Having had my Indy on the road since Feb this year I'm now at the end of my tether...

I get a nasty chattering at a constant speed over 50mph and a horrible vibration at 60mph upwards when accelerating.

I'm on my 3rd propshaft, and just replaced the diff (3.64 LSD), not all at the same time in an attempt to isolate the problem, and still the same vibe - Its not going to shake the car to bits, but will accelerate fatigue on the whole car (especially the back end) - I maintain Helicopters so have a fair idea about vibes, causes and solutions...

If I disconnect the prop at the front and run the engine, it runs smoothly in all gears right upto 11,000rpm in 6th.

Anyone any ideas or experienced this before?

Any help would be appreciated, cheers.

How do the output flange, centre bearing and diff input line up ?

i.e. how far away from being in a continuous straight line are they.


I should just have said - "how is your drivetrain alignment", shouldn't I ?

Maybe

I would've thought about normal, maybe 5 degrees - The whole point of universal joints/flexible couplings is to allow for slight misalignment... Although, with the trans tunnel covers of, back end jacked up, car in 1st gear (spinning the drivetrain slowly) everything looks spot on, no wobble, nothing sus at all.

My next train of thought is taking the whole drivetrain off and getting each part balanced (somewhere) but this seems excessive but like I said, I've had enough!

Just so I know who to avoid . Is the sliding joint allowing enough movement and not binding?

could it be a clutch alignment problem?

Peteff: Prop is from MK, although seems fine, all joints lubed and move freely, no play in the joints, binding or tight spots.

Nick 205: The clutch is inside the lower half of the engine casing (Bike) and as such, disconnecting the front of the prop and running the engine at 11,000 rpm in 6th gear (so that just the output shaft is turning) would highlight any problems with the engine/gearbox/clutch... Honda made the Blackbird very smooth with 2 balancer shafts and is rigidly mounted on the bike frame - It really is that smooth!.

Thanks for your comments guys.... Problem still here though

Don't mean to be simplistic - have you balanced the wheels/tyres? Are the rear hubs new - possible lateral accident damage? Looking elsewhere other than your previously indentified problems.

Everything on the car is either refurbished or brand spankers.

The original wheels n tyres - now my wets (Team Dynamics Tornado with BF Goodrich Profiler G) were brand new, fitted and balanced... Just fitted a brand new set of Team Dynamics Pro Race 1s with Toyo Proxes R888, again came fitted and balanced, I saw them being balanced. All 15" wheels.

Besides, I'm pretty sure its not a tyre imbalance, the chattering noise I mentioned is mechanical.

Perhaps wheel bearings? Although if it were I think you'd just have vibration and not the mechanical chattering I'm unfortunate enough to have.

Chris: Yeah, there's a spacer fitted. Nothing moving there.

[Edited on 25/11/04 by Jim1556]

[Edited on 25/11/04 by Jim1556]

Have you got the spacer in for the central mounting bracket - drivers footwell. Is the support functioning correctly...




As you can see from the pic - I would say our prop was 10 degrees out of straight - we don't have any problems with imbalance anywhere.

i noticed that my new clutch plates and uprated springs notably improved the drivetrain vibration on my Indy.

although no expert Iwould say that to find the problem you really need to run it on a rolling road, possibly with a load = to the drivers weight in the car. Disconnecting the prop - jacking it up etc. is not simulating all the forces acting on the car whilst driving.
If you jack it up & run it make sure it is very secure, but you need the rear suspension loaded so the drive shafts are at their working angle.
If the vibration is through the whole car I would examine inside the drive shaft joints very carefully, there are lots of roller bearings etc.
good luck.

Problem I have experince of in other halve's rwd bmw is wheel bearings, terrible vibrating sound and noise Need replacing, booked it in for december). are cv joints likely to make noise if on way out? were these donor or recon items?

Ned.