Powerlite starter motors

[ill_will]

That's a nice installation ElanDNA. A couple of questions if I may:

- it looks like you're referencing the fuel pressure to the intake vacuum rather than to barometric pressure, was that for a specific reason?
- what is the (I think) throttle cable arrangement on the top of the cam cover?
- is that a vacuum balance bar, and are you using that to run the booster, headlights and a map sensor, or some combination of them?

Many thanks,

Will

[gus]

A further update on this.

I ended up getting a RAC800 unit via Kelvedon (their part number is RACESM8) but have had some issues with it and thought the information might be useful for others looking to replace/upgrade their starter motors.

Some dimensions for the RAC800 co-axial starter:

- Pinion throw of approx 8.2mm (confirmed by powering from battery, but you can also rotate the pinion by hand to extend it)
- Distance starter mounting face to ring gear approx 32.4mm (this will vary engine to engine and corresponds to distance block to ring gear)
- Distance starter mounting face to pinion face nearest ring gear (disengaged) 27.7mm
- Clearance ring gear to pinion (disengaged) = 32.4 - 27.7mm = 4.7mm
- Overlap pinion (engaged) = approx 3.5mm (c.f. ring gear width of approx 8.5mm)

The picture below shows a mock-up with the disengaged clearance.

Some people have reported pre-engaged starters chewing up ring gears (NB I do not think this model specifically, but others that are available.) With this amount of engagement the pinion is still meshing in the portion with chamfered reliefs, i.e. not the full gear profile. I wanted to aim for a minimum of 7mm engagement and didn't try running it under power as-was.

After an email exchange with Powerlite, they have confirmed they do a RAC814 which is identical other than having an extra ~5mm throw, which should resolve this issue nicely. I'm exchanging the motor for this type and will update my findings here, but provisionally this sounds like the one to go for.

IMG_20240503_111933.jpg

What a horrible piece of crap
seriously
Max required offset from pinion to ring gear: about .100" or about 2.5 mm
So,first it is simply the wrong starter for the car.
8mm of throw?
Never seen a starter with so little throw.
Most starters are designed with about .300" [8mm] of engagement
So they need a minimum of 10 mm of throw assuming 2 mm of offset, preferably 12 mm minimum throw, 3 mm offset, 9mm engagement

While the numbers provided don't' quite add up, it feels like an Austin Mini starter. A little deeper than I would think[close to the flywheel at rest], but probably works in that car

I would first ask the seller what the projection should be, 8 mm is far too small.

I think this is not designed or intended for the Lotus TC, no matter what they claim

[2cams70]

FYI - The early Mk1 Escort vans came with a crank handle. That’s why when you see pictures of Escort Twin Cams you can see a hole in the front panel in line with the crankshaft centerline. It’s obscured on standard Escorts because they have full width bumpers. It was only available on commercial variants because time is money and you can’t have a commercial vehicle out of action for long. Maybe you guys could adapt something similar for the Elan using Escort parts. Especially so if you have fitted an aftermarket starter motor. Lighter and always up for action unlike an electric starter. It would also provide a good incentive for you to keep your engines in their most reliable form - i.e standard and with sensible compression ratios.

Hopefully the manufacturers of these starter motors have chosen premises located on hills so customer cars can be roll started when required.

[RichardHawkins]

2 cams,

Many years ago as an impecunious student with a scruffy old Morris 1000 I always used the handle to start the car. I lived next to a couple with young children who I did not want to disturb. Turn on the ignition, three clicks on the choke, turn the engine gently with the handle until it gently kicks back, then swing the engine with handle. The engine always started with virtually no noise. I miss the starting handle.

Richard Hawkins

[2cams70]

2 cams,

Many years ago as an impecunious student with a scruffy old Morris 1000 I always used the handle to start the car. I lived next to a couple with young children who I did not want to disturb. Turn on the ignition, three clicks on the choke, turn the engine gently with the handle until it gently kicks back, then swing the engine with handle. The engine always started with virtually no noise. I miss the starting handle.

Richard Hawkins

Yes people think of them being on cars of the 1920's but they were actually around for a lot longer than that!

[h20hamelan]

Then you could add a power take off as in my Lada Niva 1600

[ill_will]

The RAC814 arrived, so an update.

It is a slightly shorter (axially) and slightly larger diameter unit than the previous one, but still a decent amount smaller than the Lucas unit. It weighs approximately 2.8kg.

The offset between pinion and ring gear is approx 1.5mm as best as I could measure it. The total throw is approx 11mm. On the Powerlite website this unit is designated as for the Elan whilst cross checking the previous one it did not specifically mention the Elan but iirc mentioned various Austin/BL cars. I will leave it at that.

It is 9 tooth, and 1.6kW according to their website. Interestingly when bench testing you can see it achieves the full 11mm throw but then the free running throw is approx 8mm. When installed in the car however, friction between the pinion and ring gear whilst it is cranking retains it close to full throw, which in my set up gives more of less full engagement.

I blued the teeth and checked engagement, which looks to be approx 8mm x 3mm.

It turned over a tight freshly built engine nicely and I got oil pressure (plugs out.) I haven't tried plugs in yet.

What is striking is that it is quite noisy. I also tried the original 10 tooth Lucas starter and that was maybe slightly quieter but in the same ballpark. This might be because I have never had my ear a foot away from a cranking engine before, but it isn't a particularly nice noise!

Looking at the ring gear teeth, the tooth profile is very crude. I guess the sharp corners might gradually wear and things quieten down?

These are the ring gear teeth after maybe 2-3 minutes total cranking time during the various tests. I gave them a light brush to get the dirt off which is why they look a bit brassy in colour.

Any ideas? I can live with it, but it's not nice.

[alanr]

Your choice of course but I don't quite understand why you have chosen not to fit the Powerlite RAC472 MS 9 tooth like myself and others have done which is a more robust design (no plastic internal gears). It is a more robust unit and the model Powerlite recommend for our cars.
Mine works very well and is quiet in operation.

Alan.

[2cams70]

The RAC472 is just a modified Toyota Camry starter. Originally a Denso design it's now copied by all the usual Chinese knock off manufacturers. I doubt Powerlite and suchlike are forking out for the Denso version. See link example (this will be a knock off):

https://auto8.com.au/part/c/10002-elect ... 4-128.html

Every Toyota Camry I've ever driven has had a very reliable and very quiet starter motor.

The other RAC800 looks similar to the Brise. I don't know where this comes from and doesn't seem to be based on a regular production starter. It's probably designed more around racers who care less about how reliable and quiet their starter motor is.

[ill_will]

Hi Alan,

I originally purchased an RAC472 but then decided to go down the coaxial route for a few reasons: to avoid having a solenoid hanging off the side; to lose a bit more weight; and because the pinion is supported at both ends rather than cantilevering out. Also I figured if painted black it would appear reasonably stock at a glance. The only negative was the plastic gears, and only time will tell how they turn out.

But each to their own, and I don't mind doing a bit of development work, particularly with a company like Powerlite who have been very responsive.

The profile of the gears doesn't look too dissimilar to the 472, and the original Lucas starter makes a similar nasty noise which made me assume the ring gear profile was the main cause of the noise, but this might be wrong.

Cheers,

Will

[RichardHawkins]

Will,

You mentioned using a 9 tooth and then a 10 tooth pinion. Was this with the same ring gear? My understanding is that those two different pinions should not be able to mesh with the same ring gear, did you notice any damage?

Richard Hawkins

[2cams70]

That ring gear is interesting in that it doesn’t appear to have a lead in on the teeth. Original ring gears used with the Lucas inertia starter always had a lead in. How many teeth does it have?

[ill_will]

Hi Richard,

You're correct that it was with the same (standard 110 tooth) ring gear.

I did quite a bit of searching on here a while back and concluded that Lotus/Ford seemed to have used both 9 and 10 tooth starters at some point with the 110 tooth gear. But there is a lot of contradictory information!

Whilst my testing was for a very limited number of starts there is no obvious damage to be seen.

If I've understood correctly, 9 tooth/110 tooth was the standard configuration on the Elan - in this case, the noisier of the two combinations I have tried. The meshing shown by bluing on the 9 tooth pinion looks ok (no obvious contact at the peaks or troughs of the gears, and only contact of the drive face) but I guess there could be some other differences in the pinion geometry. I havent tried bluing the 10 tooth pinion yet.

The 10 tooth Lucas starter was the one originally on the car when I got it. I have a lot of service invoices from about 1981 up to 1990 with "BeeBee Racing" I think they were called and remember that the car was collected by them to fix starter motor failure a few times, so chances are it isn't the original unit.

Cheers,

Will

[ill_will]

2cams70 - it's a trick of the camera angle, it is a standard 110 tooth ring gear and has chamfers on the side away from the camera (photo taken through the starter hole, and the Lucas starter engages towards the camera whilst the pre-engaged style units throw away from the camera.)

Cheers,

Will

[gus]

I could be wrong as there is sparse real information, but I do not believe there were 10 tooth pinions in the original market. I think they came to be in the reman market, and it could be for several reasons. I took this pic a few weeks ago in reference to noisy engagement.

Know first that all starter pinions are bastard gears, far fewer teeth for their diameter than any normal gear would be designed. The measured dimension shown is not a real dimension, but it implies a dimension that should be consistent gear to gear
If the gear on your starter is significantly different, then it is different and may not mesh properly.