Radical 930 starter ideas and options?

[Andrew Robertson]

Hi All,

got my Mclaren M1C replica chassis and panels out of the container yesterday, got it home and slung the engine and transaxle in to see how it would fit. I had the chassis built without engine or trans mounts so I can do that here. This is a SBC and inverted 930 combo using renegade hybrids adaptor and kennedy flywheel and clutch. As you can see from the photo is that there is absolutely no way I can get the starter motor in. The bottom arm inner mount is smack in the centre and only about 50mm behind where the starter should go. The chassis is quite narrow through the rear bulkhead area.

So my questions:

1. has anyone come from the front, using the adaptor plate as a mounting face, and used a starter with a long pinion mounted in a similar location to the stock chavy starter? This could work if I had ring gear made that was about 5mm larger in diameter so I could get a shot at it coming from the front, and I could find a starter with very petit offset gear drive.

2. does the input shaft in the 930 transaxle go all the way to the rear cover, and would it be feasible to extend it through the rear cover and fit a drive mandrel on it for an external starter unit?

3. any other ideas? It's given me a headache.

Thanks for your help.

Andrew Robertson, Wellington New Zealand

 

[Jac Mac]

I went thru a similar problem & tried to have a starter made with extended pinion, 'They' the starter people were unwilling to build anything with the pinion further than 2.5" (65mm) from the effective mounting face/lugs where the pinion is unsupported due to the bending moment imparted to the shaft.

From your pic it appears that you will need to fit a small dia ring gear to the fwd face of your flywheel and possibly make a one/off block mount starter adaptor to match that ring gear dia. I do remember that a Hillman Imp ring gear was a popular choice for chevy conversions like this back in the old George Begg era of sports cars etc.

That said, have you got the engine/trans combo at the optimum height with regard to halfshaft height/geometry etc yet... its a bit hard to judge from your pic.

BTW.. a belated welcome to the forum!!

 

[Russ Noble]

Hi Andrew,

I went through the same sort of exercise. As Jac Mac has said you will need to move your ring gear forwards. I did this with mine and used a HiTorque 928 starter to match up to the Porsche ring gear.

Well actually, we made an alloy flywheel to take a forward mounted ring gear and mounted the starter on the adaptor plate as you are contemplating. I had the advantage of designing from scratch so it was easy to configure it to suit, once I had determined the way to go.

See my build thread http://www.gt40s.com/forum/gt40-build-logs/16138-kiwi-scratchbuilt.html around post #136

You won't get a 5mm larger ring gear in the bellhousing and even if you had a thickish adaptor plate and tried to fit it in that, I think you'd still foul the Porsche bell housing bolts. Plus you've already got that ring gear, and it's bolt on, so you might as well re-use it.

The input shaft is one piece all the way through to the back cover. I'm sure what you are thinking could be done but you'd need a hell of a lot of torque to spin that shaft. Honestly, I think it would be easier, cheaper and more practical to do it all in the bellhousing.

Oh..... and welcome to the forum, there seem to be a lot of guys here in kiwi land who have built or are building McLarens of one sort or another. Probably not surprising.......

 

[Fran Hall RCR]

Run the trans in its proper/standard orientation and invert the ring and pinion...starter pocket will then be mounted high......but without seeing the rest of your chassis/suspension layout it may be a dumb answer.

 

[Russ Noble]

That would see the motor sitting WAY higher. That's obviously an issue for Andrew bcoz the simpler and less involved answer is to just sit the trans a little higher so the starter clears the bottom link. I presume he has discounted that approach for handling/fitment reasons, so he's not going to want the motor a whole lot higher than that again.

 

[Fran Hall RCR]

But he does say he had the chassis built without engine and trans mounts too...so a compromise may well be in order..

 

[Phil]

Andrew:
I had a similar situation....seems like everyone finds this interference point with the mounting points and chassis configuration such as you have.
We solved the problem by disassembling the starter and adding additional material to the ears on the front of the starter. The interference point was the solenoid and if the face of the starter is modified it can be rotated counter=clockwise to clear the suspension components.
This involved welding on additional material, then re-machining the starter nose to "true it up". So far it all works.
I can post some photos if you need them.
Any competent shop can do this and the starter comes apart and re assembles rather easily. Now that your photo finally loaded on my computer I can see you have another issue, and moving your motor up a bit might be in order.
Cheers
Phil

 

[Andrew Robertson]

Thanks very much Jac Mac, Russ, GT40fran and Phil.

The engine & trans location is close to optimum, and if I raised it or inverted it I would be up for a minimum of a 3 inch lift and 2 inches rearward of the whole lot so it would really hurt CG and polar moment.

Currently the adaptor plate is actually smaller in the ID than the flywheel and has to be put on first. This is because of the light interference fit locating ring on the adaptor that fits inside the bellhousing. If I mounted the ring gear on the forward side of the flywheel I would need to leave that locating ring intact on the adaptor plate and machine a recess in the engine block side, put the ring gear on a series of stand-offs so the starter pinion did not drive through and hit the flywheel on engagement (the ring gear is only about 2-4mm larger in diameter than the flywheel).

The assembled flywheel and ring gear would need to be assembled as a stack with the adaptor sandwiched in between, and something like cap screws with heads tacked to the ring gear would act like studs that went right through the stand-offs, flywheel and pressure plate.

I think this would work if I could find a starter that is both shallow and small in the girth around pinion area. I've got a spare hitachi-style chevy starter (pictured below) and if I use the starter head block as a sacrifical peice I can get the pinion head of that into fairly tight spaces, but even then I'm going to have to scallop the dry sump oil pan significantly (also pictured - don't be fooled by the negative image - the extra width is on the starter side unfortunately).

You guys that have done this before - is that what you did?

Thanks for your help,

Cheers, Andrew

 

[Jac Mac]

Since your going dry sump simply fit the pressure line in the plug that lines up with the pressure gallery above the now redundant filter, block off that old block filter area/pump to filter gallery & mount the starter in that area on other side of the block.. use a remote filter & feed this 'new fitting' & the one @ front of block if your doing dual feed. This way you might just get away without having to doctor the dry sump pan.

 

[Andrew Robertson]

Superb suggestion Jac Mac - the filter is being used as part of the dry sump set-up in its stock location but I can easy remote it somewhere else and do as you say. I'll have a nosey and report back.

Cheers, Andrew

 

[Andrew Robertson]

Yeah that'll work - Cheers.

 

[tim]

Hi Andrew, Hope these pics mite give you some ideas

 

[tim]

The starter

 

[tim]

Hi Andrew, I have the same problem with a 930 / LS3 engine in my race car. The starter is in the way of the lower suspension arms. I will ask Chris (Flatchat) if he could design a similar adaptor for the 930 / LS to solve this problem. The above adaptor is for the G96 getrag / SBC.

 

[TonyL]

Thanks very much Jac Mac, Russ, GT40fran and Phil.

The engine & trans location is close to optimum, and if I raised it or inverted it I would be up for a minimum of a 3 inch lift and 2 inches rearward of the whole lot so it would really hurt CG and polar moment.

Hello Andrew!
I have just taken delivery of the chassis built just after yours. Interestingly Richard was thinking you had inverted the ring gear and suggested I do the same. For my LS1 block, there does not seem to be room to fit the starter body in close like the SBC block since the cross bolted mains are wider there and the Kennedy flywheel I have is not terribly large. Instead I had them widen the rear track 4 inches so a custom starter should just barely fit. They had the geometry checked by an old F1 designer buddy who said the wider track should not hurt handling.

cheers,

TonyL