80 series xcess backlash in centre diff or clutch

Submitted: Saturday, Jan 14, 2006 at 08:03
ThreadID: 29681 Views:12121 Replies:8 FollowUps:3
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Hi all,

I have a 1991 turbo diesel 80 series cruiser with 280,000 on the clock.
There has been a clunk under the centre of the vehicle for some time. It has developed gradually (over years not days or weeks). It is almost exactly the same as when a diff has excessive backlash. All uni joints and splines are O.K.

It is quite difficult to take off smoothly and to change gears smoothly and reminds me of a performance vehicle I owned years ago with a racing clutch. It is either engaged or disengaged, there is not much in between.

Anyway my first thoughts were that there is something wrong with the centre diff but my best mate, who is a very good mechanic, has driven it and swears that it is the springs in my clutch plate. My cruiser has done a lot of heavy towing and he says the springs have lost their sprung and must be rattling inside the clutch plate and so when you go to engage the clutch the slack is taken up quicly before the springs do their job.

Does this make sense to anyone else?
If the centre diff plays up will it give this type of symptom?
Is is common to have problems with the centre diff in an 80 series?

Your input will be appreciated as I am sure both jobs will not be cheap so I would like to get the diagnosis correct the first time.

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Reply By: Member - Alan H (QLD) - Saturday, Jan 14, 2006 at 08:34

Saturday, Jan 14, 2006 at 08:34
My 1994 80 series with 270 on the clock has excessive backlash.

It seems to have been there forever and I have got used to it and passed it off as inherent to having the three diffs. I think it has slightly got worse over the years and this may be wear over this time.

The clutch has the usual 80 series shudder. The clutch is original and I tow a trailer on most trips.
AnswerID: 148479

Reply By: Ian from Thermoguard Instruments - Saturday, Jan 14, 2006 at 08:52

Saturday, Jan 14, 2006 at 08:52
Hi Brett,

AFAIK, 'clunky' diffs are usually due to excessive crown-wheel to pinion backlash, rather than lash in the differential gear cluster. And, of course, the centre diff has no crown-wheel and pinion.

At 280,000km, I'd say you've well and truly had your money's worth out of that clutch. Why not drop the transmission to replace the clutch plate (and pressure plate and bearing, while you're at it) and, if the old clutch plate DOESN'T have shot springs, then have a think about delving into the transfer box.

By the way, you say the uni joints and splines are OK, but have you checked how much backlash you have in the front and rear diff pinion shafts? Also, remember that after 280,000km, all the splines and gears in the clutch, gearbox, transfer box, prop shafts, both diffs and axles will have worn to some extent - maybe it's just the cumulative total adding up?
AnswerID: 148484

Reply By: STEVE069 - Saturday, Jan 14, 2006 at 11:06

Saturday, Jan 14, 2006 at 11:06
Hi Big Woody have you checked the front drive flanges and CV splines?
AnswerID: 148504

Follow Up By: Member - DOZER- Saturday, Jan 14, 2006 at 14:13

Saturday, Jan 14, 2006 at 14:13
The clunk is heard at the centre diff, but the reason for it is usually worn c/v joints and /or drive flanges. If yours are 280000kms old, you will be able to rock the front drive shaft twice as much as the rear, hence the centre diff has to differenciate for this whenever you back off or power on. Real hard to change gears without clunking the box....
Now, the clutch may be another issue....if your saying you have no inbetween on and off or it shudders etc etc, then it is worth having a look, but id start with the 4 wheels off the ground and move each driveshaft with transfer in neutral.
Its also a good idea to get someone to rock the cruiser when its on all 4 while you look at each uni.....sometimes they can feel ok, but rocking the car will soon show up movement.
FollowupID: 401765

Reply By: 120scruiser - Saturday, Jan 14, 2006 at 11:28

Saturday, Jan 14, 2006 at 11:28
Hi big woody
Most of the early 80 series clutches only had a damper rubber in it and no spring.
My 8/92 80 series only had this and when I removed the clutch the damper rubbers were totally gone. I put a new daiken clutch in and had nothing but noises so after 12 months pulled it out and put a genuine toyota clutch in.
With the toyota clutch the rattles were gone and there was smooth engagment of the clutch again.
If you put yours in 1st gear and then slowly take off and let it idle along in first, see if you have a rumbling sound around the gearbox especially in low range. If you do you need a new clutch. The worst thing is the clutch friction surface is probably fine but the dampers will be gone. The 1hz series of engines puts out alot of engine vibration and the clutch soaks this all up and totally destroys the dampers.
The new clutch that goes in from toyota still has the rubber dampers but they have also installed a damper spring which should make it more tolerable.

Bear in mind that if you have a little bit of wear in the rear diff, a little bit in the transfer case, a little bit in the centre diff, a little bit in the front diff, a little bit in the drive shafts, a little bit in the front hubs it all adds up. There may be no excessive backlash in any one part but you may have little bits in several parts. This is normal for an 80 and the problem is where do you start to rectify it. If you wanted to rectify all the little bits you would be up for thousands.
I have always said it takes 100 000 km to learn to drive an 80 series gently.
My recommendations would be to put a new genuine clutch in and you will find it will be significantly better.
AnswerID: 148505

Follow Up By: Big Woody - Saturday, Jan 14, 2006 at 17:28

Saturday, Jan 14, 2006 at 17:28
Hi 120scruiser,

You have pinpointed it exactly. When I idle in and out of my long driveway I have exactly thae rumbling sound that you are talking about. Others above are steering me to the front swivel hubs and CV's but all of these were rebuilt about 500 km's ago.
The clutch doesn't slip or shudder, but it is very sensitive.
I think I will will get a genuine Toyota clutch, pressure plate and thrust bearing and fit them in the next few weeks. I will let you know how I go.

Thanks mate,
FollowupID: 401785

Follow Up By: 120scruiser - Sunday, Jan 15, 2006 at 09:52

Sunday, Jan 15, 2006 at 09:52
When the dampers get really bad you can hear an audible clunk when you are starting the engine and it just fires up. That is the dampers taking up the slack.
An engine if slowed right down actually vibrates backwards and forwards. This is due to one cylinder being up on compression so the compression is forcing it down. Combine this with valve spring compression and it all adds up. The 1hz is very noticable and thats why it is hard on manuals and clutch's.
A perfectly balanced engine is a V10. I used to drive a V10 Mercedese Benz truck and when you walked in front of it while it was idling you could hardly here it purring.
The 100 series doesn't seem to be as bad on clutch's, I haven't invesitgated to see if they use a different harmonic balancer or not.
Glad to be of assistance.
FollowupID: 401877

Reply By: streeter - Saturday, Jan 14, 2006 at 15:55

Saturday, Jan 14, 2006 at 15:55
big woody
had the same in my 93 i changed the clutch which it needed doing any way but noise and backlash was still their put new swivel hubs and cv joints in and its now running smooth as a babys bum and now clunking
AnswerID: 148539

Reply By: streeter - Saturday, Jan 14, 2006 at 15:57

Saturday, Jan 14, 2006 at 15:57
oops should read no clunking
AnswerID: 148540

Reply By: Billowaggi - Saturday, Jan 14, 2006 at 23:03

Saturday, Jan 14, 2006 at 23:03
Hi All , as said above the clunk is not just the centre diff but accumulated wear throughout the entire drive train front and rear it is usual in high k constant 4x4's [take an old Range Rover for a spin sometime!.]
Regards Ken.
AnswerID: 148626

Reply By: udm - Sunday, Jan 15, 2006 at 14:52

Sunday, Jan 15, 2006 at 14:52
We have 2 80´s, they both had the same problem, it´s gotta do with worn splines in front diff/front axles/front wheel flanges and worn cv´s. Did I forget something lol?

AnswerID: 148749

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