rbrettctd

Anyone know the tooth of gear I will need, or know how to do the math? Im swapping a 727 to a Getrag for those who dont know, and keeping my 3.07 rear for great mileage, atleast till I can afford a new (bigger) axle.

dpuckett

Keep the 3.07. You cna only get a 3.31 in a Dana80.

What you can do is keep your stock speedo gears in the Getrag, hook the sensor/ cable up to the outlet on the side of the tranny, leave the gear reduction adaptor out (if it's a 2wd Getrag, you have one). Run a knwon distance (10mi down interstate works), and see how many miles have rolled over on the odometer. Divide the miles travelled by miles shown, and that is the ratio of adaptor you need. Call any speedometer shop and they should be able to make an adaptor for $50-60, and it will FIT your vehicle perfectly.

Daniel

rbrettctd

How do I hook up the sensor without the gear reduction adaptor in there? And I had thought about going with a 14 bolt, disc brakes, limited slip, and 3.73s or 3.54s if I found them....but that is in the distant, distant future.

RumbleFish

http://www.bgsoflex.com/speedo1.html

I used this when I tried to figure out the gear I needed to correct for 315's.

dpuckett

The sensor and adaptor use the same threads- it just bolts on there. You ARE referring to the one on the transmission, right?

DP

PapeCAT

No no no... The Speedo gear that WAS in your 727 will come out and fit in the getrag (at least on my 2wd it did)

rbrettctd

So just put the gear in the reducer?

PapeCAT

yeah the interface is the same on both trannies. I forget the tooth count on the speedo gear but I believe it was the colour red (maybe 36 teeth??). the one I pulled out of the getrag was the colour green with 31 teeth for 3.54s

dpuckett

NO, NO, NO, NO!!! geez, kids these days You leave the gears in both transmissions. Take the adaptor box off the Getrag, as there is little chance (though a chance- there were some late 92s and 93s that had 3.07s with the Getrag) it will be right. Hook your speed sensor/ speedo cable (depending on which you have) into the side of the transmission, where the 90 deg adaptor box attaches (leaving the adaptor box off). Then do as I stated earlier.

FWIW, ALL of my Getrags has had the yellow (30tooth, I think) gear, with different ratio adaptors off the side to compensate.
DP

rbrettctd

Im gonna try using the 90* and the gear from the 727, as thats what worked for papecat.

PapeCAT

yeah the 90 reversing and the gear out of the 727 was all I needed for my speedo cable. My speedo is an all mechanical, no speed sensor at all fwiw. I tried hooking the cable straight up to the trans @ first and it didn't work, needed the 90 reversing coupler !

rbrettctd

Oh okay, mine has a speed sensor. Ill try it with the 90* and if that doesnt work Ill go with the straight. I dont see how leaving the Green gear (the one that came with Getrag) would be right, as that is for the 3.54 rear. Im gonna count my teeth on the drive gear and compute it to be sure.

PapeCAT

yea you need to stick the red gear in the getrag for sure!