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Making the speedo work in a TH350.

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Old Jul 13, 2005 | 05:17 PM
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Default Making the speedo work in a TH350.

Correct me if I'm wrong, but what parts are needed is a reluctor wheel and speed sensor. If you are converting from a 6 speed, you'll need the 6 speed reluctor wheel and if youre converting from an A4, you'll need the 4L60E reluctor wheel because they have different number of tooths and you cant interchange because the reading will be off. Also, if youre converting from an A4, the reluctor wheel will press right on, but if youre converting from a 6 speed it will not fit because the T-56 and TH350 have a different size output shaft and the T-56 reluctor wheel will have to be machined to fit. Is this all correct? Is this a hard task to tackle? I'd like to keep my speedo in case I do ever take it on the street even though its a track car. Now of course, mounting the actual sensor is something youre going to have to rig/fab up yourself correct and it has to be positioned precisely so that it gets accurate readings. Anyhow, fill me in or correct me if Im wrong because I need to decide what I'm going to do before tomorrow morning, my tranny is in the process of being built locally and I'm either going to take him the parts or just do without a speedo. Thanks.
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Old Jul 13, 2005 | 08:17 PM
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i just plugged mine intomy front wheel sesor. it was free and it doesn't get thrown off when you put different size tires out back.
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Old Jul 14, 2005 | 10:07 AM
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Plugged it into your front wheel sensor? If that does work accurately, how did you manage to plug it in way up in the front? How about did you route the wire without it being in the way of anything or possibly being damaged? Lastly, are the harness connectors the same?
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Old Jul 14, 2005 | 11:42 AM
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Yes it works flawlesly. you do have to splice the wheel sensor plug and your wheel sensor. Basically just leave your wheel sensor pluged in (it is already safely routed to the computer) and follow the wires to the computer find the pin outs for the speed sensor and splice.
you do lose your ABS but i took that out a long time ago.
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Old Jul 14, 2005 | 11:44 AM
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Oh and you put in your front wheel heigth for wheel heigth. and put 2.76 for your gear ratio.
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Old Jul 14, 2005 | 11:56 AM
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Sounds easy enough. Do I have to do any modifications to the computer? Losing ABS isnt a problem because I took it off long ago. Is there anything else you lose or affect by splicing the speed sensor into the wheel sensor? I didn't understand your 2nd post.
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Old Jul 14, 2005 | 02:50 PM
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What i meant was that if youy just splice the wires the speedo is going to be off. Use edit or HP tuners to change your gear ratio to 2.76 and tire heigth to what ever your front tire is. i have 195 r 15's. Don't take everyones word for the heigth. i measured the actual circumference of my front tire and divided it by pi and got like 24.84" or something, not 26" like everyone says.
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Old Jul 14, 2005 | 03:19 PM
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So changing the gear ratio to 2.76 and entering in your tire height as your front tire is required to get accurate readings? Why is this?
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Old Jul 14, 2005 | 04:00 PM
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The gear ratio change is due to the pulse variance from the trans output shaft speed and the wheel sensor output signals. The front tire size is due to the fact that you are no longer using the rear tire to calculate the speed of the vehicle, but rather the front tire.
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Old Jul 17, 2005 | 09:36 AM
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Im glad i saw this post ive been dealing with this for a while and waisted hundreds of dollars on false information. IM going to go ahead and do it the ABS way. I herd about it when it was a brand new ieda and nobody had figured out the gear ratio tire size deal yet, but now that the math and thinking has been figured out for me im going to take advantage of that! Thanks!


Spdfreakls1

Last edited by NosboySS; Jul 17, 2005 at 09:38 AM. Reason: Nossboy didnt log out! lol
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Old Jul 17, 2005 | 11:19 AM
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No problem man. it just took a little figuring and i got it to where it works perfect.
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Old Sep 16, 2005 | 11:34 PM
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Originally Posted by SUX2BU
No problem man. it just took a little figuring and i got it to where it works perfect.
I just wanted to confirm that calibrating the speedo for 2.76 gears for this is DEAD on.

Thanks alot, SUX2BU. Saved me alot of time and guess work.
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Old Sep 17, 2005 | 12:16 AM
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no problm man just happy to add some info to tha site.
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