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.

Darren Boyle · #8 04-05-2009

The older black pullies have not been in the kits now for some 8+ months or so at least, yours must be an older one. The machined pullies are MUCH better (hence why we now put them in the kits too)

ScottyP · #9 04-05-2009

Thanks Darren. Looks like I'll have to lay my hands on some new pulleys.

How does using XX4 pulleys affect performance?

YoungChazz · #10 04-05-2009

Without looking carefully, I think it's been more like 21 months since we sold a Kit with the original black molded pullies. We converted when the Squared was released in '07. Yes, you'll want to carefully dress up the flanges, and make sure to glue the sonic-welded flange to the pully.

It's important to get them cleaned up because the belt is not nearly as strong as the plastic, so you'll tear up the belt if you haven't already. Even a single short fiberglass strand protruding from the side of the belt and it's all over -- replace the belt now before it tears up the pullies too.

Build the X - 5 driveline and check it before you assemble the driveshafts and suspension. Run the motor slowly with the bottom cover off and observe the path followed by the belt. Move the idler pulley from side to side by adding small shims between the bushing and idler bar or removing a small amount of material from the bushing until the belt is running perfectly straight and right in the center of all four pullies. This is crucial to long belt and pulley life.

The black pullies will work fine. The machined ones, especially the drive pulley, are better, but you can run the car for a long time with the black pullies. When it's done correctly, the X - 5 will run very fast for many race weekends with no problems. Like anything else, if built sloppily, it won't last long.

Migs · #11 04-05-2009

scotty, u can use xx4 diff pulleys and the belt pulley, all it does is change the internal ratio of the car, so you'd need to adjust the gearing, im running them on my car, no dramas, u just need to remember that u need two rear xx4 diff pulleys

super__dan · #12 04-05-2009

Just to add, conclude.

The newer machined pulleys are MILES better than the old moulded ones, particularly the centre drive pulley which is MILES MILES better than the moulded one.

The xx4 ones fit (though 2 rear ones needed) but change the ratio so you'll need to be likely a couple of pinions lower than on kit size.

If you were sold the kit on the premise that it was the current spec X5 squared, I'd ask them to change the pulleys for you, especially if yours have flashing on the teeth.

Kopite · #13 04-05-2009

hmm, so you could run a xx4 pulley in the front and overdrive the car?

ScottyP · #14 04-05-2009

Thanks all.

The kit wasn't purchased from a shop, so that would explain why it was old and had the molded pulleys. No problem though. Will just have to pick up the new machined gear set.

On another note, the kit came with VLA rear arms, but non VLA hubs. I take it you have to run these in the inner holes? Initially I had them in the outer holes, but the drives shafts are then too short.

Cheers,
Scotty

super__dan · #15 04-05-2009

Stan - You can and I have a 2nd one way diff made up with a xx4 pulley on. Ran it indoors but needs to be tried outdoors to really know what's going on.

Scotty - Yes, you can only use the inner hole. Just make sure the extra material on the outside doesn't catch your wheels. It catches one type but can't remember which, most just cut the outer hole off.

See this thread for extensive discussion on the rear end options and some nice pics from me