Tachometer pegging gauge now

ArticiferTom

New member

Equipment
B21 TBL
Aug 21, 2011
21
0
1
Drums Pa.
Tachometer pegging gauge now/FIXED

Just purchased a B21 with mechanical tach and hr cable . Found cable broke on engine side , replaced . Tach now works but seem to peg and bounce the needle past the numbers , a lot when rpms up . I know old vehicle speeds and tachs worked on magnetic pulling the needle on a clock spring to work . Is this a instrument problem or drive problem ? Searches here did not show this kind of problem .
 
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North Idaho Wolfman

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Pull the drive portion on the front of the engine and check for smooth operation.
If that side is good then it's most likely a bad / worn out Tach.
 

100 td

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That reminds me to oil my cable. The tach is available for $180, but can be pulled out of the dash so hopefully you'll get some joy with removal/cleanup and replacement, if it's not the drive end.
 

ArticiferTom

New member

Equipment
B21 TBL
Aug 21, 2011
21
0
1
Drums Pa.
Thanks guys , You have kind of confirmed my feeling of it being in gauge .I'll lube engine side and is, new cable, but add to that and have unhooked at gauge till can remove this weekend . What is best lube for drive reduction on engine, oil or grease ? Heard both being used here ,also cable was going with spray cable lube as opposed to dry based .
 

kubotasam

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Alfred Maine
If a drive cable is sticking or is forced into to tight of a bend will make a tach behave like that. It binds inside its covering and winds up, when it releases the tach jumps. Before tearing the dash apart pull the entire cable out, connect it to the tach and spin it with an electric drill.
 

ArticiferTom

New member

Equipment
B21 TBL
Aug 21, 2011
21
0
1
Drums Pa.
Re: Tachometer pegging gauge now/ FIXED

Fingers crossed! Took your advise removed cluster and used old cable in plastic sleeve, curved , drill driven . Found needle would bind and jump to peg . Noticed to be positional on how cable entered back of gage . Next disassembly confirmed dried out bearing/bushing , note rust in bottom of gage area . Also found grease on hour meter reduction gears dried out . Cleaned gears with tooth brush and made plastic barrier to protect numbers and shield paint and decals from carb cleaner to flush out dirt from bushing area . After blowing clean rubbed bearing grease in to bottom where cable enters to fill as much as could . Then added machine oil from top in to shaft and bush , grease kept from dripping through . A little grease on the gears .
Man ; did it turn easy then . Reassembly and test showed smooth operation , but did drip cleaner on green tint of panel background removing it in area of the two . Anyone know if is spray on repair for that ?
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