930 Brake Booster - Pre and post-86 differences

[Wobbly]

Hi all - in my search to slowly piece together the bits for my 930 brake upgrade for my 74, I've come across two different turbo boosters. The part number up to 84 is "930.355.027.00" and post 84 is "930.355.027.02" (until the 964 that is). Does anyone know the difference between these, if any? Or was it just a subtle part # revision? Thanks

[Bill Verburg]

Originally Posted by Wobbly

Hi all - in my search to slowly piece together the bits for my 930 brake upgrade for my 74, I've come across two different turbo boosters. The part number up to 84 is "930.355.027.00" and post 84 is "930.355.027.02" (until the 964 that is). Does anyone know the difference between these, if any? Or was it just a subtle part # revision? Thanks

they changed the boost ratio from 2.25 to 3.00 for '85-89 911s

[Steve@Rennsport]

While not precisely on the subject, why don't you simply use the non-boosted 23mm MC for your application?

These brakes are so powerful on these light cars that with the right pad, the pedal effort is quite modest.



FWIW,... I've been driving a '74 w/930 brakes for 32 years,...

[Wobbly]

Thanks guys - I've been heading to the boosted setup due to expectations of a heavy pedal. I'm not a big fan of the pedal effort of the standard brake system and figured that would persist without the booster ... ?

[GrantG]

I have Steve's manual 23mm setup in my car (930 brakes on a 73 911) and the pedal effort is not bad at all with lots of feel/feedback.

[GaryR]

Or how about the boosted SC brakes? I have a complete Booster/MC/reservoir assembly I could sell you!

[Wobbly]

Sorry, already got 3 out of 4 930 calipers. But if you have a single 930 front then I'd gladly take it

So how does the pedal effort to stopping power feel with the unboosted setup vs the stock (non-turbo) setup?

[Steve@Rennsport]

Originally Posted by Wobbly

So how does the pedal effort to stopping power feel with the unboosted setup vs the stock (non-turbo) setup?

With the proper pads and drilled rotors, its about the same. The boosted setup is a tad lighter, however I find it too much for these light cars with their relatively smaller tires.

JMHO, but you should talk with a whole bunch of people who have this exact package on their early cars before making a decision. I've installed a LOT of these systems on '67 to '75 cars and to date, nobody has complained about pedal effort.

The Devil is in the Details,....

[Wobbly]

Thanks for the feedback guys ... I managed to find a relatively cheap pre-85 booster listed on dcautomotive which I bought and had shipped across to me. The part number listed that I ordered was "930.355.027.00" (as discussed above).

The part turned up in the mail today, but interestingly it seems to be a different booster, but I can't work out what model it is for. The part number of the booster they sent me is "930.355.025.05".

Any idea what model this part is from? I can't see it listed in any parts diagrams on dcauto for any model of 911/930. Being a numerically smaller part number could it be a superceded part from early in the turbo from 78 on? I'm hoping not an oddball part from the pre-78 930...

[Bill Verburg]

Originally Posted by Wobbly

Thanks for the feedback guys ... I managed to find a relatively cheap pre-85 booster listed on dcautomotive which I bought and had shipped across to me. The part number listed that I ordered was "930.355.027.00" (as discussed above).

The part turned up in the mail today, but interestingly it seems to be a different booster, but I can't work out what model it is for. The part number of the booster they sent me is "930.355.025.05".

Any idea what model this part is from? I can't see it listed in any parts diagrams on dcauto for any model of 911/930. Being a numerically smaller part number could it be a superceded part from early in the turbo from 78 on? I'm hoping not an oddball part from the pre-78 930...

the only part # that I have that is even remotely similar is
959.355.025.05 which is the booster for a 959 and listed for $3156.86 in '02

the only boosters listed for 911/930 are
911.355.027.00 used '77 -'83
930.355.027.00 used in '84
930.355.027.02 used '85 up

[Wobbly]

Weird ... wonder if its for a specific market e.g. EU etc? Here's a pic .... its an ATE booster...

[uwanna]

The booster you have is indeed the correct one for an '86 and up 930! Here's a pic of the one I have which is identical to yours. This unit came attached to 23mm MC, and also had the later style "retangular" fluid reservoir which is used on the hydraulic clutch models. However, the hyd clutch oil supply line spigot is plugged. (don't know, but suspect the 930s of those years still used mechanical clutch)

[Bill Verburg]

It must be a super-session #

[Wobbly]

Ah, super - mystery solved. Strange that the part number is numerically smaller. I picked this up for $150 so sounds like I got a good deal