paging Bill Verburg or other brake guys

[andy s]

Been a long time since I have played with my air cooled cars (I know, I know, but the GTB1 Caymans are pretty cool I must admit..), so I am getting some back on the road.

I have a 75 3.6, wide body, all the suspension mods, 17" wheels, but ironically, the car has stock S brakes on it. Stops like poo......

I posed a couple weeks ago, that I found a set of big reds on my shelf and acknowledging they need to be machined and find adaptors for them, my questions are;

In todays world, it is still cost effective to have someone re-machine big reds or is it more cost effective today to go find some Cayman brakes? (honestly not sure what years/models give Big Red level of braking and thermal performance - so would love input on that too)

if its have the Big Reds redone, who is doing that these days?

Thanks!

[dannobee]

First verify that you have struts with 3.5" caliper bolt spacing. If you have 3.0" struts, you'll need to swap them out for 3.5" ones.

The 3.0" struts don't take kindly to the adapters needed to fit big red style calipers as there is an offset on the ears that, when the big caliper is fitted, the brake pad will hit the ears.

If you have 3.5" struts a simple aluminum adapter will allow them to fit. You'll need change the rotors to the 930 style, along with a flat hat. Or use the 322mm 2 piece rotors off of a 993 turbo and a use flat hat.

To balance it out, you'll need to change the rear brakes. I'll let Bill recommend what to do in the back, as there are a lot of options and only a few "right" ones.

Also, you'll need to swap out the master cylinder to a larger size.

[andy s]

Thanks Dan, yes, the car has Bilstein coil overs on it. yes, 3 1/2." and yes, I know a new master is in the plan

I do understand I will need the Alu adaptors and of course I will be doing front and rear , but my question is more of should I go done down path of the Big Red's I have (that would need to be machined and if that route who is doing it these days) or knowing the 993tt are long in the tooth, are people putting on Cayman brakes (I don't even know it the Cayman's are the same dimensionally as the Big Reds, but I have seen chats about folk putting Cayman brakes on early 911's)

[nickelplated5s]

I have Boxster's on a SWB with a 22.5 MC and 3.5 struts. BV opined front brake bias and he is correct. When he chimes in listen.

[Bill Verburg]

Originally Posted by andy s

Been a long time since I have played with my air cooled cars (I know, I know, but the GTB1 Caymans are pretty cool I must admit..), so I am getting some back on the road.

I have a 75 3.6, wide body, all the suspension mods, 17" wheels, but ironically, the car has stock S brakes on it. Stops like poo......

I posed a couple weeks ago, that I found a set of big reds on my shelf and acknowledging they need to be machined and find adaptors for them, my questions are;

In todays world, it is still cost effective to have someone re-machine big reds or is it more cost effective today to go find some Cayman brakes? (honestly not sure what years/models give Big Red level of braking and thermal performance - so would love input on that too)

if its have the Big Reds redone, who is doing that these days?

Thanks!

Start w/ rotors, they are the most difficult part to modify

now you have,20x282 & 20x290
next step up is 24x282 f w/ 3.2 A calipers

next is 32x304 & 28x309 930s, w/ these you can easily use 930 calipers f/r, 993 calipers f and r, 964 calipers f&r

next is 32x322 993tt/RS front w/ a 28x309 930 rear use 993 Big Reds or 928GTS big black or 964RS/t medium big black but you are stuck w/ 993 rear, maybe 993RS rear but I've never done or seen that

you do not want Boxster calipers other than for optics

996 aka Boxster S can be used w/ their native 28x318 rotors w/ mods to the hubs and caliper adaptors

bias is fair to poor w/ most of the above, 930s calipers on 930 rotors being best and easiest to install 993 is next best

most of the water cooled caliper give even worse bias and want really huge rotors, fronts are easy rears are not.

the best advice I can give is to use either Elephant's 930 setup or a Brembo or Stoptech kit

none are going to be cheap
back in the day Race Technology had a great 993RS kit but I don't think that it is available any longer

[mike sampsel]

Might be worth looking at the Wilwood stuff. I believe they now come with wipers, which in the past was a drawback (no dust seals), but now with the seals maybe not.

Might be less $'s than the others?

Here they speak of the wiper dust seals:

https://www.wilwood.com/calipers/CaliperList?subname=FNSL4R-Dust%20Seal

Suspect there might be some other drawbacks compared to ER's setup. Still might be worth a look at.

Just sayin ...

[nickelplated5s]

Originally Posted by Bill Verburg

you do not want Boxster calipers other than for optics

the best advice I can give is to use either Elephant's 930 setup or a Brembo or Stoptech kit none are going to be cheap
back in the day Race Technology had a great 993RS kit but I don't think that it is available any longer

Go the 930 route since you have them. Try PMB in UT for the machine work. BV aside my Boxster's are much better than stock. Your P is also carrying more weight than mine. "Go big or go home," it's only money.

[Bill Verburg]

Originally Posted by nickelplated5s

Go the 930 route since you have them. Try PMB in UT for the machine work. BV aside my Boxster's are much better than stock. Your P is also carrying more weight than mine. "Go big or go home," it's only money.

Here are some comparisons of various possible brake setups for a 911







The main weakness of stock 911 is the smallish thermal envelope, they develop more than enough torque to lock and slide most tires that fit a 911, but in repeated very hard braking(track) they can't process the heat, resulting in unlimited temperature rise of the components, leading to failure, most commonly boiled fluid but glazed pads and point hardened rotors are also common.

any brake set that can't deal w/ the thermal load isn't an upgrade

Boxster brakes using 3.2 Carrera rotors are actually a downgrade from 3.2 w/ stock ATE calipers, while they do have a slightly larger thermal envelope than the '83 and earlier w/ 20mm rotors the extra potential for generating brake torque is wasted because the rotors are the choke point, not the calipers

additionally brake bias is worse, while not dangerous it is wasteful of braking potential

These cars can effectively use bias down to ~1.49 and even lower w/ the right setup. Boxsters on 3.2 rotors are 1.669

[PeteKz]

Agree with nickelplated5s. If you already have a set of calipers, you might as well stick with the 930 setup. You have a 3.6 engine in the car. If you take it to the track, it could use more braking thermal capacity. It won't be reasonably priced.

[911TerryT]

After starting my own thread on upgrading brakes on a 83 and reading this one and others, seems like the 930 set up is the best. My question is if I order 930 calipers/rotors from Porsche am I ordering 20+ year old technology? If I order the Brembo Granturismo set up am I ordering new technology?
Has there been any changes in the calipers over the years?

Lastly, is there modification needed on the 930 option for a 83? I was told the fronts bolt up but the backs require some alteration/bracket?

[Bill Verburg]

Originally Posted by 911TerryT

After starting my own thread on upgrading brakes on a 83 and reading this one and others, seems like the 930 set up is the best. My question is if I order 930 calipers/rotors from Porsche am I ordering 20+ year old technology? If I order the Brembo Granturismo set up am I ordering new technology?
Has there been any changes in the calipers over the years?

Lastly, is there modification needed on the 930 option for a 83? I was told the fronts bolt up but the backs require some alteration/bracket?

The issue wrt 930 calipers is in the back, fronts are a bolt on w/ 3.5" struts, but the 911 rear has 3" mounts while the 930 rear has the same 3.5" mounting as the fronts.

Porsche did once upon a time offer 930 rears w/ 3" mounts but i don't believe that they are still available

Elephants 930 kit is a straight bolt on all around, w/ correct 3.5" fronts and 3" rears and the correct bolt on rotors.

One very nice feature of 930s is that they fit under 7 & 8" x15 wheels

Yes there have been some great advances in caliper design, but most modern calipers want rotors that are incompatible w/ 911 use and have bias issues as well. That's why i always advise to select rotors first then the calipers that fit them.

Brembo or Stoptech or whoever will also include rotors in their kits but again the 930s are the gold standard which should be used for comparison.

[Bill Verburg]

PS on the 930 rear calipers w/ 3" mounts
911.352.540.00
I have no idea if they are available now

[SBell]

Originally Posted by Bill Verburg

PS on the 930 rear calipers w/ 3" mounts

911.352.540.00

I have no idea if they are available now

Don't know if they still sell them of if they're available still but I believe Rebel racing sold something similar as well

Sent from my SM-G991U using Tapatalk

[andy s]

Ok, so being I have the 993tt calipers, can you recommend someone to do the machining and refinishing?

I know Bill that this is a lot of brake for a 911, but its the same setup I have on my 3.8 2030lb 425hp air cooled race car and am happy with it.

clearly this car at 2400lbs and 275hp might not need all that brake, but I am know as a late, very hard braker and I do plan to track this car some.

[nickelplated5s]

PMB in Utah.

[Bill Verburg]

Originally Posted by andy s

Ok, so being I have the 993tt calipers, can you recommend someone to do the machining and refinishing?

I know Bill that this is a lot of brake for a 911, but its the same setup I have on my 3.8 2030lb 425hp air cooled race car and am happy with it.

clearly this car at 2400lbs and 275hp might not need all that brake, but I am know as a late, very hard braker and I do plan to track this car some.

I have the same 993RS on both of my cars and know how good they are




you don't want to use 993tt rears , the 993RS are physically the same but have 30/36 pistons instead of tt 28/28. The small tt rears move bias way to the front

from left 993tt rear stock, 993RS rear modified for 911 rear use w/ a caliper adapter, 993RS/TT front


another snag after the rear calipers are modified is the mads to the rear rotors. there the 993 center parking brake section is machined away and a 911 parking brake section is pinned in. It would be nice if there was a 28x322 2 piece set available but the rotors need to be ~330mm or bigger to allow 2 piece bolt up w/ parking brake



Race Technology made mine but I don't think that they do that any longer

The only place you will ever use these to their full potential is at a race track

the fronts are easy as the 993tt is a bolt up 2 piece design , so unbolt the hat and bolt on a flat one,
front caliper adapter





it's far easier to start w/ 930 f/r rotors and use 993 f/r calipers
the front needs a caliper adapter like the RS and the rear needs some fairly simple mods


fill the existing mounting holes w/ threaded aluminum rod, and redrill for 3" mounts some minor clearanceing of the throat area and you're done

[andy s]

guess I am going to double check the dia of the set I have and go from there.

I thought the rear Alu trailing arms were 3 1/2" spacing, no?

[andy s]

Nickel, who is pmb?

[PeteKz]

https://pmbperformance.com/

[nickelplated5s]

It's probably not race tech approved but here's a way to handle heat. Put some dry ice, bagged, in the brake ducts. It will just sublimate off and not wet the rotors. Once in a while I get a wonky idea that would work. Of course this would be strictly for track time.