[AT] Dumb tractor hauler truck question

[charlie hill]

Tape is always an option Dave or bigger tires but the tire option would do 
away with the pulling advantage I gained with the rear end swap.

However, I am back to my original premise.  After a bit of internet sluthing 
I have found the information that I remembered from changing the 
transmission out.  It appears to be a secret that GM and the transmission 
industry doesn't want told.

On the transmission in my truck there is a plastic gear on the tail shaft. 
In the bottom rear of the tail shaft housing there is a bulged out spot 
right under that gear.  In that bulge is a machined boss where the 
transmission/speedometer sending unit sits.  There is another plastic gear 
that runs on the one on the tail shaft on one end and turns the transducer 
on the other end.   That gear is changeable and color coded depending on the 
rear end and tire combination of the vehicle.  The magnetic pulse for the 
speedometer is read after that gear set so switching out the driven gear 
changes the frequency of the pulse to the speedometer.

I found the information on a web site and armed with it called two local GM 
dealers.  At the second one I got a parts guy that knew what I was talking 
about.  He checked his books and gave me a part number.  That number is 
tenative because first I need to pull the sending unit out of my 
transmission and make sure I have the drive gear (also color coded) that I 
think I have.  If it is a 17 tooth gear colored red I'm in business with the 
part # the guy gave me.  If not I need to have him look up the other 
options.

Thanks for the help guys.

Charlie
----- Original Message ----- 
From: "Dave Merchant" <nesys_com at ameritech.net>
To: "Antique tractor email discussion group" <at at lists.antique-tractor.com>; 
"Antique tractor email discussion group" <at at lists.antique-tractor.com>
Sent: Friday, October 08, 2004 3:40 PM
Subject: Re: [AT] Dumb tractor hauler truck question


> Tire size would also have an effect on this.
>
> Some of use would solve this problem with some sticky tape + magic marker 
> on the speedo glass....
>
> Dave Merchant
>
>
> At 08:13 AM 10/8/2004, charlie hill wrote:
>>Thanks for everyone's input.  Doug I don't think you are right with 
>>regards to my truck.  I don't doubt what you are saying with regards to 
>>later years but not for the 89.  Here's why I believe that.
>>
>>When I replaced the transmission I put one out of a Z 28 Camaro in it. 
>>We changed the tail shaft and the speedometer sending unit over to the one 
>>that came with the truck and it all worked fine.  It seems to me that if I 
>>get the speedometer sending unit from a truck that had the 3:42 gear in it 
>>to begin with all should be fine again.  Maybe not?  Anyway I'll do as 
>>Walt suggests and talk to the  local transmission guru.
>>
>>Charlie
>>----- Original Message ----- From: "Doug Tallman" 
>><dtallman at accnorwalk.com>
>>To: "Antique tractor email discussion group" 
>><at at lists.antique-tractor.com>
>>Sent: Friday, October 08, 2004 12:45 AM
>>Subject: Re: [AT] Dumb tractor hauler truck question
>>
>>
>>>  NOW I need to get the speedometer to read accurately.   I
>>>>know how to do that.  I just need to replace the sending unit with the
>>>>corect one.  My question is where to buy the sending unit.
>>>
>>>Charlie, it isn't that simple. I think I read in one post that it was an
>>>89?? The calibration for the speedo is in the dash. There is a diode 
>>>group
>>>that goes in the back of the dash and then you blow certain ones for the
>>>correct calibration. Probably better to let someone that is familiar with
>>>doing this handle it. You can get the programming clip at the dealer.
>>>
>>>
>>>
>>>           Doug Tallman
>>>           dtallman at accnorwalk.com
>>>           VGTCOA Ohio Regional Director
>>>               Greenwich, OH USA
>>>
>>>_______________________________________________
>>>AT mailing list
>>>http://www.antique-tractor.com/mailman/listinfo/at
>>
>>
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>
> Dave Merchant
> kosh at nesys.com
> nesys_com at ameritech.net
>
> http://www.nesys.com
> http://www.nesys.org
>
>
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