FAQ Converting HF2AV Transfer Case into Part Time Transfer Case (3 Viewers)

[IBCRUSN]

I wonder if I go to a part time system like this, can I get away with my stock front drive shaft instead of a dc?

While this may not be the only solution it will certainly reduce the drive-line vibration and rapidly wearing u-joints provided you don't routinely need 4WD at high speed on or off road.

Drive shaft vibration is actually one of the reasons I elected to pursue this with Beno as I have a fairly low lift ~3.5". After destroying a set of caster correction bushings I chose to install Slee's caster plates to get my caster where it needed to be. As it turns out the caster is slightly more negative than necessary for the lift height. Since I have no desire to go taller this then is an attractive option as I'm able run 36"s with nearly no rub (if only I had 5.29 and a money tree she'd be on 37"s). The ability to disconnect the front drive-line from spinning completely will alleviate the vibration and prolong the life of chromo birfs when installed.

 

[slow91fj90]

Bump TTT

 

[Pin_Head]

The ability to disconnect the front drive-line from spinning completely will alleviate the vibration and prolong the life of chromo birfs when installed.

Yes, but welding the center differential isn't going to disconnect the front drive line. It will just be permanently locked and always spin the same speed as the rear. Other than eliminating the drive line backlash contributed by the center differential and the need to push the center diff lock switch, I don't see that it accomplishes much. It is kind of like welding an ARB air locker so you don't have to push the lock switch.

 

[motorsargeT]

Yes, but welding the center differential isn't going to disconnect the front drive line. It will just be permanently locked and always spin the same speed as the rear. Other than eliminating the drive line backlash contributed by the center differential and the need to push the center diff lock switch, I don't see that it accomplishes much. It is kind of like welding an ARB air locker so you don't have to push the lock switch.

You're missing the point. This is not the same as "lincoln locking" a differential. It does disconnect the front driveline. They are removing the spider gears and welding the rear output to the case.. The case is always driven and by welding the rear output to it, the rear will always be driven. without the spider gears, the front output will not be driven AT ALL until it is locked in by the cdl actuator which actually locks the front output to the outside housing of the center differential. This gives you true 2wd/4wd. It is identical to a twin stick setup, but one "stick" is an electric actuator.

 

[alia176]

Well put.

 

[OGBeno]

IBCRUSN should have received the case today.

We'll be waiting for his posts and he does the heating/welding and gets it ready for return back for reinstall.

In the convening time period since I took the case apart, (and seeing how easy it was to take apart) I've decided that I will be taking the one installed on my rig apart and just installing the rear bits of this case, and thereby having another VC (ouch, $1300 from Toyota!!) and another rear section/ center diff that I can put back together and still having a full time case, or a core if someone else would like to do this to their rig after testing on my truck has been completed. And I will be doing some serious testing before I head out on my upcoming trips in April and the Rubithon.

 

[Pin_Head]

You're missing the point. This is not the same as "lincoln locking" a differential. It does disconnect the front driveline. They are removing the spider gears and welding the rear output to the case.. The case is always driven and by welding the rear output to it, the rear will always be driven. without the spider gears, the front output will not be driven AT ALL until it is locked in by the cdl actuator which actually locks the front output to the outside housing of the center differential. This gives you true 2wd/4wd. It is identical to a twin stick setup, but one "stick" is an electric actuator.

Thanks for the explanation. It makes sense now. The only issue might be that when the front side gear is removed there will be nothing to support the rear end of the front output shaft, so it might wobble a bit with only the front ball bearing supporting it.

 

[OGBeno]

Thanks for the explanation. It makes sense now. The only issue might be that when the front side gear is removed there will be nothing to support the rear end of the front output shaft, so it might wobble a bit with only the front ball bearing supporting it.

A spacer is installed that supports the front spider gear in place and does not allow it to fall back out or to wobble around. In the part time kits from Mark's and some other places, a machined bushing (generally brass) is installed that matches the ID of the front case where the front output shaft sits and supports the spider gear.

Anything can be used really as long as it supports the spider from moving around or falling out. IIRC, Michael at ACC used the cross shaft/locating pin and one of the thrust washers welded on upside down that fits in nicely into the front case area supporting the spider gear.

-o-

 

[Pin_Head]

A bushing sounds like a better solution than using the side gear as a support because where the side gear shaft rides in the carrier is a steel-steel contact and is not designed as continuous high speed bearing surface.

 

[OGBeno]

A bushing sounds like a better solution than using the side gear as a support because where the side gear shaft rides in the carrier is a steel-steel contact and is not designed as continuous high speed bearing surface.

I like the idea of a bushing as well. Any competant machinist should be able to machine something pretty easily. I piece of brass pipe could work as well as long as the OD of the pipe piece and the ID of the front case were reasonably close in tolerance, but yeah, to do this correctly a nicely machined bushing would be ideal. IBCRUSN and I will talk about this and see what we come up with.

Thanks for the suggestion.

 

[Pin_Head]

I am partial to needle bearings, but this would require machining of both the shaft and the housing. This would not be hard if you have a lathe. A bushing would possibly have enough friction to cause the front shaft to spin with the front unlocked.

 

[IBCRUSN]

A bushing sounds like a better solution than using the side gear as a support because where the side gear shaft rides in the carrier is a steel-steel contact and is not designed as continuous high speed bearing surface.

There is actually some sort of a metal alloy bearing in the case halves (feels like aluminum) that supports the front and rear side gears in addition to the needle bearing. Thee is also a thrust washer with holes which allows for oiling of the bearing and thrust washer bearing surfaces on the gear and case half.

With regard to the bushing or ??? to maintain spline engagement I'll need to look over the FSM to see what the potential speed differences could be. My knee jerk feeling is there will be little to zero because as MotorsargeT mentioned the front output will not normally be engaged and will only be along for the ride i.e. freewheeling and once engaged will rotate at the same rate as the rear (locked).

We'll see, I'll take a closer look tomorrow and see what we can get accomplished.

Here's a useless fact...the front & rear side gear splines are the same as the 30 splines on the birf outer.

 

[Pin_Head]

My knee jerk feeling is there will be little to zero because as MotorsargeT mentioned the front output will not normally be engaged and will only be along for the ride i.e. freewheeling and once engaged will rotate at the same rate as the rear (locked).
.

If the idea is to disconnect the front drive shaft so that it won't be spinning and wear Longfields, then the front shaft will be stopped, while the carrier rotates at the same speed as the drive shaft or about 2,000 RPM at cruising speed.

 

[motorsargeT]

If the idea is to disconnect the front drive shaft so that it won't be spinning and wear Longfields, then the front shaft will be stopped, while the carrier rotates at the same speed as the drive shaft or about 2,000 RPM at cruising speed.

Exactly. There will be some drag applied to the front output shaft due to gear oil viscosity and shearing, but effectively it is not moving while the carrier is. the spacer would need to tolerate some difference in speed where it touches the front gear, but there is almost no force against it. It is only there to keep the front gear from falling out.

 

[alia176]

The spacer that's attached to my spool seems to be made of UHMW or something similar. I don't if this helps or not!

 

[OGBeno]

The spacer that's attached to my spool seems to be made of UHMW or something similar. I don't if this helps or not!

Did you do a test fitment before installing permanently? Do you remember if the Oz spacer pressed against the front side gear in the front case?

Thanks.

 

[silverhorse]

Seems that the size of that spacer/bushing would be crusial to the longevity of this modification.

 

[OGBeno]

Seems that the size of that spacer/bushing would be crusial to the longevity of this modification.

Possibly.

Since I contacted a few MUD vendors with some questions about doing this mod (none of them returned any of my PM's ), I am not sure how important a spacer is going to be in making sure this works well, or, how important a professional spacer is in making this work as opposed to a shade tree concoction.

Again, the goal of this mod. is for a shade tree to be able to do it in their home or with the help of a welder/machinist.

Once IBCRUSN has some work done on his end and when I get the case back and install it, I think we'll be able to tell exactly how important the spacer is.

I do know that "denis" on MUD did this to his diesel 80 series and from his accounts to me all is well in his xfer case and he is--from all indications--hardcore shade tree.

 

[OGBeno]

Well, while I wait on IBCRUSN's results, with the expert guidance of a local NM club member (DanS HJ-45), we sandblasted, powercoated and rebuilt a set of FJ60 Aisin hubs. They were in good shape originally when I bought them off of MUD and they came out looking beautiful.

I really love the Aisin's and wish I had more funds so that I could purchase the correct flange style ones for the 80 series hub, but alas, the FJ60 ones will have to do for this application.

Anyway, onto the pics!

First pic of the hub knobs/rings sandblasted. I really love sandblasters. I want one of my own!

Pics of the them getting powdercoated and then coming out of the oven. Dee-licious!!

Next we start rebuilding the parts. These pics will be in order in terms of how Dan showed me the correct process for doing these. It was not as hard as I thought this would be. In fact, it was down right simple once you saw how everything was fit together. Nice and smooth.

And the final, awesome-o-city results: Totally epic:

Thanks to DanS HJ-45 for the guidance and assistance with the process. The FSM was not as clear as Dan was and now I feel significantly more confidant in being able to do a set of my own.

Anyway, that's about all from Aisin hub land.

Best.
-onur

EDIT: I've also added the FSM pages from the HZJ80 manual on rebuilding hubs/components as a reference. Looking back on the work that Dan and I did yesterday, I think we pretty much followed the FSM, though Dan's expertise allowed better explanation of how pieces fit together especially orientation.

 

[silverhorse]

Maybe Denny at Marks4wd can enlighten us, on the spacer. Beautiful work on the hubs, BTW