Things that go bump............

[curtis]

I am having great problems tracing a noise from the rear of my BN2.
I would describe it as a metallic tap/bang. It arrives when going over uneven surfaces and can be produced to a lesser extent by pushing up and down on the driver's side (LHD) rear wing.
I have had the car over a pit and have checked the following which show nothing untoward.
Exhaust not touching.
Springs not broken.
Bushes recently replaced.
Shock absorbers topped up and working.
Shock absorber links appear OK.
Shock absorbers are bolted tight.
U bolts tight.
With a breaker bar I can't produce anything unusual when under the bushes.
The shackle pins have not been replaced but don't appear to be worn..see above.

Going crazy.

Any ideas ?

 

[Patrick67BJ8]

I am having great problems tracing a noise from the rear of my BN2.
I would describe it as a metallic tap/bang. It arrives when going over uneven surfaces and can be produced to a lesser extent by pushing up and down on the driver's side (LHD) rear wing.
I have had the car over a pit and have checked the following which show nothing untoward.
Exhaust not touching.
Springs not broken.
Bushes recently replaced.
Shock absorbers topped up and working.
Shock absorber links appear OK.
Shock absorbers are bolted tight.
U bolts tight.
With a breaker bar I can't produce anything unusual when under the bushes.
The shackle pins have not been replaced but don't appear to be worn..see above.

Going crazy.

Any ideas ?

Double check the shocks. If they were loose at any time in the past they could have made the mounting hole(s) oval shaped and if they are all the tightening you do will be useless. This happened to me.

 

[bighealeysource]

Hey Curtis,
Like Patrick said, I would double check the shocks. I had the same problem as you describe and checked the shocks and all nuts and bolts were tight and turned out the problem was the bolts were maybe a 1/16th of an inch or less from actually being up snug against the mounting plate. So under inspection appeared to be tight but in reality, the entire shock unit would move when you hit a bump or uneven road patch and got the infamous clunk. Put another lock washer on and solved the problem.
Good luck,
Mike

 

[RAC68]

Hi Curtis,

I 100% agree with Patrick and Mike as this is most common and is the easiest thing to check. I would also check the end links of the springs as a deformed or missing rubber bushing will also provide banging.

Good luck,
Ray (64BJ8P1)

 

[tahoe healey]

Same problem. Only the elongation was in the shock body. World Wide replaced it and no problem. When I put them back together, I used hefty star washers and lock tight.

 

[Bob_Spidell]

I recommend using Grade 8 flatwashers under the bolt heads. This increases the clamping surface area and hence total clamping force (also distributes the force over greater area of the shock body). Do not use lockwashers under the bolt heads as they will dig into the crappy, soft shock body metal and the bolts will loosen (look at the shock mounting 'ears;' you may well see where lockwashers, if used, have dug into the metal). Don't use 'standard' (non-hardened) flatwashers as they will deform and not provide as much clamping force.

I use Grade 8 flatwashers, threadlocker and torque the bolts to spec on the front shocks and have never had a bolt come loose. Tried threadlocker on the rear shocks and had one come loose--only time threadlocker didn't work for me--so went back to split lockwashers on the back (nut) side of the bolts and they held. Doesn't hurt to use threadlocker, too ('belt and suspenders').

 

[tahoe healey]

I did use hardened washer along with the star lock washers. This was recommended on this forum a couple of years ago. That's what this forum is all about. Two years now and now problem with that annoying "bump".

 

[Bob_Spidell]

I did use hardened washer ...

Which you didn't mention in your previous post. Are you saying you 'now' have the problem again, or you have had 'no' problems? I'm interested because it was probably me that recommended using hardened flatwashers (I use them religiously in stressed applications, just like they're used under head nuts/bolts). If that approach hasn't worked for someone I would try to figure out why.

IMO, it doesn't hurt to repeat info on this forum occasionally as new members may have joined in the last couple years, and new approaches are still discovered to old problems.

 

[tahoe healey]

Nope. No problems with the hardened washers and star locking washer. Of course, now I've cursed it and it will be a problem. And I do think it was you who recommended the hardened washers.
The hardest part of this was getting a socket in that little space. I had to use a long, thin tube socket to get it real tight.

 

[curtis]

Thanks for the thoughts.
I'll revisit the shockers. I have my doubts, but then that's what some of you said !!
If anyone has any other thoughts.................

 

[Patrick67BJ8]

Thanks for the thoughts.
I'll revisit the shockers. I have my doubts, but then that's what some of you said !!
If anyone has any other thoughts.................

This is what I did to my Front & Rear Shocks to keep them tight and from loosening. It's called "spot facing".

 

[Bob_Spidell]

Thanks for the thoughts.
I'll revisit the shockers. I have my doubts, but then that's what some of you said !!
If anyone has any other thoughts.................

I believe you said you checked the shock bolts, and that the 'bump' doesn't happen when you bounce the rear end, so it may well be something else but, for the life of me, I can't think of what else it could be. Something bouncing around in the boot, maybe?

 

[Bob_Spidell]

Looks like a good idea (I prefer threadlocker to lockwasher on flatwasher, though). The rear shocks I've seen have something similar from the 'factory;' just the right size for a Grade 8 flatwasher.

 

[curtis]

Thanks for the thoughts.
I'll revisit the shockers. I have my doubts, but then that's what some of you said !!
If anyone has any other thoughts.................

I believe you said you checked the shock bolts, and that the 'bump' doesn't happen when you bounce the rear end, so it may well be something else but, for the life of me, I can't think of what else it could be. Something bouncing around in the boot, maybe?

Yes it does appear when I bounce the rear end and its nothing loose in the boot.
Wondering if it could be the shackle pins ? Bushes are newish but I don't know if the pins could cause this? I couldn't see any movement with a bar under the spring end.

 

[57_BN4]

A few years back I had an old car with an annoying clonk from the rear which came and went. Turned out to be somebody had tried stealing/siphoning petrol from it long ago and dropped their hose arrangement in the tank