915 grarbox fill plug

[Classic 911]

Hi.

I am looking for a fill plug for my 1982 915 gearbox that I can modify to mount a temp sensor in.
I am looking for one that looks like the one in the picture. Anyone that knows if this one will fit my gearbox?
The one in the last picture is the one my gearbox has at the moment.

Cheers






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[6cylboxer]

Take into account that the Fill Plug will be above the oil level - It might not be the most desirable location for a temperature sensor

[Classic 911]

Originally Posted by 6cylboxer

Take into account that the Fill Plug will be above the oil level - It might not be the most desirable location for a temperature sensor

Thanks very for your your input

Yes I know the sensor absolutely should be placed in a better and lower location on the gearbox housing than in the fill plug to be submerged totally in the oil and thus give accurate reading.
The reason for choosing the fill plug is that it’s the quick and easy way to get some sort of temperature readings.
Given it will mean that the sensor only will get oil splashing combined with the internal air mixture I will have to ad "some" degrees to the readings to get an idea of the "life inside" the housing.

But if someone has a equally quick and better way and idea of where to mount a sensor without dismantling the gearbox I would really appreciate the input

Cheers


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[Sboxin]

This is what we use - but we also have a cooler and CMS race built 915 (very expensive) . . .

https://californiamotorsports.net/products/cms-915-fork-cover-plate

Regards,
Roy T

Originally Posted by Classic 911

Thanks very for your your input

Yes I know the sensor absolutely should be placed in a better and lower location on the gearbox housing than in the fill plug to be submerged totally in the oil and thus give accurate reading.
The reason for choosing the fill plug is that it’s the quick and easy way to get some sort of temperature readings.
Given it will mean that the sensor only will get oil splashing combined with the internal air mixture I will have to ad "some" degrees to the readings to get an idea of the "life inside" the housing.

But if someone has a equally quick and better way and idea of where to mount a sensor without dismantling the gearbox I would really appreciate the input

Cheers


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[smadsen]

Be careful using any plug in the fill hole that protrudes into the gearbox. Having the magnet knocked off and land in the bottom of the case is a somewhat common occurrence. It's caused, I believe by the OEM steel plug being over-tightened into the aluminum case and cutting the pipe thread deeper into the aluminum. The factory only put the magnetic plug in the drain, not the fill. Many feel you catch twice as much "fuzz" if you retrofit the magnetic plug in both. I think that not to be the case.

I think a temperature sending probe might get battered by the internal gears. If you insert one, make sure you have clearance inside the box (like with a lump of clay) when it's tightened down.

[Mahler9th]

I think the thread pattern is likely the same.

I agree, not the best place to get temps.

There is at least one thread somewhere in these Forums about transmission oil temps to which WEVO contributed-- might be worth a look.

WEVO have a product that one could use for a temp sensor:

https://www.wevo.com/Products/TransmissionProducts/WevoTransmissionProducts-Cooling_XT095OilOutletBottomCover.htm

WEVO are local to me and I have known them for over 20 years.

My application has been club racing.

During this time I have used a 915 transmission driven by at times a 3.8 and currently a 3.6. Horsepower from around 330 to 360 or so. Longest races have been ~35 minutes, and highest ambient temps have been 100-105.

I strongly considered installing a pump and cooler set up, but decided it wasn't worth the bother.

Several friends installed them back in the day, only to discover that the temps never really got high enough for much, if any benefit.

What has been far more important for me is diligence in general transmission maintenance, in replacement of worn parts, and in use (shifting).

[Classic 911]

Originally Posted by 6cylboxer

Take into account that the Fill Plug will be above the oil level - It might not be the most desirable location for a temperature sensor

Thank you for the tip Yes I have taken that into consideration

[Classic 911]

Originally Posted by smadsen

Be careful using any plug in the fill hole that protrudes into the gearbox. Having the magnet knocked off and land in the bottom of the case is a somewhat common occurrence. It's caused, I believe by the OEM steel plug being over-tightened into the aluminum case and cutting the pipe thread deeper into the aluminum. The factory only put the magnetic plug in the drain, not the fill. Many feel you catch twice as much "fuzz" if you retrofit the magnetic plug in both. I think that not to be the case.

I think a temperature sending probe might get battered by the internal gears. If you insert one, make sure you have clearance inside the box (like with a lump of clay) when it's tightened down.

Thank you for the input Yes I have taken those things into consideration


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[Classic 911]

Originally Posted by Sboxin

This is what we use - but we also have a cooler and CMS race built 915 (very expensive) . . .

https://californiamotorsports.net/products/cms-915-fork-cover-plate

Regards,
Roy T

Thank you Roy
Yes I have been looking at that solution but I find it too expensive


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[Classic 911]

Originally Posted by Mahler9th

I think the thread pattern is likely the same.

I agree, not the best place to get temps.

There is at least one thread somewhere in these Forums about transmission oil temps to which WEVO contributed-- might be worth a look.

WEVO have a product that one could use for a temp sensor:

https://www.wevo.com/Products/TransmissionProducts/WevoTransmissionProducts-Cooling_XT095OilOutletBottomCover.htm

WEVO are local to me and I have known them for over 20 years.

My application has been club racing.

During this time I have used a 915 transmission driven by at times a 3.8 and currently a 3.6. Horsepower from around 330 to 360 or so. Longest races have been ~35 minutes, and highest ambient temps have been 100-105.

I strongly considered installing a pump and cooler set up, but decided it wasn't worth the bother.

Several friends installed them back in the day, only to discover that the temps never really got high enough for much, if any benefit.

What has been far more important for me is diligence in general transmission maintenance, in replacement of worn parts, and in use (shifting).

Thank you for the tip Yes I have been looking at that cover plate but I find it too expensive for what I am after.


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[daltvater]

Just reading through this thread. I wonder if this is a possibility?
https://www.lindseyracing.com/LR/Parts/911ODP.html

[GH85Carrera]

Originally Posted by smadsen

Be careful using any plug in the fill hole that protrudes into the gearbox. Having the magnet knocked off and land in the bottom of the case is a somewhat common occurrence. It's caused, I believe by the OEM steel plug being over-tightened into the aluminum case and cutting the pipe thread deeper into the aluminum. The factory only put the magnetic plug in the drain, not the fill. Many feel you catch twice as much "fuzz" if you retrofit the magnetic plug in both. I think that not to be the case.

I think a temperature sending probe might get battered by the internal gears. If you insert one, make sure you have clearance inside the box (like with a lump of clay) when it's tightened down.

I bought my 911 26 years ago. After the first transmission oil change I put the magnet core, drain plug as a fill plug. I kept the one ad the drain plug so I have two. The differential throws oil on the fill plug constantly, so it likely will be a decent place to use as a temp sensor. And I get more metal fuzz on my fill plug than I do on the drain plug. Just a coating, but any it caught did not run around inside before getting to the bottom plug.

My fill plug is still pristine looking after cleaning it, and it certainly has caught a lot of crud in the many miles I have driven it. Just my one car sample pool of data. I will continue to run a magnet core drain plug in my fill plug.

[kevingross]

I'll be less equivocal than other posters: putting the temp sensor in the fill plug will not give you useful information. The old-style 19 mm external hex plug is probably easier to machine a sensor into than the new style 17 mm internal hex plug, and you'll be able to remove the plug without first removing the sensor from it. As an alternative to these tapered plugs, you could use a straight thread plug with a seal ring (crush washer) https://belmetric.com/steel-hex-drive-metric-drain-plug-din-910/?