So I got new wheels and tyres. Since fitting them, I have a low rpm vibration in what seems to be just the left/passenger door card. The wheels are balanced and aligned but are ET40 vs ET37.5. Ive asked before on here and was told it makes no difference but its the only difference left so...

At 60 mph plus, all the way through to 80 ish, theres a hummy, very fast paced but low amplitude vibration in the brake pedal and the steering wheel that are matched. 

It seems to be rpm and gear related as its felt in 4th and 5th starting at about 2300rpm. The vibration is slower in 4th than 5th. Everything is fine at all other speeds including 4th and 5th until over 60 mph.

This leads me to believe its load related and could by my axles or gearbox. It doesnt go when the clutch is pressed tho so I dont know if thats barking up the wrong tree. The low rpm vibration is there in neutral, clutch up or down.

Ive replaced the top mount (belt end) and the bottom mount (gearbox to subframe) and no difference.

Ive had the car inspected and theres no physical signs as to why it would occur.

Am I looking at a gearbox issue? Or more likely to be axles? Or is it the wheel offset being different? Im stuck. 

Also, is it normal for there to be minor play and a clicking from the gearbox when rotating the wheels ever so slightly back and forth? 

You've answered your own question:

4 hours ago, SquidgyB7421 said:

So I got new wheels and tyres. Since fitting them, I have a low rpm vibration in what seems to be just the left

Put the original or correct wheels back on

1 hour ago, DaveT70 said:

You've answered your own question:

Put the original or correct wheels back on

You assume too much. Not possible.

Very possible I'm afraid.

Warped or not to spec.

 

Not warped, had them balanced, would have shown up, and only spec change is the offset. Same size otherwise.

Just to be 100% clear - are they Ford wheels?  And by that I mean is the centre bore correct?

7 hours ago, SquidgyB7421 said:

Also, is it normal for there to be minor play and a clicking from the gearbox when rotating the wheels ever so slightly back and forth? 

Depends what you mean by 'minor', but essentially no.  Without being there, it could well be a wheel bearing.  Does the vibration increase/decrease if you load each side of the car in turn - and by that I mean on a long left-hand bend you are effectively loading the right front, and vice versa.

Warped wheels can still be balanced.  Though it's easy to see when they're spun on the balancing machine.

If the only change is the wheels then it has to be them.  Interestingly I had a similar issue when swapping Titanium multispokes for Zetec flat spokes.  I was doing it to sell the car so didn't look any further into it, just assumed the wheels were warped or not balanced as they were a bit tatty and super cheap.  Probably coincidence though.

If you want to test the offset theory, but a pair of 5mm wheel spacers and stock them on the fronts just to see if that makes any difference.

3 hours ago, orangecurry said:

Depends what you mean by 'minor', but essentially no.  Without being there, it could well be a wheel bearing.  Does the vibration increase/decrease if you load each side of the car in turn - and by that I mean on a long left-hand bend you are effectively loading the right front, and vice versa.

As in essentially zero. More of just the inertia of the wheel in the change of direction. Single click as you go from anti clockwise to clockwise. 

Intermediate drive shaft bearing?

Slightly less on a long left bend than a right but no increase from either direction.

3 hours ago, TomsFocus said:

Warped wheels can still be balanced.  Though it's easy to see when they're spun on the balancing machine.

If the only change is the wheels then it has to be them.  Interestingly I had a similar issue when swapping Titanium multispokes for Zetec flat spokes.  I was doing it to sell the car so didn't look any further into it, just assumed the wheels were warped or not balanced as they were a bit tatty and super cheap.  Probably coincidence though.

If you want to test the offset theory, but a pair of 5mm wheel spacers and stock them on the fronts just to see if that makes any difference.

Thats my only theory left considering its in the brake pedal, which is fairly odd. 

My only potential way of diagnosing any particular part would be to have it up to speed on a lift and do a bit of feeling around with a metal kebab skewer. See if I can feel it somewhere.