Brake booster/servo help

arcdef

arcdef

Club Member
Hi all,

Took the 280z out for first time this year at the weekend. Noticed the brake booster making a strange sound along with pretty poor pedal feel (spongy and felt weak). I rebled the brakes but still felt soft and obviously sound from booster didn't stop.

Does this sound like I need a new booster? Also can you confirm it is the standard 280z booster and any idea which master cylinder is fitted?


20210222_120415.jpg 20210222_120424.jpg

Thanks!
 
Turn & Burn

Turn & Burn

Club Member
Doesn’t look like standard booster or m/c either.
Spongy brakes more likely caused by air in the brake lines tho. (Despite bleeding). Faulty booster (servo) usually gives a numb feel rather than a spongy feel, but I agree it shouldn’t make that noise, possibly a broken spring?
Pull off the vac line off the check valve on the bulkhead and try sucking a vacuum, if this doesn’t hold the booster is leaking, this could be leaking air or fluid in from the master cylinder which would account for odd pedal feel. It could also be the check valve on the bulkhead thats not holding vacuum.
New boosters are pretty cheap from Rock-Auto so not a major issue if it’s all gone wonky!
 
toopy

toopy

Club Member
Spongy and weak is more likely to be a MC problem, usually when the booster is failing or the vacuum pipe is leaking, the pedal would feel harder/firmer because assistance is reduced.
That said the booster can fail and cause a spongy pedal but its far rarer, although that's exactly what mine did!
However the air escaping noise isnt good either way, so check hose connections and the non return valve. Remove the pipe from the inlet manifold and suck on it to see if there is vacuum. Its possible the seal in the booster unit has developed a leak, but i would expect a firmer pedal not softer.

As Turn & Burn said, he replied while i was typing, but i posted it anyway.
 
arcdef

arcdef

Club Member
Turn & Burn said:
Doesn’t look like standard booster or m/c either.
Spongy brakes more likely caused by air in the brake lines tho. (Despite bleeding). Faulty booster (servo) usually gives a numb feel rather than a spongy feel, but I agree it shouldn’t make that noise, possibly a broken spring?
Pull off the vac line off the check valve on the bulkhead and try sucking a vacuum, if this doesn’t hold the booster is leaking, this could be leaking air or fluid in from the master cylinder which would account for odd pedal feel. It could also be the check valve on the bulkhead thats not holding vacuum.
New boosters are pretty cheap from Rock-Auto so not a major issue if it’s all gone wonky!
Click to expand...

Thanks, I'm nervous to order a new booster as i thought it looks different also and don't then want the issue of a new one not fitting! I've also not seen a master cylinder that looks like that in another 280z which further fuels my doubt!

I will go and give the check valve a test in a bit and try bleeding again. Definitely don't feel confident driving with the noise though in case it lets go when out on a drive!
 
arcdef

arcdef

Club Member
Removed the check valve and the noise stopped so good news is that it doesn't seem to be the booster.

Still need to get a firm feel though, need to practice the bleeding some more!
 
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