Smiths Speedometer drive Rebuild Explained...(2013)

grandpaul · Apr 23, 2013

I would think that obtaining some soft metal pins and carefully cutting them to length, then tapping them in place ("mushroom" the ends) would be an easy enough fix for the four rivets on the main gear retaining ring...

(that is, if your main gear is not excessively worn)

Mr. Rick · Jun 3, 2018

Pulling up this old thread to show what I found after pulling apart an eBay purchase.
A Comnoz noted in a related thread, case hardening the ring gear might be a good idea.

Smiths Speedometer drive Rebuild Explained...(2013)

Also a comment about disassembly: It's pretty easy to remove the closed end cap by sending a 1/8 punch (actually slightly under .125") through from the cable end. Might wanna mark the splines just before exit, to help line up for reassembly.

But you only have to remove this if the pinion gear is bad, which can be felt with a fingernail and seen under magnification. I'm drilling out and replacing the original 1/16" rivets with 3/32 x 7/32 semi-tubular rivets.

Tornado · Jun 4, 2018

Anyone running one of the inductive pick conversions:
http://kullendesign.com/smithgaugewebsite/smiths-speedo-drive-conversion-kits/

Mr. Rick · Jun 5, 2018

So to go electronic with a modicum of originality, we are in for about $400 ?

ntst8 · Jun 5, 2018

Tornado said:
Anyone running one of the inductive pick conversions:
http://kullendesign.com/smithgaugewebsite/smiths-speedo-drive-conversion-kits/

Yep, have done a few thousand miles on my ES2, works a treat.

Tornado · Jun 6, 2018

Something I'll keep in mind for when my OEM speedo drive explodes...heard they can rip the speedo clockworks out if the cable is yanked out. So, replacing the clock with digital when that happens seems reasonable.

Mr. Rick · Jun 6, 2018

I've had many failures, all resulting in the drive gears catching, turning the drive clockwise, which pulls the inner cable straight out of the speedometer with no damage to the speedo itself. So far...

AgentX · Oct 20, 2019

Looks like I have to take a look inside my speedo drive; this has been hugely helpful. Thanks to all. I will get the rivets out tomorrow and find out what's causing the binding in my unit and if I can fix it...

Question, as mine has obviously been fiddled with: what are the o-rings/washers that fit around the pinion? Mine lacks them. Are they intended as seals? Does the pinion ride on them, necessitating a friction-free surface? How tight do they fit on the pinion shaft? It seems no one sells the parts separately, or I'd just order them, but I'd like to find something to match.

texasSlick · Oct 20, 2019

Mr. Rick said:
I've had many failures, all resulting in the drive gears catching, turning the drive clockwise, which pulls the inner cable straight out of the speedometer with no damage to the speedo itself. So far...

When the ring gear wears to razor sharp lands, the gear will catch and spin the drive on the axle. This can damage the thin hub cover (The one with the three rubber covers). Do not allow the wear to progress that far.

Slick

Lineslinger · Oct 21, 2019

Here are a few close ups after disassembly and cleaning

AgentX · Oct 21, 2019

Nice!! Looks great.

[EDIT: Looks like I found the cause of my drive binding up...missing one of the washers/bushings on the pinion. Put a shim in there and it seems to run pretty smoothly. Now I just gotta rivet the center retainer back in, lube it up, and reassemble.]

I just took mine all apart, hoping to find the source of the occasional binding I felt when turning the wheel-driven ring gear by hand. Even with the gears all out, cleaned and reinstalled, it binds every few revolutions at different points on both the ring and pinion gears, so I'm thinking it's not an imperfection or bit of grit caught in there as I originally suspected. Gears look to be in great condition.

So...is it normal for these to bind at all when turned by hand? When rattled at the bind point, the ring gear frees itself, so perhaps it's not an issue in practical use?

Thanks for the insight.

concours · Oct 21, 2019

I slather mine with moly grease (from the inside, not the fitting) every time the wheel is off for a tire change.
45,000 miles so far.

gortnipper · Feb 25, 2021

AgentX said:
Nice!! Looks great.

[EDIT: Looks like I found the cause of my drive binding up...missing one of the washers/bushings on the pinion. Put a shim in there and it seems to run pretty smoothly. Now I just gotta rivet the center retainer back in, lube it up, and reassemble.]

I just took mine all apart, hoping to find the source of the occasional binding I felt when turning the wheel-driven ring gear by hand. Even with the gears all out, cleaned and reinstalled, it binds every few revolutions at different points on both the ring and pinion gears, so I'm thinking it's not an imperfection or bit of grit caught in there as I originally suspected. Gears look to be in great condition.

So...is it normal for these to bind at all when turned by hand? When rattled at the bind point, the ring gear frees itself, so perhaps it's not an issue in practical use?

Thanks for the insight.

@AgentX did you ever get to the bottom of why your gears were binding?