speedometer too slow

[mickeypowa]

Thanks for your answer, I begin to understand everything, it's a good feeling !
So I counted the revolutions of the driven gear compared to driveshaft.
When I do 4 revolutions of driveshaft, I have a little bit more than 1 revolution of the speedo driven gear so I guess I have a ratio of 0.27 more or less...
My driven gear seems to be yellow on the photo, so maybe I have another combo drive/driven gear ?


when you say a "30 teeth blue driven gear", I don't find it in the chart, there is 20 and 37 teeth corresponding to blue color ?

When you say that I need to have 0.55 ratio, that's make completely sense because my speed on the speedo would be 2 times more and I think I would be Ok !

 

[MrSony]

Ahaha ! No, my cutlass is a left hand drive actually. Here in tahiti we drive on the right and we have the steering wheel on the left. It was imported in 1980 on the island, I think there was an oldsmobile seller here at this time...
Maybe it's the gopro used for filming which modify the shape of the screen and make you believe it's a right hand drive ! 😉

The camera plays many tricks it does.

 

[UNGN]

Make a note or mark the rotation of the speedo driven gear housing and pull it out (grab on with pliers or visegrips and pull/twist it out). Look inside the transmission with a flashlight to see the color of your drive gear. Then we can see if there is a driven gear that will make it right or if you have to change your drive gear.

If that is a 41 tooth yellow driven gear, it would need a 25 gear to work, and they don't make one, soooo.... you would need to go into the tailshaft to change the drive gear along with the driven gear..

 

[mickeypowa]

Ok, thanks for all your advices, I will have a look inside the transmission as soon as I can, maybe this week end !

 

[mickeypowa]

Hi guy !!! Merry christmas !!
So I had some time this afternoon to check my drive and driven gears colors.

I have a green drive gear : 9 tooth and an orange driven gear : 35 tooth
It gives me a ratio of 0.257 like I expected.



So I was thinking of changing only my driven gear ( easier ) by a 17 tooth, it would give me a ratio of 9/17=0.53, almost 0.543 the perfect ratio for 2:29 rear ratio. what do you think about that ?
I have a link :
http://www.ebay.com/itm/TH350-Speedometer-Driven-Gear-17-Tooth-Teeth-Turbo-350-Speedo-/310820794824


I have noticed something else : when I pulled out the driven gear housing, the was only a little oil droping, I was expecting a "geyser" like in the video and not at all...

Is it normal ? I had jacked up only the driver side maybe that's why only a few oil droped ?
And after putting the driven gear back, I check for the transmission oil level under the hood and I shows "full". But as my trans has been changed I wonder if the level reading is good or not ?

 

[mickeypowa]

Hi guys !!
Could somebody help me for the driven gear ? the 17 tooth driven gear instead of the 35 tooth should be ok ?

I've read that you can put 8 quarts of oil in a th350. So it means that if I empty it by take out the oil pan, then I change filter and put the gasket and pan back, then I must put 8 quarts of oil ?!

Thanks !

 

[UNGN]

The 9 Drive/17 Driven should get you as close as anything else. Should be within a KM or two. Much better than what you currently have and the speedo will likely be more steady, also.

 

[80special]

Hi guys !!
Could somebody help me for the driven gear ? the 17 tooth driven gear instead of the 35 tooth should be ok ?

I've read that you can put 8 quarts of oil in a th350. So it means that if I empty it by take out the oil pan, then I change filter and put the gasket and pan back, then I must put 8 quarts of oil ?!

Thanks !

I've always been told that it depends on converter, trans cooler size and so on. If you google it you'll see anywhere from 5-10+. Best bet is to get it level and warm and then check it running. If it was dry, like brand new ,then shift thru gears slowly, pausing in each one with the brake held.

And my 1980 had cruise control. My speedo cable broke inside the cruise mechanism. It was located on the inner fender well. Speedo cable went from dash, to that cruise control box, then had a cable from there to the trans. Not sure if any1 mentioned it already, or if yours had it.

 

[mickeypowa]

Ok so I've just ordered the 17 tooth driven gear, it's gonna be great to have the speedometer properly working ! 😉

On my car I haven't the cruise control, the speedo cable goes directly from the speedometer to the transmission.

Yes, when I check with the dipstick my trans oil level, it shows full on the dipstick.
But when I took out the driven gear, almost no oil dropped.
that's why I was wondering if maybe my dipstick wasn't reading good as my trans is not the original one it has been changed and the front of my car has been lowered...

 

[Texas82GP]

You mentioned you jacked up the car on the driver's side. I think that is why almost no fluid came out. If you drop the pan and change the filter, I would fill it by first pouring in four quarts, then start checking the fluid level with the car sitting on level ground, idling, in park. Take note of how much fluid comes out if you are uncomfortable with the accuracy of of the dipstick. If your car has a deep aftermarket transmission pan, then you probably should start with five quarts. If the transmission was shifting fine and the fluid looks good, there may be no reason to doubt the accuracy of the dipstick.