Lotus Elan

Starter motor woes

PostPost by: fatboyoz » Fri Aug 15, 2014 7:48 am

Rohan,
For future reference, could you please jot down the numbers on the starter.
Cheers,
Colin.


rgh0 wrote:The Bosch starter I used was from 1970's Escorts, it was also used on the Mazda 626 in late 70's and 80's I believe and maybe other cars where Ford and Mazda were sharing engine and car development from around that time. Bosch supplied a new 9 tooth pinion versus the 10 tooth one used by Ford. Its a 3 bolt mount but the two bolts line up with the Elan bell housing and you just leave the third bolt hole empty

Bosch Starter 2.JPG


cheers
Rohan
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PostPost by: bob_rich » Sun Aug 17, 2014 7:22 am

Hi All

A question for those following this thread

with a Bendix starter the flywheel tooth lead in faces the rear of the car as the bendix pulls in from the rear going forward info the ring gear. With a pre engager the pinion is driven in from the front so should the ring gear be fitted with the tooth lead in front facing ?

Trying to get the best option as I only want to do this once and then as another post says Drive the car !

thanks in advance for any help

Bob
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PostPost by: twincamman » Sun Aug 17, 2014 7:26 am

1-P1010002.JPG and
1-P1010002.JPG and
heers mine ..a nasty bit of work .they were supplied by Dave Bean so they should be correct .ed
dont close your eyes --you will miss the crash
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PostPost by: promotor » Sun Aug 17, 2014 8:02 am

Pre-engaged ring gears don't have a lead in so it shouldn't matter which way you fit it. The only thing I would consider is allowing the part number to be visible on the flywheel once fitted so that you can refer to it later if needed or relevant (one flank of the ring gear will be seated home so the part number may not be visible if placed face down).

For a standard Lotus twin cam flywheel you can only fit a 132 tooth ring gear - the 135 tooth ring gear has a different (larger) internal diameter. 132 teeth should mean and 11 tooth pinion on the starter if using Lucas or Bosch parts.

I seem to remember that the starter in your pictures could be made to be used with either a inertia or pre-engaged type ring gear but the combination of teeth had to be correct.

How does the starter of yours work? Does it act like a Bendix or a pre-engaged? Ie does it slot into the ring gear and then rotate (and turn the flywheel) like a pre-engaged, or rotate into the ring gear face a-la Bendix type? The Bendix style of engagement is the reason for the teeth having a chamfer/leading edge whereas the pre-engaged type doesn't need them..
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PostPost by: rgh0 » Sun Aug 17, 2014 12:12 pm

fatboyoz wrote:Rohan,
For future reference, could you please jot down the numbers on the starter.
Cheers,
Colin.


rgh0 wrote:The Bosch starter I used was from 1970's Escorts, it was also used on the Mazda 626 in late 70's and 80's I believe and maybe other cars where Ford and Mazda were sharing engine and car development from around that time. Bosch supplied a new 9 tooth pinion versus the 10 tooth one used by Ford. Its a 3 bolt mount but the two bolts line up with the Elan bell housing and you just leave the third bolt hole empty

Bosch Starter 2.JPG


cheers
Rohan


Currently away from home but will post when I get back, I recall posting the numbers on the Bosch starter many years ago but cant find the relevant post now. The Bosch starter has no specific number for the overall assembly that I can find and the various elements ( mounting plate, body, solenoid etc) have different part numbers on each

Use of a pre-engage versus inertia starter makes no difference to the right pinion and ring gear ratio and tooth count. I don't understand all the variations Ford used but the Lotus standard 9 tooth pinion and 110 tooth ring gear works for me. I have seen lots of comments from people that the 10 tooth pinion also works with the 110 tooth Lotus ring gear and I can believe that as it is not a precise gear fit the 9 is tight and the 10 is loose but they both work. What works on the 135 tooth ford ring gear I don't know but I suspect 10 tooth as specified by Ford is best.

one day I will do the detailed gear design analysis to understand whats going on with all the variations but it is not a priority for me now ( I think I posted that comment also about 10 years ago :lol: )


cheers
Rohan
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PostPost by: TroonSprint » Sun Aug 17, 2014 12:53 pm

The Wosp starter that both Bob and I have is a pre- engaged type. The pinion shoots backwards by about 13 mm before the motor turns. I have always understood that no chamfer is needed with this type. I fitted mine yesterday after inspecting the flywheel gear teeth, which look fine right round. The trickiest bit fitting it was to plug in the white/red wire that triggers the unit. The socket for it faces backwards and it is impossible to see whether you are in line with the spade terminal once your hand is down the side of the engine.

Mike
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PostPost by: fatboyoz » Mon Aug 18, 2014 4:09 am

Rohan,
Apologies, t'was me who requested the part numbers back in 2008. Failed to record your reply in my info' folder, but will print it off and file it away.
Here is the link to your previous reply:
lotus-twincam-f39/torque-starter-pinion-depth-t18357.html
Cheers,
Colin.


rgh0 wrote:
fatboyoz wrote:Rohan,
For future reference, could you please jot down the numbers on the starter.
Cheers,
Colin.


rgh0 wrote:The Bosch starter I used was from 1970's Escorts, it was also used on the Mazda 626 in late 70's and 80's I believe and maybe other cars where Ford and Mazda were sharing engine and car development from around that time. Bosch supplied a new 9 tooth pinion versus the 10 tooth one used by Ford. Its a 3 bolt mount but the two bolts line up with the Elan bell housing and you just leave the third bolt hole empty

Bosch Starter 2.JPG


cheers
Rohan


Currently away from home but will post when I get back, I recall posting the numbers on the Bosch starter many years ago but cant find the relevant post now. The Bosch starter has no specific number for the overall assembly that I can find and the various elements ( mounting plate, body, solenoid etc) have different part numbers on each

Use of a pre-engage versus inertia starter makes no difference to the right pinion and ring gear ratio and tooth count. I don't understand all the variations Ford used but the Lotus standard 9 tooth pinion and 110 tooth ring gear works for me. I have seen lots of comments from people that the 10 tooth pinion also works with the 110 tooth Lotus ring gear and I can believe that as it is not a precise gear fit the 9 is tight and the 10 is loose but they both work. What works on the 135 tooth ford ring gear I don't know but I suspect 10 tooth as specified by Ford is best.

one day I will do the detailed gear design analysis to understand whats going on with all the variations but it is not a priority for me now ( I think I posted that comment also about 10 years ago :lol: )


cheers
Rohan
'68 S4 DHC
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PostPost by: bob_rich » Mon Aug 18, 2014 2:26 pm

Hi all

I have done some more measurements on the damaged ring gear through the access hole where the starter motor fits. By a simple measurement over a know number of teeth and comparing with a known 110 tooth ring gear on a old Xflow engine I have it looks like it has around 130 teeth on the damaged ring gear. This with a 9 tooth pinion I think will go a long way to explaining the problem. I think the engine builder fitted a exact replacement for the ring gear that was on the engine as I despatched it to them and was used with an old 10 turn pinion Bendix starter. It always sounded a bit cranky but ran for around a year B 4 I started the rebuild.

Info I have suggests that when Fords used 130 (ish) teeth they had an 11 tooth pinion so the mismatch to a 9 turn one would be very severe.

Mike I think your motor is a higher power one that mine but is, if I am correct, still designed for the Twink engine from what I can see a 9 turn pinion with a 110 ring gear should be the way to go but a 10 tooth one has also been used by some.

Bob
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PostPost by: wobblyweb » Mon Aug 18, 2014 6:20 pm

Just been going through all of this on the other thread "Starter Ring Teeth"
The old Mini starter looks the same as a Lotus 2 bolt and has 9 teeth on the pinion.
My guess would be it is the same starter.
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