The Stovebolt Site Forums The Shop Area General Truck Talk speedometer cable

How far should the cable go into the speedo head and also the trans. New cable and stock, reworked, speedo head and sm420 trans. Took it out for a drive and speedo only got to 10 mph and I know everyone was going about 30 mph. Got back home and checked it for kinks and too small a bend, everything looked good. Pulled it out of trans. and put a drill on it and it went to 35 mph,so I know that it goes faster than 10 mph. It seems like when I put it in the trans. that I have to pull it out of the speedo a little. Any input will help. 53 3100 root

I have 3 different cables for my 49 1/2t. All have a small round stop on the speedo end about 3/4" from cable end. i.e. the cable extends 3/4" from the end of the stop into the speedo head. I couldn't find a good picture.

I had to lube a few 1980's vintage GM speedometer cables.

The square plastic end on the metal cable that drove the speedometer head never was even with the end of the cable housing end that connected to the back of the speedometer. In fact it was shorter. Though it had to be that way because the cable was held in place by a clip to the speedometer.

My 1935 Buick cable was worked on about 45 years ago and I do not remember much about that.

Now last week I found out that my son's 1946 truck was missing the cable when I disconnected the cable housing from the speedometer. So I ordered a new cable and housing. This vintage cable housing uses a screw cap connector on both ends.

It just so happens that the new housing and cable was delivered today. And the cable extended past both ends of the housing.

Root, had/having some similar problems with my 52 w/700R4 tranny. The speedometer is good, checks good with drill ect. Took a ride with the speedometer cable hanging under the dash. It turns, then stops, them does it again, jumping, stopping.
I have a new cable!
Don't know about your SM420 but when this happens, in my experience, it is usually the plastic gear the cable gges into.
.....Once, on my 37 it was a simple fact the NEW speedo cable was to SMALL on the square end. Took to a friend how does this kind of work and he made me one out of the CORRECT size and have never had a problem in the past 10 years. (cheap china stuff)

May not help you but just saying.......

One of the cables I purchased had the collar set to far back
...pic...
...pic...

Went to the auto parts and found one set correctly

...pic... 3/4 inch as mentioned above.

DADS50...he's got all those pictures!! Looks just like my cables!

Hurt my back yesterday so will not be able get under my truck or dash for about a week. I will check the length then. Will also check the the square end for the right size. Thanks everyone for your input. Root

Not that I,m knowledgable on this,
But what would happen if you cut the tip off of the stickout down to 3/4"
Would the other end still have enough to grab the drive gear?
Just sayin.......
regards,
steve sr.

I think the cable would be too short for the cable housing.

Finally got back on the speedometer, took out the end on speedo and found it was 7/8 inch, so going to cut off to 3/4 inch. Also going to check the square end and see if it is .104 - .150 which it should be. Thanks all for the info. and the pictures. Will keep you informed on the results. root

Well, jacked up truck after cutting off the cable, started it up and put in third gear, only went to 30 MPH, jumped around a lot found out that the odometer dose not rotate. Called a locale guy that rebuilds them, found that the old gears inside are plastic and have a habit of breaking. He uses gears from the 55-59 which are alum. So this fall I will remove half the dash to get it out and rebuilt. Tried to contact the guy in Portland that rebuilt mine, but guess what, he will not answer E-mail, but still sell on E-Bay, so I am SOL. 53 3100 root

root, did you try to message the guy from Portland, through E/Bay?

On one of the links there is a parts business that sells brand new odometers for speedometers and they are not hard to change.

The speedometer needle on my 1935 Buick jumped around and did not read steady.

My dad had me take the speedometer out of the dash. He then sprayed a shot of some type of cleaner or lubricant on the mechanism careful not to get any overspray on the face.

My memory is not clear but I think it was carb cleaner because a can of that was always around. Then his warning do not get any on the face of the speedometer.

He did not spray it as he was cleaning up a carb or backing plate. The speedometer appeared dry nothing dripped.

Another reason I think he used carb cleaner was that the needle mechanism is light and needs to spin freely. Cleaning the dirt was all that the mechanism needed. Lubricants would add weight and drag for the needle has to spin freely.

That speedometer was still working when I sold the Buick 25 years later.

If I fully tighten the connection to the speedometer, the dial goes nuts and gets stuck while driving. If I back off on the speedo connection just a bit, it works great.

55 shaker, yes I tried going through E-bay no answer. Gauges look great but no service. Wally/Montana tried both ways. thank both of you root