Brake Booster Vacuum Leak...?

[JH32]

Hi guys

A couple of months ago I replaced the clutch master cylinder and booster in my R32 GTR and in doing so had to pull the brake booster back so that I could get the clutch master/booster out. Once everything was back together, the car just didn't feel the same. It now seems to run rich, the brakes feel quite doughy, and it just doesnt seem to have as much as power as it did when it was tuned about a week before I pulled everything apart.

I never really joined the dots though until now... could a vacuum leak in the brake booster cause the above symptoms?

I have bled the brakes in the proper fashion, though to no avail. The brakes used to feel fantastic, very bitey (Brembos) and the car isn't driven much so it's not the pads/rotors.

As mentioned, it was tuned about a week before I pulled the clutch / brake boosters out and it was running beautifully - I don't remember it running overly rich following the tune. Today I hit the accelerator while my mate was following in his car and he said he could smell the fuel and could see the black smoke come out the exhaust.

I also tried squirting WD40 all over the various vacuum lines around the brake booster to see whether I could notice the revs jumping up but no such luck.

Could it indeed be the brake booster or vacuum line, or should I just leave it to the professionals when it hits the dyno next week for a look-see?

I have attached a photo of the brake booster and the region of the various vacuum lines that I squirted the WD40 over.

Cheers

[scotty nm35]

Sounds like the old booster was leaking, why was it changed?

You will need to get a retune now the leak is fixed if that's the case.

[JH32]

I had to change the old clutch master because it was leaking fluid. Come to think of it, I don't think I changed the clutch booster, only the master cylinder; I think both the clutch booster and the brake booster are the originals.

I think that the vacuum leak (if there is one) must have developed since doing this work; can you damage brake boosters if you're not gentle with them?

[scotty nm35]

The boosters are fairly robust, but the seal around the master cylinder shaft might be leaking, or the brittle vac hose may have split?

[JH32]

Thanks for your replies Scotty, I think I will replace a number of the vacuum hoses around the area and see if that has any effect because as you say they do seem to be quite stiff and brittle.

[scotty nm35]

Beware, the booster hose has a one way valve inline that will need to be installed into the new hose, otherwise your brake booster won't always work.