[Zook_Fan]

I have tried a lot to try and get this resolved but can't seem to top it. Here is what is happening. While driving at around 80km/h (specifically between 78 and 84 on the gps) I get a LOT of vibration through the wheel. It shakes fairly bad through the steering wheel but there is no sound to go with it. It feels as though it is coming from the front of the car (fairly obvious) but I don't know where. It has brand new wheel bearings all round, new brakes, I have checked the uni's, new oil in diffs, gearbox and engine. I don't know what would be causing it... If i had a broken engine mount it would be all through the speed range wouldn't it?

oh and it is a 91 WT Sierra.

[Ben_Sierra]

You had the wheels balanced lately?

[Zook_Fan]

never.

[Junior_91]

Wheel balance mate get them done and see what happens.

[Ben_Sierra]

In my experience missing wheel weight or badly balanced wheel will cause exactly the symptoms you are describing...

[Zook_Fan]

righto, i will chuck my roadies on and take them for a spin to see if it is the tyres

[S13RR4]

Most cars have two wobble spots then when travelling at a certain speed it hits a sought of resignating frequency and causes the car to vibrate, it is to do with your wheel balance as ben suggested.

Most have one around the 80 mark and somewhere around the 120 mark, give or take some km's and the severity depends on your car, wheels and tyres.

mine does the same just above 80, but once I get passed about 90 it goes away,

it can be reduced by wheel balance, in which they sometimes rotate the tyre on the rim to try and find a more balanced fit, although larger tyres and more so mud tyres are usually more difficult to get a perfect balance and eliminate this problem

theres my 2c any way

[Zook_Fan]

ok will do that but will an engine mount cause anything? i am pretty sure i have broken my passenger mount

[S13RR4]

I dont know for sure mate, only know that cause I used to work in a tyre shop, it could be a similar thing with the resignating frequency with the engine reving at a certain rpm, but I would more likely say its the tyres,

best bet is to replace engine mount (probably wouldn't hurt anyway)
and do the run with roadies to isolate if its the tyres causing the problem

[royce]

sounds like classic wheel balance or bent left front rim to me

[Jccck]

I had some trouble with an unbalanced driveshaft awhile back, causing the same thing when in 4WD or 2WD with front hubs locked at ~90km/h

Little wobble in the front end

If having your tyres rebalanced doesn't fix it.. Have your drive shafts checked too

[S13RR4]

dont think your meant to go that fast in a sierra with the hubs locked in cause the front drive train components aren't balanced like you said,

with hubs unlocked it should only be the middle and rear drive shaft spinning and they are balanced, front drive shaft probably isnt and same with front axels hence not meant to go over 50km/h or something (dont know the actual speed but I know its less then 90)

[steak_knife]

Jccck wrote:

I had some trouble with an unbalanced driveshaft awhile back, causing the same thing when in 4WD or 2WD with front hubs locked at ~90km/h

Little wobble in the front end

If having your tyres rebalanced doesn't fix it.. Have your drive shafts checked too

Or unlock your hub's..

[v6zookie]

allso check if a front wheel has a bubble (broken wires inside the casing) it would also give the same efect . but at this stage would be small. as it tears the problem becomes ---- well it bows.

[stockman]

Common symptoms of badly balanced wheels.

I don't think it would be a engine mount. I too also had a broken left mount and only realised when I pulled the motor out.

[lump_a_charcoal]

S13RR4 wrote:

Most cars have two wobble spots then when travelling at a certain speed

This is correct.

My car's two wobble spots are 10-50kms, and 51 - 120kms.

[S13RR4]

hahahha yeah and like I said, give or take a few kms

wait... I just re read your post, you make me look like fool,

hahh I more refering to all cars, Sierra's just wobble fullstop. But the two wobbles I was speaking of are generally caused by wheel balance

[mightymouse]

If you dont find that your tyres are out of balance, check that the front wheel bearings have been done up tight enough, it often happens that after a little time running the bearings bed in and become a little loose in the case therefore causing just this type of problem.

[S13RR4]

v6zookie wrote:

allso check if a front wheel has a bubble (broken wires inside the casing) it would also give the same efect . but at this stage would be small. as it tears the problem becomes ---- well it bows.

this is known as seperation, when air is able to get between the layers or rubber and hence seperate them

[squirezook]

This is a topic that comes up a lot. Some times it is very hard to track down. If your front end is in excellent health eg. kingpin bearings wheel bearings, shackles and steering are all good then it can only be tyres. Even new tyres can have a deformity eg. out of round a lump or bulge.

I had never had a shake in my ute until the other day I removed a tool box 30kg from behind the driver side in the back.
The first bump I hit I got the death rattles so bad I had to stop it shook the car that bad it broke the passenger side engine mount and flooded the engine causing it to stall.. WTF When I got back I put the toolbox back in and went for a drive. Could not make it shake?????? Removed toolbox and yep shaking violently. The only thing I could put it down to is ds front spring is a little lower and ps rear is a little lower and the weight of the box was sort of balancing that out. Oh and my 31's road tyres are well worn so could be just the tyres out of round and out of balance.

[steak_knife]

squirezook wrote:

The first bump I hit I got the death rattles so bad I had to stop it shook the car that bad it broke the passenger side engine mount and flooded the engine causing it to stall.. WTF

I have seen snapped kin pin's do this, drive on a smooth road & it's fine, till you hit the rough, goes crazy.
Last one I saw had no movement in it, wasn't until I pulled it out that I found it busted.

[Zook_Fan]

finally got around to swapping my tyres around today and it was the muddies that were making the vibration. new problem now though.. What bearing in my rear diff would make a noise similar to that of a turbo winding up? Not only is it annoying but a cop pulled me over today and did a full inspection of the car and then told me he originally pulled me over becase 'P' platers aren't allowed turbo's and he was sure by the sound of mine i had one

[whincup]

i have exactly the same problem. i think its due to lack of oil in the rear diff in my case... check that first. lack of lubrication would do it.

[PeterW]

sideways with Muddies, gives the impress of a Turbo

[JrZook]

S13RR4 wrote:

hahh I more refering to all cars, Sierra's just wobble fullstop.

Speak for yourself, mine drives quite nice

[Zook_Fan]

whincup wrote:

i have exactly the same problem. i think its due to lack of oil in the rear diff in my case... check that first. lack of lubrication would do it.

yeah that was my initial thoughts but i drained the diff and put new oil in there and the noise is still there

[removed1]

hey, i bet me left nut thats its the king pin(s). As the Jimny and the Sierra share the exact diffs, I've had a torturouse year or so of wobble and trying every thing to get rid of it and that even took three attempts of finger plate balancing... The only thing that fixed it was a complete front end fix of the king pins...

[Zook_Fan]

well lop it off and send it in. the wobbling was from the tyres and the noise is coming from the back... no king pin problems

[Zookin_85]

Check the rear wheel bearings, my sierra was making a whining noise.
I found mine to be the rear left wheel bearing! its worth a shot imo.

[Scrawny]

Zook_Fan wrote:

well lop it off and send it in. the wobbling was from the tyres and the noise is coming from the back... no king pin problems

You can get additives for the diff that can help with noises. You'll probably find the whole thing is rooted though, bearings and crown wheel/pinion.