Small Shudder Approx Every 4th or 5th Wheel Rotation.

Sunroof

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My Floride S has a very small shudder felt through your backside perhaps every 4th or 5th wheel rotation. It feels to be in the rear. It is more pronounced at higher speeds. Not there at all at slow speed say 60 kph. If it was a tyre or rim surely it would be there continuosly. My tyres are 14 years old and the front two were out of round and have just been replaced. Yes, I am about to order a full set of Michelins from UK. But I'd like to find the shudder before replacing the whole set.
 
If it is very small and only comes on at higher speeds I would not rule the wheel/tyre out. On the contrary.

The fact that only happens every fourth or so rotation might rule it out but everything in the car spins faster than the wheels.

Just for the sake of sanity and because there's nothing to it, I would do a tyre rotation and check. Use the new front tyres.

Other than that, clutch bearing? Clutch assembly?
 
Before you spend a fortune importing some michelins - have a think about getting some standard 15" rims converted to a 5.5" width. 15x5.5 is not exactly common, but not that rare. I've had quotes from a wheelwright to supply and fit either 5" or 6" rims to my standard centres for about $150. About half that cost is the rim. However, I am looking to get some 5.5" rims off an Astra, Honda Jazz, Hyundai etc and use them for the conversion. A world of great tyres opens up at these widths, starting with 175/60R15 for the fronts and 185/65R15 for the rear. This combo will lower the front ever so slightly and give the swing arm rears a little more squish. The look from the side of the car will be almost identical to stock tyres in terms of sidewall height and rim size. These two calculators are very useful for playing around:

https://tiresize.com/calculator/ to compare the dimension of a tyre choice with the standard tyre size

https://www.wheel-size.com/calc/ to see if a new tyre/rim will fit and help you calculate the correct offset to keep handling happy

Just a thought!
 
My thought is to immediately check that all wheelnuts are tight and not binding before they secure the wheel to the hub. An improperly secured wheel will give that exact type of shudder or shift intermittently as road conditions and speeds etc change and it wobbles. The other that can do this is insecure springing or suspension shifting. A good inspection of all securing points may eliminate problems with the directional geometry of the car.

Ken
 
Before you spend a fortune importing some michelins - have a think about getting some standard 15" rims converted to a 5.5" width. 15x5.5 is not exactly common, but not that rare. I've had quotes from a wheelwright to supply and fit either 5" or 6" rims to my standard centres for about $150. About half that cost is the rim. However, I am looking to get some 5.5" rims off an Astra, Honda Jazz, Hyundai etc and use them for the conversion. A world of great tyres opens up at these widths, starting with 175/60R15 for the fronts and 185/65R15 for the rear. This combo will lower the front ever so slightly and give the swing arm rears a little more squish. The look from the side of the car will be almost identical to stock tyres in terms of sidewall height and rim size. These two calculators are very useful for playing around:

https://tiresize.com/calculator/ to compare the dimension of a tyre choice with the standard tyre size

https://www.wheel-size.com/calc/ to see if a new tyre/rim will fit and help you calculate the correct offset to keep handling happy

Just a thought!
Thanks for the thought but I do already have wider 14 inch rims that have been on and off the Floride S over time. And mags on my 10. No I am even going down from 145 to 135, originality is what I aim for with this car. 4CVG on this site will shudder at the thought. Actually about $800 for 4 tyres and tubes and $450 for freight is expensive I know. But the Cooper Tyres on my Landrover cost that and never a thought about trying to do it cheaper. If the Mrs knew what they cost for the Floride it might be different.
 
If it is very small and only comes on at higher speeds I would not rule the wheel/tyre out. On the contrary.

The fact that only happens every fourth or so rotation might rule it out but everything in the car spins faster than the wheels.

Just for the sake of sanity and because there's nothing to it, I would do a tyre rotation and check. Use the new front tyres.

Other than that, clutch bearing? Clutch assembly?
Yep good thought, if its tyres then the steering wheel will shake. I do have a wheel balancer with a gauge that can measure out of round tyres, rims, etc. I suppose I should have checked. But the smooth periods sort of ruled out tyres in my mind, but perhaps not.
 
I thought about it a bit more and the frequency of the shudder would suggest a resonance type process not a simple rotation induced problem (wheels or other things). I wonder if you could suspend the car and "drive" it to the speed where the shudder happens. Leave rear wheels off. Would be good if suspension were compressed to normal ride height. Difficult to do safely but not impossible. This would definitely rule wheels out (or in).

Or maybe not. If the effect is a complex compound of many rotating things, it's going to be a lot of fun to diagnose.

One thing that comes to mind is a ball bearing. When they're new, you can spin them on your finger (all grease and lube out, perfectly clean) and they go smooth and uniform round and round. When they are a bit worn, the play allows them to rattle and they don't rattle at rotation frequency because there is a little precession in the ball-cage assembly, so you hear a rattle going at a slower frequency probably as the balls re-arrange themselves in the cage to take up the play.

I did have a similar symptom in my R10 when the thrust bearing was worn. Still worked fine but I could hear it because my ear was finely tuned to distinguish the sound under the racket of all other noises. My wife thought I was an OCD idiot.

I don't think the steering wheel would shake if it wasn't a problem with the front wheels (or other gubbins in the front end).
 
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Dunno about the Floride S, but the R8 driver's handbook has 145-15 as an option on the 4" rims. I've recently fitted 145-15 XZX tyres to the R8, with a surprisingly large (to me) improvement in steering, particularly improved turn-in. I got two of them from Richards Tyrepower in Perth and two from Stuckey Tyre Service in Melbourne, all for $275 each, preferring to support local where possible. Both are excellent to deal with but Stuckey usually have them in stock. I run tubes, not least because the early R8 rims are not safety rims and, yes, there's much debate on THAT subject!

Doesn't matter how many times I have them balanced, it is hard to avoid a bit of vibration at the front on super smooth bitumen around 100 kph. And that is after having the wheels rolled etc.

I wonder whether you have a very slight bend in a half shaft or a UJ with a bit of slack? Are the silentbloc bushes in the trailing arms OK? The trailing arms locate the whole engine/transaxle unit parallel to the car.

Should I ask about a certain R10 front wheel bearing? OK for local I guess! :)
 
What about rear end alignment, perhaps too much toe one way or another causing the tyres to bind up ever so slightly then periodically release?
 
Thats a few options I can try. There are no 145 Michies only 135 so 135 it is. Trouble with interstate tyre supplies I still have to pay freight. Local Tyre Power says he cannot get Mitchies in either 135 or 145 but does sell other Mitchlin tyres. I'll check the suggestions above. The R10 has all new wheel bearings on the front, the rears were not long ago replaced. The rears on the Floride have also been replaced a couple of years ago.
 
If as you said initially it is every few turns of the wheel, I would suspect the wheel bearings.
Think about it. On each turn of the axle shaft, the balls between the inner and outer race
will roll and progress about half a turn. If there is some degradation of one of the balls and a corresponding
collapse in one of the race grooves, the ball will hit the bad spot of the race cyclically at a lower frequency
than wheel rotation.
Or, are the hub nuts correctly tightened and seated.?
 
If as you said initially it is every few turns of the wheel, I would suspect the wheel bearings.
Think about it. On each turn of the axle shaft, the balls between the inner and outer race
will roll and progress about half a turn. If there is some degradation of one of the balls and a corresponding
collapse in one of the race grooves, the ball will hit the bad spot of the race cyclically at a lower frequency
than wheel rotation.
Or, are the hub nuts correctly tightened and seated.?
Jack up wheels, you should be able to feel this if bearings faulty
May as well start car and engage gears to see what shudders when wheels are off
Worn tie rod ends are notorious for shudder
 
Thats a few options I can try. There are no 145 Michies only 135 so 135 it is. Trouble with interstate tyre supplies I still have to pay freight. Local Tyre Power says he cannot get Mitchies in either 135 or 145 but does sell other Mitchlin tyres. I'll check the suggestions above. The R10 has all new wheel bearings on the front, the rears were not long ago replaced. The rears on the Floride have also been replaced a couple of years ago.
Covid supply problems perhaps.... Stuckey in Melbourne hasn't 135 or 145 in stock according to their website, although they usually have. I must have been lucky. They are made in batches in Serbia so I guess we have feast or famine! There is/was a 135-15 Nangkang and French friends use Firestone in that size. Dunno who makes 145-15 - never looked.

Good re the front wheel bearings! :)

I'll be interested to hear about the rear end noise. Case hardening failing on the wheel bearings? Our R8 rears did well over 300,000 without any play but when I pulled them down for a precautionary change at about 50 years they had no play but were a bit rough. Apparently you can get fully sealed ones now but I'll not wear out what I have in my lifetime!
 
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I was thinking about hub nuts as well. Given that the bearings in the rear are ordinary ball bearings it is difficult to get the nut spot on. Too much or too little pinch and they won't be happy.

Even if new, I would still inspect them. A grain of dust, a little bit of force and you can compromise the race or the balls or both.

Wonder if you could get angular contact bearings but I think I know the answer already.
 
From memory the rear hub nuts are first done up to 160 ftlbs with a flat washer. Then the nut undone and the cone washer inserted and again 160 ftlbs. But I have checked the fronts for worn ball joints, tie rods, etc. Used a long bar and a 19mm socket and got a little more out of the rear wheel nuts but the fronts were tight. I'll do all the checks suggested above first, then take it for another drive.
 
My money would be on one of the universal joints at the diff.
 
My Floride S has a very small shudder felt through your backside perhaps every 4th or 5th wheel rotation. It feels to be in the rear.
Could be embarrasing if it were anywhere else!!:evil:
 
The fronts have taper roller bearings, I wouldn't tighten those too much or they will collapse. Ask me how I know. Take out play, go a tiny little bit more and supervise in use.

Haakon is right, the rear unis need checking too.

Come to think of it, the rear joints are not really constant velocity, never thought about this, I wonder if this is not inducing premature wear somewhere?
 
From memory the rear hub nuts are first done up to 160 ftlbs with a flat washer. Then the nut undone and the cone washer inserted and again 160 ftlbs. But I have checked the fronts for worn ball joints, tie rods, etc. Used a long bar and a 19mm socket and got a little more out of the rear wheel nuts but the fronts were tight. I'll do all the checks suggested above first, then take it for another drive.
The fronts have taper roller bearings, I wouldn't tighten those too much or they will collapse. Ask me how I know. Take out play, go a tiny little bit more and supervise in use.

Haakon is right, the rear unis need checking too.

Come to think of it, the rear joints are not really constant velocity, never thought about this, I wonder if this is not inducing premature wear somewhere?
My R8 is on its originals at 360,000 km. The good thing is how clean they are kept inside the swing axle pivot system.
 
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