X5 transmission issue - HELP!!!

ScottyP · #1 03-05-2009

Well, thought I was close to finishing my X5 tonight. Guess again!

With the transmission all assembled, there's a growling sound when the spur is rotated, as if the teeth on the belt are catching somewhere along the way. I've disassembled and checked everything, especially the transmission tunnel, which I thought may have been the cause. In fact, I reassembled the transmission without the tunnel just to be sure! Growl was still there.

The only thing I can think of that I had to build up the layshaft and idler gear assembly without the two washers. PLUS I had to remove some material from the alloy spacer that sits next to bearing. The instructions say you should not have to do this, but I had to in order to give the tiniest bit of end float in the layshaft. So, the idler gear is now perhaps more off-centre than it should be. Could this be the cause?

Incidentally, my kit came with a poxy two piece black idler gear, not a one piece one shown in the instructions.

Throw me a bone guys and help me get this thing running!

Cheers,
Scotty P.

_sleigh_ · #2 03-05-2009

I wouldn't worry too much about the layshaft assembly. I had to do similar to get a fraction of end float on mine too.

As to the noise, have you trimmed the rear diff carriers. I'm talking about the mouldings on the diff bearing holder that were originally designed for the XX4 roller bearing. These might be catching to diff pulley?!? Could also be the front bulkhead, have you trimmed it as per the manual?!?

Apart from that, it could just be a dodgy bearing or a bearing that's nipped up tight somewhere. Try disconnecting the driveshafts front and back, then try spinning the transmission again.

YoungChazz · #3 03-05-2009

Often X - 5 driveline problems become evident when you remove the bottom cover and watch things go 'round.

_sleigh_ · #4 03-05-2009

Very true Youngchazz, mines even got a sexy carbon cover

super__dan · #5 03-05-2009

With the large spur the car sounds loud when rotating slowly (like when checking mesh), however once running on track mine sounds very quiet. Unless you've been running it and it's still loud, could that be it?

I don't follow about the idler, you mean the roller on the tensioner bar?

Darren Boyle · #6 03-05-2009

Double check that your pinion grub screw is not catching the flat area of chassis just behind the motor mount location as it rotates, I had this today and had a very siniliar noise to what you ar describing, I simply removed a little of the material from this area and it was cured.

As the lads of said, watching through the bottom with the cover can tell a lot of stories.....

ScottyP · #7 04-05-2009

OK, I've discovered the problem. On the diff pulleys, there is some flashing on the inside of the of the sides of the pulleys. When the belt is trying to enter the pulley, it is getting caught on the flashing, causing the 'growling' sound. I've tried to trim the flashing and make it as smooth as possible, but the belt is still getting caught on a couple of section of the pulleys. This is annoying to say the least.

I will try running the transmission in on the bench and hope the problem goes away.

I suspect my kit is an old one and don't think it has the newer machined pulleys (the ones I have are black). Will the new machined pulleys solve the problem? Do XXX4 pulleys fit? I seem to recall no such problems when I ran the XXX4 some years ago.

Cheers,
Scotty P.