Massive panic!

[Steveyk]

hi guys, I need a bit of advice. yesterday I was cruising up the M1 about 75 with the c-diff in auto as usual. with no warning I suddenly got a horrendous metallic grinding noise coming from under the car, and I could feel it through the gearstick. it was only happening on a light throttle, accelerating made it stop, as did lifting off the gas. it got so bad I was considering pulling in and calling recovery, but I stopped at some services to check the wheels and the obvious stuff. before leaving the services I switched the diff off auto and into fully open, and never heard another peep.

I'm worried sick now that the centre diff is about to explode or something equally horrible and expensive.

has anyone experienced anything similar ? it's booked in for a service thursday but I've got to travel 150 miles home first!

[John Mc]

You hadn't run over a motorway worker had you? More common than you would think

You haven't changed tyres recently or anything have you? (i.e. they are all roughly the same tread and wear). I read this can put undue stress on the diffs... no diff oil lights on?

Does it make the noise if you put it back into auto again now?

[Steveyk]

just had a look underneath, no motorway workers as far as I can tell! it was a properly horrible noise. I've not driven it since but I'll give it a go later on. nothing's changed on the car although the stupid turbosmart boost controller has upset the ECU and the warning light is on. could this affect the operation of the diff? the boost controller is coming off when it's serviced anyway. it seems to me if it was something broken or worn out then it'd be noiisy all the time?

I've only had the car a few weeks and I'm worried to death it's going to explode in a shower of cogs and springs!

[John Mc]

just had a look underneath, no motorway workers as far as I can tell! it was a properly horrible noise. I've not driven it since but I'll give it a go later on. nothing's changed on the car although the stupid turbosmart boost controller has upset the ECU and the warning light is on. could this affect the operation of the diff? the boost controller is coming off when it's serviced anyway. it seems to me if it was something broken or worn out then it'd be noiisy all the time?

I've only had the car a few weeks and I'm worried to death it's going to explode in a shower of cogs and springs!

There are plenty of noises that can occur on these, some easily explained and some expensive! If you were driving along at a steady speed and a noise suddenly started it may be something on the limit that has failed.. certainly worth getting it checked as it is difficult to say what a noise might be over t'internet

[Crockel]

just had a look underneath, no motorway workers as far as I can tell! it was a properly horrible noise. I've not driven it since but I'll give it a go later on. nothing's changed on the car although the stupid turbosmart boost controller has upset the ECU and the warning light is on. could this affect the operation of the diff? the boost controller is coming off when it's serviced anyway. it seems to me if it was something broken or worn out then it'd be noiisy all the time?

I've only had the car a few weeks and I'm worried to death it's going to explode in a shower of cogs and springs!

There are plenty of noises that can occur on these, some easily explained and some expensive! If you were driving along at a steady speed and a noise suddenly started it may be something on the limit that has failed.. certainly worth getting it checked as it is difficult to say what a noise might be over t'internet

As other Members have said stay calm until you get it checked properly. Diagnosis of noise over the internet is always nigh on impossible. Good job someone like John answered first - if you had posted on Scoobynet someone would probably have tried to convince you that you bought a 'cut and shut' and what you heard was the welds failing before the car falls into two halves!

I once had a problem on my Subaru whereby it made this really strange noise and vibration whenever it went over 50 mph. Prior to taking it to the garage I had convinced myself that just about everything conceivable on the car might have or was just about to fail! It turned out to be a wheel bearing and when the old one was removed the wear on it was barely visible (tiny scorching on the inside of the hub). Once changed the noise/ vibration stopped instantly and never returned. It sounded and felt horrendous but ended up being something reallly simple....

Please let us know how you get on.

L

[Ant]

A stone trapped between the gearbox and gearbox cross member could be the cause as can the exhaust touching part of the body, the noise would change when going on or off throttle due to the engine and gearbox moving slightly on there mounts due to the torque reaction, so could be nothing serious hopefully.

[Steveyk]

Thanks a lot guys, it's off for a service today so I'll get it checked out. Oddly enough on the way home with the diff in auto it didn't make any noises at all. I have read stories about having to have all 4 tyres changed together? My front two are a different brand to the back two. If they're a different diameter surely this will confuse the diff?

[John Mc]

Thanks a lot guys, it's off for a service today so I'll get it checked out. Oddly enough on the way home with the diff in auto it didn't make any noises at all. I have read stories about having to have all 4 tyres changed together? My front two are a different brand to the back two. If they're a different diameter surely this will confuse the diff?

Different diameters will not do your diff any good if the diameters are too far out, I think it is about 3mm difference but someone will probably tell you with more certainty...

I think the difference in diameter means one shaft turns slightly quicker than the other and when the gears engage in the diff gearing, it means they aren't engaging at exactly the same time which will put more stress on the teeth of one diff gear more than the other... again, someone who knows what they are talking about will probably tell you better

[Steveyk]

Right, had the service done today and the verdict is not good. I need front discs, front drop links, rear pads, new rear tyres and possibly a new gearbox. The guy has driven the car and reckons the 'box needs stripping to find the fault. Which may mean I have to have a whole new gearbox and DCCD! AAAAAAAAAAAAAARGH! I mean seriously, my old WRX had done 100k and was tight as a drum, surely the WR1 should be a tough cookie? Maybe I've just bought a pup. Dammit.

I think I'll do the brakes and drop links then replace all 4 tyres and see if that makes a difference first...

[Crockel]

Right, had the service done today and the verdict is not good. I need front discs, front drop links, rear pads, new rear tyres and possibly a new gearbox. The guy has driven the car and reckons the 'box needs stripping to find the fault. Which may mean I have to have a whole new gearbox and DCCD! AAAAAAAAAAAAAARGH! I mean seriously, my old WRX had done 100k and was tight as a drum, surely the WR1 should be a tough cookie? Maybe I've just bought a pup. Dammit.

I think I'll do the brakes and drop links then replace all 4 tyres and see if that makes a difference first...

I see you only bought the car a few weeks ago so two quick questions: who did the inspections when you bought it and is the garage who suggested all this work a well known/reputable garage with good experience of Subarus?

I am certainly not looking to rub your nose in it, but setting aside the gearbox issue, all the work the garage suggests you need would have been picked up by the most basic inspection in a few minutes. If the drop links have passed their sell by date they would surely have been noisy on the test drive and depending on how bad you would probably have felt them through the steering. Unless you have 'ragged it' up and down cobbled streets and then emergency stopped it solidly since purchase all of these faults would have been there at purchase.

Turning to the gearbox, I think any decent Subaru mechanic should at least have an educated idea what part has failed to cause the problem (if one has indeed failed).

I would be interested in knowing who looked at your car today- at the moment I am inclined to say get a second opinion- especially if you had it inspected at purchase.

L

[CAVEMAN]

yeah..seems like a logical first step.

Although this will only improve handling and the braking...not really sure if it will tackle the problem at all buddy.

Usually the 6spd is pretty darn tough...and the DCCD is a tried and tested bit of kit also...however the WR1 was the firsy UK production scoob with it on I think. Certainly the first STi anyhow..

They have been known to break, and you can find 2nd hand units kicking about from time to time...

Having different sized tyres on will knackered the centre diff for sure...just like having a mismatch between front a rear diff ratio's.

chin up mate....it could of been a lot worse...you could of been forced to buy and drive a 306D turbo instead!!.... sorry john.

[John Mc]

chin up mate....it could of been a lot worse...you could of been forced to buy and drive a 306D turbo instead!!.... sorry john.

"Buy"? WTF...? Nicked

[Steveyk]

306 Dturbo? My little bro had one and I thought it was pretty good?! To be honest the minor things don't concern me, they're easily fixed, but I think I'll take it to Subaru for a second opinion. I just want my baby fixed! Cheers for all the advice guys I feel better now! I will post the results when I've got it sorted in case it helps anyone in the future...

[Steveyk]

Right. Update on the diff noises. When you're driving in a straight line, the front and rear axles and propshafts should be rotating at exactly the same speed. If one or two wheels start to rotate faster then the centre diff will start to lock, correct? Therefore, if your FRONT wheels have an overall diameter 16mm more than the BACK wheels, then the back wheels, being smaller, will be rotating faster than the front at any given speed. Following this to it's logical conclusion, the centre diff will interpret this difference in rotational speed as wheel slip, and start locking the centre diff, or at least it will put undue pressure on it. However, because the rear wheel speed never matches the front wheel speed, the diff is in a permanent state of 'lock'.

I don't know the technical ins and outs of the DCCD, but this seems like the basic principle.

My temporary solution to this problem, not having four new tyres to hand,
was to put the two BIG wheels on one side and the two SMALL wheels on the other, and adjusted the pressures accordingly. To my mind this means there is only a speed difference on the AXLE diffs, similar to negotiating a long sweeping bend. Result? Diff noises gone. No strange grumbles on the overrun, and I can adjust the diff on the move without any lurching and grinding. Who'd have thunk it? My only fear is that all the time the tyres were mismatched may have damaged the diff, but I'll invest in a set of tyres and see how it goes.

[Bonovox]

Right. Update on the diff noises. When you're driving in a straight line, the front and rear axles and propshafts should be rotating at exactly the same speed. If one or two wheels start to rotate faster then the centre diff will start to lock, correct? Therefore, if your FRONT wheels have an overall diameter 16mm more than the BACK wheels, then the back wheels, being smaller, will be rotating faster than the front at any given speed. Following this to it's logical conclusion, the centre diff will interpret this difference in rotational speed as wheel slip, and start locking the centre diff, or at least it will put undue pressure on it. However, because the rear wheel speed never matches the front wheel speed, the diff is in a permanent state of 'lock'.

I don't know the technical ins and outs of the DCCD, but this seems like the basic principle.

My temporary solution to this problem, not having four new tyres to hand,
was to put the two BIG wheels on one side and the two SMALL wheels on the other, and adjusted the pressures accordingly. To my mind this means there is only a speed difference on the AXLE diffs, similar to negotiating a long sweeping bend. Result? Diff noises gone. No strange grumbles on the overrun, and I can adjust the diff on the move without any lurching and grinding. Who'd have thunk it? My only fear is that all the time the tyres were mismatched may have damaged the diff, but I'll invest in a set of tyres and see how it goes.

My head hurts

Hopefully sounds like you are getting to the bottom of this!

[Steveyk]

What I'm getting at is that I measured the diameter of the front wheels vs the rear wheels. The front wheels were 1.6cm bigger than the rear, causing the centre diff to start locking because the back (smaller) wheels are going round faster. This was putting strain on the diff because it was trying to make both sets of wheels rotate at the same speed. By putting one big and one small wheel on each axle, both pairs of wheels and therefore propshafts will be going at the same speed, not confusing the diff. The only trouble now is that with slightly smaller wheels on the R/H side of the car it torque steers like a pig. The answer is new tyres. And I don't need a new gearbox! But I've proved my point about worn and new tyres affecting the DCCD. I'm just happy it isn't something mega serious! WOOHOO!

[chiroman]

This:

http://www.clubwrx.net/forums/sti-trans ... ained.html

or this may help

http://bbs.scoobynet.com/technical-topi ... ation.html

http://bbs.scoobynet.com/143750-centre- ... ion-5.html

[hightower]

well diagnosed fella glad to hear it looks like it has worked out ok

[CAVEMAN]

yep, good news buddy.

But now you are putting stress on the front and rear diffs. Best get new boots allround as soon as you can mate.

Hope you haven't done any long term damage though.