TT Comps and bolt size

cheechy

cheechy

A2OC Donor
I've recently fitted TT competition alloys to my tdi90.

I've had the wheels balanced 3 times now and cant seem to get rid of a very slight wobble at motorway speeds. I'd normally put this down to wheel balancing but you start to question at the 3rd attempt right? :)

So wheels aren't 100% perfect as youd expect for wheels that are in the range if 18 years old...but look more than good enough.

I tried swapping wheels around to no avail.

Do next train of thought is bolt length. I know the wrong length can cause issues but I'm trying to work out if the standard 27mm is about right for 7.5 wide wheels? I've actually got 32mm boots fitted on the back but I'm starting to think they might be too long and not able to torque up to spec.

For info I had pepperpots on previously...fronts with no spacer and 27mm bolts, backs with 5mm spacers and 32mm bolts.
 
Can I suggest that you refit your pepperpots to rule out anything not wheel / tyre related as this was your last known good datum.
Are the wheels true and each time did they need rebalancing? What condition were the tyres in? What ET are the comps? Why are you mixing the wheel bolt lengths? Are the bolt you are using the correct profile head for the wheel - some bolts are conical and some are spherical for a reason.
 
Pepperpots were only taken off around 10 days ago no shaking. Bolts are all conical and have been fitted without issue in the past.

The reason I'm mixing is that I'm stumped as to whether the bolts are too long or short...or indeed the 5mm difference in size may be negligible anyway.

Tyres are brand new ps4.
 
cheechy said:
Pepperpots were only taken off around 10 days ago no shaking. Bolts are all conical and have been fitted without issue in the past.

The reason I'm mixing is that I'm stumped as to whether the bolts are too long or short...or indeed the 5mm difference in size may be negligible anyway.
Click to expand...

Checking the bolt length required seems a simple matter. Fit one of the bolts you used with the pepperpots into that wheel while it is off the car, and measure how much bolt protrudes out the back of the wheel. Now transfer the same bolt to one of the TT comps, and measure how far it extends from that wheel. I'm assuming that you're not using spacers. Then you'll know whether or not you simply need standard bolts, or something of a different length.

Can you be more specific as to the precise rims you are now using by identifying the appropriate page on this site:

Audi Alloys from Alloy Wheels Direct

Get your perfect Audi Alloy Wheels from Alloy Wheels Direct. Optional tyres & fitting - Fast Worldwide Delivery on orders (Free on UK orders over £100).
www.alloywheelsdirect.net www.alloywheelsdirect.net

Thanks
 
I've seen some places fail epically at balancing. Others do a great job.

You're sure your bearings are not on their way out? By motorway speeds you mean 70mph+? or 50-60?
It's quite possible that the rims are not totally round, but the tyre shop should be able to see that on the balancer without any issues. You're also sure that the mating face on the hub is totally clean?
 
Yup I know one isnt 100% for sure but shop assured they were able to balance.

From speed I'm getting from around 65mph to 70mph (as obviously I dont speed :) )

Good shout on bearings I'm not hearing any droning but I'll try and move the wheels around next time I lift the front up.

Again though I do have doubts given the pepperpots didnt have amy issues only 10 days or so back.

I can see me trying to rebalance first the 4th time i suspect!
 
to clarify here: i have (had for a long time) a minor vibration at motorway speeds / 120km/h. In my case, it's the rims; the centering ring I use doesn't match nicely with the spigot from the hub and it doesn't sit well in the rim. So they vibrate gently. Not always at consistent speeds, not always seriously, just vaguely annoying. If these are OEM rims, the centre should not need a spigot / centering ring as the hole should be the correct 57.1mm. But they still need to sit cleanly on the car hub face.
When I didn't tighten wheel bolts up well on the Octy, that was obvious, it clunked a lot. As were many of the balancing acts I've seen... and the hub that just recently failed - that started failing halfway through Sweden a few years back and it was bouncy as hell. Awful.

the way I know the bearing is shot now? spin wheel with hand on spring. It's obvious when the bearing is shot - and in my case, you can hear it, too :) Just don't want to drop the €200 to fix the darned thing...
 
cheechy said:
Thanks I'll revert to stock 27mm just in case that's the issue
Click to expand...
Just saw this thread and I think that could well be part of your issue.

As has previously been mentioned, make sure the knave of the wheel where it mounts onto the hub is perfectly clean and smooth (and the hub itself too) as I have seen on numerous occasions wheels bobble slightly on a wheel balancer only for it to be that the wheel isn't mounting perfectly flat due to a foreign body of some sort.
I personally always sand the knave of my wheels with a 150mm 80 or 120 grit sanding disc on an orbital sander before balancing the tyres and fitting them on the car to make sure they are perfect.
I also always balance my own wheels/tyres so I know they are perfect but I know this isn't possible for most people and they are reliant on the competence and care of the fitter but always have your tyres dynamically balanced rather than statically balanced meaning the weights are put on the inner and outer edges of the barrels or inside of the rims, not just the inner edge which ensures they are far more accurately balanced.
Also try to take a look at the inner lip of the rims when they are spun on the balancer before the fitter applies the weights as you can then see if there are any flat spots from potholes and any wobbles and always fit the truest wheels on the front as you probably wouldn't feel any slight wobbles on the back of the car, where as you would on the front at speed, even if they do balance up ol with the weights.
Also make sure your tyres pressures are correct as that can make a big difference too.

Your TT comps will fit perfectly and bolt straight on and just need standard bolts but you really need to check the rims to see how true or not they are.

I hope some of this helps or at least might help someone else a little?
 
cheechy said:
Pepperpots were only taken off around 10 days ago no shaking. Bolts are all conical and have been fitted without issue in the past.
Click to expand...

VW group rims use ball shaped (aka spherical) wheel bolts not cone shaped wheel bolts.

You should only use the correct shape for the rim.
 
Thanks for input ...and on last point I'm on stock bolts so they must be spherical I guess. The longer bolts were also the same type.

Changed around and took.for a run with stock length bolts and still getting some rumble it seems, all be it it was being interrupted by the noise of grinding metal...I'll need to take the wheels off to knock some stones out I guess.

Given the refurb guy (an a2 enthusiast himself) gave the wheel centre / knave a flatten down with a sander whilst I was there it sounds like I'll need to find a quality wheel balancing service locally.
 
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The rims might be buckled. Up/down and/or left/right buckle.

No amount of wheel balancing will take out the vibration from a buckled rim.

It's best not to use wheel spacers that aren't hubcentric...and you can't get hubcentric wheel spacers that are less than 10mm...and not all 10mm wheel spacers are hubcentric.

A hubcentric wheel spacer centres the rim on the hub. If the wheel spacer sn't hubcentric, the rim might not be centred exactly on the hub resulting in wheel vibrations even if the wheel has been balanced.
 
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Take them to a wheel refurb Co, and ask them to check for roundness and truth. Ring them first, to check if they will do this for you and how much.
If there is a problem, they will be able to put it right (probably).
Mac.
 
Rims look to be fairly true but there are undoubtedly undulations in there that look to be causing a slight wobble at motorway speed. I get some would put up with this but this is a pet hate of mine - i cant stand any kind of wobble at speed as it feels like control is being taken away from me when I'm driving and it affects overall driving comfort.

The wheels have just been refurbed for info so they were not bad enough to merit correction.

I'm not using spacers on these wheels.

I phoned a highly thought of Edinburgh wheel specialist this morning and booked in for Thursday. They feel confident that they can balance these with a bit of time and properly calibrated equipment.

If this doesnt provide perfect results the next step will be a visit to a Hunter balancing centre as they will achieve the result but at 4 times the cost :)
 
Another option is to use a product like Equal granules which are placed in the tyre and balance is effected by centrifugal force throughout the running life, a filter valve insert is required tho
 
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