S3 v12 Lucas starter motor does not fit

[Danetype3]

Hi All,

A starter motor conundrum, to me at least:

So I have learned that my 160 teeth flywheel should match with the (new high torque) 25mm pinion Lucas starter motor. But that does not fit at all as you can see in the picture. The bearing at the outer end of the pinion hits the flywheel even while it is still retracted (did a few engine rotations by hand before I noticed the issue, hence the light wear on the bearing).

I do not know the history of the car, but on the SN tag it says the original engine is 7S10914LB. The current block is however 7S2836SA (FED 71). I think some of the 10914 parts have been moved onto the 2836, among other the flywheel. That would explain the 160 teeth in the older block.

Does anyone know if the location of the starter motor has changed in the engine block evolution?

Or could there be another explanation why this new Lucas starter motor does not fit? The design with the large bearing at the end looks strange. It seems to block the pinion teeth?

[DWW]

I don't know much about the subject let alone S3's but I hear people mentioning shims which may be the case here.

[bitsobrits]

To me the thing at the end of the starter pinion looks more like a cap than a bearing. And made of a fairly soft material from the looks of the marks.

[mgcjag]

That looks like an after market high torque starter motor......have you compared it to your original.....also check the actual part number there are many different units...you may have been sent the wrong one or it may have been packaged wrong.......either way you should check the throw out and pinion measurements befor installing.....Steve

[Bob.]

There was no change to the starter motor position throughout V12 etype production, nor were any mounting spacers used.
Substitute starters, unlike the OE units, have no bearing outboard of the pinion and the damage you are seeing is probably to the pinion retaining ring which moves in and out with the shaft and pinion as a unit.







As you rightly say the original engine 7S10914LB, a low compression unit from around March 1973 would have had a 160t ring gear with 25mm 9t starter pinion, whereas 7S2836SA, a high compression unit from around May 1971, would have had a 143t ring gear with 29mm 9t starter pinion. The changeover occurred in May 1972.

For your 160t ring gear, If the starter you have been supplied with has a pinion of 25mm diameter with 9 teeth then it likely has the right pinion but the wrong mounting plate fitted, giving the wrong radial position of the pinion.

Hope this helps.
Bob

[Danetype3]

Thanks for confirming that there was no change to the starter motor position Bob.

And I think you might be right with a possible wrong mounting plate. I also tried the 29mm pinion starter motor (ordered that one thinking the engine number meant something..) and that retaining ring did not touch the flywheel. And I could imagine that both 25 and 29 mm pinion starter motors have the same mounting plate because the difference in flywheel size would be accounted for by a different pinion diameter, not a different position?

The not-fitting 25mm 9 gear starter motor is the C34956 from SNGB which according to their manual is for engine 4098 up to 7000. I think this is also meant as a replacement for 7001 and up, but I will follow up with them to be sure and also the mounting plate type.

[mgcjag]

Hi.....note that the starter bolts to the bellhouseing....i dont knoww if there is a difference in bellhouseings for older / new engins....but is your bellhouseing correct for the enging number?

[Danetype3]

In the S3 the starter motor mounts directly to the engine block.

Here a picture of the 29mm pinion where the black retaining ring floats (just) above the 160 teeth flywheel (the pinion itself might hit, but we know it is the wrong size):



And the SN indicates the standard S3 7001+ flywheel is mounted on this engine:



Conclusion, if the 29mm pinion retaining ring is ok, a 25mm pinion should also fit. So, back to SNG.

[mgcjag]

Hi..whats your name...please try to put it in the signature area with your car model......info here from Jag S3 service manual point 5 "Remove two bolts securing motor to bellhouseing".......im no S3 expert.....i know that the S3 used different model starters.....are some bolted to the block others to bellhouseing?.......Steve

[Bob.]

The original Lucas M45G starter flange is threaded, bolts passing through the bellhousing, then through the block flange into the starter. (Many aftermarket devices use nuts and bolts although not the one shown below.)

These pics may help understanding.

Original Lucas M45G


Aftermarket (brand unknown)






Comparing images on the SNGB webite of their Lucas branded devices, there is a striking resemblance to the ones manufactured by Powerlite. Unfortunately the dimensions shown on the Powerlite webite are not very helpful in this case, but they might be worth approaching if SNGB can't help.

[mgcjag]

Hi Bob...thanks for posting....Steve

[Danetype3]

Just to follow up, I ended up putting back the original starter motor. This has good clearance. The high torque version does not fit on this car with the older block and newer flywheel. Apparently this mixing of parts does add some tolerance, although I would not expect that from these parts to this extent.





Servicing the old style starter motor was a fun job to do. There are some service manuals online for the M45G. I learned that the Solenoid actually has two coils cleverly switched. One for pulling in and one for keeping in place. Who new

Here is a helpful part number list. I ordered some parts but the seals were disappointing, very bad aftermarket.