Jump to content


Photo
- - - - -

Minispares Gtr101 Temp Sender Specs


  • Please log in to reply
7 replies to this topic

#1 BaronVonchesto

BaronVonchesto

    Mini Mad

  • TMF+ Member
  • PipPipPipPip
  • 123 posts
  • Location: Kuala Lumpur

Posted 09 June 2018 - 12:48 PM

So I needed to change my temp sender and found that my gauge was always reading max at normal operating temperature.

 

Pretty sure its not overheating as Ive driven the car for over an hour at high revs and had no steam coming out. So i figured I would test the sender to calibrate the gauge and share the specs for everyone's benefit.

 

The way i did it was like this:

1) dipped the sender in an ice water bath for 5 minutes, then measured the resistance between the terminal and body with a multimeter

2) let it sit in the air for 20 minutes, then dipped it in hot water for 5 minutes

3) with the multimeter hooked up, i dipped the sender into a pot of boiling water over the stove, ensuring that the sender does not touch the pot, then waited for the multimeter reading to settle down.

 

Here are the results for the Minispares GTR101 sender (1970 on type)

 

0C - 1717 ohms

100C - 57 ohms

 

attached is a graph to help you guys figure out the resistance it should put out at operating temperature. I believe it should be 88C for an A+ and 85C for a standard A.

 

Assumption, the temperature sender resistance changes linearly with temperature (as most thermistors do)

Attached Files



#2 Moke Spider

Moke Spider

    Crazy About Mini's

  • TMF Team
  • PipPipPipPipPipPipPipPipPipPip
  • 7,598 posts
  • Location: NSW
  • Local Club: South Australian Moke Club

Posted 09 June 2018 - 07:52 PM

Good work and many thanks for posting here.

 

I went through a similar exercise a few months back, though I only went from just below boiling down to 500C as I've found none of the senders I've been getting are right with them all making the gauge read hotter than things actually are.



#3 BaronVonchesto

BaronVonchesto

    Mini Mad

  • TMF+ Member
  • PipPipPipPip
  • 123 posts
  • Location: Kuala Lumpur

Posted 10 June 2018 - 02:03 PM

I would love to test it at a constant 50 and 80 Celsius, but that requires equipment to reliably hold the water within a narrow enough temperature margin so as to be accurate enough to take a measurement.

 

I dont have that, hence why an ice bath and boiling water. 0C and 100C are easy constants to achieve and hold.



#4 BaronVonchesto

BaronVonchesto

    Mini Mad

  • TMF+ Member
  • PipPipPipPip
  • 123 posts
  • Location: Kuala Lumpur

Posted 10 June 2018 - 02:05 PM

actually, im thinking the mini temp sender may not be very linear, so a good proxy would be to have the sender sit at room temperature water, and measure the resistance at that temp as well.

 

but you need to have a thermometer that can accurately tell your room temperature!



#5 phillrulz

phillrulz

    Mini Mad

  • TMF+ Member
  • PipPipPipPip
  • 297 posts
  • Location: North West London

Posted 10 June 2018 - 04:31 PM

If i get a chance to get the temperature bath out at work ill get a full characterization. 



#6 Moke Spider

Moke Spider

    Crazy About Mini's

  • TMF Team
  • PipPipPipPipPipPipPipPipPipPip
  • 7,598 posts
  • Location: NSW
  • Local Club: South Australian Moke Club

Posted 10 June 2018 - 07:34 PM

actually, im thinking the mini temp sender may not be very linear, so a good proxy would be to have the sender sit at room temperature water, and measure the resistance at that temp as well.

 

but you need to have a thermometer that can accurately tell your room temperature!

 

I've only noted down what I did so I could add a resistor to correct it in the normal range, however, the sender I tested wasn't linear if I recall.

 

To hold a 'constant' temp, I just used a 2 litre kettle of water, bought it up to near boiling and then took my readings as it cooled down, though to keep the water as near constant temp throughout, I was gently stirring it and had the transmitter under test and the reference gauge at the same level and close to each other within the kettle.

 

Not to the 1/2 a degree accurate, but all I was after was +/- 2 or 3 degrees.



#7 BaronVonchesto

BaronVonchesto

    Mini Mad

  • TMF+ Member
  • PipPipPipPip
  • 123 posts
  • Location: Kuala Lumpur

Posted 12 June 2018 - 12:13 PM

If i get a chance to get the temperature bath out at work ill get a full characterization. 

Would be great if you did this!



#8 Moke Spider

Moke Spider

    Crazy About Mini's

  • TMF Team
  • PipPipPipPipPipPipPipPipPipPip
  • 7,598 posts
  • Location: NSW
  • Local Club: South Australian Moke Club

Posted 12 July 2018 - 07:10 AM

OK I've dug out the data that I've recorded back in Feb of this year and also found some other data.

 

mO886LJ.jpg

 

Notes;-

 

The Smiths Sender TT-6811-01 wasn't done by me but these figures were given to me a few years back. This is a 'universal' type sender, usually supplied with their loose temperature gauges (or recommended to us with them).

 

The Resistances and Temps were measure in water, in a jug and all at the top of it, The water was bout up to boiling and as the temperature dropped (over about an hour!) the water was gently stirred to equalise the temp of it, check and then a resistance value measured.

 

It does definitely appear that there are different Senders for different cars and gauges. eg, where a gauge has H-N-C in the case of a Mini, N up to 1975 was 820 C and from 1976 on, 880 C.

 

The Gauge that I have that was being used with the sender I was looking to match is a 'loose' Smiths type. It's face numbers 50-90-140 ©, with a mark representing 70 and another 115. The Resistance with 10 Volts applied, needed to show 70 was 140 ohms and  for 90 was 80 ohms. I haven't yet checked this measurement of any cluster type gauges, but I suspect it;'s different to these.






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

Mini Spares