K Series Starter gear clearance issue

[Grant Dryburgh]

Hi all, wondering if anyone has come across this issue on their 7. 
 

When I bought my 7 I noticed the starter sounded awful when cranking the engine, high pitched whine/screech. My guess was a bad motor or simply incorrect clearance between the starter gear and the flywheel. So I removed the starter and noticed the starter has oval holes for the bolts and the spacer plate does not. I refitted and clocked the starter motor as far as I could clockwise to gain more clearance between the starter gear and flywheel. Worked a treat and the noise was gone sounded perfectly smooth as it should. 
 

However, the awful noise has slowly come back and I've found the starter has worked itself back in towards the flywheel. I'm guessing the torque of the starter is pulling it back over when cranking. 

Anyone had this issue and found a solution ? 
My only thought at the moment is set the starter and spacer in position drill through both then press a pin in so it cannot rotate in towards the flywheel again ?? 

[Wrightpayne]

I've had a K since '98 and been a member all that time and dont recall ever seeing this issue before. 
 

Perhaps someone live Revilla can confirm whether the starters have slotted fixings.

[Grant Dryburgh]

Yeah it's a strange one, been having another play about with it today, there really is minimal movement when bolting it up but it seems to make all the difference. there's no visible damage or uneven wear on the starter gear or flywheel just seem to get this awful noise if it's not in exactly the right position 

 

[revilla]

Someone like Revilla ...

Now there's a scary concept!

So that looks like the end plate off the standard Magneton 9141 380? I've just checked out my spares and yes, they are slightly elongated, about 10.8mm by 12.0mm so just over 1mm play to allow rotation of the motor.

I don't understand though ... the motor should be accurately located (other than for rotation about the axis of the motor shaft) by the outer circular "step" being a snug fit into a circular recess in the spacer ring. If the motor body were to move within the elongation of the mounting holes, it should only be able to rotate about the centre line of the pinion gear, and let's face it the motor rotates about this axis in operation ... I can't see how it could be affecting the clearance of anything, or the angles at which any parts meet.

As you can see in my picture, the small recess in your pictures for the small drive gear doesnt show at all on the outside so the nose of the motor really is symmetrical in rotation about the motor axis.

One thing that can lead to nasty noises from the starter is if the ribbing on the side of the block has not been relieved enough to allow the starter to sit accurately square on to spacer ring and the mounting face of the bellhousing. If this was the case here, I guess that if the motor were to rotate under its own torque it could press more against the block and lever itself slightly out of position.

But the other thing I can't understand is this; the motor is clamped to the bellhousing by a stud and nut at the top and two M10 high tensile capheads which should be done up pretty tightly. There will be several tons of clamp load and the friction should be enough to prevent the motor from turning in the way you describe. It just shouldn't have the torque to overcome that kind of clamp load (it does turn the engine with a fair torque but a lot of that is the large gearing between the small pinion gear and the large flywheel ring gear, the actual torque at the motor is a lot less). Unless of course it was catching on the side of the block as above and not sitting flat to the bellhousing, in which case it might be a bit more free to walk in the direction that relieved the forces on it. Still sounds odd to me though.

With the starter bolted in place, try folding a piece of cardboard and slipping it between the starter and the block. It doesn't need to be thick, you only need a fraction of a millimetre clearance, you just need to make sure that there's no contact between the motor body or solenoid at any point. You should be able to slip the card in feely behind the motor and solenoid at all points.

If your mounting holes are elongated by more than the amount I measured, I have this spare end plate:

 

Does it look to be generally the same shape and fit as yours?

You're more than welcome to try it out to see if makes any  difference if you want.

[revilla]

PS: I've never worried about aligning my starter in any particular position within the play afforded by the elongation of the holes; I'd never even really noticed that there was scope for movement. So long as all the bolts go through, it's on. I've never had the issue you describe and never heard of anyone else having it either.

[psarfas]

Is your engine fitted with the standard flywheel? I changed mine to a steel TTV lightweight one and it now makes the sound you describe when the starter is engaged. Plus an awful rasping noise on the overrun in the lower gears. Possibly something to do with the resonance of the different material... Not one of my better 'upgrades'.

[Grant Dryburgh]

Yeah spent yesterday having another play around with it and your exactly right Revilla, the elongated holes are only letting the starter rotate in the spacer. When offering it back upto the car I have noticed there is a very small amount of movement in the spacer but I'm talking maybe 1mm so I can't see how that would have such an effect. 

The noise is really quite awful when it occurs, I'm almost embarrassed to start the car with the screech that follows. 
 

I,ve refitted the starter but this time clocked the motor as far anti clockwise towards the flywheel as I can and at the same time kept the spacer pulled back as far from the flywheel as I can. My thought is if the motor is pulling the spacer over, with it now hard against the fasteners it shouldn't rotate and the spacer should remain where it is. 
 

As you said though Andrew with the clamping force of those fasteners it shouldn't be going anywhere anyway. I've tightened them as much as I dare, any tighter and I think I might risk rounding something off. Seems to be sounding ok when cranking in this position so I'll see if it lasts this time. It's had me scratching my head for hours this issue 

 

Ps as far as I'm aware it's the standard flywheel the car would of came with, I'm assuming the caterham motors came with a slightly lighter flywheel than the regular mg rover units ?? Certainly isn't a fancy aftermarket one anyway 

[Grant Dryburgh]

Also meant to add there is plenty clearance between the motor and the block so it doesn't seem to be a result of fouling on the engine block 

[revilla]

Are you sure that when you've been clocking it back, you haven't disturbed anything else at the same time? In your photographs it looks like the face plate has been off and things greased? Could it be something else you are doing at the same time that's relieving the squeal for a while? The bearings on the motor can make awful noises if on their way out.

[21jigsaw]

There were different adaptor plates for different  starter motors the odd one being a Bosch I seem to remember could this be the issue?

[SLR No.77]

Is there definitely enough clearance behind the starter? If I recall correctly there's a substantial amount needed to be ground off the block to clear the mounting flange of the starter, not just the body, this could be easily overlooked.  A starter mounted slightly out of square would cause the binding noise you're describing.

Stu.