79 L82 with cruise that doesnt work and a bouncy speedometer. My question is what is usually the
first common problem with these? Is it the cruise tranducer, lack of grease in the cables, or a chewed gear. Is the plastic gear at the tranny? thanks in advance for any insight as to where to begin!

 

Just my limited experience - My 79 L48 had the same issue - the lubrication was gone, and I read that it's best if you just replace the cable. Mine was not a cruise control car, so I swapped out the entire length (one cable from Speedo to tranny) - it was a pretty easy fix.

I THINK with cruise you have two cables - one that goes from speedo to transducer, then another from transducer to transmission. I've read of people changing the portion between the speedometer and transducer to fix the same issue, but a forum search would confirm that for you. Hope this helps.

 

For a car with cruise control, the potential problem areas are: (in order of likely priority)

one of the speedo cables is binding up, the most likely being the one from the tranny to the cruise unit; the cruise control head has gummed-up and needs to be cleaned; the speedo drive gear in the tranny has cracked or gotten worn where the cable engages and the cable is not slipping intermittantly; the speedo head is dirty or beginning to have mechanical problems.

 

thank you for the teriffic advice. when you say cruise control head are you refering to the cruise tranducer or somewhere underneath the dash? I think when you say speedo head
that means where the cable hooks up to the speedo, clean that area?
once again thank you I can tell you know your stuff!

 

thanks man i appreciate it cooper

 

The cruise transducer is what I was referring to. The mechanism inside can get dirty/sticky. If you are not into mechanical disassembly....and you diagnose the problem to be that cruise unit...you can replace it with yours in exchange for decent money. Or, if the head doesn't really work and/or you don't need it, you can just put one length of cable between the tranny and the speedo. Personally, I use my cruise...a lot...and wouldn't want to be without it. But, others have little use for them. That is strictly up to you.

 

thanks man this is really helping me. what im planning on doing is taking it apart at the tranducer and at the tranny and cleaning it up real good and lubricating. would love to get cruise working again but there is more troubleshooting. old vettes are somthin else but me and my son love em

 

Cool! Last time I checked (several years ago), that part was pretty much non-existant. Just located one on a vendor's website.

I've opened mine up and cleaned it a couple times, but the internals are pretty much shot. I also have the bouncing speedometer, and have replaced the lower speedo cable. Can't wait to get the replacement transducer!

 

I hope you have better luck than I've been having. Cables not broken, however very worn. I have replaced the transducer & ordered both cable from NAPA. Hope to have if fixed tomorrow.

 

I had a bouncy speedo on a 72 and found it had one strand on the speedometer cable that frayed and stuck out just a little and was catching the wall of the cable housing. New cable and issue was solved.

 

ok to follow up I took the cables apart at both sides of the transducer and at the tranny
cleaned and lubricated with a small amount of wd-40. it took out some of the bounce in the speedo but still bounces at lower speeds then levels out on the freeway.
Does anyone know for sure if a new tranducer will solve the problem.?
Also does anyone knowif there is electrical troubleshooting involved with getting the cruise
control button to work on the turning signal lever? mine doesnt do anything when you push it. Is that just vacuum or is there a circuit in there?

 

I have the same problem with my '76 (no cruise) but it mostly happens when decelerating and it somewhat stabilizes when accelerating... I've been taking the mid point of the high and low points of the bounce to estimate speed so far... Now I have an idea of what to check at least (when I get to it anyway...).

 

A new lower speedo cable cured this problem thanks for the help

 

Did you replace the entire cable and housing or just the cable?
I completely disassembled the transducer and oiled the gears inside it. I cleaned the face plates of the copper and the magnet inside the transducer. I replaced the cable from the transmission to the transducer but didn't replace the cable housing.
I still have a bouncing needle at low speeds. Above 40 it seems to stop.
My cruse did work briefly then it worked +/- 10 MPH. Now it's not working at all. This all happened within the first 15 miles after lubing and replacing the lower cable only. I used Lubraplate spray to lube the lower cable.
Has anyone actually taken apart the transducer?

Any help would be great.
Thanks

 

I replaced the entire lower cable and that fixed my bouncy speedometer completely. I still do not have the cruise working and need help with that

 

I am not sure what you mean about housing?

 

I took mine apart recently and found two problems that would cause a lot of drag on the cable coming from the transmission.
The first thing I noticed is that the shaft that the calbe goes into on the transducer was not turning easily by hand. The shaft passes through a bushing that had become gummy form old lube.
I was able to clean it out with a little carb cleaner sprayed in the crevice where the shaft passes into the bushing on the outside of the transducer.
This freed up the shaft and it turned easily after this. However how to lube it to keep it turning freely. I put a little pentrating oil in the same area and that seemed to do the trick. But I wanted a way to get lube in there later. So I drilled a small hole into the bushing to the innner shaft in order to get a spray can hose into to apply lube in the future.

[IMG][/IMG]

When I opened it up all looked good until I took the top half apart. It looked pretty rough and draggy.

[IMG][/IMG]

So I took a dremel and some polishing compound and eventually got it to look like this.

[IMG][/IMG]



I put it all back together and it turned much better than it had before. I re-installed it. I then took the cable from the trannie and removed it took the cable out of the housing and it was also gummy with old lube. I cleaned out the housing with copius quantities of carb cleaner then I cleaned the cable in the same manner. Grease up the cable and put it back in the housing, reinstalled it. Now no more bouncy speedo.

 

Nice pics. I cleaned mine much the same way. I used copper cleaner that my wife had to clean stuff. It worked real easy. Didn't need to use the dremel.
I had good results as well. Cruse now works and speedo doesn't bounce but, it's only been 50 miles.

 

does your cruise work now? mine isn't getting power to the transducer, not sure how to fix that

 

Funny you should ask. It was working just great! Now the speedo stopped working and began to make a loud clicking noise. I found that the transducer was tied up once again. I took it apart and found that the copper part was once again blackened on one half. It seems that it keeps getting too close to the iron part (magnet) and when the (2) parts rub they discolor the copper pc. and scratch the iron pc.
I'm giving up. I ordered a replacement from RockAuto and should get it after the weekend.
If you are still having problems post something here and I'll be reminded to report my findings after I install the new transducer.
-ALSO-
I removed the single screw from the botton of the backside of the transducer. See my post (8-9-2013 @8:52AM) Look at the right half of the pic. It's the little screw that on the bottom side that attaches to the spring. I then took out that copper part with the spring attached to it. This is the part with the rod, the part that Reelav8r polished with the dremel. I reassembled the transducer without this part and my speedo works great at all speeds no bounce at all. Note that the CC will not work but, untill I get my new transducer I'll know how fast I'm going. Yeah "Bubba" visited.
By the way do yu have a (2) or (3) wire transducer?