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Recommend a front diff?

Clark75K5

Clark75K5

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Looking to replace my broken pegleg with a posi, had originally looked at the detroit truetrac but it says REAR ONLY?
Going to do a full R&R while i'm at it including R&P.

Not going to be doing any extreme offroading/rock crawling, mainly muddy logging roads and sometimes snow.
 
I'm sure many people run them up front. The part number should only be different when going between 28-spline and 30-spline applications. Where do you see "rear only"?
 
913A481 is listed as being for IFS trucks (88-03), so it wouldn't work in the front of those. Even if you have a 30-spline front 10-bolt, it might have the wrong bearing sizes. It looks like you would want 912A557 (front) or 912A556 (rear). Of course you have to know which axleshafts you have, as these parts are commonly swapped over the years.

Trutrac application.JPG
 
Chickntrk said:
If it’s a front 10 bolt my personal opinion is leave it open and add something to the back, for your intended use it’ll take you everywhere you want to go
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I'd agree if the rear isn't already G80 (Gov-lock) or some other sort of traction device.

I spend a bit of time each year on muddy/snowy logging roads, and I leave mine out of 4WD until the Gov-lock starts to lose traction. With good tires, I can go quite a ways before I need the front, which is open.

But. That said. I'd still like to experience a truetrac up front. From a few accounts however, they can lead to broken axleshafts, even when not pushed hard. Probably very condition-dependent.
 
For any desire less then a true locker up front a T/T is a great option ! Still easy on parts ( it’s all in how the extra traction is delt with ).
If you find a deal on a rear application T/T you should be able to invert the internals and still achieve the desired bias ratio in a front end application.
Something to think about…
 
Rear is definitely open and the front diff doesn't even turn the axles, (it makes a lotta noise though!) there is some carnage which I still need to inspect. The weather has not been real cooperative in the Pac NW this spring.
 
I’ve run a true-trac in my front 44 for a while now. I love it. Totally seamless and I’ve only found one scenario where it was annoying. It was on a particular was a partially snow covered road. The truck wanted to dart to the side that had traction. If the road was all snow covered it was fine.

The tru trac on rocks is pretty slick as if you have a front tire hanging in the air, you just drag the brake a little bit and that will get power to shift to the wheel on the ground. It’s pulled mine up and over stuff with the rear open.
 
Clark75K5 said:
Rear is definitely open and the front diff doesn't even turn the axles, (it makes a lotta noise though!) there is some carnage which I still need to inspect. The weather has not been real cooperative in the Pac NW this spring.
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If the front doesn't work at all, and it's definitely the differential that's the problem (as opposed to tcase or hubs) then I suppose you have a choice once you dig in. If it needs a new carrier, I'd be inclined to install a truetrac at that time. I am guessing it would still be significantly more expensive than keeping it an open diff. Truetracs are not what I consider cheap.

I'd seriously consider getting something in the rear though. I don't know how well the rear 10 bolts hold up to a truetrac, but either that, or a 14SF with a govlock. Those can be had relatively inexpensively, but they aren't just a drop in, other work will need done (perches, shocks, figure out the lug studs, etc).

Rear *really* helps being non-open. I can't emphasize that enough. It helps even on muddy roads, where you don't have to keep the speed up to make progress. You can let the axle do the work. There are a couple of spots I drive fairly regularly in the woods that are impassable with an open rear, but I can get through both with the rear locked.

Not saying "My 2wd can go anywhere a 4wd can!", just that in mild conditions, a locked rear makes a significant difference. But so will an operable front axle lol.

Hard to tell, but when dry this slough would be impassable by any 2wd car. This was 2wd.

 
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I just bought a True-Trac for the front and rear of my '88. Ordered 30-spline axles at the same time. I had to do some research to find the one recommended for the front. Even called Detroit and verified it was the right one. I'll try to find the part numbers and post them tomorrow. (It's almost 2am here now.) But it is for the front and everyone I contacted on the forums had nothing but good things to say about them. Takes a special bearing kit (8.6 vs 8.5.)
 
I purchased my Truetrac differentials from East Coast Gear Supply. I called them to verify I was ordering the right parts. I ordered GM 10-Bolt Install Kit Master $95 (GM 8.5-MIK-HD) Ordered two of those. Bearings and races are different than the 8.6". Phone number 919-672-2705.

The Truetrac's are both GM8.5"/8.6" 10-Bolt Posi (30-Spline) (I upgraded axles from 28-spline) Detroit Truetrac (GM 8.6-DET-TT) $554.99 at that time. Both boxes say the same part number which is probably East Coast Gear Supply's number, I would think.

The unit for the one I think is for the front says EatonPerformance TT70853041 on the box also . Their number is 800-328-3850.

I'd give them both a call and they'll tell you what unit fits the front. I sure hope they say the same PN or else I may be sitting on two rears or two fronts, LOL!

Hope that helps.
 
According to this video, the difference is swapping the gears from one side of the differential to the other. I think it affects whether your primary wear is on the center of the diff or the outer covers.

 
You'll love the truetrac unless you're in the rocks and your wheels come off the ground. The model number with the letter "A" at the end is the one for the front. I put a spartan lock in the front on mine and kinda wish I had just done the truetrac. Make sure you buy a gear oil with NO additives. I use Mobil Lube 80w90, it's designed for manual transmissions and is different the Mobil Gear Oil. If you're worried about your front axles, I suggest buying the spicer chromolly axles. You can update to 30 spline that way for more strength too, even though at the end of the day it's a 10 bolt. I did this in the rear of my 88', kinda wish I had done it in the front too. I'm pushing 33in tires and mine is street queen so I'm not worried about blowing any diffs.
 
jimmyleetn said:
You'll love the truetrac unless you're in the rocks and your wheels come off the ground.
Click to expand...
Huh? All you got to do is apply a small amount of brake to get the wheel in the air to lock up. The tru-trac will send power to the wheel on the ground. I was skeptical at first but I've used the technique many of times and it works.
 
ZooMad75 said:
Huh? All you got to do is apply a small amount of brake to get the wheel in the air to lock up. The tru-trac will send power to the wheel on the ground. I was skeptical at first but I've used the technique many of times and it works.
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I've never heard of this technique, but I don't have any rocks in my part of the world to climb. This just makes the truetrac that much better of an option. Thanks for the information!!!
 
Something to watch for here is when changing 28 spline to 30 up front is factory shafts all neck down to the same size between the splines and the seal so there's really no reason to change unless you're going to use an aftermarket chromoly shaft. At that point you pick up some strength and just have to decide if you stick with 28 spline and the ability to find spares more easily or go to 30 spline and have a little stronger inner shaft.
 
I must confess, I did the 30-spline for a little added strength but mainly so I can add as an upgrade since I plan on selling the truck eventually.
Stephen said:
Something to watch for here is when changing 28 spline to 30 up front is factory shafts all neck down to the same size between the splines and the seal so there's really no reason to change unless you're going to use an aftermarket chromoly shaft. At that point you pick up some strength and just have to decide if you stick with 28 spline and the ability to find spares more easily or go to 30 spline and have a little stronger inner shaft.
Click to expand...
Probably not worth the return on investment though.
 
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