Alternator and PAS Pump Pivot Bolt

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Alternator and PAS Pump Pivot Bolt

Postby Simon_P » Mon 03.03.2014, 15:52

Hi All,

Doing the belt change I notice that my pas pump pivot bolt is seized.

P/N A100E6129F - Obsolete

The same problem on the alternator has immobilised my car for a week (m9 bolt!) so Id like to plan ahead.
Does anyone know the size of the bolt and the thread pitch?

Thanks,

Simon
Last edited by Simon_P on Tue 04.03.2014, 21:33, edited 1 time in total.
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Re: PAS Pump Pivot Bolt

Postby Brit-Car-Nut » Mon 03.03.2014, 16:23

Simon_P wrote:Hi All,
Simon


Doing the belt change I notice that my pas pump pivot bolt is seized. P/N A100E6129F - Obsolete

Does anyone know the size of the bolt and the thread pitch?

I measure it to be a M8 1.25 x 85mm (at least) - I measured a bracket, so if you add a washer maybe consider 90mm

The same problem on the alternator has immobilised my car for a week (m9 bolt!) so Id like to plan ahead.

Lotus Part # A100E6417S is still an active part number at Lotus: 2.08 GBP

Are you sure it isn't an imperial 3/8 inch diameter bolt? Worth a closer look...
Last edited by Brit-Car-Nut on Mon 03.03.2014, 17:07, edited 1 time in total.
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Re: PAS Pump Pivot Bolt

Postby Simon_P » Mon 03.03.2014, 16:55

Thanks Jon,

I'll have an accurate measure for the length later. I've got an M8 Tap so ready to do battle.

There isn't much left of the alternator bolt but I checked some of the drilled-out remnants and they appear to be 1.25 pitch which is standard for M9. Also the head was 14mm a 9/16 socket was too loose and I don't have a 14mm socket. I'll take a closer look as I need to buy the tap if it is M9. I gave up trying to buy a M9 x 90 bolt so have already ordered from Stratton.

Simon
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Re: PAS Pump Pivot Bolt

Postby Brit-Car-Nut » Mon 03.03.2014, 17:07

Simon_P wrote:Thanks John,
Simon


I'll have an accurate measure for the length later. I've got an M8 Tap so ready to do battle.

I measured from the outside of the mounting bracket to the far side of the threaded end and it was just under 85mm.

There isn't much left of the alternator bolt but I checked some of the drilled-out remnants and they appear to be 1.25 pitch which is standard for M9. Also the head was 14mm a 9/16 socket was too loose and I don't have a 14mm socket. I'll take a closer look as I need to buy the tap if it is M9. I gave up trying to buy a M9 x 90 bolt so have already ordered from Stratton.

You could have considered drilling out the threaded end of the bracket and used a 3/8" bolt with a flange nut or even gone a bit crazy and drilled the bracket to insert a 3/8" heli-coil thread repair.

I know that is a bit of heresy, but it is a plausable solution for a hard to find bolt...
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Re: Alternator and PAS Pump Pivot Bolt

Postby Simon_P » Tue 04.03.2014, 21:32

Thanks John I have an M8 x 90 bolt so I'll start with that. With the alternator I was expecting just to put an M10 bolt straight in. All other options are indeed Heresy!... but possible as a last resort

The alternator bolt is strange it has a
14mm AF head (M9) - as far as I can tell ......as it is still firmly wedged into an undersize socket - when I say wedged, I mean pressed on with a 12 ton press.
The shank of the bolt is just over 9mm (M9) with corrosion 0.360" not 5/16" 0.3125" or 3/8" - 0.375"
The thread Pitch is 1.25 (M9 coarse or M10 Fine) 20.32 tpi - Ive checked against 20 tpi which is the closest imperial thread and I can see the error
The thread major diameter is 9.91 mm which is close to M10 9.97 mm

I understand that you would want clearance on a long steel bolt in aluminium but why go to the effort of rolling a non preferred M10 thread on the end of an M9 bolt? It does however explain why it took me hours to get it out. (the corrosion builds up in the clearance and the thread is too large to pass through it.)

I have ordered the new bolt from Lotus and it will arrive Thurs/Fri. I would hate to find that I have been measuring some random bolt that a PO had bodged in (dealer serviced before me) and bought a non standard tap that is the wrong one.

Please could someone measure the thread of the bolt ... I'm screwed if it isn't M10 x 1.25.

- I've edited the title to reflect the discussion.
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Re: Alternator and PAS Pump Pivot Bolt

Postby Brit-Car-Nut » Tue 04.03.2014, 23:23

Simon: I dug around in the core engine area and found a block with the alternator bracket still installed and it even had the bolt loosely threaded in it.

The bolt is a 10mm 1.25 x 90mm with a 14mm head. I measure the shaft diameter to be around 9.08mm / .357 inches

bolt.jpg

The lock washer on the shank is a TIGHT fit and won't come off over the thread unless I twist and expand it a bit.
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Re: Alternator and PAS Pump Pivot Bolt

Postby Simon_P » Wed 05.03.2014, 00:04

Many thanks John! You are a Gent.

So it is a bit of an odd one. I don't usually buy fasteners from Lotus but I'm pleased to say that the factory price is better than buying a standard bolt. All of the bores are clearance for M10 so an M10 x 1.25 bolt would do when these become NLA.

I can only assume that corrosion caused the bolts to seize in testing and the compromise was a special bolt.

I'm also hoping that the washer comes as part of the 'assembly' as it doesn't have a part no - Least of my problems!
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Re: Alternator and PAS Pump Pivot Bolt

Postby Brit-Car-Nut » Wed 05.03.2014, 01:32

The washer is just a "spring" washer that was made to 10mm but with a wider gap and then squeezed closed after installing. I would probably use a decent amount of anti-seize during reassembly.
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Re: Alternator and PAS Pump Pivot Bolt

Postby Simon_P » Sun 09.03.2014, 00:46

The Lotus alternator bolt does come with the washer.

all back together now!

I have left the PAS bolt to soak. The head moved but the thread didn't!

The nut on the other side is larger than 12mm A/F - and I can't get that to move either - Is it welded to the bracket?
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Re: Alternator and PAS Pump Pivot Bolt

Postby Brit-Car-Nut » Sun 09.03.2014, 00:50

Good News. Time to go for a drive!
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