I put a SROD from an '80 into a '79 F100. I put in th etrans before I looked at the drive gear and I can't get a straight shot at it now to see. It is either a 6 or 7 tooth gear. Anyone know what it should be?? I can't get the speedo to read correct, but I'm not totally against the speedo being at fault, another story. The 3 speed used a 19 tooth gear, speedo read way low after the trans swap. I have switched to a 16 tooth, but speedo is still reading low. The truck has a 2.75 ear, so a low tooth count on the driven gear is going to be the case. I was just trying another to see how much better the speedo would read. Anyone here with a SROD know any specifics? Whats the drive gear? What driven gear are you running and what rear do you have? I know the formulas, don't need that info, just some info from someone with this setup. Thanks in advance.

 

no one has a clue?

 

Methinks those with the SROD don't mess with it much except to swap in a Mazda or ZF or T18 etc.

IIRC, one tooth on the driven gear is worth 5 to 7 mph--this from a Numberdummy post some time in the last year or so.

I'd go out and look at mine, but it's in the crusher.

 

Well I figured out the problem. There is bad info on the web . .imagine that I suspected I may have a bad cable, with a weak spot that was winding up and not giving accurate readings. I had swapped the speedo to see if there was any difference. My original speedo would bounce 30 or more mph sometimes. The new speedo solved that, but wasn't anymore accurate as to actual speed. When I pulled the cable, I found no weak spot ( I have run into this before ). Ok, so what gives ?? I looked in at the drive gear and my driven gear, something didn't seem right. The helix was angled the same way on both gears ( should be opposite ). I rechecked my info online that says ( SRODs use the speedo gear that a 3 speed uses because it mounts on the drivers ( left ) side of the trans . .WRONG !! They use the same gear as a toploader. Yes they come at a different side . . but they ride below the drive gear. Whereas, the toploader is on the other side, but rides above the drive gear. So it uses the same gear. Many places on the web it is stated incorrectly. So the gear mesh was wrong. I switched to a toploader style gear I had and now all is well. Of course now I'm fighting with whether to run a 16T or 17T driven gear to be the most accurate reading . . . but that I can handle gladly. So .. I hope this helps someone out there too.

 

Will try to remember that. Where in Pasadena? I'm near Caltech.

 

Pasadena, Maryland

 

Silly me. I was thinking "..what if it's Texas???"/ Didn't look in the profile.

So, there's ANOTHER Pasadena on top of the two I knowed about...hhhmmm.