Wheel vibrations with 15" on '72 B

[neilr]

greeting one and all,

Ive recently put 15" minights on my 72 BGT, however, when you get up over 55mph on a smooth bit of road you get intermitent vibrations through the steering, in fact it feels like the wheels are badly in need of balancing, except for the fact that it suddenly stops for a minute or so nd everythings smooth as you like, then it returns (repeat for duration). Doesnt happen below about 55mph though. You can also feel slack in the steering while its doing it. However, whith the 14" rostyles on it, the effect is hardly noticable at all. Ive had an MG specialist drive it (with 14s on it) and they came back with ''nothing wrong wih it mate" Ive had a good look and cant seem to find any play in the steering at rest or anything untoward such as dodgy bushes that need replacing.

I wanted to drive it to lemans in June but unless i can solve this i wont as there is obviousley something wrong with the it. I'm taking the wheels to be balanced tomorrow morning just to totaly rule it out (cant see how it can be that though given the intermittent nature of the fault). Could it be a steering rack in need of replacing? I'm assuming that the effect (whatever it is) is increased due to the extra mass of the 15" wheel?

thanks
neil

[wadgebeast]

Sounds like kingpins have worn out, that being one of the more common faults. As you say the extra leverage of the 15" wheels is just exaggerating it.

[thegman]

how is it under breaking - does it lean to one side or the other? i agree with above - suspect it is a king pin.