Mike1982

What is the part number for the 928 brake pressure regulator? My stock one is old and the rubber seal around it came off so I want to just upgrade to that one. Where is a good place to buy it? Pelican Parts doesn't look like they have it.

Oddjob

The 5/33 bar proportioning valve is 928 355 305 02

Mike1982

Also, how do you guys like this upgrade over stock? My car just went from my daily driver to summer/fun car so I don't have to worry about the winter.

Gator_86_951

I just recently changed this out. There is definately more rear brake. I haven't had my car at Sebring yet, but I would imagine under heavy braking more rear brake would cause the car to be a little more jumpy. You will definately see better over all brake performance under consistent heavy braking.

Oddjob

My guess is that under normal street braking conditions, you likely do not often exceed the standard valve's set pressure of 18 bar (above which it starts to proportionally reduce pressure to the rear), so you may not notice any difference at all.

It only becomes apparent during very hard or threshold braking.

TheRealLefty

I had a 33/5 sitting around on my 994S parts car and didn't even think about it for several months after purchasing a Turbo S. Swapped out the 18/5 immediately upon discovery of this little brass nugget. As Oddjob suggests, very little if any difference on the street, but once you get the juices flowing at track speeds, the car seems to have more overall grip under heavy braking, somewhat less dive and noticeably less front pad wear.

Jon Moeller

Running track pads on all 4 corners, I was getting significant rear lockup on my 951 with the 33/5. I'll get a better review once I sort out some other braking issues.
-J

Oddjob

Which then also leads to noticeably more rear pad wear....

I did notice a little more rear end happiness during trail braking on my turbo S, but I think that could have been sorted out with some alignment tweaking.

Alpine951

I got one from parts heaven last month for $10. They pulled it off a 928.

Waterguy

It might be a better upgrade for the Turbo S, which has ABS and more front brake bias than the regular 951. Its on my upgrade list.

Jolly

Not needed for street. For track, on hard braking, the back end can get very squirrly (lock-up), especially if the ground is cold/wet, or there is elevation change in the braking zone. Requires smooth braking technique.

I will trade you my good 928 valve off my car for a good working 951 valve.

Jolly

ibkevin

I reviewed posts and bought one after a careless driver pulled out in front of me, and without ABS, put annoying flatspots in a new set of tires. I especially like the idea of putting more load on my 245's.
With imature and pre-occupied drivers everywhere, good brakes are a must. Just watch your rear view!

streckfu's

?Do the brakes need to be bled if this is changed? Isit difficult?

I've been thinking of this as well.

Sam Lin

I've got a spare 5/33 valve sitting around, brand new in box, if anyone wants to buy it from me. Paragon wants $90 for one, e-mail me if interested.

Sam

Eyal 951

what else would cause a rear bias? my valve is stock, yet my rears lock first.
~Eyal