Using a thrust block in the front diff? (1 Viewer)

[RredFJ40]

Yes, I know I don't need it but....

Putting a rear third in the front and wondering if I can leave the thrust block on the pinion shaft? My thinking is that this would allow the axle shafts to not drop into the differential if I don't put inner birf circlips on (or outer clips at the hub, too?). This would effectively accomplish the same result as a Martack, right?

I'm going to go try it and see how it works, I'll post up a result.

 

[RredFJ40]

So far it seems like it works. Though the thrust block has 2 flat and 2 curved sides, so hopefully the axle shafts are sitting on the flats.

The inner shafts don't drop away from the outer shafts and both won't drop in from the hub splines.

 

[GLTHFJ60]

That's a good idea right there.

You'll want to keep the outer snap ring on the birfield stub shaft so that it can't drop into the knuckle ball and tear it up, but this thrust block idea should be more or less equivalent to a Martack.

 

[RredFJ40]

That's a good idea right there.

You'll want to keep the outer snap ring on the birfield stub shaft so that it can't drop into the knuckle ball and tear it up, but this thrust block idea should be more or less equivalent to a Martack.

Actually, the inboard snap ring on the inner axle will keep the birfield from going inboard too far. This whole setup allows you to remove the lockout hub as one unit, the birf by itself incase of a break, and easy removal of an inner stub if the inner breaks the splines off in the birf.

 

[GLTHFJ60]

Actually, the inboard snap ring on the inner axle will keep the birfield from going inboard too far. This whole setup allows you to remove the lockout hub as one unit, the birf by itself incase of a break, and easy removal of an inner stub if the inner breaks the splines off in the birf.

No, the Martack is there so that you do not have the snap ring on the inner axle, because it's a PITA to take out and install. What you're getting at is that you don't want to take off the snap ring on the birfield stub shaft. That one is easy, super easy. I didn't understand that before.

If you want to pull everything as one unit then skip the hub all together. Pull the face off, take off the snap ring, then pull the knuckle caps and pull the whole thing out off of the axle.

 

[RredFJ40]

No, the Martack is there so that you do not have the snap ring on the inner axle, because it's a PITA to take out and install. What you're getting at is that you don't want to take off the snap ring on the birfield stub shaft. That one is easy, super easy. I didn't understand that before.

If you want to pull everything as one unit then skip the hub all together. Pull the face off, take off the snap ring, then pull the knuckle caps and pull the whole thing out off of the axle.

I completely understand what the Martack is for (as evidenced by my previous posts) You really think it would be easier to pull the trunnion caps and wiper seals and tie-rod end and taking the entire knuckle, disc, and hub? Is that what you are saying? I think we're having some miscommunication here. Try rereading my last post. There are three snap rings to deal with, the one I keep is the INBOARD inner axle ring (which is OUTSIDE of the birfield inner cage).

 

[GLTHFJ60]

Yes, I do think that if you need to replace your birfield on the trail, that it is easier, and takes less time, to take off the knuckle caps, steering arms, wipers and calipers instead of completely disassembling the hub assembly. You don't have to remove the tie-rods because they're bolted to the steering arms. I've done it both ways, definitely prefer the entire knuckle removal method.

I always forget about the second snap ring on the inner axle shaft, since it never, ever, has to come off. We're on the same page now. FYI, your first post said you were removing "the snap rings", so I must have missed that you were keeping one.

I would imagine that you're good to go with your current setup. Go wheel a bit, take her apart and then see if you have any marring on the birfield, which would indicate that it is contacting the knuckle ball on the housing.


Finally, no reason to be a dick, just trying to understand what you're doing so I can answer your question

 

[RredFJ40]

Hmmm, didn't think I was being a dick by trying to clarify. I've run a Martack and no stub shaft snap ring for the past few years. I was just checking to see if anyone had any thoughts on using a thrust block for the same purpose.

Thanks for chiming in, especially since no one but you or I apparently care!

 

[jcj_78FJ40]

Actually, the inboard snap ring on the inner axle will keep the birfield from going inboard too far. This whole setup allows you to remove the lockout hub as one unit, the birf by itself incase of a break, and easy removal of an inner stub if the inner breaks the splines off in the birf.

You want to remove the inboard snap ring which is way more of a PIA than the one on the outer shaft.

With that said, I used to run the thrust block in the front of my 40 with a semi float ARB.

My advice would be to install the thrust block then the axle w/out the birf. Push the axle all the way in. If the machined surface doesn't go past the Axel seal then your good.

 

[GLTHFJ60]

You want to remove the inboard snap ring which is way more of a PIA than the one on the outer shaft.

With that said, I used to run the thrust block in the front of my 40 with a semi float ARB.

My advice would be to install the thrust block then the axle w/out the birf. Push the axle all the way in. If the machined surface doesn't go past the Axel seal then your good.

That's a good test right there. Good idea

 

[lcwizard]

I'd have to investigate ...the axle will only slide in until the splines hit bottom on the side gear. When i have custom shafts built I always minimize the spline length for that reason... as a backup safety measure. I guess you could also put a Martack on the inner spline also. Marlin's Martack is basically just another way of minimizing spline length

 

[woytovich]

Are you all talking about 55, 56 and the one at the red arrow?

 

[GLTHFJ60]

Yes @woytovich. Running without snap rings makes disassembly a little easier.

 

[woytovich]

Meaning disassembly of the shaft to the birfield... right? And meaning just 55 & 56... as the red arrow clip is easy-peasy to remove... right?

 

[jcj_78FJ40]

Just 55.
Quote:http://www.4crawler.com/4x4/CheapTricks/AxleRebuild.shtml#Martack
Note:
Where did the term MarTack come from, you might ask? Marlin (of Marlin Crawler fame) was one of the first people to come up with the idea of using small tack welds on the inner end of the axle to replace the function of the little C-clip that normally holds the outer end of the axle inside the Birfield joint. This makes train repairs of broken Birfields easier, since you can carry only the joint and you avoid the need to hammer or pound the broken Birf off the inner axle.