My transmission started leaking at the big main gasket right in the middle so I'm going to be pulling it in the next couple weeks. I had my trans rebuilt already about 3 years ago and I'm wondering while I'm at this, should I have my guy drill and weld a bung for a temp gauge and if so, where? Has anyone done this?

 

I would see if it's possible to use the drain plug hole for a sending unit.

 

my E9 has a temp sender as standard...
it uses the fill hole for this... it has a special plug that is threaded for the temp sensor...

 

Hmm... I don't see why it can't be done but obviously the sender will be sticking slightly into the tranny so I'm wondering where the best place to put it would be and if anyone's done this yet. Surprised more people haven't chimed in. I get nervous driving the car 3 hours to the track, then driving it hard there and all the way home. Last time I lost it, it was right after a road trip. No apparent reason either, it seemed like the tranny got so hot that it burned the fluid.

 

That's a good idea and will probably work but I think I'd rather it be a totally different spot so I don't have to mess with it, get a good seal and leave it alone. I change my fluid pretty often.

 

Drill on tranny? I wouldnt do it.

 

This.

 

I was thinking about doing something like this to log temps in my drivetrain to see if my trans , tc, or rear diff would benefit from a remote cooler. I was more concerned about the rear diff and tc as they dont work with a lot of fluid to begin with, but I dont read much on here about folks having temp issues with the rear diff, so it must not be much of an issue.

 

I was wondering about the same thing, I currently have my evo out of order because of the transmission burning up. If you do get this done can you let us know on here?

 

Yea as much as I don't want to say it, I've never had diff issues yet but I did replace the tcase two years ago. My main concern is the trans tho, I don't see why it can't or shouldn't be done so I think were gonna go for it. I guess I'll find a place for it once the trans is apart. I've never split it myself so I'm unsure of how it's all together, where the gears are for clearance etc but I doubt a couple centemeters of sensor will give me trouble, I just figured someone with a lot of experience on our trannys would chime in and give thought. Now I'm also thinking pressure gauge as well but don't know if that's really nessisary.

It took me 4 months to get a new plastic speedometer gear last time because a piece of 4th gear got into it and ground it up, I figure with some gauges I can save myself a lot of hassle down the road. I don't want to go thru that again, the shop charged me for the 4 months because the car was on their lift the whole time. Total bill was $3900 and the only parts I needed were 4th gears and the speedo gear.

 

I was looking around and I found out that most oil temp senders are 1/8 NPT, which has an OD of .401" (nominal) I'm fairly certain the drain plug is more than big enough to drill and tap to that size. I think that's the best bet, because it's immersed in fluid constantly, but it's out of the way of the moving parts, almost regardless of how long the probe on the temp sensor is.
Under no circumstances would I consider drilling the aluminum transmission case. That would be begging for problems.

 

I really don't see why, a bung can be welded on. Maybe I'm just over looking something or you know something I don't about our aluminum trannys. I wouldn't use a cordless drill, I'll have a machinist do it.

 

Pipe thread is tapered, that's how it makes a seal, and aluminum is really soft. I see it being a place for potential leaks very easily if you have to remove it more than once or twice.

 

I would rather drill and tap the case but ONLY when you have the trans disassembled. I assume you will already have the trans disassembled to repair the leak. I've done this on DSM 5 speed transmissions. Just make sure you have the probe at a level that is below the fill plug so it will be submersed in fluid at all times.

 

Drilling and taping the case shouldn't be an issue, round holes don't tend to propagate cracks. Try giving TRE / Shep a call and explain your deal. They're both really good on the customer service end and have probably done sensor installs before.

Let us know how it goes. Very interesting to get a better feel for the stress the drivetrain is under.