Bizarre clonk / jolt from the front end of Fiery!!!

[sae70]

Hi there Bob

Yes with all four wheels/tyres on the ground

Perhaps I was not so clear

Forgetting all of the other possible causes of the clonk that I feel I've eliminated so far bushes, CV's, bearings, UJ's etc.

When she is sat with the gearbox in Neutral & the transfer box in 4H (normal everyday tarmac driving position) & all four tyres are in contact with the ground it is not possible to turn the rear prop shaft more than perhaps a twentieth of one whole turn back & fourth, maybe even less. I would consider this to be the norm. As you say Bob with the gearbox in Neutral it is the back lash in the diff that's the limiting factor only allowing such a small amount of rotation in the rear prop shaft. Fierys front prop on the other hand, has a little over a quarter of a turn of rotation in it before something limits the rotation Now when I put Fiery into first gear with the transfer box still in 4H I then get only as much play in the front prop as I do the rear before putting her into gear.

Does this make better sense

In my head this points more towards a fault with the diff than the transfer-box/gearbox, what do you think

I really need to get that darn drain plug out & see if there are any teeth stuck to it

 

[BobMurphy]

In my head this points more towards a fault with the diff than the transfer-box/gearbox, what do you think

That's just as I thought.

I would drop one end of the front propshaft and see just how much play there is in the front diff/CVs (I.E. remove the transfer box from the equation).

Then jack each front wheel off the ground in turn and examine the backlash between each wheel and the diff's companion flange (with the other wheel on the ground). It must be possible to grip something to determine if the play (if any) is in the diff or CV joints - you may have to slip back the inner rubber boot to stop back-lash in the drive shaft(s).

Its unlikely to be the transfer box, unless you've been driving around with the centre diff locked (but then the problem would be more constant if the centre diff has broken).

Interesting one, this


Bob.

 

[Chris]

Maybe the hamster has just fallen off his wheel inside the diff with all the jolting that he got last weekend Steve.

C

 

[Bounder]

What happened with my diff was as the front bearing collapsed, the pinion actually bent. Badly.
This locked the whole diff up.
If your bearing is just slightly bad and the pinion is just a little bent as it turns the teeth contact the ring gear and make the car jump.
Unlikely your pinion will look as bad as mine, mine was damaged by heat as well at motorway speeds.

IMG_0436 by Spearo, on Flickr

IMG_0435 by Spearo, on Flickr
Hopefully your sump plug looks better than mine.

IMG_0426 by Spearo, on Flickr

 

[sae70]

Bloody hell That's a mess

The thing with mine is it isn't jumping all of the time In fact so long as I'm easy on the power & driving in a straight line no problems in the most part, but put down some power & clonk-knock, jolt Put some steering either way into the equation, especially @ low speed & clonk-knock, jolt....clonk-knock, jolt....clonk-knock, jolt.... If it does turn out to be the front diff it's acting as if there is something wrong with the planet/sun gears & it's as the outer whell rotate more than the inner maybe

I'm not totally up on how a diff works but the noise & jolt are far more prevalent when turning & more so when turning right

 

[Andrew Prince]

I feel I've eliminated so far bushes, CV's, bearings, UJ's etc.

Sorry, Steven, I know you say you've ruled out the CVs and bushes but have you really? The more you describe, the more it sounds to me like a knackered bush (with the usual caveat of the unreliability of internet diagnosis - we can only try and guess based on what you describe). If you haven't done so already, I think you should take off both ARBs and properly inspect the bushes. I.e. hold them in your hand, not prodding with a screwdriver while it's still fitted to the truck - you haven't described how you inspected them? It could even be a bush on the rear ARB causing these symptoms as the suspension loads on the left when turning right. Particularly as the unsprung weight of the live rear axle is much greater than the front.
Removing the front struts, control arms etc to check the bushes may be too much of a PITA to do but how else are you going to categorically rule these out? Yes you can stick a crowbar in and test for excess play but you need to know what you're doing (I.e. I would not be confident of my ability to determine excess play this way )

I think you should rule out the CV and bush possibilities (check anti-roll bar bushes too!) first Work your way from easy to hard....

Likewise you might only be able to properly inspect the CVs when they're off the truck. I appreciate that this is a lot of work on an IFS. You could take it in to a CV specialist who might be able to better check the CVs while still on the truck. I am not convinced that a tug here and there and a visual inspection of the boots is giving you the definitive answer - of course you might be a CV expert, in which case I take my words back

Have you opened the diff drain yet? Obviously any big shards of steel will be a giveaway as per Bounder's catastrophe.. Fingers crossed it's not that!

Of course the 90s experts' advice should supercede mine - just trying to help!

 

[BobMurphy]

so long as I'm easy on the power & driving in a straight line no problems in the most part, but put down some power & clonk-knock, jolt Put some steering either way into the equation, especially @ low speed & clonk-knock, jolt....clonk-knock, jolt....clonk-knock, jolt....

Can you tell (or hear) if the noise is coming from the front (axle) or underneath (transfer box) ??

Not easy, I'm sure, as the propshaft will probably transmit the noise as well.

If you lock the centre diff (only briefly) the diff should lock-up and the drive will be straight to the rear axle. The planet gears should then lock the planet carrier and drive the front axle as well. If the planet gear teeth are damaged and are causing the clonking noise they should still lock and any noise from that source should cease.

If the planet gears/planet carrier are totally shot the front axle will still turn independantly - but then you wouldn't get any drive with the diff open, so we know it isn't that .

Keep poking and let us know what you find

Bob.

 

[Cabman]

im going for cv

 

[Bounder]

I agree with Cabman, CV sounds most likely. Hopefully its not the diff.
Thing is, changing the front diff isn't actually that hard, its just time consuming and awkward.
I am going to run fully synthetic diff oils next service, The front especially is marginally lubricated considering the work it does, and the heat it has to put up with.
It has about 1/3rd the capacity of oil as the back diff....

 

[sae70]

I do hear what you are all saying with regards to bushes, CV's, UJ's etc And maybe I should have been more specific in the first instance, I've replaced all of the steering bushes for new poly ones in the last couple of months. Likewise with regards all of the front ARB bushes (now poly) & new drop links, I no longer have an rear ARB so can't be that. I lay underneath my truck for a good couple of hours before each time I go off-roading & grease & touch & pry & poke everything so I'm very familiar with her in that way. When this fault first presented itself I to thought CV or bearing so I jacked up each front wheel independantly & checked for wheel bearing play & upper & lower ball joit play with a crow bar. At the same time I used a pair of 18" slip joint pliers to grip each of the front drive shafts to check the CV's for play & also went right back through the prop shafts checking each UJ in turn for play (as I said the one with the most play was the new one that I fitted only very recently from Milners ). I also used a long (approx 24") straight cold chisel to give me purchase on the engine/box & rear links to check for excessive play in any mounts.

But all that said the only anomaly I can find is the excessive rotation (nearly half a turn) in the front prop shaft when the gearbox is in Neutral.


































Anyways I've managed to get the drain plug from off of the diff using a large Cold Chisel & Ball Pain Hammer

And this is what I found

Is that normall

















And her's some more

So, wanted one R17 front diff & housing

 

[silvercruiser]

Not good

that will be the clonk then as it is missing a tooth. i hope you get hold of a diff without to much hassle.


Joe

 

[Chris]

Sorry to see that Steve. I rather suspected that it was your diff. You just needed to get the plug out to confirm. Having had a front diff go, I recognised the clonk that you were talking about. You don't get that with anything like an ARB of CV on a 90. I guess that in a straight line there isn't any load on the drive line and the turning of the wheels applies load. Normally one tooth missing wouldn't supply all of that 'slack' that you found and I would suspect that there is more damage in there. Teeth don't just fall off. There are places for other bits to hide in there of they have broken off.

Now's the time to get the front locker in, eh? Fitting the diff is dead easy really. I would order the spares that you'll need in good time then you'll be ready to rock. You'll need two snap rings for the drive shafts and I would really suggest doing the outer oil seals whilst it's on the bench. The rear companion flange has to come off to get the diff over the front cross member (might be different on a long wheel base before anyone says) as there simply isn't enough wiggle room, so I'd get an input shaft nut too. Front diffs from 'normal' 90s have a very easy life and you should be able to get one with confidence. It's only loonies like us who break them.

Chris

 

[Jon Wildsmith]

That looks like a bit of side gear tooth.

 

[BobMurphy]

Ah well . . . That narrows it down a bit

I'm sorry it isn't something simple (and cheap), but knowing is better than not knowing.

Now we have a diff rebuild / replacement thread to look forward to

Bob.

 

[TonyP]

Ah bugger Steve, not good....

As Bob says, at least you know what it is

 

[Bounder]

Shizer.
Thats not good, but at least you discovered it during low speed manoeuvres.
What mileage is on yours? Mine let go around 260k miles so they are quite robust but I guess offroading loads things differently.

 

[Andrew Prince]

Bugger - bad luck, Steven! Hopefully you get it sorted with as little pain as possible.

 

[sae70]

Thanks for all of your kind words of support lads

I'm lucky that Fiery isn't my/our principle vehicle & that the wife commutes to London by train each day. Fiery really is a toy that can often sit unused for 2 to 3 weeks @ a time, I only used her twice between Lincomb & this resent trip organised by Ben to Shropshire & that was only to yank my trailer down to the dump So no need to rush, I've used her a couple of times today despite the fubard diff with very little clonk knock jolting I may remove the front prop in case I need to use her for anything before I can sort out a new/secondhand diff, but not sure if this will make any difference really.

Lets face it, it could have been a lot worse and I suspect that this has been like this for quite some time now

I've never been able to remove the front diff drain plug since I bought Fiery and as I always check the levels/condition of all of the oils in my off roaders not just when I first buy them but after & before each time I go off roading it was bugging me a little that I couldn't easily remove it without risking greater damage, so I just left it resorting to doing all that I needed through the fill hole. The other oddity with regards the drain plug is that it is a 10mm hex and not a 12mm as suggested by all other threads that I've read on the subject (10mm for the fill hole & 12mm for the drain hole) both of Fiery's are 10mm Now that I have removed the drain plug I can see that the thread protrudes into the diff housing by a couple of threads once it has been fully tightened & that these threads have been damaged by all of the loose teeth flying around It would appear that this is the reason behind the drain plug being so jammed in place The other thing that now plays on my mind is the fact that I replaced all of the steering bushes the week before Lincomb because of how the steering occasionally felt & I now think this was due to her loosing drive up the front end every now & then, a precursor to the diff finally having enough maybe.

It will be interesting to see what it all looks like insude when I finally get it off & apart because as I say I've used her a couple of times today without to much drama

I've put my details onto 24/7 parts & both on-line find a part services, I've also email all of those that are breaking Collies on the bay so fingers crossed it shouldn't be to long before a replacement can be found & all will become clear

If anyone knows of someone breaking a Collie that may have an R17 diff please let me know & I'll give 'em a call

I have already been offered two through the on line parts finders, but one to far away without post or confirmation of type & the other is just way, way to much money

 

[Chris]

I know you are a man of the World, but do watch out with 24/7 parts. You will get a million automated mails telling you that the part is in stock. That's where it all goes t*** up. I had a mail and bizarrely found myself half a mile from the place in Birmingham the next day! I dropped in. Did they have the part? Did they b*****s. Catalogue of similar issues until I finally got the part from our own Mr Rubie.


You really DO need to find on that you can see in the flesh. Remember that we are all here to help mate. !f there is one in the UK somewhere, we'll give it a viewing, somehow, if you need us to. OK? One of these is easily transportable by car.

Chris

 

[sae70]

Just had a call back this afternoon from one of the chaps that I e-mailed on eBay from Monmouthshire to say that he has a 98 lwb manual Collie coming in on Thursday morning that will have a good front axle fitted & that if I'm interested he will call me then to confirm type & it's mine if I want it

So just to confirm diff types R16, R17 & R56 Are all R17 diffs the same ratio And while we are at it, is there a list of what models should have what ratios fitted as in the back of my mind I'm wondering if Fiery has the correct front diff fitted ie one that matches the ratio of the rear diff Worth checking I guess before getting to far down this road

So I'm after;

Knowing if all R16, R17 & R56 diffs have the same ratios with respect to there model number

A list of gear ratios specific to Collie models

And a refresher of how to check what ratio my rear diff is