective pad I've had in the car and I've tried a few....

Options seem to be to fit the servo off the 3.2, I have some of the parts. The engine is a 3.2 so I have the servo take-off.

Maybe simpler is a 4 pot/2 pot caliper swop with stock Porsche pads (to reduce squeeks), but not sure if the stock master can deliver the fluid without a long pedal travel?

Anyone have some advice/experienced please to share with some approx. costs?
I know early Boxster calipers are an option, but I bet these are hard to find and will need a re-build.
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
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Re: Current thinking on better brakes for 1973 T?

Post by inaglasshouse »

Graham
I don’t know what would be the best path for your car. But I do know that Boxster calipers are not hard to find - you’ll find hundreds on eBay. They made a lot of Boxsters and some have reached the scrap stage.
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Re: Current thinking on better brakes for 1973 T?

Post by redrobin911 »

my mate greg does them - see the link, call him metion my name, http://gtech911.com/Porsche.html
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Re: Current thinking on better brakes for 1973 T?

Post by 911hillclimber »

Ah!
Good start!
Thank you both.
I thought it was the 2.5 Boxster Brakes you needed and now these cars are classics and cheap, cars were not being broken. Shows what I know!
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Re: Current thinking on better brakes for 1973 T?

Post by rhd racer »

Hi Graham

I have Wilwood 4 pots on the 914 and they are frankly unbelievable, but take more effort than the Boxster brakes to fit as hardware is not off the shelf. In my experience, Boxster 3.2 brakes would be the best upgrade for you.

For info, Boxster 3.2 and 2.5 REAR brakes are the same (piston size, pad) so exert the same performance, however the 3.2 runs a wider vented disc, therefore the billet caliper is wider to accommodate. The 3.2 fronts also operate on a wider vented disc than the 2.5, and are physically larger with a bigger pad and piston.

On the 914 I upgraded the master cylinder to the merc derived 23mm version sold by D911 amongst others as it is the same physical size, has the ports in the same place but pushes more fluid. Feel is much better than my upgraded already 21mm MC produced. I would say this is a must, bolt on, and less than £100.

For info, to get equally awesome brakes on the Boxster which is heavier, I created a hybrid of 3.2S fronts and 2.5 fronts on the rear (these are bigger than the standard rears but on a narrower disc). I managed to get cross drilled upgraded rear discs to match the standard cross drilled fronts. In this guise, though it took some working out, the brakes are just as awesome as the 914.

Across the 2 cars there isn't much I haven't tried over the years!

Hope that helps
Wayne
93 964 C2
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71 914/6 3.0 - gone

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Re: Current thinking on better brakes for 1973 T?

Post by 210bhp »

Doesn’t Nick Moss do an upgrade discs and calipers set?

Regards
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Re: Current thinking on better brakes for 1973 T?

Post by Nine One One »

Are Boxster front callipers too big for 15” Fuchs?
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Re: Current thinking on better brakes for 1973 T?

Post by KS »

Contact Carbon 12 (Chris Rudling) for their six-pot and four-pot caliper conversions. I ran them on El Chucho and they are superb. They fit within 15in wheels, too...
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Re: Current thinking on better brakes for 1973 T?

Post by Sam »

The C12s KS mentions are the same ones Early 911 fit I think.

I'd be surprised if Boxster ones fit under 15s, the smallest Boxster wheels were 16s.
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Re: Current thinking on better brakes for 1973 T?

Post by Nine One One »

This might help you make a decision?

http://forums.pelicanparts.com/porsche- ... rakes.html
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Re: Current thinking on better brakes for 1973 T?

Post by 911hillclimber »

Again, thank you all.
Keith, did you use a larger m/c to move those Pistons?
My wheels are Dage Sport 15" wheels.
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
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Re: Current thinking on better brakes for 1973 T?

Post by Mick Cliff »

Nine One One wrote:Are Boxster front callipers too big for 15” Fuchs?
From memory 2.5 Boxster (NOT S!) calipers fit under 15" wheels
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Re: Current thinking on better brakes for 1973 T?

Post by rhd racer »

I agree with Mick that the 2.5 is the normal conversion but I am pretty sure a 3.2 caliper will fit with a creative bracket. If you remember that the Boxster adaptor kits are effectively a thick ally bar which is tapped to accept the top mount of a Boxster caliper and drilled for the radial mount of the standard strut - this effectively loses about 1" of usable space for the caliper. If you created something in steel I am pretty sure this could be overcome.

When I did my conversions much of the caliper space was dictated by the disc you are using, and from memory the Boxster disc is a larger diameter which then compromises the space available for the caliper under the wheel. As long as the caliper can sit 1mm or so over the disc without fowling the bell then you are utilising the max pad area without clearance issues. My Wilwood calipers are pretty enormous but fit under 15s on SC discs front and rear. Incidentally, SC discs were required due to their depth, matching the operating window of the caliper as the 3.2 ones that went before were too thick.

I can definitively say tomorrow, I have the wheels off the 914 as it happens and a spare 3.2 caliper, I just can't get to the caliper without moving a few cars to get to the box. I will revert tomorrow and confirm!

There are a number of guides online which confirm the disc thickness and diameter through the years which allow you to match a disc for various caliper applications.

By the way Graham, if you choose a 2.5 conversion, I have a set of rears that I do not need

Regards
Wayne
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99 Boxster 2.5 > 3.4 hill climber

71 914/6 3.0 - gone

'You see Paul, hill climbing is like making love to a beautiful woman. You get your motor running, check your fluids, hang on tight and WHOA..30 seconds later it's all over!' Swiss Tony
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Re: Current thinking on better brakes for 1973 T?

Post by 911hillclimber »

Yes, that is what I thought too, hence saying calipers from the 2.5 litre 986.
You have made me think!
I seem to remember KS doing an article on Porsche brakes some years ago?
Maybe that is where I've read it.

Wayne, I was thinking of a total 4 corner up-grade to max the change, so could be interested.
Need to do a bit more homework.

Planning a few changes for the 911 this winter, paint, lowering the suspension and brakes, maybe a light flywheel and Sach alum clutch.
Might go 6" and 7" Cookies too.
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Boxster 987 Gen II 2.9
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Re: Current thinking on better brakes for 1973 T?

Post by rhd racer »

No problem.

Just had a look at the front Wilwoods - they were radial mount and just needed the mounting holes enlarging to metric by about 0.5mm, so offer a brand new bolt on caliper with a huge pad area. I can send you the details if interested.

The rears were the same physical size, but a smaller piston to give me the correct bias. The rears required a creative bracket. SC discs all round. Of course, a hybrid approach could work with a bolt on Wilwood front, and a 2.5 Boxster rear with the normal ally adaptor bars. A brake bias would allow you to fine tune. This makes it all bolt on, but you have lots of engineering skills so doubt you would be put off by doing something bespoke!

If you are not in a rush, given I am only 60 miles or so away, I can take you out in both cars early Sept and you can decide for yourself!

Cheers
Wayne
93 964 C2
99 Boxster 2.5 > 3.4 hill climber

71 914/6 3.0 - gone

'You see Paul, hill climbing is like making love to a beautiful woman. You get your motor running, check your fluids, hang on tight and WHOA..30 seconds later it's all over!' Swiss Tony
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