Subaru 4wd system.

Ok. When I hit c70mph over 3,000revs the front of the car suddenly starts to vibrate severly. Its getting worse, if I backed off it would stop however yesterday the vibration followed my speed down to 40mph. When I came to stop and started off again the vibration had disappeared.

Now I’ve redlined the car to see if it’s the revs in 2nd/3rd – the car pulls fine and no vibration at 6,000revs. The severe vibration only appears when Im on the motorway at 70/3k+.

Elimination:
-It cant be the suspension as the car would pull when I let go of the wheel (even on the motorway the car doesn’t pull/stays dead-straight). I have also visually inspected the suspension boots etc for leaks/splits.
-It cant be the wheel balancing as the vibration was still there when I reduced the speed on the motorway and I cant drive through the vibration?
-All tyres are inflated/no imperfections in sideways
-There are no leaks from the engine etc
-The car doesn’t overheat/rise above its normal temp, engine revs don’t rise/erratic etc, checked oil and coolant levels- fine.

(I could be wrong on the above- including balancing?). A Kwik Fit told me you can drive through the vibration if it is balancing?!

Could it be a dodgy engine mounting?- but this would vibrate the car at any speed inc when I redlined the car?
Loose Driveshaft? (as above?)
Something else lose in the engine bay (gearbox etc)- had a new clutch fitted a month ago.

I just want to eliminate/trouble-shoot as much as poss before I have to drop the car off at the indie to investigate. Not flush at the moment.

You can drive through vibration on balancing, but perhaps you weren’t going fast enough (and didn’t want to).
It clearly set up some big wobbles if it followed down to 40mph.

Has it always done it, or is it new?

Started a week ago- I dropped to 4th, floored it then changed back up and it ‘disappeared’ again. Shrugged and carried on. On Sat though it started again and progressively got worse and worse’ yesterday (on sliproad/40mph).

I really really wanted to ride again yesterday 👿 😳

Ps. I didnt want to drive through the vibration as the car/vibration was really bad. I’ve driven a couple of cars with bad balancing and this was alot worse- almost as though the engine was loose!

Are any of your wheel nuts loose? I had that happen on one of my cars, and it didn’t feel like you thought it would

Have you had new tyres fitted at one end?, 4WD systems don’t like it if the difference in tread depth is great, it changes the rolling radius & the car thinks one wheel is going faster than another.

Checked the wheelnuts. 2unfit2ride all tyres are same age (except one on the rear but that was changed c2,000miles ago).

If it was say a dodgy engine mounting- you’d feel vibration at all times?

Could it be a faulty mass air flow sensor? The greater the speed etc? (I am guessing here)

TBH, there are to many variables to guess, engine/gearbox mount would notice if you went through the revs with the car stationary, only rolling/suspension stuff would be speed dependent, try dipping the clutch/putting it in neutral whilst the vibration is happening to see if its engine related.

One tyre warped/flat spot? Loose engine mount? Loose aero undertray? Could be many things!

Seems pretty likely to be the front wheels / tyres in one way or another, whether it’s unevenly worn tyres or unbalanced wheels. Swap the rear tyres onto the front and get the wheels alligned, should solve the problem.

Sound like a CV joint – they sometimes smooth out when the speed/load are right but have a hard time staying smooth when the load is applied and then dropped ie – when accelerating and deccelarating. I’ve had a cv joint and an engine mount go on one of my cars and the engine mount porblem feels like teh cars is trying to kangaroo around more than vibrate.

Cheers guys. Marmoset, is it possible to self-diagnose a cv joint? Jack the car and where do you check for play?(what parts do you hold when ‘wiggling’?)….

I just want to avoid the ‘hours’ that a garage may add onto a bill whilst they diagnose a problem! 😉

it’ll take them about 10 seconds to tell you if it’s a CV joint or not

Just had a quick google- there is no clicking/noise on lock to lock

What kind of centre diff does it have? There could be a problem with that – I know some haldex diffs do wear out pretty quickly, also have a quick look at the universal joints on the driveshafts..

You haven’t locked your little dog in the boot and forgotten about him, have you?

(Calls RSPCA)

Hora, where abouts are you ? I have a four poster ramp which we could get it on and have a good look around. I’m in Nottingham.
Not sure about Subaru’s but you may have balancing weight’s on the longer of the drive shaft’s, you could check to see if one is loose or has fallen off. Who fitted the new clutch btw?

Hi Gravy, thank you for the kind offer, I’m in Manchester though. A Subaru indie fitted the clutch.

it sounds like a universal joint, on my old truck I had the same symptoms and checked it by clambering underneath and seeing if there was any lateral play in the joints, that was pretty easy to do as it was high off the ground and crawling around under it didn’t require a jack, there also weren’t any trays or things in the way?

Sounds like a wheel bearing.

There is only a sump guard at the front. I had a peak under yesterday. Any idea what it looks like? Is that an expensive mechanical job on a vehicle – i.e do you have to remove alot (man hours) to get to change?? 😕

takisawa2- it cant be. There are none of these signs:
A classic symptom of a bad wheel bearing is noise, so if a wheel is making "funny" noises when driving (squeaks, chirps, squeals, moans, etc.), or you hear a grinding noise when turning, it may indicate a bad wheel bearing. Other symptoms include steering wander or possibly a pull to one side when braking.

have you walked round it, grabbed each wheel and given it a good hard wobble to see if anythings moving?
guess it could be a wheel bearing?
does it make any other noises if you steer hard left or right?
if you’ve got alloy wheels – are they buckled?

When was the last time you had the brake pads checked? Something similar happened to my Frontera a year or so ago when the nearside front caliper seized and wore all the pad material away.

It ended up being a recon caliper, but that was a lot cheaper that bearings, CV joints etc.

have you walked round it, grabbed each wheel and given it a good hard wobble to see if anythings moving?
Yes.
does it make any other noises if you steer hard left or right?
No noises.
if you’ve got alloy wheels – are they buckled?
Steel wheels. I aint no pimpy 4×4 driver 8)

when the nearside front caliper seized and wore all the pad material away.
Hmmmmmmmmm -it could be a sticking caliper however it’d pull surely to one side. Did yours pull?

If its a sticking piston- Armed with GT85, screwdriver etc I could try resetting myself? (of course remove pads/cover disc)

I’ve just realised its you Hora! ok, before you start to disassemble the engine block,
…have you tied any balloons to the Ariel? 😆

MrNutt, could be one of the wheel-Hamsters not feeling too good? 😉

When it occurs, if you put your clutch in what is the result?
Blown shocks can bounce a tyre like mad at highway speeds but be apparently fine at low speeds. No pulling would be caused.
Sticky calipers usually do cause some degree of pull, but I did have a sticky rear that pulled so little it was hard to distinguish from road camber, and it didn’t happen all the time.
You usually can drive through balancing issues, but its possible to have a pair of wheel imbalanced that harmonise occasionally and this makes an odd stretched out vibration range, but still acts the essentially the same.

My first tests would be
a) Does it go (immediately) when i dip the clutch and coast?
b) Does it go if I brake, lightly or firmly?
c) Does it go immediately if I let right off the throttle?

My first tests would be
a) Does it go (immediately) when i dip the clutch and coast?
b) Does it go if I brake, lightly or firmly?
c) Does it go immediately if I let right off the throttle? (no)

I’ll test using this criteria and comeback later on this aft.

Well with C down you rule out misfires or engine fuel/sparky problems. Leaves you with mechanical issues only.

If it continues when you dip the clutch you know its 99% likely to be powertrain or suspension, not engine mechanical. Vibrations can be very very hard to narrow down at times, often helps to have a mate in the car to hunt while you concentrate on remaining on the road!

Does your car have a dual mass flywheel? I know these can be prone to transmitting some very weird vibrations if faulty.

I’d also recommend checking for a sticking caliper.

Just take the damn tractor to a garage.

dual mass flywheel- Will check if it does..

Tractor? I love it. Tonka, it smells like a slurry pit inside, the footwells are full of wrappers etc and the rear seats are covered in dog-footprints.

I can’t be bothered to look – is it a forester?

If its a 4wd, its probably a foobar’ed transfer box – when they changed the clutch it exposed weaknesses in other areas of the transmission. That’ll be nice and cheap to fix…

flange transfer box works fine though. I tried it yesterday.

Second the sticking caliper – I wasn’t a subaru or 4wd but I had that problem on one of my rear wheels and it gave pretty much the symptoms you’ve described. It didn’t shake through the steering specifically though, more that the whole car shook.

Is it not permenant 4wd?

driveshaft?

Lootenant- the whole car shakes (confirmed by the passenger).

If it is a sticking caliper can you resolve yourself? (DIY)

flange- sod off. Your scaring me! 😥

It is permanent 4wd however I switched between the two and it engaged fine/as normal on both.

Have you had the balancing re-checked? Had a scoot through and couldn’t see if they’re new tyres? A weight coul’ve come off or if you done more than a 1000miles on the tyres the balancing is more than likely going to start going out. You hit any pot holes recently? Got to kwik fit or somewhere like that and get your tracking checked on all 4 wheels. My money’s on one of these. If your brake is sticking you’ll be burning through fuel too. Onn a stright section of road if you put your foot down does the car veer?