Need Help to know if this will work

[RJQuick]

I have a 74 C20 with 14bolt rear end, 3.73 gears; however it does not have posi traction. I want to change out the differential. Here's what I've found, but I'm not sure how to determine if it will fit before purchasing it.

33 SPLINE GM 9 1/2 INCH LOCKING DIFFERENTIAL. THE HOLE UNIT HAS LESS THAN 5000 MILES ON IT. WITH A SET OF 373 RING AND PINION GEARS. COMMONLY REFERRED TO AS A GOV-LOC POSI UNIT. IT HAS 14 BOLTS ON THE DIFFERENTIAL COVER AND 12 ATTACHING THE RING GEAR TO THE CARRIER. THIS COMES WITH BEARINGS AND RACES

any in put would be appreciated.

Thanks.

 

[marks86]

first off do you have a full floater or a semi floater?

 

[RJQuick]

How do I check that?

 

[RJQuick]

http://www.gmsquarebody.com/forum/attachment.php?attachmentid=1046&d=1296634108

according to this picture from the sticky post on this forum I have a 10.5" Full float.

 

[77 K20]

Then that diff will not work. You have the 10.5" ring gear, that diff for sale is the semi-floater 9.5"

A lot of people do not like those gov-locs to begin with even when new.

I've had 2 of them, and neither one broke but they have some odd characteristics I didn't like.

 

[RJQuick]

I'm looking to keep the 3.73 gear ratio. Do I just need the posi unit or pinion gear as well? I'm not sure the process I need to take; some direction would be great.

Thanks.

 

[77 K20]

Hopefully someone with more knowledge on differentials will chime in here...

But as long as your existing gears look ok there is no reason to change out the pinion gear. (edit: might be good time to change the seal if your pinion is leaking though)

Are you set on a gov-loc? Or are you looking for a posi with clutch packs in it? Or a full locker? Depending on which one you get the install will be a bit different.

I have a detroit locker in mine. At least with that type of locker you keep the stock differential case. All you do is split the stock case in half, remove the spider gears and drop in the detroit locker.

Other companies might be different... I'm not sure.

 

[77 K20]

To put a gov-loc differential into a truck that used to just have an open differential then you need to have a gov-loc specific differential case it looks like. I vaguely remembered they had a different case... so looked it up. Yep.

The gov-loc has 3 "support pins" that come off it it. An open differential has 4.

That would mean you would need to take the ring gear off of your old case and then move it over.

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[MadOgre]

I appreciate the desire to have some traction but installing aG80 gov lock into your vehicle is a complete waste of time and effort.

First because its gonna break and second because its gonna break and then you will have to do this all over again. You could simply fork out the cash for a Detroit true trac and a set up kit which gives you new bearings seals and preloads for your pinion, And be done with it the right way the first time. Not to mention that the Detroit true trac is tuff as nails and completely awesome for traction other then a full locked axle. BUT you have to set the gears up properly with new bearings or you could have issues.

 

[MadOgre]

Yep notice all the broken spider gears in that picture 77K20 posted. That's what a G80 looks like.

 

[77 K20]

I appreciate the desire to have some traction but installing aG80 gov lock into your vehicle is a complete waste of time and effort.

First because its gonna break and second because its gonna break and then you will have to do this all over again. You could simply fork out the cash for a Detroit true trac and a set up kit which gives you new bearings seals and preloads for your pinion, And be done with it the right way the first time. Not to mention that the Detroit true trac is tuff as nails and completely awesome for traction other then a full locked axle. BUT you have to set the gears up properly with new bearings or you could have issues.

A true trac would be my first option for a street driven truck. I have one in the front axle of mine. I liked it so much I was able to talk a buddy into getting one on the rear axle of his Silverado. He loves it.

Downside is they cost $200 more than a Detroit locker (Eaton no-spin)

 

[MadOgre]

A true trac would be my first option for a street driven truck. I have one in the front axle of mine. I liked it so much I was able to talk a buddy into getting one on the rear axle of his Silverado. He loves it.

Downside is they cost $200 more than a Detroit locker (Eaton no-spin)

yep gonna put one in my 14 SF next spring.

How does it feel in the front?

 

[MadOgre]

The Gear Center swears up & down its the toughest differential out there.

 

[77 K20]

yep gonna put one in my 14 SF next spring.

How does it feel in the front?

Sadly it doesn't even feel like it is there! That is a good thing... but after spending the money on it I wanted to know it was there.

It is perfectly smooth. No clunking, clicking. Doesn't inhibit turning. I have been very happy with it. The only time I wish I had a locker was once when I had a front tire up in the air- it doesn't transfer torque when the friction of the tire in air is zero. I put my foot on the brake to help, and it did a bit.

The more you use it the better the torque transfer gets also.

 

[MadOgre]

Sadly it doesn't even feel like it is there! That is a good thing... but after spending the money on it I wanted to know it was there.

It is perfectly smooth. No clunking, clicking. Doesn't inhibit turning. I have been very happy with it. The only time I wish I had a locker was once when I had a front tire up in the air- it doesn't transfer torque when the friction of the tire in air is zero. I put my foot on the brake to help, and it did a bit.

The more you use it the better the torque transfer gets also.

Crazy! Was that off road or on the street ? Cause that would be sweet if they work just fine in the front on the street.