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Bigg_kayz

Is It The Diff? Is It The Driveshaft? Is It Something Else?

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Have been having issues with my Ba xr6t mkii manual , for a while a whirring sound would come and go slightly between 60-80 km/h (I put it down to just about time for a centre bearing change over. then after about 3-4 weeks of driving to and from work I gave it a little throttle from a standing start and it made a very bad vibration through the car , pedals and gearstick. after that , any hard acceleration of more than 1/2 throttle would make bad vibration and the whirring sound had now become a Humming sound heard and felt above 50km/h. and an all around feeling of "something isn't right" was lingering ....
a couple of days after this (about 60-80 kms later) I was driving with barely any acceleration at 60km/h and the whole car broke into vibration with a metal on metal sound present, the car also seemed to now have some resistance under acceleration as if the handbrake had been left on....
Babied the car home about 30km away and every time I would hit an incline and had to give anything more than a touch of acceleration the car would vibrate/drone and hum violently . on the very last hill to my house I honestly didn't think I was going to make it. the last 2kms. when
I got home I took it apart and on this video is what I found......

If anyone can point me in the direction of what it might be? and the costs involved / possibly even someone in the northern perth area that can fix it, with quality workmanship?

Until I get it fixed im leaving it parked up . im hoping it'll get me to the repair shop without the cost of a tow, though I've been told too much vibration being sent back through the gearbox etc could be very bad?

car runs 500+rwhp on 15psi

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Looking at that video, is there meant to be a dent in the drive shaft?

Where in Perth are you? NOR or SOR?

Edited by masda74

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At some point the drive shaft has slightly scraped a curb/ as the car is low. (not during its life with me) the shaft was taken to final drive and weights were put on to sort out any possible issue.

 

I ended up taking it down to DBS in malaga (driveline Balance services) . top blokes , got me in the day after I called, had it done and dusted within 5 hours. end up needing the Rear Cv , front rubber coupling and the centre bearing all replaced. got away with it for just under  $1000, that was with the removal , reinstall and balance too.

 

Then the next day came..... lots of clunk and knocking , even prominent on idle (manual). releasing the clutch harshly , knock as usual but now it was LOUD. pretty much over the noises I got the rear and front up on stands, went through the whole underside from diff to front stabilisers , checked all the bolts etc etc. pretty much all the bolts were lose on the gearbox  mount that connect with the exhaust hanger bracket (2 on the top , 4 on the bottom) also the 4 bolts that connect the trans plate to the chassis were lose so I did them up too, I dont have a torque wrench so I just did them up fairly tight . I did the same with some insulator stabiliser brackets at he front of the car as they weren't what I would call "tight" either.  Its probably not the best thing to have over tightened them, but id rather them tight and stay on , than loose causing vibration/ with the strong possibility of  something falling off (which it already had).

 End result after a few text drives. Pretty much next to no noise, and what I thought  for months and months (since I bought the car) was gearbox roll over noise had gone too, only slight knock sound if im being a bit sh*t with the twin plate heavy duty clutch on gearing up or down , just sounds like the tiniest bit of shaft play where the 2 piece shaft  meets or the shaft meets the gearbox? Oh and the car actually performs a lot better, boost comes on way quicker and general cruising or rolling up to a set of lights ( in gear or in neutral) is a lot "free moving" due to what I realised was there resistance being caused by badly aligned shaft and  rear cv that shat itself. All in all im happy, the bolts were all tightened last night so im going to go for another drive today.

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Great result just from tightening a few things up!

I've wondered before how cars don't just fall apart with all those nuts and bolts under there being exposed to the vibration.  Loctite on all threads seems the only way to be sure, but I'm no mechanic.

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It'll probably be the way I'll go after I do a re-check of everything in a few weeks. Its due for oil and filter so I shall do it then. Fully agree about the nut and bolt comment. A lot of cars are slapped together these days , many far far worse..... every heard of the "cherry" ? if you've not seen one of their cars in person you should check it out, at least for a laugh

Edited by Bigg_kayz
to extend on to what ive written

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One thing I did notice on the car whilst under it was that the dump pipe was pretty damn close to the bell housing we're talkin' less than 1cm I reckon. Whilst driving during the day today I had the A/c, notice when I was at the lights I could hear the tiniest knock and  feel it through the gear stick.  if I turned it on and off obviously the idle would drop slightly or go up and when it was On it would be noticeable, even more so when the thermo fans were switching on and off  ( once again noticeable when on causing revs to drop ). also the exhaust is big and has a massive canon on the back so it does sway quite a bit on take off.. so I knew then to keep it in mind for any more noises.

I  never used to be able to narrow the sound down and by the time I got home today it was driving me Insane. I went straight to that area to listen, sure enough that's where it seems to be coming from , problem is I cant see much from the top of the engine bay not having it jacked up and it was getting dark. The other problem is its awful close to the driver side engine mount which isnt looking extremely sad but its not looking extremely new either. cars done 140,000 now. 

I'm hoping its exhaust hitting slightly, but maybe its the engine mount... any takers? 

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Been contemplating doing the centre bearing replace myself (partially torn and sagged about 5mm) on my FGT ute and doing a bit of research about some of the driveline bits down there that may also need attention and put the job beyond my comfort level. No noises or clunking that I have noticed as yet and I do listen with window down and beats off often.

 

I have a question for the brain trust here, the following vid shows the total play in the driveline with car in neutral, The cv near the centre bearing has very little play and unsure about the back one, but at the diff end there seems to be at least 80% of the movement you can see in the front. 

 

Thoughts anyone?

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Another vid and question for the brains trust about the FG XRT ute, similar to OP, but no clunking, prolly cause the cv boots not allowing spline to reach full depth both ways. There seems to be a large amount of lateral movement in splines between the 2 cv joints. Is this normal again?

 

When tyres are spun by hand, all seems tight and quiet in diff area.

 

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