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Rear Diff Howl Problem

MarkW

Well-Known Member
Joined
Aug 20, 2014
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2,248
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morocco
Hi All,

I'm after some advice from all you useful knowledgable people

During my last trip to the Western Sahara my 95 developed a howling noise above 30mph. It's only apparent when the transmission is under load. My regular mechanic has had a look and identified play in the rear diff where the propshaft mounts. He doesn't have much experience with diff repairs so won't take on any repairs.

What are peoples verdicts on the cause of the howling and are there any recommendations for sourcing a replacement diff or repair places in the south west?
 
I think a small bit of play (rotational movement) is normal. Mine certainly has a small amount, but no howls. Quiet as a mouse in fact. Are you certain it's coming from the diff? I don't know that much about them, but apart from the lsd becoming inactive, I think they're pretty strong
 
If you grab the prop there's vertical play in the diff not just the rotational slack.

I had the whole axle off last summer to get repaired and also put a new diff actuator on. No noise until we started heading north out of the Western Sahara then it got progressively worse. I did use the locker a couple of times in soft sand to tow a friend but nothing else other than normal driving. No grinding noises just a howl when under throttle, when you let off the noise goes so seems to be when the transmission is under load
 
It sounds as though your drive pinion bearing is on the way out.

When diffs are assembled the clearances around the crown wheel and pinion are critical if it is to run quietly. The builder will (should) check the contact points on the helical teeth with 'Engineers' Blue' and adjust the shimming until the pinion teeth are contacting the crown wheel teeth in the right place.

When the pinion bearing goes this alignment is lost and you start to get incorrect contact and noise.

You should draw the half shafts and then undo the diff assembly as one unit. A specialist shop should be able to fit new bearings and shim it properly for you.

If you ignore it you will damage the teeth which will be expensive to repair (or require an exchange unit).

If you are going back to the Sahara (or similar trip) I would avoid a diff from a breaker as you won't know its history and could just land yourself in trouble :icon-wink:.

Bob.
 
Thanks Bob, that's what I was suspecting. Now I need to find somewhere to do the work darkest Dorset is where home is and my mechanic couldn't recommend anywhere local
 
My Hilux used to howl too, which I believe stemmed from getting a bit of water inside the diff. I had the mechanic strip it down, and his analysis was the hard facing on the crownwheel was wearing. He suggested replacing it, but we decided to only replace the bearings and see how it went.

The howl was still there, and I had forked out a fair bit of cash to achieve nothing. If it is the crown wheel they will go for a long time without any issues, but if you are going to strip it all down its probably worth replying (if its damaged)

Aaron
 
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this howl is load enough to drown out conversation at 60mph lol. I'm hoping its only bearings only got 5 weeks before the next Morocco Trip to sort it out. Found a local gearbox specialist so as I have a day off on Friday drive over a see what they say
 
Assume you checked the oil level and condition of oil in he diff?

Exhaust system can also howl

If you remove rear prop and lock centre diff, to give drive to front axle, does it still howl?


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Checked the oil when I started to happen all looked ok and no obvious leaks. I haven't tried taking the propshaft off I hope my mechanic tried this when he diagnosed the diff as the source.

I'll try the local transmission place this afternoon and I spoke to a place near work yesterday who said about £380 to refurb the diff. They've been recommended by a colleague so I have two options
 
Local transmission place was all shut on Friday :( So plan b is to take the diff off and take it in to the place near work. Just took it for a spin with no rear drive shaft and the noise is gone pointing to diff problems, oil level was fine and looks in good condition.

Better get working
 
i have rebuilt a few hilux diffs, and your spending the best part of 200 quid on genuine bearings and crush washer, pinion seal ant the like, so 200 quid labour, thats pretty good, cus they can take from 2 to 5 hours to do well depending on how it all goes,
 
Diff's off no sign of any problems on the gears, oils a bit dark but doesn't look like there's been any water ingress
 
noise either on or off load will be pinion bearings, usually but not always the smaller outer one nearest the prop flange as some one said it allows the pinion to move about making it not mesh against the crown wheel properly,
on the hilux the seal leaks some one changes it, doesnt set the crush washer/pinion preload the bearings run loose and feck it all up,

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Update - Took the diff into Bexhill Gearboxes close to work and they've rebuilt it after diagnosing bearings. Grand total of £350 and turned it round inside a week. The diff is back on but not driven yet as I have no MOT- I'll give it a quick spin this afternoon down a private road but should be sorted.

Whilst doing the diff I fitted a new tripod bearing on the uj greased the prop shaft up, replaced most of the studs on the diff except the 2 medium length studs. All in a productive weekend and I think except some bushes and wheel bearings I've pretty much overhauled to whole axle over the last year
 
i would say thats a very reasonable charge for a diff rebuild, sounds like he only charged you 2/5 hours labour
typically the ones i have rebuilt have cost upto 200 in parts alone altho there genuine toyo, bearings
 
just took it for a quick spin down the lane all seems ok, diff lock engaging properly. MOT tomorrow
 
Ok so flew through the MOT but haven't really driven it until this weekend and I'm still getting some noise. Nowhere near as bad a before but still there. It might be I'm just being paranoid and the noise is normal but I'm noticing it more because of the previous issue. The play in the pinion is gone but it just seems a little louder than I remember.

Only a week and a bit before I leave so no time to get anything major done now
 
The play in the pinion is gone but it just seems a little louder than I remember.

Only a week and a bit before I leave so no time to get anything major done now

What tyres are you using ??

If they are a 'knobbly-type' it may just be road noise you are hearing now.

(My life is never that simple - but you never know . . ) :think:.

Bob.
 
BFG AT's it could well just be me being overly paranoid ahead of this years Morocco trip. I honestly can't remember what it sounded like before I had the noise so not 100% its loader or not
 
well I spoke to the chap who repaired the diff, he said no damage or wear to the gears and they changed the bearings. Also did a bit of asking round and they gearbox plce is well though of and gave no reason to doubt anything they said or did. They asked me to take the truck in for a roadtest, which isn't that easy as its 170miles away at home. So I'll have to bring it up on Monday for them to check. Only 4 days before I catch the ferry :pray: not much time for any repairs if there's anything wrong.

Also heard theres big flooding in Morocco over the weekend closing some routes I was planning :(
 
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