TheSamba.com :: View topic - Transmission temperature gauge and sender

Mon Aug 06, 2012 5:17 pm

I had my syncro transmission out to fix some leaks and wanted to add a temp gauge and sender but didn't want to drill any holes. This idea came from Tom Lengyel (famed local syncro enthusiast and mechanic). I bought a cheap $18 electrical temp gauge with sender made by Equus, model 6262. I wanted one that ranged from at least 100 to 200. Some of the other ones I found started at 160 degrees.
According to info posted by Derek Drew, 160 degrees F is when parts start to go out of spec. More info here:http://autos.groups.yahoo.com/group/Syncro/message/52260

I mounted the sender on the outside of the case in one of the rib holes near the axle flange. I know this is not as accurate as an internal sensor but in my opinion is better than nothing. Other info from the posted thread above states that internal oil temps were measured with an internal probe and an IR meter on the case and temps were almost identical. http://autos.groups.yahoo.com/group/Syncro/message/52564

I cleaned out the hole with a wire wheel on a drill and used quick set JB weld to secure it to the case. The end of the sender is directly touching the case and has JB weld all around it. The JB weld should conduct heat since it is a metal compound.

Here is the wiring

I have not mounted the gauge yet but will post pic when I finish it.

Mon Aug 06, 2012 5:39 pm

Nice job.
I have been monitoring my trans and front diff temps for a while now.
Derek and I discussed why you would want to do so years ago and Im glad i did.
I am using internal sensors and have them wired up to my aftermarket engine management harness so the data is shown on my Display LINK on the dash.

Tue Aug 07, 2012 6:51 am

Yeah, that is way cool. It should be standard equipment. Thanks for the clear pictures and great parts info ..

Tue Aug 07, 2012 7:17 am

Nice, I'll have my bell housing off soon so I need to do this!

Tue Aug 07, 2012 8:03 am

I wonder if Bostig could add the trans temp to the turbo
software so it could be log'd on my Dash Daq?
I will be watching and waiting to see how FrankenSuby
makes out with his choice for sendor placement. From
what has been discussed so far it should work fine.

Tue Aug 07, 2012 8:28 am

BillM wrote: I wonder if Bostig could add the trans temp to the turbo
software so it could be log'd on my Dash Daq?

x2?

Tue Aug 07, 2012 9:40 am

I am considering mounting the gauge to the bottom of the diff lock panel. The equus gauge comes with the mounting tab.

The sender is located in the area of the ring and pinion and pinion bearing so it should be close to the max temp in the transmission (I think).

I am also using Lubrication Engineers gear oil which is formulated for use in caterpillar bull dozers and heavy equipment, for maximum protection. It is synthetic and is $25 a quart. This should help keep the heat down.

Tue Aug 07, 2012 11:57 am

You'd have to be correct in assuming the R&P to be the biggest contributor to gear oil temperatures in our Vanagons. (Excellent choice on oil brands, BTW. LE is one of the very few synthetic gear lubes that I trust.)

I'm not hearing outrageous temp numbers from most guys on the various threads. In Porsche racing, we would try to keep temps below 230*, but 250* was not unheard of. We could often predict gear life in hours based on the average lube temperature. (A plate-style LSD performing through turns constantly on a road-race course contributes about 40*+ to these high numbers mentioned.)

None of this is to say that keeping gear lube temperature low isn't a good idea. I just think that the more guys we have running these temp gauges in Vanagons and providing us with feedback, the more we'll learn about what's optimum (both high and low) for our particular vehicles. From what I've heard so far, it seems that long distance driving (2+ hours ?) is by far the biggest contributor to temps that are "way too high", with temperature creeping forward from the engine.

Performing actual measurements on housings heated in an oven could go a long way toward answering some questions on what temperature should be considered too high. If anyone has a shop oven, the measurement to zero in on is that between the side adjusters on the main case, say @ 130, 150, 170 etc. (not that easy to measure without the right tools)

Tue Aug 07, 2012 12:08 pm

I'm not sure of the electrical conductivity of JB Weld, but the temperature sender shown does use the case as the electrical ground connection. If the ground resistance is high, it could cause an incorrect reading. It's easy enough to take a multimeter and check the resistance from the sensor shell to the transaxle, to determine if this is a problem.

I know that looking at the firmware in automatic TCUs that normal operating temperature is from 160F to 240F. Below 160F the torque converter will stay unlocked to actually try to heat up the trans. Above 240F it will downshift to the 1:1 ratio to reduce the heating due to gear friction. The final drive gear oil will be close to the same temperature as the ATF, so we could extrapolate that this range of temperatures is acceptable for the gear oil lubricating a ring and pinion.

Tue Aug 07, 2012 12:18 pm

Good info. But I think we're going to arrive at/agree on our maximum acceptable trans temperature to be way lower than 240 .. I'm guessing 210-220 ..

Edit: .. although we obviously want to maintain a much lower average temp

Tue Aug 07, 2012 12:35 pm

you could easily and safely drill and tap into here for a sender

that would give you potentially more accurate numbers than using JB weld

Tue Aug 07, 2012 4:05 pm

Why couldn't you drill and tap the filler or drain plug?

I'm not trying to be a wise guy here but what are you going to do differently when you know how hot your tranny is? Just one more thing to worry about. Like putting a cylinder head temp gauge in an air-cooled Vanagon. :lol:

Tue Aug 07, 2012 4:13 pm

With data collection, we can eventually decide the operating range we want, and thus program when we want the electrical pump (which feeds the external cooler) turning on & off. Or we can decide which vehicles even need the external plumbing. Some obviously do, while most probably don't.

I found a head temp gauge to be invaluable. I learned how badly I was overheating my heads by trying to run too tall a gearing on my street Ghia. Small outlay for big rewards.

Tue Aug 07, 2012 4:16 pm

gears wrote: With data collection, we can eventually decide the operating range we want, and thus program when we want the electrical pump (which feeds the external cooler) turning on & off. Or we can decide which vehicles even need the external plumbing. Some obviously do, while most probably don't.

X2 and an excellent response.

Changing you trans fluid is very easy with an inline pump :wink:

Tue Aug 07, 2012 5:34 pm

FNGRUVN wrote: Why couldn't you drill and tap the filler or drain plug?

I'm not trying to be a wise guy here but what are you going to do differently when you know how hot your tranny is? Just one more thing to worry about. Like putting a cylinder head temp gauge in an air-cooled Vanagon. :lol:

The drain plug has a magnetic stem on the internal portion to collect metal shavings so you would not want to drill and tap it. The filler plug would not be in the oil.
If I had my gearbox fully disassembled, I would have drilled and tapped the case. Since I only removed the low gear housing, I did not want to drill and tap and get metal shavings in my gear box.
The bottom of the sender is directly touching the case, the JB weld is only around the sides of the sender and should be thermally conductive. I will also be checking the case with an IR thermometer to see how well the gauge reads.

If I know my tranny is too hot I will a) slow down b) pull over and let it cool off c) get an external cooler or d) stop towing another syncro behind me (I have only done this once for 3 hours and it will probably be the last time).

FNGRUVN: How is your FJ Green paint job coming? I enjoyed hanging out and chatting with you at SS12.

Wed Aug 08, 2012 5:18 am

How about something like this for the drain plug? http://www.piersideparts.net/V323055.html

or

something like this that can be used under an existing bolt head.

http://www.auberins.com/index.php?main_page=product_info&cPath=5_24&products_id=126

Hodakaguy

Wed Aug 08, 2012 9:02 am

:bay_blue: This is a great idea , thanks. Just ordered my equus 6262, ebay. And a TDR type sensor. I can not afford any more syncro transmissions , think this will help! If not it looks cool! :D

Wed Aug 08, 2012 10:31 am

joseph928 wrote: :bay_blue: This is a great idea , thanks. Just ordered my equus 6262, ebay. And a TDR type sensor. I can not afford any more syncro transmissions , think this will help! If not it looks cool! :D

Joseph,

The equus gauge comes with the sender. Nice meeting you and hanging out at SS12.

Wed Aug 08, 2012 11:30 am

FrankenSubySyncro wrote: joseph928 wrote: :bay_blue: This is a great idea , thanks. Just ordered my equus 6262, ebay. And a TDR type sensor. I can not afford any more syncro transmissions , think this will help! If not it looks cool! :D

Joseph,

The equus gauge comes with the sender. Nice meeting you and hanging out at SS12. :bay_blue: It was great to meet you to, cant wait tell the next SS13. I like the JB weld idea but I think I will try the sender that will bolt on to a stud. If it does not work I will go with JB weld! Long live the hells revenge 6 :D

Wed Aug 08, 2012 11:44 am

presslab wrote: I'm not sure of the electrical conductivity of JB Weld, but the temperature sender shown does use the case as the electrical ground connection. If the ground resistance is high, it could cause an incorrect reading. It's easy enough to take a multimeter and check the resistance from the sensor shell to the transaxle, to determine if this is a problem.

I guess you're not concerned about this?

J-B Weld Company wrote: Q: Will J-B Weld conduct electricity?

A: No. J-B Weld is not considered to be a conductor. It is an insulator.
http://jbweld.net/faq.php#faq009