I know is blasphamy but...
 

After I upgraded my transmission to a 700R4 in my 68 the speedo doesn't work because the tranny transmits that data electronically. So until I pay for a 1000 converter box or buy a GPS speedo, I found out my Android phone has a free speedometer ap. I have a mount suction cupped to my lower windshield and this thing is dead accurate regardless of tire size. I am considering getting an actual GPS speedometer if I could get it to work with my original needle and bezel (or whatever the piece is called.) that would even be better. Still, it is pretty cool.

Re: I know is blasphamy but...
 

I was thinking the covnerter box or cheap new speedos were around $300.
I used my gps to calibrate my menal speedo from the tach.

Re: I know is blasphamy but...
 

You can also change the tranny to a mechanical output pretty cheap. Look up Bowtie Overdrives for a full new route, or you can junkyard it for the outer housing (it may be the same as other GM trannys, but don't quote me) and then just buy the driven gears you need for your axle and tire combination.

I converted the 700r4 in my 67 chevelle this way and it took me about an hour to switch out including pulling the driveshaft, the extension housing, switching gears, and reinstalling.

Re: I know is blasphamy but...
 

I have a Garmin GPS that I tested on three different (newer) vehicles and the speed indicator is dead on. I also checked the speedometer on my 68 and it showed to be accurate.

I'm a firm believer in those little devices to let you know how fast you're going or to check the accuracy of the speedometer but you should still have a regular speedometer, just in case you happen to lose the signal.

Re: I know is blasphamy but...
 

Great advice, thanks for the options.

Re: I know is blasphamy but...
 

I just use my tach. I recently swapped a 4l80e into my truck and it does not have any provision for a mech speedo, unless i buy a $600.00 tail housing, or a signal converter for $700.00.

When my converter locks up I am doing 55mph at 1400 rpm and 70mph at 1800rpm. once you know where the speeds are its just like a speedo, unless someone else drives my truck.

someday i will get a digital to mech speedo driver.

I guess you have to have a tach for this to work

Re: I know is blasphamy but...
 

The Cable X box can be bought here for $325

http://www.abbott-tach.com/orderpage.htm

And you can get cheaper electronic speedos.

http://www.summitracing.com/parts/VDO-437155/

That being said, I'm using my GPS or my laptop as a speedo right now:lol:

Re: I know is blasphamy but...
 

Wow, never seen the box that low in price, thanks. I don't have a tach so I would like to keep the original speedo look. I will check for tail-housing and if they are too much just spend the 300. (Some day when I get it saved.)

Re: I know is blasphamy but...
 

wow thats cheap i may have to do that

Re: I know is blasphamy but...
 

strip the vdo gauge down and throw it behind the factory face and needle. Shame about the digital odo. Def worth a try for $120. I made a 94 s10 FIT behind the factory face and needle. CAnt seem to get it working..... Yeah it was a factory tach cluster :(

Re: I know is blasphamy but...
 

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These guys have the electronic and/or GPS speedos. I bought the Legacy GPS one when I installed the S-10 5 speed in my Green '67 and I really like it.

http://www.speedhut.com/

Here is a thread on my install...

http://67-72chevytrucks.com/vboard/s...d.php?t=421745

I bought the "Legacy" style but they have a big selection.

LockDoc

Re: I know is blasphamy but...
 

:lol: I've been using GPS Test + on my Droid X as my speedo in my 78 for quite some time. The odometer on the speedo is pretty accurate according to mile markers on the highway, but the speedo just bounces around so I use this instead.

Re: I know is blasphamy but...
 

The bouncing would probably stop if you would unscrew the cable from the back of the speedo, pull the cable out of the housing, wash it down with some solvent, lube it good with oil and re-install it.

LockDoc

Re: I know is blasphamy but...
 

When I was about 16 (decades ago) I helped a guy make a speedometer for an old Datsun pickup, we used some magnets and a pickup out of one of those aftermarket cruise control kits from JC Whitney, the magnets mounted on the driveshaft and the pickup was mounted on the underside of the truck next to the driveline magnet. We ran the wire from the pickup up to a cheap tachometer mounted on the dash. To calibrate it I drove behind him and flashed my lights at a few speeds we had worked out earlier and marked the tack at those speeds. we had to add a couple magnets to get the tach to move, one wouldn't give enough signal to move the tach far enough.
I am not positive why we did this instead of repairing the original speedo system, it was a long time ago! I do remember it worked really good though.
If a couple of baked teenagers can figure it out how to make it work I bet a grown up adult could adapt something like this into a stock dash!
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Re: I know is blasphamy but...
 

I have done that. It fixed the grinding/whirring noise the speedo cable was making, but no effect on the speedo itself.

Re: I know is blasphamy but...
 

Nice work Airspeed. Your right, I just need to think out of the box, bradman72 mentioned just using my face on a gps speedo. I might jus do that.

Re: I know is blasphamy but...
 

From 85-90 all of the trucks (full size) are gear driven, not electric.

Re: I know is blasphamy but...
 

I was going to say, all you need is a short tail shaft end. They are mechanical. I think I took the one off my TH350 and put it on this one, but not real sure on that. Its been over 10 years since I did the swap.

Re: I know is blasphamy but...
 

Member on here named SHON sells the converter boxes. I think he mentioned $300. Uses one in his truck also. Good luck however you go. I need to do the same thing for my 4l60e conversion.

Re: I know is blasphamy but...
 

Thanks for the advice everyone.

Re: I know is blasphamy but...
 

I hadn't heard of a GPS speedo until now so I searched ebay and found this

http://cgi.ebay.com/ebaymotors/Speed...Q5fAccessories

looks pretty simple even to me.

Re: I know is blasphamy but...
 

yeah, thanks, I have had my eye on tha one, kind of wanna keep it stock. He is asking almost full price.

I am back and forth, maybe I will do the tailshaft search first, what the heck.

Re: I know is blasphamy but...
 

wonder how well that GPS speedo reallllly works... thats pretty neat!!

Re: I know is blasphamy but...
 

Mine works really good...

LockDoc

Re: I know is blasphamy but...
 

Help me out here......what's a speedometer??