Speedo...what to look for now?

[turbocvc]

Whats up guys, new member here needing some help. I've searched the boards and can't find any answers to my issue. I purchased an 87 GN last year and have been slowly getting it up and running. The speedo never really worked to begin with so here is what I've done to try to fix it..

I assumed it was the cable, so replaced with a new one. Put it back together it still doesn't work. I then pull the cable from the tranny and spun the wire with a drill and my speedo reads. So the cable and connection to the gauge cluster is good.

My next assumption was the speedo drive gear in the tranny, so I removed the speedo housing and pulled out the gear and the blue plastic gear looks fine. Checked the inside of the gear shaft and it is square not not rounded off. So now I'm clueless, and put it back together and take for a drive. While driving I accidentally knock it into neutral and all of a sudden the speedo jumps up and reads steady. I put it back in drive and speedo drops and reads 0, put it back in neutral and give it a little gas and it jumps right back up and reads again...I have no idea what to look at now...any ideas? By the way the car is bone stock.

 

[driveshaft man]

I don't know if this is even possible.....but maybe the gear inside the tranny has slipped back just enough that the thrust change on the output shaft moves in and out of engagement with driven gear.If this is true,there could be excessive wear to transmission thrust washers or elsewhere.

 

[bmackinnon]

I don't know if this is even possible.....but maybe the gear inside the tranny has slipped back just enough that the thrust change on the output shaft moves in and out of engagement with driven gear.If this is true,there could be excessive wear to transmission thrust washers or elsewhere.

That's what I'm thinkin'......

 

[BenPutnam]

I had the same problem with mine, it is the gear on the governor.

 

[Martin U]

I chased the same thing for awhile. It wasn't until I got out the mic's did I find the problem. The wear was so even I couldn't tell that the O.D. of the gears were under sized. The two gears were spinning against each other under a load making for very even wear pattern. I replaced BOTH gears and have not had a problem since. Very annoying,easy fix
Mart

 

[Lee_Burough]

You can buy those gears here. They used to have a page online explaining all about it, but have redesigned their website since I saved that link.... Good Luck.

 

[turbocvc]

So do I need to go ahead and replace both the speedo driven gear and the govenor gear? The speedo driven gear has a little wear on it but not that noticeable, a couple of the teeth looks to have a very slight groove. So how hard is to replace the govenor gear. Keep in mind I am by no means a tranny expert. Can I get to it by dropping the tranny pan?

 

[Lee_Burough]

So do I need to go ahead and replace both the speedo driven gear and the govenor gear? The speedo driven gear has a little wear on it but not that noticeable, a couple of the teeth looks to have a very slight groove. So how hard is to replace the govenor gear. Keep in mind I am by no means a tranny expert. Can I get to it by dropping the tranny pan?

I don't know....Call TCIauto and see.

 

[MeanBuicks]

You can buy those gears here. They used to have a page online explaining all about it, but have redesigned their website since I saved that link.... Good Luck.

Here's the page you were referring to: TCI - COMPONENTS: Speedometer Gears Not sure if they have inventory on the TR gears though.

 

[Martin U]

Yas you do have to drop the pan to have access to the gov gear. speedo gear from the end of cable at side of trans. easy fix. I wouls replace both, so you don't have to do it twice.

 

[BenPutnam]

Replace both, mine both looked fine but just didn't touch.

 

[turbocvc]

Ok, so I went ahead and ordered some new gears. So once its in and it warms up a little here, I'll try and tackle it. I'll keep everyone updated as to whether it fixed the problem or not. Thanks guys.

 

[turbocvc]

Update...so I got the gears in and got a chance to replace just the speedo gear since I haven't had time to drop the tranny pan to get to the other, will do that when it gets warmer. Compared the old gear and the new gear side by side and it looks identical in size and pattern, can't really tell that its worn from the naked eye. Took it for a test drive and finally...the speedo works. The only problem is that its a little bouncy at low speeds 0-30 mph, 30 mph and up, it reads steady. Heck I'm just glad it finally sends mph readings to the ECM. Anyways, thanks guys, I'll swap out the govenor gear once its warm and hopefully everything is good.

 

[Martin U]

Be carefull driving it!! It still jumps because you still do not have FULL engagement on BOTH gears. Which will just cause the same problem all over again. One will cause the other to wear If it is still skipping that means it is jumping out of mesh and wearing one of the gears away
Mart