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Old 11-12-2014, 11:10 AM   #1
PanelDeland
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Speedo gears from scratch

Left the NC gathering of the Goofs sat afternoon and as I merged onto the interstate, my speedo quit. So yesterday I was going to pull the driven gear and inspect it to see what was going on. There wasn't one. I'm sure it's in the tailhousing. So I'll be pulling that to get the old gear/pieces out. Since I have no idea of the gear count on any of it,I would like to just order new drive, driven gears and all the seals and clips etc. I figure I might as well replace all of it while I'm in there. So how do I determine the gears I need from scratch?
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Old 11-12-2014, 11:20 AM   #2
LockDoc
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Re: Speedo gears from scratch

Quote:
Originally Posted by PanelDeland View Post
Left the NC gathering of the Goofs sat afternoon and as I merged onto the interstate, my speedo quit. So yesterday I was going to pull the driven gear and inspect it to see what was going on. There wasn't one. I'm sure it's in the tailhousing. So I'll be pulling that to get the old gear/pieces out. Since I have no idea of the gear count on any of it,I would like to just order new drive, driven gears and all the seals and clips etc. I figure I might as well replace all of it while I'm in there. So how do I determine the gears I need from scratch?

You should be able to tell from the color of the plastic that the gear is made from and the color of the gear on the output shaft.. Check this site out:

http://www.transmissioncenter.net/sp...n_______va.htm

There is also a chart down a ways that you can use to calculate what you need.

LockDoc
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Old 11-12-2014, 12:04 PM   #3
PanelDeland
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Re: Speedo gears from scratch

Good info LockDoc. Unfortunately I don't know the color of either. I was hoping to order all new seal, gears, and clips and just replace everything in there in one sitting (or laying).I wasn't wanting to have it apart while I waited on parts.
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Old 11-12-2014, 05:56 PM   #4
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Re: Speedo gears from scratch

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Originally Posted by PanelDeland View Post
Good info LockDoc. Unfortunately I don't know the color of either. I was hoping to order all new seal, gears, and clips and just replace everything in there in one sitting (or laying).I wasn't wanting to have it apart while I waited on parts.

I'm not sure how you could do that and be 100% sure of getting the correct parts the first time....

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Old 11-12-2014, 06:50 PM   #5
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Re: Speedo gears from scratch

Quote:
Originally Posted by PanelDeland View Post
Left the NC gathering of the Goofs sat afternoon and as I merged onto the interstate, my speedo quit. So yesterday I was going to pull the driven gear and inspect it to see what was going on. There wasn't one. I'm sure it's in the tailhousing. So I'll be pulling that to get the old gear/pieces out. Since I have no idea of the gear count on any of it,I would like to just order new drive, driven gears and all the seals and clips etc. I figure I might as well replace all of it while I'm in there. So how do I determine the gears I need from scratch?
http://www.tciauto.com/tc/speedometer-gear-calculator/
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Old 11-12-2014, 06:56 PM   #6
71meangreenc10
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Re: Speedo gears from scratch

Deland,

What trans are you running? I have built both types. The PATC site is a good one to use, plus they have a lot of parts in stock.

Smitty
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Old 11-12-2014, 08:17 PM   #7
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Re: Speedo gears from scratch

I see it says:

"All 2004R transmissions use a 1" diameter steel driven gear housing."

What does that mean to me in practical terms, since I have a 200-4R I'll need to calibrate? I can read, so I know the driven gear is 1" in diameter and made of steel, but there's no mention of how many teeth or anything.
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Old 11-12-2014, 09:10 PM   #8
mechanicalman
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Re: Speedo gears from scratch

Quote:
Originally Posted by davepl View Post
I see it says:

"All 2004R transmissions use a 1" diameter steel driven gear housing."

What does that mean to me in practical terms, since I have a 200-4R I'll need to calibrate? I can read, so I know the driven gear is 1" in diameter and made of steel, but there's no mention of how many teeth or anything.
It means very little, it just refers to the "bullet" that holts the driven gear into the housing. Not well worded, it means the housing is steel, but sounds like it means the gear is steel but it's plastic. Refer to this link for pictures of the driven gears and 1" steel housing.
https://www.google.com/search?q=2004...0QsAQ&dpr=0.95
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Old 11-12-2014, 10:08 PM   #9
PanelDeland
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Re: Speedo gears from scratch

Had a brain Fart. I figured it out. I'm going to use the calc and just plug in a random drive gear and see what the calc shows. I may have to try more than once but some combo has to be right and then I'll order what has the least percentage of variation.

BTW it's a Saginaw 3 speed.
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The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion.
You can't fix stupid,not even with duct tape.
"My appearance is due to the fact that "GOD" does punish you for having too much fun!"
Barrett-Jackson has perfected alchemy,they make rust into gold!
"You can lead a horse to water but you can't saddle a duck"
"Cleverly disguised as a 'Responsible Adult'
"Sometimes your Knight in shining armor is just a retard in tinfoil"

Last edited by PanelDeland; 11-12-2014 at 10:14 PM.
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