Clonk on Braking

[svenedin]

I am getting a clonk from the front suspension right side (driver’s side) on braking first thing when the car is cold. The clonk will happen two or three times and then becomes a tut, tut, tut noise on braking rather than a clonk. Then it disappears completely and will not happen again unless the car is left for several hours. The handling is completely normal.I will ask the experts here in France on Minors on Tour but any ideas? I think it is a sticking polyurethane bush. All the bushes are poly and around 2 years old.

Stephen

[svenedin]

Following a conversation with another MoT colleague this is due to loose tie bars. The nylock nuts I used have worked loose probably from driving on cobbled streets. Very dangerous if the tie bar(s) had detached. I am putting castle nuts and split pins back. The same thing happened to an MoT-er last year but I didn’t know this.

Stephen

[philthehill]

If you are going to put the castellated nut back on the front of the tie bars use 'R' clips instead of split pins.
'R' clips were used instead of split pins on the tie bars of the Morris Marina/Morris Ital.
The 'R' clips are stronger than the split pin.

[svenedin]

Thanks Phil. R-clips will have to wait until I’m back in the UK. For now I’ll put castle nuts or any other nut that fits as locknuts in addition to the nylocks already fitted. Will have to see what nuts we have between us on this trip.

[svenedin]

Thé nylock nuts had worked loose and were on the end of the thread.I have tightened them and there is now plenty of thread showing. I no longer trust thé nylocks though. Someone in the group thinks they may have some castle nuts

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[Bill_qaz]

Have they been used more than once? EG fitted and refitted, they are most effective on first use. Or fit two plain nuts one locked against the other until you get home.

[svenedin]

Have they been used more than once? EG fitted and refitted, they are most effective on first use. Or fit two plain nuts one locked against the other until you get home.

No they are new and have only been fitted once. Yes, if anybody has the correct nuts

[Bill_qaz]

Anyone got loctite or purchase locally refit nylocs and leave overnight to cure, maybe an idea for your peace of mind

[svenedin]

Yes but unfortunately it doesn’t seem to be the tie bars after all (though the nuts were definitely loose). The clonk is still there and unchanged. I don’t understand why it goes away completely after a few minutes driving

[myoldjalopy]

Just a guess, but could it be wear in the steering rack causing the sound, which is then quietened after the rack oil gets squeezed around by the bellows after a bit of driving? I did once have a car that had an occasional tapping noise from the RHS of the rack but it was not constant and sometimes absent for long periods.

[Sleeper]

A quick-fix when re-using nylok nuts is a hammer blow to the crown, re-compresses the nylon.

John ;-)

[Bill_qaz]

Yes but unfortunately it doesn’t seem to be the tie bars after all (though the nuts were definitely loose). The clonk is still there and unchanged. I don’t understand why it goes away completely after a few minutes driving

Is it something in your new front brakes and it changes when used a couple of times.

[svenedin]

Yes but unfortunately it doesn’t seem to be the tie bars after all (though the nuts were definitely loose). The clonk is still there and unchanged. I don’t understand why it goes away completely after a few minutes driving

Is it something in your new front brakes and it changes when used a couple of times.

It’s possible. I don’t think so but I can’t be sure at this stage. Tomorrow morning I am going to borrow some axle stands and check everything I can. I just want to either find the fault or reassure myself that it’s not something dangerous that is going to fail at speed.

[svenedin]

Just a guess, but could it be wear in the steering rack causing the sound, which is then quietened after the rack oil gets squeezed around by the bellows after a bit of driving? I did once have a car that had an occasional tapping noise from the RHS of the rack but it was not constant and sometimes absent for long periods.

Could be but only just started doing it.

I am puzzled. If it was something loose I would expect it to get worse at speed but it doesn’t. After 5 minutes driving it’s like nothing at all is wrong.

[Bill_qaz]

Maybe cylinder are being pushed back, does the brake feel change? Try pumping brake a couple of times before initial drive and see if alters the noise.

[svenedin]

Maybe cylinder are being pushed back, does the brake feel change? Try pumping brake a couple of times before initial drive and see if alters the noise.

Will do. It could be anything. I did try repeated braking from low speed to a stop earlier and it clonked every time then 5 minutes later, nothing. Brake feel felt normal the whole time. I even braked hard enough to lock the front wheels (on purpose)

[svenedin]

All completely sorted. Loose front brake back plate bolts. Thanks for your help!

Stephen

[myoldjalopy]

Well done! Peace of mind now for further adventures in France!

[svenedin]

Well done! Peace of mind now for further adventures in France!

Exactly!

[Bill_qaz]

Glad you sorted it, an all round bolt check sounds in order after your rebuild, 2nd loose fitting
Maybe being a bit too gentle on assembling?