Outer Limits 4x4 Board

I'm just getting used to my new 31's, but im disturbed by a brief rumble, that feels as though it is coming from the rear axle/diff/ tailshaft. It happens when I pull off in first, but is fine from then on. Could this be somthing to do with the larger tyres? Should I be getting a gear reduction for 31's? Could the diff be damaged?

Cheers for any feedback

How aggressive is the tread pattern on your tyres champ? It may just be the tyre lugs as you take off and come to a stop making that rumble bud if it's only happening in first gear.
Simple answers can sometimes alleviate the issue without too much drama.
Having said that and you think it's something else, if you've got A/T's or similar rubber that won't 'rumble', then check your rear shaft for play. Hold the pinion firmly and try to twist the yoke back and forth, if you see or feel any movement in the uni cross(es) then you'll just need to do uni's. Also check to see if there's any movement in the pinion bearing as well by trying to move the shaft up and down- the flange will move up & down if it's on it's way out.
Further to that, if it's not tyre tread or uni's etc, it will most likely be your diff center or wheel bearings.
Process of elimination mate, easiest to hardest aye...

Mike

if its a vit it will be the slip joint out of the transfer.

Out of interest Joe, why would it only appear to do it in first gear? Does increasing the spinning velocity iron out the vibration he's experiencing as he speeds up?

Mike

i reckon its spring wrap - heavier tyre is harder to turn, hence the rotational force might be going through the leaves...

Thanks for the feedback guys,

The tyres are maxxis mud terrains, so I guess they are reasonably aggressive. Compared to my 215 BFG AT's. And I do feel some slight vribration when braking and coming to a stop, which I can also feel through the brake pedal.

Cheers

alien wrote:i reckon its spring wrap - heavier tyre is harder to turn, hence the rotational force might be going through the leaves...

Going on his profile i think he is in a vitara, though i could be wrong.

Layto....

lay80n wrote:

alien wrote:i reckon its spring wrap - heavier tyre is harder to turn, hence the rotational force might be going through the leaves...

Going on his profile i think he is in a vitara, though i could be wrong.

Layto....

Yeah you'd be right. That gets me thinking. A leaf sprung Vit ey? Hmm. Is that even worth contemplating? Unless someone dumped a Vitara body onto an old sierra, hilux or lancruiser.

As per Joe, check the engagement of the slip yoke, but also the condition of the unis.

It will only show in 1st gear as that's when the most torque is being transfered, but as you pointed out the speed is also low so you'll feel each oscillation.

It might have only showed up now because you'll be pulling away against more load due to the taller tyres so more force is going though the driveline for longer.

It is possible it's tyre/lug squirm, play with tyre pressure if you suspect this as higher pressure should have a large effect on this.

You defiinitely didn't change anything in the suspension when you went bigger tyres?

Steve.

No. I already had 40 mm coil spacers in it long before I got the bigger tyres.

Your comment on tyre pressures is interesting, beacuse I havent checked the pressures since I got them, but I think they are a bit high for my vehicle.

Thanks again guys