Any rear differential temperature sensors?

[dparm]

Are there any sensors in the rear diff to monitor temperature? Has anyone ever logged any data to see what the typical temperatures look like for street driving and perhaps on the track?

[Helmsman]

Yes, that would be interesting to know about! Mine is grumpy and grining when cold, even more after fluid change (assumingly with FM but still), which I kinda like as then it works. After some driving it calms down and becomes silent. But what temps are we talking about?

Hopefully some of the experts can chime in!

[whats77inaname]

Originally Posted by dparm

Are there any sensors in the rear diff to monitor temperature? Has anyone ever logged any data to see what the typical temperatures look like for street driving and perhaps on the track?

The AWRON Kompressor II gauge offers the rear diff temp monitoring among its other monitoring capabilities.

https://europeanautosource.com/awron...mw-e9x-m3.html

[dparm]

Originally Posted by whats77inaname

The AWRON Kompressor II gauge offers the rear diff temp monitoring among its other monitoring capabilities.

https://europeanautosource.com/awron...mw-e9x-m3.html

Interesting. Is that pulling data from an existing sensor? Can Carly or other apps query it?

[Killerfish2012]

Run Royal purple 75W-140, and call it a day. It's truck tough.

[whats77inaname]

Originally Posted by dparm

Interesting. Is that pulling data from an existing sensor? Can Carly or other apps query it?

Tom @ EAS would be a good source of information to confirm/deny.

[doogee]

No there are no sensors in the differential.

[dparm]

Originally Posted by doogee

No there are no sensors in the differential.

Then how is that AWRON gauge doing it?

[admranger]

Originally Posted by dparm

Then how is that AWRON gauge doing it?

Likely they have the "capability" to take data from a sensor you install in the diff.

FWIW, I had a temp sensor in the E36M3 race car years ago. Before installing the Rogue Engineering finned differential cover (which looks very similar to the M-diff cover), I saw scary diff oil temps (e.g., 275 deg F). Not as scary as the transmission oil temps (300+ deg F ), but scary nevertheless. Once I put on the Rogue diff cover, temps dropped, never topping 250 deg F on the worst day (109 deg F green flag air temp). Standard was around 240 deg F iirc.

Now the M-variable diff may be completely different as far as temps go. The temps I quoted above were from a stock, non-M variable diff (since they weren't on the E36's) 3.15 LSD and also from a custom Diffs Online 3.73 diff with different ramp rates than stock. FWIW, the Diffs Online diff was awesome! Loved it.

Hope this helps.

[dparm]

Originally Posted by admranger

Hope this helps.

Interesting info, thanks.

What was the FD in that car? A larger ratio will run hotter. The M-DCT's FD is only 3.154:1. Also, was that car spec'd for 75w140 like ours?

[BPMSport]

Originally Posted by dparm

Then how is that AWRON gauge doing it?

The diff temp displayed is likely a calculated value provided by the DSC module. The DME also uses this calculated value to reduce redline should temperatures exceed thresholds.

[doogee]

Originally Posted by dparm

Then how is that AWRON gauge doing it?

Doesn't make sense. There are NO sensors in the diff.

[dparm]

Originally Posted by Mike Benvo

The diff temp displayed is likely a calculated value provided by the DSC module. The DME also uses this calculated value to reduce redline should temperatures exceed thresholds.

Interesting, though that doesn't completely surprise me. The DSC module knows what the wheels are doing, how much yaw there is, etc., so it could infer what the LSD is doing. There must be some complex logic in there to estimate the temps!

[admranger]

Originally Posted by dparm

Interesting info, thanks.

What was the FD in that car? A larger ratio will run hotter. The M-DCT's FD is only 3.154:1. Also, was that car spec'd for 75w140 like ours?

I'm not sure I know what you're asking, but I'll guess. The diff for for the 1995 M3 was a 3.15 to 1 ratio, stock (1996+ got 3.23 to 1 diffs). I had a custom 3.73 to 1 diff built for me. Hope I guessed correctly.

I'm pretty sure that that diff used 75w-90 oil.

[code7rpd]

The Awron includes a sensor that replaces the drain plug on the differential.

[dparm]

Originally Posted by code7rpd

The Awron includes a sensor that replaces the drain plug on the differential.

Thanks. Was hoping there was a sensor there from the factory.