Loud rear suspension bang when wheel drops

[goltho]

Every time the car "takes off" i.e. the weight comes off the rear axle e.g. an inclining undulation or ramp ends and the rear wheels drop suddenly, there's a long bang from the rear passenger-side corner. I've rebuilt the front suspension on two 75s but part from changing a pair of rear springs, have little experience of the rear end.

There's no indication of play in any direction with the wheel jacked up but then it's fully unweighted so that I can't emulate the movement. Any thoughts?

Dougie.

[xsport]

is this the zt you are working on ? i had this exact problem with my 75. in my case i had been supplied with the wrong length shock absorbers, i bought online . they were advertised as r75 rears. indeed they were ,but the seller had not realised that the shocks were for the very last model 75"s ( contempory) . these had the mgzt suspension set up. when i removed mine again and compared the new against the old ones, the new ones were shorter. i wondered why i had to jack up the rear arms so high to fit them. so i would suggest that you check that you have the correct length springs and damper combination if this is in fact your problem. what you could be experiencing is the shocks bottoming out whilst going over road humps , before you have" landed" so to speak. ..... and whilst you dont need much speed for this to occur , it certainly makes quite a thud.

[goltho]

Originally Posted by xsport

is this the zt you are working on ?

Thanks. I don’t have a ZT any more (see sig). The springs and dampers are original on the rear.

Dougie.

[Typhoon190]

Is the bump stop still in place? If they are the original shocks, it may be that the bump stop has disintegrated?

Item 6 from Rimmer Bros.

https://rimmerbros.com/Item--i-GRID001548

[goltho]

Originally Posted by Typhoon190

Is the bump stop still in place? If they are the original shocks, it may be that the bump stop has disintegrated?

Item 6 from Rimmer Bros.

https://rimmerbros.com/Item--i-GRID001548

Wouldn’t that cause the issue in the opposite direction I.e. when the damper is compressed?

[Typhoon190]

Sorry, quite right.

So when the weight is taken off the wheel, the spring will extend and take up the play from the failed component I guess. This could point towards the top mount, item 4 perhaps?

I saw this on the front of a little fiesta. When the car was on the deck the suspension felt 'loose', but when jacked up the play disappeared when checking by hand. The front top mount had failed.

[sln8458]

Originally Posted by xsport

is this the zt you are working on ? i had this exact problem with my 75. in my case i had been supplied with the wrong length shock absorbers, i bought online . they were advertised as r75 rears. indeed they were ,but the seller had not realised that the shocks were for the very last model 75"s ( contempory) . these had the mgzt suspension set up. when i removed mine again and compared the new against the old ones, the new ones were shorter. i wondered why i had to jack up the rear arms so high to fit them. so i would suggest that you check that you have the correct length springs and damper combination if this is in fact your problem. what you could be experiencing is the shocks bottoming out whilst going over road humps , before you have" landed" so to speak. ..... and whilst you dont need much speed for this to occur , it certainly makes quite a thud.

I have just replaced the rear shock on my 05 Contemporary with 'standard' ones. I am now a little worried that I have fitted the wrong ones.

I used this thread https://the75andztclub.co.uk/forum/showthread.php?t=104 and Rimmers website (has the same info) to purchase the new shocks.
This is the label from the old ones I removed:


And here is the label under the rear seat squab.


When did Rover change the rear setup on the Contemporary?
From what I have seen in my car it has the stansdard setup (label under seat & label on shock)

SteveN