Speedo gear in transmission
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 807
Likes: 2
From: VIRGINIA BEACH VIRGINIA
Speedo gear in transmission
My speedo has not worked in a few years and I thought I would try to tackle it now. I know that the speedo, cables, transducer and the little gear on the on the end of the "bullet" are all good (all have been changed over the last couple of years). I can feel that the gear inside the transmission is stripped.
How do I go about changing that out? Do I have to drop the transmission? The transmission is a turbo 350 automatic. Then the next question is what new gear should I get? It is a stock motor, tires, rear end and transmission.
Thanks for you help.
Dan
How do I go about changing that out? Do I have to drop the transmission? The transmission is a turbo 350 automatic. Then the next question is what new gear should I get? It is a stock motor, tires, rear end and transmission.
Thanks for you help.
Dan
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
First, are you absolutely sure that the speedo gear in the "bullet" does not have a crack at one corner on the square-drive at the end of that gear. That is very common when the cable tends to bind up; and the cable will just spin in the end of that gear because of the crack. It is difficult to see unless you are really looking for it.
The internal gear is "rarely" the problem, as it is made of a harder material than the 'driven' gear (in the bullet). It is possible that the retainer clip on the inner gear was not installed correctly or has fallen out somehow. But, I would be very surprised to hear that the inner gear teeth had failed/become stripped.
The internal gear is "rarely" the problem, as it is made of a harder material than the 'driven' gear (in the bullet). It is possible that the retainer clip on the inner gear was not installed correctly or has fallen out somehow. But, I would be very surprised to hear that the inner gear teeth had failed/become stripped.
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 807
Likes: 2
From: VIRGINIA BEACH VIRGINIA
7T1,
That is what I have been reading. I think I will go through it all again (it has been a couple of years) and check everything again. It sounds like to get that one out of the transmission is way beyond me anyway. Thanks for the reply.
Dan
That is what I have been reading. I think I will go through it all again (it has been a couple of years) and check everything again. It sounds like to get that one out of the transmission is way beyond me anyway. Thanks for the reply.
Dan
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 807
Likes: 2
From: VIRGINIA BEACH VIRGINIA
I pulled the tail shaft off of my 350 auto transmission today to try to figure out why my speedo has not been working. I checked the gear on the bullet (grey) and it was fine, no cracks or anything. The gear inside the trail shaft (orange) was missing a lot of the "threads" on it. Not sure what caused it to strip but it looks like I will put a new one on. Also saw that my tranny pan gasket and oil pan gasket was leaking so I will get some new ones of those also.
My exhaust is out of the way this time so it is a little easier to get to everything.
My exhaust is out of the way this time so it is a little easier to get to everything.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
When you install the new gear on the trans output shaft, make sure the little locking tab is installed properly. It locks that gear onto the shaft and keeps it from moving laterally.
I suspect that the shaft gear has been stripped for some time and the speedo gear was installed afterwards. Both were likely stripped and only the cable gear was changed trying to get it to work. When you buy the shaft gear, make sure that it is compatible with the cable gear that you have. GM trannies usually had 2 different shaft gears and each could have several cable gears for different speedo ratios. But, some of the cable gears can only work with one or the other shaft gear; not all cable gears will work with all shaft gears.
I suspect that the shaft gear has been stripped for some time and the speedo gear was installed afterwards. Both were likely stripped and only the cable gear was changed trying to get it to work. When you buy the shaft gear, make sure that it is compatible with the cable gear that you have. GM trannies usually had 2 different shaft gears and each could have several cable gears for different speedo ratios. But, some of the cable gears can only work with one or the other shaft gear; not all cable gears will work with all shaft gears.
