930 starter/ring gear?

Hi Guys,

I'm just playing with starter/ring gear placement at the moment prior to machining up a flywheel. I have a 930 ring gear and a Hi Torque reduction drive starter. This starter is for the Porsche models which have the ring gear a long way back from the engine, I want to run the gear in the forward position close to the engine. I understand there is no long nose reduction starter available so will have to use the Porsche (Bosch) heavy duty unit, which by most accounts is well up to the job although expensive.

As I cannot lay my hands easily on a longnose Porsche starter, I was hoping someone on this forum may have an old one lying around that they could roughly measure the distance from the mounting flange to the front of the pinion teeth. Thanks in advance.

That is one way to go. There is another, which has just dawned on me and which I would prefer, that is to mount the starter on the front of the adaptor plate under the motor near the normal Ford position. Of course that Porsche starter would then turn the engine the wrong way! I need to find a 'normal rotation' starter motor with a pinion compatible with the Porsche ring gear. The Porsche ring gear has very square teeth compared to most others I have seen. Has anyone been down this track before? How is the starter on a 928 mounted? Would something off a 928 turn the right way and have the right teeth? That being the case I would use a new Hi Torque 928 unit.

I'm hoping the Porsche experts on this forum can help me out.

Unfortunately here in NZ this is exotic stuff and most of it is pretty thin on the ground, so it's not that easy to just go and look at something to check it out. If I take a stab and order it from overseas and it's not right, time and distance is against me for returns! I think I'm already the proud owner of a redundant brand new Hi Torque Porsche starter motor, I don't want to make it two if I can help it!!

However I do see the 928 option as the best bet. Is anyone able to compare the tooth profiles of the 928 and the 930 or G50 ring gears? Also would someone able to measure the OD of a 928 ring gear in case thats an option too?

BTW I have done extensive searching and reading on this forum and elsewhere, before asking these questions.

Any help or info much appreciated.

Thanks.

Russ,
As I think I have told you already I have used the Holden 202 6cyl ring gear when making up small dia clutch & bell housings for SB Fords. The tooth profile suits the ford starter pinion and if your really stuck you can use the Holden Auto flexplate sandwiched between crank/flywheel ( all you have to do is file one bolt hole and enlarge the centre hole to ford size ). If Holden ring gear dia is too small to allow mounting in std position by sump you can get a marine version that may be able to be mounted in the porsche position as the 'nose' of the starter can be exchanged to suit most applications. 'Road Runner' in Hamilton have supplied these to me in the past.

Jac Mac

Thanks Jac Mac,

Already checked that one out! 292 OD. I need max 280 OD. Even XK,XL,XM Falcon and Escort/Cortina @ 283 is just too tight. Hardly any clearance on Porsche 280 OD and not much meat to machine out. However Falcon is a possibility if the 928 scenario doesn't work.

Advantage of the Porsche gear is that it's bolt-on. How does shrink-on go on aluminium?

Thanks,

Try these ;
Repco part no:

Fiat- 280.8 mm OD -256.2mm ID-12mmwide-131t- pn,430
Fiat- 277.2 mm OD -256.2mm ID-12mmwide-129t- pn,431
Mitzi-281.1 mm OD -245.5mm ID-9.7mm w -110t- pn,472
Alfa- 276.2 mm OD -219.8mm ID-10mm w -110t- pn,488
Alfa- 277.6 mm OD -227? mm ID- 10mm w -130t- pn,497

Then of course there is the humble Morrie Minor/Austin A35 etc which I believe was OE at 10.84" OD(275.6mm). 9.56" ID (242.8mm) several widths and 107 teeth. pn 359 ( obviously other widths have different pn.)

Shrink fit on alloy should be backed up with several set/cap screws to prevent movement.

Jac Mac

Thanks Jac Mac, will check those out.

Still looking for Porsche starter info.

Cheers

Regardless of which flywheel ring gear one chooses, the tooth pitch must be compatible with the starter pinion gear. I tried to get a grip on the various ring gear pitch information to no avail. Does anyone have such information? Unfortunately Porsche has a habit of making components to their own specifications, and rarely interchange with industry standard parts.

Andy

The reason for all this is I don't want to have to machine the flywheel out of a massive piece of billet aluminium! So I have looked at numerous options to get the ring gear near the motor.

Problem is, it's not easy to see anything in the flesh out here, or get measurements. The current idea in the last few hours, (thanks Jac Mac!) is to run a flex plate type ring gear mount off the back of the clutch cover bolts. This looks like the best option so far and should be possible to get the ring gear in the right place to suit the starter motor.

Cheers

Russ,

I sense that you're close to a solution.
There are a few manufacurers of rear start bellhousings, starters, and starter rings here in the US. One such that I will direct you to is: Quarter Master Racing Clutches
In the catalog, select Rear Mount Starter Bellhousing to illustrate what is available. You will find they make a ring gear that bolts to their clutch pressure plate. I'm not sure if this gets you closer to what you are looking for.
If you call QuarterMaster, I think you'll find them refreshingly willing to work with you, as they did with me on past special projects. They do custom work, however now is the start of the racing season and they're pretty tied-up with Nextel Cup and other professional race series work. Kennedy Eng'g. I believe will sell you a Porsche starter compatible ring gear, but then you'd still have to adapt it somehow. Tilton would be another manufacturer to check with.

Good luck,

Andy

Thanks Andy,

Out here most of us just tend to build these things ourselves. That way we get what we want and often it's quicker than trying to import something.

The Porsche trannies already have a rear mount setup. As I said, I've got a ring gear and starter, it's just a matter of trying to get a few measurements to suss things out for the best setup for me. But as you observe, I think I'm nearly there.

Thanks,

I know 2 porcshe workshops Russ.
I maybe able to get the info you are after.

I think you may find the long nose is on the duel mass flywheels.
I have both flywheels at work to do measuring for a job and the ring gear is closer to the motor.

You want distance from flange to end of snout and # of teeth.
What else.

Jim

Thanks Jim,

That's about all I need. I think tooth count should be 9. What's the chance of laying your hands on 911 and 928 ring gears and comparing the tooth profiles? Also maybe OD's. The 928 idea won't easily work for me due to issues with the chassis and a shallow dry sump but I feel would be a nice simple solution for guys with a more conventional chassis and pan.

Latest and easiest plan I think is to extend the shaft on the starter forward so it can slide in a spigot in the adaptor plate/bellhousing. That way I can put the ring gear in the most suitable position and space the pinion to suit. That's 'Plan F'

Cheers

Ross

This is all I could get.

Long nose starter is for the duel mass flywheel.
Bosch # 001 110 059
Porsche # 964 604 104 00
Flange to end of shaft 113mm
Flange to end of gear 87mm
10 teeth.


short nose
0 001 312 110
flange to end of gear 36mm
9 teeth.

G50 RG 280 OD 241 ID. 132 teeth

915 ring gear 276 OD 234 ID

He did think the 930 RG was the same as the G50.

No info on the 928 as they had no parts to look at.
I hope this helps.

Ross have you thought about running a drive plate of an auto.
Bring the starter in from the engine side( if room) and bolt a flywheel over the top of the drive plate.
The flywheel only supports the clutch.
(I bet your sumps in the way isnt it)

Jim

Thanks Jim.

The 930 ring gear is not quite the same. I have one here. 280 OD 132T but 234 ID. Not 241 ID. Obviously the 930 and G50 starter options are the same and will work with either RG so long as the RG placement suits the starter. Presumably the G50 RG with larger ID, if it's the same width, will be lighter which is always a consideration.

Obviously I would have been better off to get a G50 RG but that's life! All this is info which previously I had been unable to find. Hope it helps someone else in the future.

Yeah I did look at the front mount option that was the reason for trying to get some 928 data. That won't work for me coz I'm running a very shallow dry sump set up and the scavenge outlets don't leave enough room for the starter motor. Might work on the LHS with some sump mods though. I think this could be a good option for a wet sump setup all the same.

Thanks for taking the time to add to the picture.

Cheers

To further add to this and thank some guys who have PM'ed me

I have a lot to chew on at present. I am down to two basic options now. First is machine up a new longer pinion driveshaft for the Hi Torque starter and support the end in a bush or bearing in the bellhousing or adaptor plate. This will work but requires a wee bit of accurate machining. No problem as Lim has the gear and ability to do it.

The other option which will require some chassis and oil pan mods is to mount the starter off the adaptor plate alongside the motor. Using a 928 starter which is basically the same as the 930, but reverse rotation. Photo's I have been able to view indicate the 928 ring gear has the same tooth profile as the 930 so the 928 pinion should be good. I'm keen to use the 930/G50 ring gear because it's bolt on.

This second option is my preferred one right now, as it involves less machining, KISS always, and since it would make any future changes to gearbox type much easier to carry out if I don't have to redo the starter/flywheel thing again. And you never know when a cheap LG600 or similar is going to come out of the woodwork!!

So I am going to take the plunge and order a 928 starter and G50 ring gear from the States to have a play with!

Cheers