Free play in freewheeling hubs

Submitted: Tuesday, Oct 15, 2013 at 06:27
ThreadID: 104720 Views:1435 Replies:4 FollowUps:1
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Hi all,

I've just had the transmission in my troopy rebuilt as well as changing the diff centres myself. (Detroit locker in the back and trutrack in the front)
The transmission is an auto out of an 80 series cruiser.

Since then I've noticed a harsh clunk when coming off the throttle suddenly and getting back on it.

I figured it was due to freeplay some where in the driveline. After having all that work done it was little more difficult to pin point the cause.

I got under the car and noticed there is a lot of freeplay in the front prop shaft. After removing it I confirmed it was neither from the transfer or diff.

Because its now constant 4x4 with the cruiser box the front hubs always need to be locked. I removed the front flange off one of the hubs and there is no free play between it and the axle but rather the big splines between the two halves of the freewheeling hub.

The auto box has been in there for about 200k so the drive has been transmitted through the hubs the whole time. When the hubs are unlocked the freeplay in the driveline disappears. I'm guessing they weren't really designed for this and that they have become worn overtime contributing to the freeplay in the front of the drive line.


Before I hit up eBay and get some new hubs I just wanted to ask if anyone has had similar problems with worn hubs creating excessive freeplay. Or if there is maybe something I've overlooked.

Thanks lads.
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Reply By: Ozhumvee - Tuesday, Oct 15, 2013 at 10:50

Tuesday, Oct 15, 2013 at 10:50
You would be better to fit the solid drive flanges like the 80 has and give the FWH the flick.
Peter
1996 Oka Motorhome

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AnswerID: 519724

Reply By: Mudripper - Tuesday, Oct 15, 2013 at 12:43

Tuesday, Oct 15, 2013 at 12:43
I'll go with Peter on this one. One of the advantages with FWH however, is that you have the ability to disconnect the drive to the wheel if you happen to snap a CV. I did this once in the bush and instead of the shaft shearing, the CV bell housing section exploded and would have chewed out that entire section of the front axle housing, had I not had FWH to disconnect it. So FWH do have their place obviously. Particularly seeing that you have lockers. It's quite easy to snap genuine Toyota CV's, especially if running larger diameter tyres.

Anyway, back to the point. Your's being a full time 4WD, I would say to go with something like this: Drive Flange

Not sure if that's the right one for your model but I think most of the 40, 60,70 and 80 series front hubs are the same. I'm happy to be corrected on that however.

Good luck!

Cheers,

Tim.
AnswerID: 519727

Reply By: pop2jocem - Tuesday, Oct 15, 2013 at 13:11

Tuesday, Oct 15, 2013 at 13:11
Running a constant 4WD transfer case with free wheeling hubs disconnected will obviously require the centre diff to be locked continuously. With normal open centre front and the standard (read useless) LSD rear should be no problem but with a Detroit in the rear and a Tru track in the front I wonder if driveline problems may surface further down the track. Maybe as has been suggested fit the front drive flanges from a 60 or 80 and carry the FWH's as backup in case of a CV failure to disconnect that side.

Cheers
Pop
AnswerID: 519728

Reply By: Ross M - Tuesday, Oct 15, 2013 at 13:21

Tuesday, Oct 15, 2013 at 13:21
rb30e
If you have a front and back locker AND you are using a centre diff then the action of the front and rear shafts will be different than with the use of open diffs.

As you turn, the rate of rotation speed required will suddenly drop to the relative speed of the inside wheel of the turn. If normal diffs, the rotational speed is an average of the rotation rate of both inner and outer wheels. With lockers the inner wheels drive on a turn and the "outers" ratchet over.

With two lockers there is two sets of ratchet mechanisms and they will have some slop in addition to the crownwheel backlash. As you mentioned, the FWH may contribute to the slack but they are usually fairly close in their spline drive sections, both on the shaft and in the sliding collar.

My view is, it is more likely to be the front locker ratchet/crownwheel back;ash is what is felt although all slack will be additive in the driveline. The centre diff will have two sources of slack as well.

Ross M
AnswerID: 519729

Follow Up By: rb30e - Tuesday, Oct 15, 2013 at 15:44

Tuesday, Oct 15, 2013 at 15:44
Thanks all for the prompt and helpful feedback

I've just requested a quote for the 80 series axle drive flange and end cap off Toyota. Can get parts at bulk pricing so not much point going non genuine.

I Can see the advantages of having both setups, our troopy is more set up for touring than hardcore bush bashing and only fitted with 265/75/16 so nothing to OTT in the tire department.

Regarding the slop in the driveline the rear with the Detroit locker is actually pretty tight. The front diff is a trutrack setup which isn't actually a locking diff more so an LSD with worm gear setup rather than clutch plates or cones. It does not operate in a ratchet fashion like the Detroit locker.

I determined it was in the freewheeling hubs after removing the prop shaft and checking the backlash in the transfer which was minimal then the backlash in the front diff by removing the centre section of the freewheeling. Hub so that I could watch the axle end while turning the pinion flange. Virtually no slop in both the diff and the cv splines. Once the freewheeling hub is reasembled you can feel the slop between turning the pinion flange and waiting for some movement in the wheels. Once again if the freewheeling hubs are unlocked there is no slop felt because the hubs are no longer engaged and transmitting drive to the wheels.

Regarding running the vehicle in 2wd with the hubs unlocked and the centre diff locked. Drive will still be transmitted through the front diff and to the axels just not from the axle to the wheel. I don't really like the idea of running the front driveline like this without any load for extended periods.

I think one other advantage to having the FWH is its a good anti theft device as we are doing round the world trip in the troopy. Leaving one or both unlocked and with the transfer case in neutral and a hidden kill switch would probably be enough to confuse any half bit theif.
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FollowupID: 799979

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