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speedometer, not tachometer question

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uuccio(at)gmail.com
Guest

Posted: Mon Jul 28, 2014 12:07 pm Post subject: speedometer, not tachometer question

 	  Quote: 	
		   Tachometer-measures engine rpm

 

 Thing that measures in Km/h - speedometer (drive train rpm)


	


Thanks for correcting me Raymond. I meant the speedometer. 



It's a 1990 Toyota Hilux so I expect it's driven by cable not electronics (but I'm no expert here so correct me if I'm wrong).

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skywagon

Joined: 11 Feb 2006
Posts: 184

Posted: Mon Jul 28, 2014 1:30 pm Post subject: speedometer, not tachometer question

Sacha,



If, indeed it is cable drive, that is probably the problem.

The cable drive interior gets dry over time and lots of friction develops.

Figure out a way to disconnect the top end of the cable and spray a silicon 

based spray or similar down the interior of it.

It will take some time to work the lubricant down a tight cable.

Don't use WD-40.  It congeals after time and in a long cable drive that is 

bad situation.  David



______________________________________________________________________________

---

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uuccio(at)gmail.com
Guest

Posted: Mon Jul 28, 2014 7:52 pm Post subject: speedometer, not tachometer question

Thanks for the tip David. 

Knowing nothing about how these things are built I assumed that this was an electrical problem (I was imagining it was the sign of a faulty ground connection) but I guess I was a long way off the mark.  Apologies for the off topic post and thanks again for everybody's help. 



Sacha



 	  Quote: 	
		   On Jul 28, 2014, at 23:29, "David Lloyd" <skywagon(at)charter.net> wrote:

 

 If, indeed it is cable drive, that is probably the problem.

 The cable drive interior gets dry over time and lots of friction develops.

 Figure out a way to disconnect the top end of the cable and spray a silicon based spray or similar down the interior of it.

 It will take some time to work the lubricant down a tight cable.

 Don't use WD-40.  It congeals after time and in a long cable drive that is bad situation.  David

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nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jul 29, 2014 6:38 am Post subject: speedometer, not tachometer question

At 10:32 PM 7/28/2014, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: Sacha <uuccio(at)gmail.com>



 Thanks for the tip David. 

 Knowing nothing about how these things are built I assumed that this was an electrical problem (I was imagining it was the sign of a faulty ground connection) but I guess I was a long way off the mark.  Apologies for the off topic post and thanks again for everybody's help. 



 Sacha 	


   The warnings for WD40 are on point. This is VERY

   useful product for a narrow range of applications

   none of which included long term lubrication . . .

   ESPECIALLY high pressure (gears and chains).



   One interesting use of WD40 was in the after-dunking

   refurbishment of this target . . .



  http://tinyurl.com/qaxjmk9



   Many missions for this aircraft were flown over water

   where it was recovered on a parachute at the end

   of the mission. After hoisting out of the water,

   the engine was removed and submerged in a barrel

   of WD40 . . . the rest of airplane's components

   were rinsed off (avionics was in a water-tight

   compartment), checked for operation and the whole

   airplane re-assembled for the next mission. Broken

   parts were replaced (missiles would often damage

   parts of the airframe due to direct hits). Every

   MQM-107 operations base had a 'bone yard' of targets

   from which serious replacement parts could be

   salvaged.



   The engine would be spun up with air to clear

   the WD-40 (and bits of seaweed) and reinstalled.

   The airplane was ready for the next mission!



   Flex drives are quite common in modern aircraft.

   Most notably flap systems where a centrally mounted

   power unit's energy is 'piped' out to ball-screw

   actuators in the wings.



   Each system designer probably has their 'favorite'

   lubrication material based on temperatures, speeds

   and shaft loads. A web search will produce a bucket

   full of first hand advice most of which is probably

   adequate to the task. EVERY kind of 'slick' stuff

   has been used at one time or another on a flex shaft. See:



  http://tinyurl.com/mmkushv 



   Checked the service manual for my '87 GMC

   p/u. It says:



 [img]cid:.0[/img]

   In another GM service manual I found this

   reference:

 [img]cid:.1[/img]

   Didn't find any specifics on the makeup of

   this product but some inferences that it was 

   a special graphite bearing lubricant specific

   to speedometer cables.



   Flex shafts are common in single engine tachometer

   drives as well. The core of the shaft can be pulled

   out of the jacket. You can wipe down the flex shaft

   with a rag and solvent. Flush the jacket with a

   can of carb or brake cleaner squirted down the upper

   opening. Follow with compress air to get it DRY.



   Get a small bottle of graphite. Autoparts stores

   used to offer a bottle of graphite that could

   be screwed onto the speedometer (upper end)

   of a cable and left in place while you "drive

   some miles" with some notion that the graphite

   would distribute down the shaft with time and

   motion. The better technique is to squirt about

   5CC of graphite into the empty jacket then

   push it through with strokes of clean and

   dry flex shaft.



   Flex shafts with high torque on them WILL

   run harder against the jacket wall and graphite

   is not a high pressure lubricant. But for speedo

   and tach shafts, I suspect that graphite is

   never wrong.

       



 

   Bob . . .

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raymondj(at)frontiernet.n
Guest

Posted: Tue Jul 29, 2014 11:01 am Post subject: speedometer, not tachometer question

I have used powdered graphite to lube speedometer cables since the '70s 

with good success.  I'd check with the mfgr and see what they recommend.



Raymond Julian

Kettle River, MN



The things we admire in men, kindness and generosity, openness, honesty, 

understanding and feeling are the concomitants of failure in our system. 

And those traits we detest, sharpness, greed, acquisitiveness, meanness, 

egotism and self-interest are the traits of success. And while men 

admire the quality of the first they love the produce of the second. 

-John Steinbeck, novelist, Nobel laureate (1902-1968)



On 07/28/2014 04:29 PM, David Lloyd wrote:

[quote] 

 <skywagon(at)charter.net>



 Sacha,



 If, indeed it is cable drive, that is probably the problem.

 The cable drive interior gets dry over time and lots of friction develops.

 Figure out a way to disconnect the top end of the cable and spray a

 silicon based spray or similar down the interior of it.

 It will take some time to work the lubricant down a tight cable.

 Don't use WD-40.  It congeals after time and in a long cable drive that

 is bad situation.  David



 ______________________________________________________________________________



 ---

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