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t-5 speedometer question

Discussion in 'The Hokey Ass Message Board' started by wrenchbender54, Feb 10, 2007.

  1. I've searched the archives, but didn't find what I need to know. With the popularity of the t5 trans conversions, I'm sure I'm not the first person to run into this. I've got an '89 S-10 t5 that I'm planning on sticking behind the 261 in my '54. The problem is, '89 ran an electronic speedometer. Is it possible to convert this trans to a mechanical speedo? Is the tone ring for the PM generator held on the same as the mechanical speedo drive gear? Is it just a matter of swapping parts, or do I need to look for an older trans?
  2. George G
    Joined: Jun 28, 2005
    Posts: 1,273

    George G

    No it won't swap over. The manual drive has a gear and the electronic is different. You would have to take the rear of the trans off, swap parts , then you have the problem of dialing the sppedo gears in for tire size etc.

    This is on ebay. I would by one but it is bit spendy. Any lower cost devices out there?

    Cable X Manual / Electronic
    Speedometer Adapter
    ble X is the easy, cost-efficient way to operate your stock mechanical speedometer with a transmission equipped with vehicle speed sensor. The Cable X is basically an universal adapter that will pick up the electronic speedometer signal and will operate the cable driven speedometer to the corresponding speed. It's a snap to install with only three wires - hot, ground a signal. No costly installation of drive gears or long messy cs t de with.

  3. Phil1934
    Joined: Jun 24, 2001
    Posts: 2,613


    I got one from an old 3 speed and it fit right in. Even had the same driven gear.
  4. leon renaud
    Joined: Nov 12, 2005
    Posts: 1,933

    leon renaud
    from N.E. Ct.

    Theres a reluctor wheel that mounts on the rear end yoke check out v8 s10 sites they run into the same problems using other transmissions behind v8s I'd give you links but i'm too computer dumb
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  5. What holds the driven gear onto the output shaft?
    In the t5 parts/ service manual that I have, they show a clip and a snap ring that hold the driven gear on. I'm assuming that the clip somehow keeps the gear from spinning on the output shaft. I'm going to pull the extension housing off of my t5 tonight and get a better look at things.
    As far as the calibration goes, that's not a big deal to figure out.
  6. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,410

    Flat Ernie
    Tech Editor

    IIRC, it's just a clip that goes between the drive gear & the shaft - one part of the clip goes into a small hole on the shaft, the other side holds the clip. Don't recall a snap ring, but that doesn't mean there's not one - been a while since I've had one open & fooled with the gear.

    The area where the gear rides is machined & larger diameter than the section of the shaft on either side of it for several inches, so moving the gear presents a couple challenges.

    I have no idea how the reluctor or pulse generator for the electronic speedo is held on, but would be surprised if it was very different from the speedo gear...
  7. Phil1934
    Joined: Jun 24, 2001
    Posts: 2,613


    I think confusion is from 6 speeds that are electronic only and maybe very late T5 are like that, but I bought a 1990 t5 and the electronic signal generator plugs into the transmission just like a mechanical drive. The driven gear is on the end. Can't help on the drive gear as I haven't looked in a while.
  8. Watching this thread very close as I have a T-56, 6 speed with electronic. I'd also like to swap it over to mechanical....or find an electronic speedo that works in a 40 Buick dash and find a proper wiring diagram..
    Sitting and watching for a speedo "guru' to post an answer to the original question...
  9. krusty40
    Joined: Jan 10, 2006
    Posts: 817


    My experience with the T5 tailshaft (S10 style) is that even if you replaced the electric stuff with mechanical stuff (in the same tailshaft), it won't work... the angle of the opening in the tailshaft for the electric sender isn't right for using mechanical stuff (I've tried)... so it's either find a mechanical sender tailshaft or use a $$converter. vic
  10. Phil1934
    Joined: Jun 24, 2001
    Posts: 2,613


  11. mecutem
    Joined: Oct 6, 2002
    Posts: 582


  12. Thanks for the input everyone. Krusty, I wondered about the placement issue, guess that answers my question. Mecutem, there's some good info in that link. Looks like I'm going to have to find a mech. speedo driven gear housing, and a set of gears, and make it work. Unless I happen across an older t5 to canibalize. You can make anything work, it just depends on how much fuckin' around you're willing to do to get there. Thanks again.
    Joined: Apr 17, 2005
    Posts: 1,349

    from New york

    Just took an S-10 t5 and an Iroc t5 apart to mount the tailshaft from the S-10 to the Iroc box.....The S-10 did not have a snap ring on the tailshaft {this has nothing to do with the speedo} yet the Iroc did...Since i had mocked up my entire truck using the S-10 box {overall dimensions are identical to the Iroc} including the driveshaft i figured no sweat, everything should boltup indentically....Well, except for one thing....That snap ring now prevent my driveshaft from fitting.....I couldn't bolt the shaft to the rear end because the snap ring prevented the shaft from sliding the into the tailshaft far enough to get it in..This wasn't a problem during mockup since the S-10 box didn't have this snap ring.....Ended up cutting about a 1/2" off the front yoke {i wasn't taking that tranny apart again since it was now in the car} and that gave me just enough room to get the driveshaft in

    Anyone know why one box would use the snap ring and not the other?
  14. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,410

    Flat Ernie
    Tech Editor

    Different yokes.
  15. Different yokes for different folks.
  16. Here's an update on this perticular problem. I went to the local transmission shop (owned by the father of a friend of mine). He let me dig through the pile of used parts he had. I found the correct extension housing and an output shaft from a mechanical speedometer S-10 T5. There is a definite difference between the mechanical speedo extension housings, and the electric speedo housing. The output shafts are very similar. In fact, the machined portion of the shaft that the drive gear sits on is in the same location as the machined portion that the reluctor sits on. In theory, all a person would need to do is drill the hole that the retaining clip fits in, and you'd be able to re-use the newer output shaft.
    Since I originally posted this thread, I've done a lot of research. As soon as I get the new bearings and blocking rings for my trans, I plan on doing a tech post on the rebuild/conversion. There is a pile of information out there, it's just a matter of looking in the right places to find it. Now that I've found it, I'll do my best to pass it on to everyone else. So, you can look for a Tech. post in the next week or so.

  17. Danimal
    Joined: Apr 23, 2006
    Posts: 4,129


    Thanks Phil, I'll be watching for this. My son and I just picked one up last weekend and it has the electronic speedo and I ain't spending $300 on the converter!
  18. scottybaccus
    Joined: Mar 13, 2006
    Posts: 4,106


    Seen it done, 1st hand. The mechanical housing does place the driven gear aft of the reluctor position, so you can't put the gear in the same position as the reluctor wheel. You can drill the hole aft of the reluctor position for the spring clip, but it is sometimes necessary to wrap the shaft with some shim stock to get the right OD to make the gear and clip fit tight. Try a slice of your favorite beer can. If it doesn't do the trick, at least you got a beer in the deal.
  19. I've got a binder in the garage full of T-5 info that I've collected from different sources. I don't remember which one it was, off hand, but I remember reading that the snap ring on the output shaft isn't necessary. More than likely, it's keeping the yoke from sliding all the way onto the shaft. I'm sure the snap ring is on there to limit the amount of travel forward that the yoke has.
  20. I'll be stopping to pick up the rebuild parts for my T-5 tomorrow morning. I bought the correct speedo gear the other day off of ebay. Now I've got some cleaning to do. I hope to have the tech. article ready by next weekend- if all goes well.
  21. Jack Ford
    Joined: Aug 24, 2009
    Posts: 5

    Jack Ford

    Just what is the problem in running an electronic speed odometer?
  22. JackdaRabbit
    Joined: Jul 15, 2008
    Posts: 462

    from WNC

    I'm dealing with this issue too, on my `63 C-10 with a electronic T5. I've been running without a speedo for a couple of years ...watching the tach is a good substitute... and so far my inspection mechanic has let me slide.
    Just recently I started asking around about an idea for putting the needle and drive mechanism from (for instance) a 1990 S-10 elect. speedo into my truck's orig. cluster. I think the number layout and needle sweep would match pretty well. I learned that GM speedos in those years used a DRAC unit that controls pulses from the drive unit to the speedo head and they can be modified to calibrate.
    I know, not a Trad fix.
  23. patterpillar
    Joined: Jun 16, 2013
    Posts: 83

    from Montana

    Tradition...much like a Fiddler on The Roof
  24. In my case I have a specialty speedo that I want to use and do not want to tear apart my transmission. I will if I have to but I really do not need another project!

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