Mech Smith's Speedo bouncing a little?

DanEC · #1 (**permalink**) 08-29-2014, 01:46 PM

It seems that the occilations of my Smiths speedometer are getting a little wider as I start to put a few miles on it. The bounciness gets greater with speed but is around 5 mph +/- at 45 to 50 mph. I have the adaptor shimmed to avoid any binding of the speedometer mechanism so it shouldn't be that. I assumed the cable was good to go as delivered but possilbly it needs to be lubed. Anyone else have this issue with a new speedometer and figure it out?

Rick Parker · #2 (**permalink**) 08-29-2014, 02:02 PM

Not much to do to the cables OTHER than lube it well ???)

era556 · #3 (**permalink**) 08-29-2014, 02:30 PM

If a reverse speedometer the reversing gear adapter needs to dis assembled, cleaned and 're assembled with a light moly grease. That should do it.

DanEC · #4 (**permalink**) 08-29-2014, 04:40 PM

Which end does the cable come out on these - transmission end?

ERA 778 · #5 (**permalink**) 08-29-2014, 05:18 PM

I helped mine by adjusting some of the bends in the cable routing. I had secured the cable in several places with cable ties and it seems that they constrained it too much. When I cut a couple of them and made the radii a little more generous, the oscillations were reduced significantly.

DanEC · #6 (**permalink**) 08-30-2014, 04:54 AM

The tightest radius on mine is probably 6 or 7 inches where from the firewall grommet to the adaptor on the back of the speedometer (street dash layout). I don't know an easy way to improve that one any. I'll re-lube the adaptor and the lube the cable and see what it does.

Thanks.

Hotfingrs · #7 (**permalink**) 08-30-2014, 06:15 AM

What are you using to lube the cable? I've always used powdered graphite on the speedo cable.

strictlypersonl · #8 (**permalink**) 08-30-2014, 07:07 AM

Quote:

Originally Posted by Hotfingrs

What are you using to lube the cable? I've always used powdered graphite on the speedo cable.

Yes! Do not use grease. It will only create extra drag and eventually break something.

rub35 · #9 (**permalink**) 08-30-2014, 07:24 AM

Get some of this. Gravity does the work for you. The graphite is emulsified in a solvent that will evaporate leaving behind a film of lubricant. I use it on motorcycle cables, works great.

Bike Aid Dri Slide 4 oz w Needle Moly Dry Film Lubricant for Cables Housing New | eBay

DanEC · #10 (**permalink**) 08-30-2014, 11:04 AM

I have powdered graphite - but what end does the cable pull from - speedometer or transmission? Looking at Bob's manual, some of the drawings appear to show a shoulder on the speedometer end which would mean I need to pull it loose and out from there. Is this correct?

Edit 1: Never mind - speedometer end it is for the record.

Edit 2: Lubed up cable with powdered graphite. Adaptor was too tight on back of the speedometer to get off for now. Went for a test drive but had no speedometer at all. I didn't have the cable engaged into the transmission gear - but the weather is looking too stormy now for another test drive.

davids2toys · #11 (**permalink**) 08-31-2014, 06:29 AM

When I bought my car the speedo stopped working or was not working correctly immediately. The cable is actually to short or has too much back and forth movement inside the sheath. Turned out to be two items.
It would be able to travel into the reversing adapter at the speedo to far, by this happening it backed out of the plastic gear in the tranny eventually killing the square drive opening. With Doug's(ERA) guidance, made a 3/8 long shim out 1/8 brakeline and installed it right on the cable at the adapter end. This prevented it from walking out of the tranny gear to far and ruining it.
Your problem of the intermittent jumping around sounds like it could be the end of the tranny gear. If I am right, it will get worse as the square drive gets more destroyed until just won't work at all.
The good thing is this gear was designed to be the sacrificial lamb, that is why it is plastic and cheap

davids2toys · #12 (**permalink**) 08-31-2014, 06:45 AM

Quote:

Originally Posted by rub35

Get some of this. Gravity does the work for you. The graphite is emulsified in a solvent that will evaporate leaving behind a film of lubricant. I use it on motorcycle cables, works great.

Bike Aid Dri Slide 4 oz w Needle Moly Dry Film Lubricant for Cables Housing New | eBay

Thanks, just ordered some. I could used it for my bike and car!

KVenom · #13 (**permalink**) 08-31-2014, 06:59 AM

Same issue with mine. Turned out to be the worst possible outcome in that the speedo drive gear on the tail shaft of the TKO-600 was bad. The possible cause to this was that the clip that holds the gear to the transmission side of the cable had fallen off. Possible excessive run out of the cable and or gear put wear on the tail shaft gear. I found the clip in the bottom of the tail shaft housing.

Don't ignore it or think you will get to it later. Check everything from gauge to transmission to make sure all is in order.

Mine started with a small bounce at the gauge.

DanEC · #14 (**permalink**) 08-31-2014, 11:25 AM

Quote:

Originally Posted by davids2toys

When I bought my car the speedo stopped working or was not working correctly immediately. The cable is actually to short or has too much back and forth movement inside the sheath. Turned out to be two items.
It would be able to travel into the reversing adapter at the speedo to far, by this happening it backed out of the plastic gear in the tranny eventually killing the square drive opening. With Doug's(ERA) guidance, made a 3/8 long shim out 1/8 brakeline and installed it right on the cable at the adapter end. This prevented it from walking out of the tranny gear to far and ruining it.
Your problem of the intermittent jumping around sounds like it could be the end of the tranny gear. If I am right, it will get worse as the square drive gets more destroyed until just won't work at all.
The good thing is this gear was designed to be the sacrificial lamb, that is why it is plastic and cheap

I can see this - first time I re-installed the cable to the speedometer and took a test drive the speedo didn't work at all. Pulled it back off and realized it wasn't inserted into the transmission gear. Made sure it was engaged in the transmission gear and reinstalled it and it was working again. It surprised me that I could install it and snug up the fitting and it the cable wasn't engaged. What you related is apparently what allowed it. I will see if I can rig up a couple small washers to go between the shoulder on the cable and the reverser to back it up a little and ensure full engagement in the transmission. I also took the reverser apart but it seemed smooth in operation and well lubed so I decided to put it back together and give it another shot of chassis lube in the zerk fitting.

I took another short drive but it started misting and had to curtail it. Still bouncing a little although seems slightly better. It seemed to get worse the other day after I accelerated up through the gears to about 70. I suspect it may be in the transmission gear - hopefully the driven gear. But it looks like I will have to pull the tunnel to get a good look at it.

KVenom · #15 (**permalink**) 08-31-2014, 12:03 PM

Quote:

Originally Posted by KVenom

Same issue with mine. Turned out to be the worst possible outcome in that the speedo drive gear on the tail shaft of the TKO-600 was bad. The possible cause to this was that the clip that holds the gear to the transmission side of the cable had fallen off. Possible excessive run out of the cable and or gear put wear on the tail shaft gear. I found the clip in the bottom of the tail shaft housing.

Don't ignore it or think you will get to it later. Check everything from gauge to transmission to make sure all is in order.

Mine started with a small bounce at the gauge.

When you go through your inspection, make sure you inspect the transmission tail shaft gear all the way around. If you have the car with the rear wheels up or the drive shaft out, rotate the tail shaft while keeping an eye on the gear. Make sure you inspect the gear thoroughly for wear.

DanEC · #16 (**permalink**) 08-31-2014, 04:50 PM

I made a spacer out of aluminum tubing, approximately 1/4 in long to position the cable end back towards the transmission gear. That's pretty much what the play in the cable appeared to be. I'll give it a try tomorrow morning weather permitting.

ERA Chas · #17 (**permalink**) 08-31-2014, 05:47 PM

Dan---
Leave the 'real, original' Smiths speedo for the DB's in the parking lot to ooh and ahhh over. Drive by the tach.
Do the formula for MPH inputting your rear gear, 1:1 trans (4th) and tire diameter. Do it for each 1000RPM. Then just look at the tach when you're in the school zone for your sedate MPH.
Also do it for near redline.
For instance, 6200 in 4th with my combination was 155MPH. Which I enjoyed whenever space allowed............

patrickt · #18 (**permalink**) 08-31-2014, 06:09 PM

Chas. is right. Because of this thread, I looked at my speedo this weekend for the first time in a long time (the Smiths speedo is in the middle of the dash). At 45MPH it was not holding perfectly steady, but was "wiggling" up and down about a half inch or so. I hardly ever look at it -- I've used the "tach" method forever. 7, 11, 17, 21, and 34 -- just do the quick math in your head. Cops tend to cut me more breaks in the Cobra than they do in my DD cars anyway.

ERA Chas · #19 (**permalink**) 08-31-2014, 06:41 PM

Quote:

Originally Posted by patrickt

Chas. is right.
Cops tend to cut me more breaks in the Cobra than they do in my DD cars anyway.

I will cherish that first sentence forever......

Police are feeling great pity that someone forced you to ride in a foam- insulated and beige example of what was by legend, a raw-boned sports racer...

davids2toys · #20 (**permalink**) 09-01-2014, 08:48 AM

Quote:

Originally Posted by DanEC

I can see this - first time I re-installed the cable to the speedometer and took a test drive the speedo didn't work at all. Pulled it back off and realized it wasn't inserted into the transmission gear. Made sure it was engaged in the transmission gear and reinstalled it and it was working again. It surprised me that I could install it and snug up the fitting and it the cable wasn't engaged. What you related is apparently what allowed it. I will see if I can rig up a couple small washers to go between the shoulder on the cable and the reverser to back it up a little and ensure full engagement in the transmission. I also took the reverser apart but it seemed smooth in operation and well lubed so I decided to put it back together and give it another shot of chassis lube in the zerk fitting.

I took another short drive but it started misting and had to curtail it. Still bouncing a little although seems slightly better. It seemed to get worse the other day after I accelerated up through the gears to about 70. I suspect it may be in the transmission gear - hopefully the driven gear. But it looks like I will have to pull the tunnel to get a good look at it.

I am only referring to the Toploader 4 sp, washer are not going to do anything for you, a spacer has to be put on the cable itself to limit its walking inside the sheath into the reverser to far. By the sounds of it, sounds like your plastic gear is shot. as I said, very cheap(18.00) and no need to pull the tunnel to R&R. I have 331 gears and it would be the green gear. I think the tooth count was 18 or 21...don't remember.
Edit:sep1 10:52
Never saw the part where you made the spacer...sorry