Knocking only under braking

[iangex]

Recently I have noticed my Rev3 knocks under braking from the offside rear. I have only noticed it for the past 2 weeks and it appears to be getting worse.

I do not notice the same knocking over bumps and it only does it once per application of brakes. Occasionally it will not make the noise at all, usually it is ok first thing but gets worse the longer I drive it for.

It does not seem to knock over bumps. I have checked wheelnuts, and all are tight.

One thing I have noticed is that there is no screw holding the disc to the hub (this is done solely by the wheelnuts, and has been fine over 3000 miles since ive owned the car).

I believe it may be droplinks (from searching, I can also twist them fairly easily), and may replace them this weekend, however it is strange that it does not clunk over bumps - only upon braking.

I will order droplinks tomorrow ('96 Volvo S40 from local factors are suitable replacements I have heard), however does this sound like a likely culprit given the symptoms?

[RENOFOXX]

i've got the exact same issues with my car m8 ! posted the same question a while back but no response from any members !! is there anyone who can help us please.

[Keri-WMS]

Have you guys got aftermarket wheels? I've seen it a few times that wheels on other cars have "hung up" on the bore of the wheel / centre of the hub, and are not actually clamping the disc at all!

Possible but unlikely though....

Something shifting might do it (loose subframe mount bolts or a torn bush), as well as more direct caliper related things. Also the shock moving in the hub carrier bit. Ok, here's what I would check:

- Proper wheel fitment (look for rubbing marks on the wheel/disc/hub faces)
- All your rear balljoints and bushes.
- Rear suspension bolts tightness (correctly torqued).
- Rear subframe bolts.
- Caliper mount bolts.
- Caliper sliders (sticking).
- Caliper slider bolt.
- Pads not loose in the carrier due to missing clips.
- Nothing rusted through and "clicking" under load as it cracks!!!!!

[iangex]

Right ok, I took off the relavent wheel and pulled/pushed at bits. Although clearly I am not able to apply the same force as under braking, everything seemed pretty solid and the bushes were intact.

However, the caliper does appear to be sticking. IIRC they dont slide totally free but this one took quite a bit of effort to budge and the seal was slightly damaged.

Did some emergency stop tests, which went fine and may have temporarily fixed it.

I would be surprised if this were the issue, given the noise, however I will replace slider and seal then go from there

[RENOFOXX]

yes i have aftermarket wheels so will check it out!! thanx

[Keri-WMS]

Ah! One more!

- "make sure the caliper can't touch the spokes of the wheel as it flexes!"

[iangex]

I forgot to say - I also have aftermarket wheels, so it may have something to do with that. The spokes do not appear to be very near the wheel and the nature of the noise makes me believe I can tick this off the list.

Will be a few weeks before I get a chance to do the sliders unfortunately.

[Keri-WMS]

I forgot to say - I also have aftermarket wheels, so it may have something to do with that. The spokes do not appear to be very near the wheel and the nature of the noise makes me believe I can tick this off the list.

Will be a few weeks before I get a chance to do the sliders unfortunately.

What about the "aftermarket wheel hanging up on the centre of the hub" possible cause though?

[iangex]

Oops, I missed this bit.

My alloys are running on spigot rings, which are a sliding fit into the alloy and over the locating section of the hub. They don't seem to be hanging up at this point.

My next move will be to replace rear sliders and balljoints (hopefully next week). Fingers crossed on this, its annoying as otherwise the car drives well

[TheBaker]

I had this issue a while back but it was accompanied by leaking break fluid, if I recall correctly the knocking was from the piston in the caliper, I had the seal replaced and both issues went away.. Not sure if the knocking was due to the seal but it started when it had been leaking so the issue was with the calipers..

Hope that may somehow help.

Highly doubt it's your drop links, it will be something involved with the caliper I bet.

"The knock is probably dueto the examination carried out by your mechanic. It will possibly be either a missing or dislodged clip on the pad/caliper carrier. "

Quote from my thread on the issue, possibly a clip has dislodged.