Looking for a speedo gear
Pro
Joined: Apr 2007
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From: Fairfax VA
Le Mans Master
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From: Australia
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Interesting "comment"!
Here is a place for ZF 6 speed speedo gears:
Three links to mechanical combinations
Without knowing the tire size your friend has mounted it's impossible to give "specific" information. A person could assume a stock tire and do the math but it could be in error. With the 3.07 and the A4 it's likely got a 17 tooth drive and a 43 driven. (the 43 is a plus because it all ready utilizes the 40-45 speed sensor. Your friend with likely stock tires will need to do a 15 tooth drive and a 45 tooth driven using his current speed sensor. He needs to do this at the same time he does the gear change. Like I mention I don't have "tire size" so there are "assumtions"!
Tire size/brand/and advertised RPM (revolutions per mile) for pure math but the number I "guessed at" would be using an "assumed" rolling radius. The 45 would be my first install, there is NO 46. If it were a little slow you could use a 44 and check. If you need part #'s just ask!
*Remember without specifics this is a WAG but a "pretty good" WAG!
Last edited by WVZR-1; Mar 8, 2009 at 09:34 PM.
Team Owner
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You know what? You're right!
I started not to comment/post at all but after reading the thread a second time and spotting the reference to the 3.07 gear. It seemed he certainly didn't need the ZF parts and following your link and looking it over I saw no references on it anywhere to material for "electronic" components. I still don't and if you check "details" on their packages they seem to specify "mechanical".
Here's an example: http://www.bowtieoverdrives.com/cata....php?ITEMID=14
Do they sell them? Maybe or likely BUT they don't seem to advertise it! I don't believe it to be a "quality response" rodj!
I posted the math aspect because if I'm correct in my "assumptions" his friend won't need the sensor that most do to accomplish the change. If he posted here asking he would get comments regarding "upside downing" the speed sensor and it would go on and on!
I started not to comment/post at all but after reading the thread a second time and spotting the reference to the 3.07 gear. It seemed he certainly didn't need the ZF parts and following your link and looking it over I saw no references on it anywhere to material for "electronic" components. I still don't and if you check "details" on their packages they seem to specify "mechanical".
Here's an example: http://www.bowtieoverdrives.com/cata....php?ITEMID=14
Do they sell them? Maybe or likely BUT they don't seem to advertise it! I don't believe it to be a "quality response" rodj!
I posted the math aspect because if I'm correct in my "assumptions" his friend won't need the sensor that most do to accomplish the change. If he posted here asking he would get comments regarding "upside downing" the speed sensor and it would go on and on!
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Team Owner
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For the sources I can refer you to you will need to have part #'s so it will be important to have your math done and know what you need.
Le Mans Master
Joined: Aug 2000
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From: Australia
However ,given that a large number of the 700R4 /4L60 /4L60E trans came with a VSS and BT O/d's is a big supplier of these components it would be worth checking out for someone who does not have easy access to a GM parts dept.
Burning Brakes
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From: Sarasota Fl
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Correct me if I'm wrong but it's 3.73 NOT a chevrolet gear so how can GM sell this?
You asked for help for your 3.73 from a 3.33 but you haven't mentioned two important values that need to be known.
1. The transmission type
2. The size of the tire
A correct "pair" can be determined from that information. If you know what "pair" is installed now and know that the speedo is correct it's possible to see if the "correction" can be accomplished with just an "easily replaced" driven gear.
I got mine from GM too. They sold me the wrong one after I had waited more than a week for it to be special-ordered from Michigan.
Did you get one the second try or "give up"?
Last edited by WVZR-1; Mar 11, 2009 at 01:52 AM.
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Didn't ask you for "height"! I only asked for "size"!!!! It's "hard" to get answers!
I'm quite sure you can be accomodated by just a driven gear! And if it's a 315/35 a 45 tooth should do well!
Answer the question and we'll "try again"!!
If your 3.33 and the ZF were original build you should have a 40 there presently I believe unless it's been -----d with. If that's the case you've already got the correct sensor so yours is "simple"! A 45 tooth gear!
Last edited by WVZR-1; Mar 14, 2009 at 08:29 PM.
Heel & Toe
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I went through this last week on my 1986. Forget about tire size, rear end, gear ratios etc. The simple solution is to buy an Electronic Ratio Adapter (ERA) from Abbott enterprises in Pine Bluff, Arkansas for $160. It is an easy 4 wire hook up. With this unit you simply measure miles by highway markers and compare it to your odometer reading. Based on the % error you set a series of switches in the black box and presto, your speedo is corrected. It took my car builder about an hour to install it in my console. I changed the switches a couple of times and actually got to within 1/2 of 1% over 10 miles, a lot closer than I would have gotten mechanically. It was nice to be able to effortlessly fine tune the thing without figuring where to go for my next gear.
Team Owner
Joined: Sep 2003
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I went through this last week on my 1986. Forget about tire size, rear end, gear ratios etc. The simple solution is to buy an Electronic Ratio Adapter (ERA) from Abbott enterprises in Pine Bluff, Arkansas for $160. It is an easy 4 wire hook up. With this unit you simply measure miles by highway markers and compare it to your odometer reading. Based on the % error you set a series of switches in the black box and presto, your speedo is corrected. It took my car builder about an hour to install it in my console. I changed the switches a couple of times and actually got to within 1/2 of 1% over 10 miles, a lot closer than I would have gotten mechanically. It was nice to be able to effortlessly fine tune the thing without figuring where to go for my next gear.
I realize you say you hit a "home run" but $160 and an hour or more labor isn't a solution for "everyone"! Some are a very easy fix for less than $20. That leaves a pretty "tidy sum" for "groceries/fuel or chillies"!
Not all ERA's are a "simple" install! The Abbott is a quality piece and I mentioned to you that it should be very stable! Not all ERA installs are "routine"! Placement of the ERA is "critical"!
Here's a very simple install for an ERA "NOTE THE FINE PRINT" at the bottom of the page:
http://www.gaugeguys.com/ratioinst.htm
Those noted are the more frequent errors! Finding someone to correct the run problems NOT realizing you could have created them with your ERA install can be quite expensive! Ford guys have more situations than most but SLP had some very costly situations with their product when they attempted "corrections" with ERA's. I believe they finally pulled their "box" from service.
In the link at least these guys mention: "there can be situations"!
The ERA is "NOT" a "FIX ALL"!!!!
Last edited by WVZR-1; Mar 24, 2009 at 06:59 PM.
Heel & Toe
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WVZR-1
Thanks and I appreciate your comment concerning cost. The first justification I had for the cost was that I was tired of searching forever and getting nothing but contrdicting advise. I could have swapped out gears forever without getting it right. Secondly with a blackbox I can change wheels at the track and correct the speedo on the spot (not that I should be looking at it on the straightaway but it's always nice to know ones speed). Finally, and I say this in all seriousness without trying to sound like a wise guy, owning a modified C-4 is an expensive proposition....period!
Thanks and I appreciate your comment concerning cost. The first justification I had for the cost was that I was tired of searching forever and getting nothing but contrdicting advise. I could have swapped out gears forever without getting it right. Secondly with a blackbox I can change wheels at the track and correct the speedo on the spot (not that I should be looking at it on the straightaway but it's always nice to know ones speed). Finally, and I say this in all seriousness without trying to sound like a wise guy, owning a modified C-4 is an expensive proposition....period!
