i have a few questions about this conversion. i'm putting a t56 in my 88 Iroc that was originally an automatic and am concerned about the speedo cable. first off- without a speedometer reading the car is not supposed to run right and will set a check engine light when the cable is disconnected. is the only thing needed to make it run right a signal at the speedo? i don't quite understand how using the SGI 5 box that eliminates the cable that runs the speedo allows it to get an accurate reading for the computer. does the computer just need to see the speedometer moving for it to work right? and how does this SGI 5 get the speedometer to move anyways? is there any way at all to install the speedo gears from the automatic onto the t56 and have it be mechanical? is there any way at all to just make the t56 mechanical and just use the orginal cable?

Read my reply to this same question about a mechanical speedo drive at the thread I've linked to below. I think my post is the fourth one from the top.

There seems to be so much interest in this I just may offer to do the mechanical conversion for members here.

http://www.thirdgen.org/techboard/tr...swap-done.html (T-56 swap done now some issues with idle)

http://www.southweststreetworks.com/

If you send them your tailhousing they can machine it to accept a speedometer cable.

i just did the t56 conversion on mine what did you do for a transmission crossmember? also has anyone gone with the aftermarket electric speedo ? im trying to find a speedo that will fit in my cluster and take the glass and trim off to install it in the factory hole . also this tail housing conversion it looks like they just put a new hole in the trans why cant i just do this myself ? btw i dont think it should change the way the car runs because we dont have the VSS in the gen three just the TCLS am i thinking correctly ?

I used a crossmember and torque arm from spohn. It's okay but the crossmember is rather low and the torque arm is noise. I rather have something different. Thirdgens do have a VSS and the idle will be crappy without it hooked up.

ok cool i fabricated a whole new crossmember i would have felt stupid if there was a stock one out there that would work.

i got one from BMR fabrication. it includes a mount for the torque are so that it is mounted on the crossmember instead of the tailshaft.

is there any kind of box i can buy that you somehow plug the mechanical wire into and it converts it into the vss signal? does something like that exist? cuz that would be GREAT!

$550 for that and you supply the housing??? I can't even think of anything to say, I'm completely speechless.

for 310 + s+h you can get a box from abbot its called a cable x box but i just spent the money for a 150 stock speedo so im going to see if a local machine shop will drill the hole in the new location for me (because i only have one shot and it needs to be perfect) then i think i can fabricate all of the other parts myself with a simple lathe

wow alloy your talking about the tail shaft i cant understand people paying 400$ for a trans crossmember

about a carburated engine will it get affected without the speedometer connected and just to be sure without the cable to box or paying the money to get the tranny fix up there is no way to make the speedometer work if you put a tranny with a vss

any body?

Well I talked to the guy and was able to get mine tailhousing done for $300. I tried the abbott cable x box first but wasn't happy with it so I went this route instead. There used to be a pdf document on here that gave instruction and measurements so that you could take it to a machine shop and have the work done. The hole has to be exact or the gears won't line up with the output shaft. Also the sleave that goes inside will have to be a good tite fit or the tailhousing will leak tranny fluid.

What specifically was the problem with the Cable-X box?

I'm not real fan of something like that, that's why I went mechanical. Cables have been around for many years now and my T5 cable works perfectly. (That's after I replaced my stock 2 pc. cable with a single pc. new one). Speedo is steady and doesn't bounce at all.

I just finished my 3rd T56 cable drive conversion yesterday. Did two for others first, then finally got time to do mine. Got one or two more to do this next week depending on when UPS gets around to delivering them.

The needle was a little bouncy because the motor that drives the cable just isn't as smooth as a directly driven cable would be. Not a big deal and it does work just fine. I orignally went with the cable x because I didn't want to remove the tail housing from the transmission. I was worried I wouldn't be able to get it back together, etc. I had the cable x box in stalled instead and it worked fine. I can't remember if I tried my cruse control but I think I did and I believe it worked fine. Anyway my tranny ended up having bad syncros and needed to be rebuilt so since I was going to tear it apart anyway I figued I get the tailhousing machined to work with my speedometer cable.

Here is a pic of my conversion.