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View Full Version : Minitruck Aisin hubs on FJ40 axle?


SteveH
06-25-2009, 12:29 AM
I put a set of Aisin minitruck locking hubs on my '78 FJ40. It seemed like the snap ring under the hub dial was interfering with the hub dial fitting flush against the hub body. I seem to recall hearing about this and remembered people saying that the snap ring was not critical and that it was ok to leave it off. Is this true? Am I missing something about the snap ring and hub dial? I think the FJ40 axles have more stub end than the minitruck ones, thus the interference, right?

It sure was nice having the factory service manual to figure out how to reassemble the Aisin hub, after the spline collar fell off the spring end. I never would have guessed how those went back together!

Thanks,

Steve

nuclearlemon
06-25-2009, 08:03 AM
snap ring really isn't necessary. issue might be that you're running the longer birfs. you could change to mini birfs. let me know if you need any...i've got a few.

subzali
06-25-2009, 08:19 AM
it sounds like your outer axle (birfield) is one of the long ones. What year is your FJ40? It sounds like you need to switch to a minitruck/'79 and up FJ40 birfield.

Red_Chili
06-25-2009, 08:40 AM
For gosh sakes, if you do that go Longfields. Stock minitruck birfs are marginally stronger than D30 U-joints. Which is to say... not very.

Uncle Ben
06-25-2009, 08:51 AM
snap ring really isn't necessary. issue might be that you're running the longer birfs. you could change to mini birfs. let me know if you need any...i've got a few.

If you don't run a circlip you will beat the axle seal to death! The Circlip keeps the birf located, without it it travels in and out constantly.

Air Randy
06-25-2009, 10:04 AM
To avoid the problem UB highlighted, you can use a bolt and washer on the end of the axle to keep it in place instead of a C clip.

Uncle Ben
06-25-2009, 10:05 AM
To avoid the problem UB highlighted, you can use a bolt and washer on the end of the axle to keep it in place instead of a C clip.

Tru Dat! 8mm x 1.25 I believe....

subzali
06-25-2009, 10:13 AM
but I'm still pretty sure his birfield is too long and that's the problem he's having.

SteveH
06-25-2009, 12:29 PM
Thanks for all your comments!

I'll take the cap of the hub off one more time and investigate. If I can get the clip on there, but it's not tight up against the hub, I presume you could install a washer or spacer to keep the axle from travelling in and out of the axle (laterally). That has to be the goal of the snap ring, right?

I'm puzzled as to why a bolt and washer would keep the axle in place in place of the snap ring? Wouldn't the head of the bolt ride against the hub dial? (If so, this wouldn't be a good thing). Is the washer bearing on any part of the hub?

The FJ40 axles are 6/78 production, bone stock. The truck had dealer-installed Warn M239 hubs that I removed to install these minitruck hubs, which are (I believe) from a '79-85 solid axle minitruck.

nuclearlemon
06-25-2009, 02:21 PM
the bolt washer thing works in the opposite situation, if you have mini birfs and 77-78 hubs.

you need to go to the mini birfs to get it to fit correctly.

SteveH
06-25-2009, 08:20 PM
Based on some preliminary measurements, the axle stub does slide in and out, but in the 'out' position, does not hit the Aisin hub cover. So, if I make a short spacer from steel pipe (approx. 3/8" wide with an ID of 1.25" and a wall thickness of .125"), I should be able to install the snap ring and have the axle operate as normal. This spacer will keep the axle from moving in and out of the axle housing. The fabricated spacer will essentially act as a 'thick Warn-style hub' within the confines of the Aisin hub.

I'll take pix and measurements if I can pull this off. Stay tuned.

Steve

Rzeppa
06-29-2009, 08:01 PM
For gosh sakes, if you do that go Longfields. Stock minitruck birfs are marginally stronger than D30 U-joints. Which is to say... not very.

LOL! So how strong, relative to mini truck birfs, are my coarse splined birfs?

Uncle Ben
06-29-2009, 08:27 PM
LOL! So how strong, relative to mini truck birfs, are my coarse splined birfs?

'Bout this strong... (http://www.youtube.com/watch?v=JBC2yYay4Uw)

Rzeppa
06-29-2009, 09:52 PM
'Bout this strong... (http://www.youtube.com/watch?v=JBC2yYay4Uw)

Interesting. I carry a spare but have never needed to use it. I have a whole box of spares at home, for some reason people want to give them to me in case I might need one.. :confused:

subzali
06-29-2009, 10:01 PM
Seems like a lot of work when a Warn lockout works just fine with the birfs you've got. I'd run a Warn until you break it (if ever), then do what I would call a proper Aisin installation, which involves replacing the long-style birf with a short-style birf at the same time. If you don't want to wait then just find some minitruck-style birfs (they aren't THAT expensive) and just do a front axle service. Not to be insulting, and maybe it's just me (and I'm ok with that if you want to tell me), but the pipe spacer seems a little hokey. I'm betting that you might end up shearing the lockout studs off if you try that; being unsupported for 1/8" or so, and withholding a twisting motion and all, it's probably going to end up being weaker than a Warn lockout (you're compounding the stress in other words). I don't see how you're gaining anything by doing that. I don't know how built your truck is, or the specs on it, but I wouldn't recommend it. I also disagree a little with buying Longfields, since it doesn't exactly sound like you need them (I'm running 31" MT/Rs and haven't broken a stock fine-spline birf (not surprisingly) and Zepp is running 33s on coarse spline birfs and hasn't broken one (again, not surprisingly considering the driving style - if you're conscious of stuff, within a certain tire, engine i.e. horsepower, and trail combination you'll probably be fine)). But again that's just me, we all have our opinions.

SteveH
06-30-2009, 12:53 PM
Update - the truck is stock, 2F, 4 speed, 33x9.5s. The spacer trick did not work, as the hub cap (containing the lock/unlock dial) hit the spacer before seating against the hub body. Oh well.

The Warn hubs work fine, but stick way out, and I just wanted to try the Aisins since I had them and they look cool.

All any spacer (or snap ring) would do is prevent the axle from walking in or out of the axle housing. the axle shaft only moves about 3/8" in and out, without the snap ring installed.

My question to the crowd is this: under what circumstances do LC axles tend to move in and out of the axle housing - when does this lateral force occur? While wheeling? hubs locked or unlocked? High torque? Coasting?

Has anyone shown significant seal wear on the axle oil seal due to this lateral axle travel? If the axle were travelling in and out of the axle 60 times a minute while driving, then yes - I can see the seal getting torn up. I can't see the seal getting worn prematurely due to an occasional axle shift. And all this only happens in 4WD, which is a small percent (too small!) of the time.

I'm comfortable with buying the grossly-overpriced Warn hub service kit and reinstalling my Warn hubs, if that's what makes sense. I'm just trying to understand the physics behind leaving the clip off.

Thanks all!

Steve

subzali
06-30-2009, 02:07 PM
With your long birfs, you cannot install an Aisin lockout because the lockout body is too short. Your only (real) option is the Warn lockout because the body is long enough to clear the entire birf and to install the snap ring on the end of the birf shaft. Even with the snap ring on, the birf can slide in and out 1/16" to 1/8". I don't know if there's any specific instance that will cause it to slide in and out, but the opportunity is there and it probably does happen (my guess is that, if anything, it might slide in and out when steering back and forth, but I haven't studied it close enough to know). Considering 80 series trucks (with full-time 4wd) are under power all the time and their axle seals last a long time even with the front axle always turning (and possibly moving in and out), I can only imagine that you will never see a 40 series seal go bad because of the in/out movement of the front axle.

To recap: With long-style birfs, only Warn lockout is possible. yes i know drive flanges etc. are available, but we're just discussing Warn vs. Aisin right now.

With minitruck/later 40 and 60-style birfs, Aisin lockout is possible OR Warn lockout without snap ring (but you can thread a bolt with a big washer into the end of the birf to keep it from sucking too far into the diff).

SteveH
06-30-2009, 02:31 PM
Matt - thanks for the reply - steering is one condition I hadn't considered, and you're likely right on the axle movement while steering. Another thought I had is that snap rings are not designed or intended to take a heavy load, so whatever lateral load is placed on an LC axle, it's not a huge amount.

At the moment, I have bolted the Aisin hubs completely onto my '78 factory FJ40 birfields. The Aisin hubs are fully installed over the long birfields - so it is physically possible to do so.

The only concession I made to lateral axle travel, was to install a short, 12mm head bolt into the end of the axle to keep the axle from moving out into the hub dial area. With this bolt in place, the axle can only move in and out about 1/8" - similar to the factory snap ring condition.

I drove the truck extensively yesterday with the hubs locked and unlocked, in 2H, 4H, and 4L, and no funny sounds were heard. I'm going to pull the Aisin hub covers tonight and see if the bolt heads gouged into the aluminum due to the axles sliding outward and hitting them. This 'bolt-in-the-end-of-the-axle' trick is temporary and may not be needed at all - just part of this experiment for now.

I can take and email photos if anyone would like, or post them here.

Steve

corsair23
06-30-2009, 03:18 PM
I can take and email photos if anyone would like, or post them here.

Steve

You never need to ask Steve :D - We love pictures :thumb:

subzali
06-30-2009, 04:01 PM
wait - so you can't get a c-clip on the birfield end or you don't have a c-clip to put on so you went with the bolt trick? I'm really confused, because putting an Aisin lockout on a long-style birfield goes against all common knowledge - unless I'm thinking something screwed up in my mind...:confuse2:

nuclearlemon
06-30-2009, 05:54 PM
fwiw i forgot to put one of the c clips on the 60 and ran it for a few years with no issues.

SteveH
06-30-2009, 09:09 PM
First pix shows solid axle minitruck hub fully installed on '78 stock front axle.

Second pix shows distance between the groove for the snap ring and the inner hub spline. This photo shows the bolt I put in the end of the axle shaft.

Third pix shows the hub dial cap and the faint groove worn by the bolt cap. The groove is due to the axle shaft moving in and out of the housing, and touching the hub dial cap.

In a perfect world, I would cut a new groove in the birfield, and cut about 3/8" off the end of it the birfield, and it would be shorter overall and the snap ring would do its job.

subzali
07-01-2009, 11:05 AM
Am I the only one who's never heard of anyone doing this before?

Steve, does that washer do anything to keep the birfield from sliding inward? I'm pretty sure the washer OD has to be larger than the shaft OD in order to work - but it still looks like the birf could freely move in 1/2" or more if it wanted to right?

SteveH
07-01-2009, 11:37 AM
Actually, there is no washer installed anywhere on the axle shaft. I only installed a short bolt in the end of the axle so that if the axle shaft travelled outward, the bolt head would 'bump into' the hub dial cap. So, the axle is already 'in' as far as it can go. This is why I tried to figure out a spacer (like a slice of pipe) that would allow me to run the snap ring. (However, the snap ring cannot be in place, as it hits the hub dial).

Thanks for your continued comments on this thread, Matt!

subzali
07-01-2009, 12:21 PM
As far as I know, the snap ring's purpose is to keep the axle from sliding inward as far as it might want to go. I don't know why exactly, as Ige stated there seemed to be no ill effects from not having the snap ring installed. Maybe under certain conditions the inner axle can bind the spider gears or something; I haven't thought about it enough to think of a reason why.

I would say the bolt really isn't doing anything for you; there should be no adverse effects of the axle shaft sliding out as far as it would want to go (I don't think it could ever slide far enough to disengage the differential splines).

I would still like to know if anybody else has ever seen this done before.

SteveH
07-01-2009, 12:55 PM
The bolt was simply to prevent excessive in/out travel, for which the inner axle seal was presumably not designed. I agree that the snap ring's purpose is to hold the axle 'out' - as you said. I'm going to play around more with the snap ring and see what I can learn.

PabloCruise
07-06-2009, 09:51 AM
Just to restate the obvious after joining the party late -

You have the long body birfs, used from '76-'78

You can run the Warn lockouts, or you can look for the long-body Aisin (ASCO) hubs that came on '76-'78 Pigs. They will have a silver face and dial and say ASCO vs. Aisin.

http://forum.ih8mud.com/attachment.php?attachmentid=156857&stc=1&d=1183957938

http://forum.ih8mud.com/attachment.php?attachmentid=156858&stc=1&d=1183957952

Good info here: http://forum.ih8mud.com/40-55-series-tech/127907-lock-out-101-faq.html

nakman
07-06-2009, 10:01 AM
When you guys say C-clip you're talking about the dealy-bop that goes on the 3rd member side, right? And snap ring is the doohicky for the hub side... just to be sure, since Ige mentioned leaving off a C-clip, which involves removing an inspection cover to replace, not a hub. so the c-clip keeps the thing from walking out, and the snap ring keeps the thing from walking in.. as has been stated multiple times now. ok back to lurk mode for me, carry on. :)

SteveH
07-06-2009, 12:01 PM
Righteous photo and good information - thanks. I had a set of those long-style hubs on my '76 Pig.

subzali
07-06-2009, 12:13 PM
When you guys say C-clip you're talking about the dealy-bop that goes on the 3rd member side, right? And snap ring is the doohicky for the hub side... just to be sure, since Ige mentioned leaving off a C-clip, which involves removing an inspection cover to replace, not a hub. so the c-clip keeps the thing from walking out, and the snap ring keeps the thing from walking in.. as has been stated multiple times now. ok back to lurk mode for me, carry on. :)

I guess I haven't been careful with my terminology. The front axle doesn't have a c-clip like the rear because it is a full floater and there is no inspection cover. There are two c-clips/snap rings that keep the birfield attached to the inner axle. Then there is a snap ring that goes on the end of the birfield shaft, and can only go on AFTER the hub lockout is installed (I believe). We are talking (at least I am) about this snap ring.

TJ, Steve is showing a picture of a long-body birfield with a short-body Aisin hub lockout installed. Only thing missing is the snap ring. At least that's what I think he's showing.

PabloCruise
07-06-2009, 12:33 PM
TJ, Steve is showing a picture of a long-body birfield with a short-body Aisin hub lockout installed. Only thing missing is the snap ring. At least that's what I think he's showing.

Thanks for the clarification. I was going based on this statement:

First pix shows solid axle minitruck hub fully installed on '78 stock front axle.