speedo cable routing

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maylar

maylar

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I replaced my deformed speedo drive with a new one and after maybe 150 miles the drive has rotated a bit and the cable is being stressed.

speedo cable routing


Never had this happen before. The axle is tight and I can't move the drive by hand. So...? Tie it to the swingarm?
 
installed a new, andover-norton, aftermarket speed- drive on my 74. also installed a new AN crush, top-hat. not having any issues. as others said, double check the drive tabs, and maybe install a new top hat, however, the top hat really doesn't "crush." my is axle is torqued to spec and not experiencing any movement of the speedo-drive. the only issue I've had is tire rub on the black outer cable covering. a simple cable re-route solved that problem.

how much clearance do you have between the speedo-drive and the rear hub cover (the hub cap looking thing)? I have about .010" clearance. don't know what's correct, just stating what I have.

edit - not sure if i'm seeing this in your photo, but is your top hat oriented correctly? my eyes may be deceiving me, but I can see what looks like a seam between the top hat and the spindle spacer. my "hat" flange is on the outer side of the speedo-drive. I may be seeing a reflection in your photo. I remember reading on another thread about how the top hat is oriented within the drive assembly.

edit2 - my original failed - rotated like yours, only on mine, I tore the end of the cable out of the connector. turns out, mine seized up from lack of lubrication.. with my new assembly it only came with a light assembly oil. per AN instructions, had to add several pumps of marine lube. just saying....
 
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New drive and top hat bought through Old Britts, I'm sure they're the current parts from AN. Top hat installed correctly, tangs are engaged. Speedo works perfectly. The old one was rubbing on the hub cover plate, so I took care not to over tighten the axle this time. Maybe I should revisit that.
 
maylar said:
New drive and top hat bought through Old Britts, I'm sure they're the current parts from AN. Top hat installed correctly, tangs are engaged. Speedo works perfectly. The old one was rubbing on the hub cover plate, so I took care not to over tighten the axle this time. Maybe I should revisit that.
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I would think you would want the 80 ft lb torque on the axle shaft. as I said, I have .010 clearance between the two.
 
joe czech said:
80 ft lb torque on the axle shaft
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80 on the drive side is OK, it is all steel on this brake side... but 80 on the speedo side is what deforms the pot metal of the speedo housing. I'd start at 40 and go up 5 at a time.
FWIW even the steel spacer on the LH side of the wheel will imprint on the hardened bearing....I now make my own and harden them once I tested AN spacers and found they were mush soft steel.
 
dynodave said:
80 on the drive side is OK, it is all steel on this brake side... but 80 on the speedo side is what deforms the pot metal of the speedo housing. I'd start at 40 and go up 5 at a time.
FWIW even the steel spacer on the LH side of the wheel will imprint on the hardened bearing....I now make my own and harden them once I tested AN spacers and found they were mush soft steel.
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What's the best torque setting when using the one piece axle?
 
dynodave said:
80 on the drive side is OK, it is all steel on this brake side... but 80 on the speedo side is what deforms the pot metal of the speedo housing. I'd start at 40 and go up 5 at a time.
FWIW even the steel spacer on the LH side of the wheel will imprint on the hardened bearing....I now make my own and harden them once I tested AN spacers and found they were mush soft steel.
Click to expand...

not trying to be argumentative and by no means an expert - have limited experience wrenching on these machines - 80 ft.lbs. - only going by torque values as defined by old britts - https://www.oldbritts.com/n_torq.html . I didn't think you would be applying torque to the pot metal housing, but torque is being applied from the axle shaft, thru a series of steel spacers, one being that top-hat crush thing - ??? - anyway, torqued mine to 80 w/ no issues so far. just sayin....
 
joe czech said:
not trying to be argumentative and by no means an expert - have limited experience wrenching on these machines - 80 ft.lbs. - only going by torque values as defined by old britts - https://www.oldbritts.com/n_torq.html . I didn't think you would be applying torque to the pot metal housing, but torque is being applied from the axle shaft, thru a series of steel spacers, one being that top-hat crush thing - ??? - anyway, torqued mine to 80 w/ no issues so far. just sayin....
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A little science is an over the top tremendous effort for some folks. Measure the over all height before installation, use for a while, remove the wheel and reinstall retorque after a few time you might be surprised to find the speedo is now dragging on the cover. remeasure the height? It will have grown... bet you a beer. How and why else does my box full of warped speedo's get like that? you can SEE the crushed and deformed metal inside the speedo body....
80ft/lb
Every time I hear "old britts" I cringe...nice guy, buy parts...good guy
"tech" not my hero...
 
dynodave said:
A little science is an over the top tremendous effort for some folks. Measure the over all height before installation, use for a while, remove the wheel and reinstall retorque after a few time you might be surprised to find the speedo is now dragging on the cover. remeasure the height? It will have grown... bet you a beer. How and why else does my box full of warped speedo's get like that? you can SEE the crushed and deformed metal inside the speedo body....
80ft/lb
Every time I hear "old britts" I cringe...nice guy, buy parts...good guy
"tech" not my hero...
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again, not trying to be argumentative (since I don't know enough about this to argue the point). sorry....
 
I gues I should have been more clear, the top hat spacer AND the speedo housing will crush, but it doesn't sound like that's Maylar's problem anyway

Do the dogs in the speedo drive turn freely by hand? Maybe they're binding, I dunno, reaching here
 
OK, update. The rear axle was a bit loose. I snugged it up with a socket on a 1/2" ratchet, and my calibrated elbow says it's about 50 now. After a 75 mile ride yesterday it hasn't moved.

I bought a long open end / box wrench for the axle long ago and actually snapped the original axle with it, so I've been aware of that ever since. But I was in my 20's then and prolly a tad stronger than I am now ...
 
mylar - everything still OK? beginning to think the top-hat crush spacer has a limited number of actual uses, or "torqued compression cycles" before it needs to be replaced. I really can't see how it can "crush" though, but there is probably a minimum height dimension (with applied torque), before it starts to deform the speedo-drive housing, causing internal binding. i'm beginning to think the top-hat spacer doesn't so much "crush" but by applying torque to the assembly, it causes the spacer to bulge in the center a bit, thus decreasing the overall height. just speculating, but thinking this is somewhat what dynodave was driving at - ???

BTW, don't know what the "hardness" of the axle-shaft is, but for a 9/16-fine thread, grade 5 bolt, the recommended torque value is 91 ft.lbs.. I would think the axle would be at least a grade 8 which would have a greater torque value, but again, don't know the specs. the 80# torque value is well below the yield for the bolt size. JUST A SUGGESTION - if torque is less than 70% spec, you might want to consider a dab of thread locker on the assembly. would hate to see thing work loose on you.
 
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I have never notice any deformation of the steel top hat. So I am not sure what crush acadian is referring to . However , every one of the dead speedo drives has deformations mostly on the inside where the pot metal contacts the inside steel "spacer".

joe czech said:
I would think the axle would be at least a grade 8
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Grade 8/ Possible but I doubt it. I quit hardness testing norton components years ago. The heads have great OEM valve seats:), some cams are hard and some are mush.
 
dynodave said:
I have never notice any deformation of the steel top hat. So I am not sure what crush acadian is referring to . However , every one of the dead speedo drives has deformations mostly on the inside where the pot metal contacts the inside steel "spacer".


Grade 8/ Possible but I doubt it. I quit hardness testing norton components years ago. The heads have great OEM valve seats:), some cams are hard and some are mush.
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just a little info - new AN top hat "crush" spacer - .309" -- original spacer, .318" - puzzled. if anything, I would have thought the original part would be dimensionally less than the replacement. not scientific though, since I don't know the original and replacement design dimensions w/ tolerance. just by those dimensions, i'm thinking they don't "crush."

on my dead speedo-drive, much like yours, deformed on the inside where the metal contacts the spacer and ring gear. tired rebuilding it , without success.

on the axle shaft - it would have to be at least grade 5 - anything less would be in the soft metal range. if torque value (9/16-fine, grade 5 @ mid-range yield) is 91 ft,lbs. - if less than 70% or 63 ft.lbs., i'd feel safer using a (blue) thread locker. only saying this because mylar's "calibrated elbow" torqued the shaft to around 50.

:cool:
 
It is common for Speedo drives to deform with the center bulging outboard. Why this happens, I do not know. It happened to my original Speedo drive, and I do know that I never over torgued the axle.

When the drive bulges outboard, it causes the inner surface of the drive to move nearer, and possibly rub on the cover of the wheel hub (that polished thin metal cover with the three plugs for the bolt up wheels). In my case, the cover was gouged to destruction.

Bulged Speedo drives can be salvaged. Warm the pot metal and squeeze it with a vise, using a socket of proper diameter to press on the center. The thickness of a speedo drive should be approx. 0.80 inches without any top hat bushing.


speedo cable routing


Slick
 
texasSlick said:
It is common for Speedo drives to deform with the center bulging outboard. Why this happens, I do not know. It happened to my original Speedo drive, and I do know that I never over torgued the axle.

When the drive bulges outboard, it causes the inner surface of the drive to move nearer, and possibly rub on the cover of the wheel hub (that polished thin metal cover with the three plugs for the bolt up wheels). In my case, the cover was gouged to destruction.

Bulged Speedo drives can be salvaged. Warm the pot metal and squeeze it with a vise, using a socket of proper diameter to press on the center. The thickness of a speedo drive should be approx. 0.80 inches without any top hat bushing.


View attachment 17477

Slick
Click to expand...
That worked for me.
 
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