Dana 27 Track Lock

Are there different track locks for the Dana 27 depending on the gear ratio? If so how do you determine them apart?
Thanks,
Jeff Z

 

I believe there are two different units - one for 3.73 and numerically lower gears (Series 3)and the other for 3.92 and numerically higher (Series 4) gears.

 

Thanks, I am running 4.88's. Any idea how to tell the difference, any part numbers to look for?

 

I'm not sure how to tell, I just know they're different! Hopefully, someone will chime in here.

 

Not sure about trac lock but on power lock there are in fact 2 different ones. The location of the mounting surface of the ring gear is off by about 1/4" and a low geared set up (4 series) will not work on a differential that's set up for a 3 series.

OK that didn't make any sense. Example...I have 3.73's in Nixon's D27. I bought a power lock thinking they were all the same. It wouldn't fit. I stood both the open diff and the power lock side by side to find that the power lock had the mounting surface of the ring gear a good bit higher than the open dif. When turned horizontal of course it puts it farther to the right and because of that the ring gear just won't mesh with the pinion gear.

I've heard that if the situation had been directly the opposite and my open dif was a 4 series and the power lock were a 3 series then the power lock would have been lower or more to the left. In this situation (so I was told) the ring gear could be shimmed over to fit the pinion gear. Again...not exactly sure on this. If it's right then a 3 series power lock would work in any D 27 but a 4 series power lock would only work in a 4 series set up.

Here's a shot of my open dif 3.73 looks compared to the Power lock 4 series.

 

there is a difference in the offset of the cases between series 3 and series 4
you would use a series 4 for 4:88 ratio
in Johns pics, you can see the difference

 

It never ceases to amaze me what I learn on this forum. How many years of accessing it does it take to carry away some type of degree?

 

Thanks very much for the info and great pics. I am looking at a unit that had 4.27 gears and I run 4.88's so I figure it should work.

 

Just my opinion, but I'd seriously reconsider buying a Traclock for the 27. They have a reputation for self destruction that is well deserved. If you look at the case you can see how much of the case is "cut-away". It's usually the case that frags. Trashlock is a name I've heard often used when reffering to these units. Consider ponying up the cash for a Powerlok. It's a much stronger unit and you can get rebuild clutch packs for around $50.

 

John's reply above is pretty accurate, however the reason there are two different offsets on the carriers has to do with the size (dia.) of the pinion gear. Either carrier will fit in a D27 and work with the proper R&P set. 3.73, 4.88 and 5.38 are all the same carrier. The 3.55 carrier only works with numerically smaller ratios. The diameter of the ring gears on all of these gear ratios is the same, it's the diameter of the pinion that changes, hence the different offsets to accomodate the pinion. Sorry for being so long winded.

 

Thanks Posi! How do you tell the difference between a trac lock and power lock? Is there a good web site that shows the difference?
Thanks

 

The Powerlok has a solid case, you can't see any of the internals. The Traclok has two rather large cutouts in the case and you can see the spider gears and other internals. If I can find a site with pics, I'll post the link. You'll have to do some looking to find either one for a D27. They're out there, but not plentiful.

 

Someone correct me if I'm wrong, but I believe that the Track lok was not offered in the D27 series.

 

I don't think the Trac lok showed up in CJs till 1972 D44 rear axle
but I've been known to be wrong

 

On a 27 3.73 gears is a 3 series carrier. That's why the Powerlock John received wouldn't work, it was a 4 series Powerlock. On a Dana 30 3.73 is 4 series but not on a 27. Unfortunately John found out the hard way. Nickmil.

 

Thanks for all of the input, I picked up a power lock that was advertised as a track lock for a Dana 27. The PO said it had 4.27 gears so I figure it will work on my 4.88's. Thanks for the info, I wanted to make sure that what I was buying was definitely a power lock and the info you gave me was right on. The description fit it perfectly, solid case with no cut outs.
Thanks again,
Jeff Z

 

If you want to go through it before you put it in, I found a clutch pack kit at Randy's R&P for a D30 Powerlok, they may have one for the 27 also. http://www.diferentials.com/ You could also try Herm at
http://www.hermtheoverdriveguy.com/

 

Thanks to everyone for the input. I was able to find a POWERlock for my 27. Anybody know a good source for rebuild parts? Are these unit easy to take apart and rebuild?
Thanks

 

Herm carries the clutch parts. Cross shafts are side gears seem to be very rare though.

 

Thaks I'll look Herm up. Does anyone know what usually might go bad on these units? I bought it used and have not torn it apart yet? I just figure I might as well take a look prior to installing it.
Thanks