Drivetrain knocking that gets louder on braking

[llessur]

Have finally taken my 2500S project out for its first test drive - goes quite well but there is a dull rhythmic knocking sound when driving. It seems to match the road, rather than engine speed but becomes noticeably louder on braking.

Any ideas as to what this could be or any way of eliminating components? I'm presuming it's either the prop or driveshaft(s). The gearbox mount is a brand new Mackay one so should be good.

[Nick Jones]

Wheelnuts tight?

Knackered UJ exploiting backlash when unloaded?

[poppyman]

How about the tyres? Are they new or old? I had a lump on my modern that made that sort of noise, it was a front one therefore worse on braking.

Tony.

[llessur]

Brand new tyres, only been on the car a while so I can't think that they've distorted yet. Will pop out and have a look and also check the wheelnuts for an easy fix.

If it's a UJ, is it easy to detect which one is worn? Can I just give the prop and drive shafts a good wiggle?

Last time I had a UJ go was on my Spitfire years ago - but I got a garage to change that for me...

[NonMember]

I had a defective tyre on one of my old Dolomites. Developed a huge bulge on the inner sidewall within a month of fitting. Worth checking.

[Pete Lewis]

i dont think uj on the 2000/2500 driver shaft suffer like the small chassis ones , 

but easy too pull the whole shaft thro the back plate , just 6 nuts and the coupling and shes off. 

very low  12lbft torque on the 6 nuts .easy to shear them off 

it took my 2000 new alloys a while to settle down, but a couple of  wheel nut  re torques and its never made a sound , but that does give  a good rumble 

do make sure the drum retaining screws are not proud of the drum .

Pete

 

 

[trigolf]

If it's a 2500 saloon, could it possibly be worn driveshaft splines?

Gav