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Sudden speedometer loss


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I had my rear brakes worked on at Midas, and asked them to pull out the worm gear and check the number of teeth and color so I could find out what I need to improve my speedometer accuracy.  The manager said he started to remove it and fluid came out so he pushed it back in and did not fully remove it.


Did the worm gear become disengaged?  Do I just need to jack up the rear of the car, pull it and reseat it?

Enquiring Minds want to know.

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The inner flex cable has simply detached from the speedometer head.



Without removing the speedometer pinion just unscrew the cable. Look in the end and you should see the flexible cable inside.  Have a care as it easily pulls out and is like handling an oily slinky. The cable end should look like this... 




Pull the cable out a couple of inches and push back into the sheath. Have someone watch the speedometer while you pinch the crimped on ferule on the end and quickly twist it between thumb and fore finger. Clockwise. (I think)  Once you have the speedometer engaged and the needle twitches when cable turned, put the cable up to the transmission pinion. You'll note that the ferule has a small raised bump that fits into a key way on the pinion to lock it in place. Getting it into the pinion without pulling it out of the speedometer is very tricky. There's not much slack and if you pull out too far it will disengage the speedometer again. If all else fails, remove the pinion and mate the cable to it making sure the speedometer moves when the plastic  gear is spun*.


If you haven't changed the transmission oil in the last 30K miles now's the time. The drain bung is on the bottom and has a magnet on it. Wipe clean so you can inspect it for wear between this oil change and the next. most transmissions hold 2 liters, I doubt the B-210 will hold more than this. It takes GL-4 80w90 which is getting hard to find. Do NOT use GL-5 and whatever you find it must be compatible with copper alloys.


If oil was spilled at the shop it really should by checked and topped up anyway. The fill bung is on the side about half way up. It's full when you can't add more. Do not force more in, it will just blow out the vent and make a mess. I use a 2 foot length of old garden hose and a dollar store kitchen funnel. Run the hose down from the engine compartment and into the fill hole. If it's cold out stand the oil containers in hot water so they pour faster.


*The pinion is held in with a 10mm bolt and a key that fits the pinion sleeve. Once the bolt is removed, the pinion should be wiggled loose and pulled straight out. Do not twist or you may crush the soft plastic gear. Have a pan ready to catch the oil. when inserting the pinion make sure to line up the key way and push straight in. Do not twist!

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First thing I did was go back to midas parking lot, disconnect, reseat and reconnect the cable at both ends to no avail.  Royal Purple claims their max gear oil is yellow metal safe (brass, bronze,  copper).  Stuff is expensive though.  Thanks for all the input Mike, I knew I could count on you to help me straighten out my head and get me pointed correctly.

3 hours ago, datzenmike said:

*The pinion is held in with a 10mm bolt and a key that fits the pinion sleeve. Once the bolt is removed, the pinion should be wiggled loose and pulled straight out. Do not twist or you may crush the soft plastic gear. Have a pan ready to catch the oil. when inserting the pinion make sure to line up the key way and push straight in. Do not twist!


Thanks very much for this, I probably would have broken the gear like I do door panels.

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It's hard to tell if the speedometer end is connected. Could you spin the gear end and get the needle to jump? I'm pretty sure this is what's wrong.


The synthetics are great but tend to leak past old rear seals. I'm using the GM Delco oil for the Corvette and Camaro and same good results. I think it's all manufactured by Shell? and just uses a different coloring agent red, purple or gold it's the same stuff. Cost me about $40 to fill the 71B I have but worth it for the improved shift quality.

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Additional question.  Will the speedometer gear from a 1200 or Z car fit into an FS5W60A transmission (from a B310/210), and does anyone have the 210 shop manual that listed the stock  speedometer gear ration?  My manual list for the FS5W63A as a 16/5.  Currently have about 12-14% difference in speedometer readings (prior to suddenly not having a speedometer).

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You should include that it was an automatic switched to a 5 speed. Some people may be unaware of your other posts. The automatic used a 3.889 differential while the 60L used a 3.700.




12% @100 is 12 MPH or 6MPH at 50 MPH.  I assume you're reading slow???? That's a lot. Do you also have over size tires??? I think they came with 155/80R13 which are about 23" diameter.



If this is a dogleg shift pattern and a 60 series 5 speed, then it's an FS5W60L and only used for just over a year in the 210 ending July '79. After this date only FS5W60A with a regular shift pattern were used.

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Actually I am reading fast.  I had 185/65 R14s on the car which were larger and was 10% off; which was easy enough to calculate.  I recently had to purchase new tires and after some research found that the 185/60 R14 matched the stock tire for height and rotations per mile.  The stock tires turned 886 revs per mile and the 60s turn 887 per mile.  Switching out to that shorter tire to match the original 13's in height caused the speedometer to up in variation.  I tested this using the speed trap down the road from me and it now shows me doing 37 when speedometer reads 43 and at 50 on the speedometer I was reading somewhere around 43.  So about 12-14%.


The current transmission in my car is the FS5W60A standard pattern, and yep it is an auto differential.  I did not know the differential was 3.88 though.  I was thinking it was 3.9.


Was just looking at datsun1200.com's speedo gear page and the default a 60 series would be 16T, so 16x.12 or .14 yields me a nearest teeth increase of 2.  Guess I should by an 18T gear, that should at least bring me down to +/-3%.


Mike are you able to link me the AC Delco oil you are using?  If not then I might have to go with Red Line MT-90 75W90 (website says its GL-4).

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Lordco did have it and was cheaper than the GM dealer. There were different part numbers in Canada also. Look for GM Delco ' Friction Modified Synchromesh Transmission Oil" I think used in the Corvette and Camaro and likely some trucks. It's semi synthetic and GL-4 compatible.




" " AC Delco Synchromesh Transmission Fluid" ... General Motors Canada Part # 89021808
" AC Delco Synchromesh Transmission Fluid - Friction Modified" -GM USA Part # 10953509

Difference between the above is labelling to meet national standards.
GM Friction Modified - #12377916 is an old part # and the above replaces it.

The MSDS for the above lists the product as "Shell MTX Fluid", and that is confirmed by Shell documentation.

Shell documentation shows is also sold by Chrysler dealers as "SYNCHROMESH TRANSMISSION FLUID" Code 1874 MTX Fluid; MOPAR Part # 4761526

The fluid is a popular recommended MTF in Getrag transmissions, Honda, and Mazda 5 and 6 speeds. Users generally report better shift feel at all operating temperatures and better low-temperature performance at cold-start.

Also it is used as the bulk fill fluid at some Mazda dealers (confirmed for Burlington Mazda (Toronto) and Mountain Mazda (Hamilton ON).

I have also heard anecdotal reports that Honda approves it's use and accepts it as warranty-approved, but that should be confirmed by the user by talking to Honda."


 I suspect this "Shell MTX fluid" is the base stock for other oils like Royal Purple and just a color additive added. Though it replaces 80w90 'weight' it is a lot thinner and vastly improves cold weather shifting and up shifting in general is faster with the same effort. Down shifting is also easier now. It was about $38 Canadian for 2 liters with all taxes. 


(I tried to get some at a GM dealer and the first thing out of the counterman's mouth was "What vehicle is this for?" I told him not to worry it was for something else and gave him the part number. He hummed and hawed saying this was a special oil and not compatible in some vehicles and kept pushing me for what i was doing with it so I told him a '76 Datsun. WELL!!! his face closed down and he acted like I had tricked him or something. They were all out and could order it. I went to Lordco and it was $2 cheaper and i didn't get interrogated.)

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Mike, thanks again for all the info.  Sounds like the counterman was looking for an up sale opportunity.  The stuff you pointed me to is different than what I kept getting hits on.  Glad I asked or I might have ordered the wrong product.

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