Heavy vibration at the rear end

[CapitanXeon]

Hello!

I'm having some issues with my car, as the rear of the car vibrates a lot at speeds between 90 and 110Km/h.

I was entirely convinced that the issue was the shock absorbers, as all four were leaking, and while i was at it, i also replaced springs for -30mm (H&R brand) so the car actually has a quite sporty feeling to it. I like it...except that the vibrations are now much worse because now the shock absorbers are actually doing its job.

The car was vibrating before tyre replacement, as well as before rim replacement, and while it could be, it's unlikely that the tyre shop messed the equilibrium two times in a row, only on the rear wheels, so while i'll try swapping wheels in and out to try, i'm not really keen on that idea.

I haven't checked much more back there, maybe some silentblocks are aging, but i don't see what could be making this mess. I went for the shock absorber idea as it felt like the wheels were bouncing instead of staying planted on the floor, but doesn't seem to be the case anymore.

I hope someone can direct me to an actual fix!

 

[richardwbb]

Stabilizer bushings perhaps or a about to fall off stabilizer? Your problem description sure sounds like it but don't blame me if it's fine there

 

[CapitanXeon]

Stabilizer bushings perhaps or a about to fall off stabilizer? Your problem description sure sounds like it but don't blame me if it's fine there

I really didn't ever get a clear view on the rear stabilizer. I'll definetely look into all rubber back there, as there is a bunch of silentblocks up front that have seen better days in its 20 year lifespan. However, i should asume that something is VERY loose to cause this? Or can be a seemingly inocuous issue?

And don't worry, i won't take nothing personal if that isn't the issue hahaha

 

[richardwbb]

No I can not be sure it can boink hard and look sound. Be aware some bolts might break before you decide to give it a thorough bolting job. Perhaps the field service manual will give you some insights on what to look for. If you have this sound both steering left and right I would look for stabilizer. If it is on one side then look for those parts moving parts that are in rubber to prevent metal on metal movement but again, be aware bolts might break.

 

[CapitanXeon]

The issue is mostly basically going straight on the highway, 60-80 mph.

On roads with turns and all that it's silent and very stable, i'm quite happy with that. All i know is that, it vibrates to pieces going straight, turns at slower speeds doesn't seem to do nothing, most turning i did at those speeds is well, all you can really turn on a highway, and doesn't change anything, so i'm inclined to think about wheels, bearings or whatever that can spin at high speed.

However, i'll take a look at every bolt i can, just to try and see. Thank you!

 

[richardwbb]

Ah yes bearings is something you might expect. To your description of the noise problem it just doesn't sound to me it is that but it is a replaceable parts that tends to go by mileage. You know how to check bearings for MOT?

 

[CapitanXeon]

Ah yes bearings is something you might expect. To your description of the noise problem it just doesn't sound to me it is that but it is a replaceable parts that tends to go by mileage. You know how to check bearings for MOT?

MOT here in Spain only pics up on bearings if your wheel is already falling off, i actually passed MOT with 0 issues on paper, but with all four shocks busted and already having this issue, so it's just a joke here.

I know that bearings aren't supposed to make determined sounds, and while driving i think i heard something, i will just jack the car up on an elevator, look for any kind of play, give it some spins to look for noises, and not much more i can think of.

 

[CapitanXeon]

Ok so, for now i haven't got the time to check anything, but i think i found something new.

I was driving home, quite sad honestly so i was going quite slow. I could sense some moving, but didn't think much about it, until i came to a traffic jam. At that point, going at like 20km/h (10-15mph) i saw the whole car was balancing left and right the whole time. I threw that at the road status, and waited for a known good road to test the same, and the same happened.

I'm willing to think that this was already happening before replacing rims and tires, but will try to get four wheels to test out, and will try to check if something is decentered, as it might be the cause of it. I will also try lifting the car and going "100km/h" to see if the front rotating assembly is fine or the vibration comes from there, as the front cv shafts make noises on sharp turns, like parking.

I will try to document this thread as well as possible so if someone sees their car doing this, can trace it out, as i'm currently out of ideas on what can be besides the wheels. All i can say is something that spins isn't spinning well, and either going very slow, or fast, but not at the middle, can be noticed.

Wish me luck heh

 

[richardwbb]

I am aware that I not really reply to what you wrote with what I write now but after replacing shockies for new ones all good. Then I decided to loosen and fasten the rears with those silly long heavy threads under those caps in the trunk. Now rear right has developed a boink sound in corners. Also the rear left after several thousand miles developed a boink. I checked it all I can not find it. A longer while ago I repaired the cable for opening trunk from drivers seat with a used one. With some help and I was surely checking everything and did it very good. It says a different boink on that side. On top of that, that is also comming from rear right now. And this last sound surely sound likes it is comming from the doors (2 door) and I can't find it. All I know is that those doors might louden the sound so it could be something else but what. Micra passed MOT recently and I saw how they checked the underside and no remarks. Now I drive it and corner it and have let go to find out where those noises are from, sadly.

 

[CapitanXeon]

News!

Yesterday I swapped the rear wheels for the fronts and viceversa, and the vibration went from "**** this car is unconfortable" to "not that bad but the steering wheel will fly away from my hands"

I can tell for sure it's a wheel issue, and presumably a wheel installer issue, as a closer look on the balancing weights, with up to 75g, doesn't look that great.

I will take the car to another place, and ask them to check both if the rims are still a circle and to rebalance them.

 

[richardwbb]

75g means something wrong. With such light rims you can't go above 50. That is a rule of thumb though. I've had some quite new stock rims (as a tyre mechanic) requiring 125g. Customers didn't come back so it must be went okay

Trick is to put air out of tyre, rotate tyre 45 or 90 degrees and balance again. Occassionally the tyre and the rim have a heavy spot on the same place. This is quite seldom. If you just balanced your tyres and this is the result you may ask for warranty since they should have rotated the tyre to the rim like I said.

Or your rim is bad (not round) or your tyre is bad (egg shaped, broken canvas) but they can tell by having a look at the wheel on a balancer. But mostly it is rotating tyre compared with rim. If they give you back your wheel with 75g they should have done the trick I said at no extra cost or tell you rim or tyre is bad. When you let them check it under warranty or not, let them put the tyre as it is now on the balancer before they remove it to see what causes the heavy weight. The heavy weight is no problem if you have no driving issues but when you have driving issues 75g is the problem or it is masking your problem. In rare cases the wheel wasn't put correct on the balancer (should not happen) so if with the wheel as first check on the balancer it looks okay they should remove all the weight and balance it, if the result is way below 75g your wheel is probably okay.

I hope this is clear to you else please post. I just wrote that out because some tyre mechanics have a hard time fault searching like I described and just rotate tyre or rebalance but then they will miss what actually causes the problem so as a owner make sure they put your wheel on the balancer, see what the real unbalanced state is (what you are experiencing) and then by looking at the rim and tyre turning if thas is good or not, then rotate tyre against the rim. Any other way might keep the real problem hidden by still a lot of weights.

 

[CapitanXeon]

75g means something wrong. With such light rims you can't go above 50. That is a rule of thumb though. I've had some quite new stock rims (as a tyre mechanic) requiring 125g. Customers didn't come back so it must be went okay

Trick is to put air out of tyre, rotate tyre 45 or 90 degrees and balance again. Occassionally the tyre and the rim have a heavy spot on the same place. This is quite seldom. If you just balanced your tyres and this is the result you may ask for warranty since they should have rotated the tyre to the rim like I said.

Or your rim is bad (not round) or your tyre is bad (egg shaped, broken canvas) but they can tell by having a look at the wheel on a balancer. But mostly it is rotating tyre compared with rim. If they give you back your wheel with 75g they should have done the trick I said at no extra cost or tell you rim or tyre is bad. When you let them check it under warranty or not, let them put the tyre as it is now on the balancer before they remove it to see what causes the heavy weight. The heavy weight is no problem if you have no driving issues but when you have driving issues 75g is the problem or it is masking your problem. In rare cases the wheel wasn't put correct on the balancer (should not happen) so if with the wheel as first check on the balancer it looks okay they should remove all the weight and balance it, if the result is way below 75g your wheel is probably okay.

I hope this is clear to you else please post. I just wrote that out because some tyre mechanics have a hard time fault searching like I described and just rotate tyre or rebalance but then they will miss what actually causes the problem so as a owner make sure they put your wheel on the balancer, see what the real unbalanced state is (what you are experiencing) and then by looking at the rim and tyre turning if thas is good or not, then rotate tyre against the rim. Any other way might keep the real problem hidden by still a lot of weights.

For my part, i was using a thumb rule that past 45g the tyre had to be unmounted and turned 180 degrees, so although with some variation, this is common practice. Unfortunately, i bought the car with very old tires and got almost instantly replaced, so i couldn't test how it behaved with the old setup. Also, i don't know if i told this, but i currently run Momo aluminium rims (which i can't find the model) with thicc spokes, so maybe if not the lightest thing in the world, they are pretty light i think.

Also, as the car doesn't really hit that much highways (it has done around 3000km on 15 months) i didn't really spot this earlier, but the steel rims also showed some vibrations, so i hope this isn't a rim/tyre issue but rather an installer issue, as this place is starting to get some bad rep exactly for this -a friend of mine with a Citroen C2 got excesses of up to 50g on one rim-.

As said, i'm putting this on hands of another garage, where my mom bought her car, and altough they were cheap tyres, they actually did gift her with four new tyres and the car works wonders so i feel it's both a way to show gratitude and to have someone that seems to know what he's doing do this. I'd do it myself but i don't have the required equipment, did it a bunch of times both in my dad's garage and in my formation so i kinda know how it's done -not too hard- so i'm betting on faulty equipment on where i did install the wheels.

Anyway, i'll explain him all i can as well as i can -i always hated when people came to us with lies, like if that was going the repair cheaper or something- and hope i can cut him as much diagnosis as possible -but i'll ask him to check if the rims are okay-.

I also lowered the car -30mm so i might eventually align the whole thing when i replace some worn out rubbers under there, but that's a thing for another day.

 

[richardwbb]

Yes I wrote 45 and 90 but that should be 90 or 180. I think it is the tyre and rim combination. And the whole explanation because I know there are tyre mechanics that are good mechanics but miss the big picture. Just rebalaning them doesn't necessarily make the problem go away and then it should happen again, so better to first find a clue for why it has a big weight. And in the first place, they shouldn't have such a tyre give such a big weight and install it in the first place.

 

[CapitanXeon]

And in the first place, they shouldn't have such a tyre give such a big weight and install it in the first place.

Yep, that's the whole point to me. They might just have a broken balancing machine or i might actually have a bent rim, but instead of checking, just put a bazillion weights and cash that sweet money in.

 

[richardwbb]

Yeah it shouldn't be that way. It may cost money but those balancing prices are flat. That you happen to have a rim with something going on, they should try to fix that for the same price. This is because people that want balanced their wheels can't help it if something is wrong with the wheel in the first place, they have the tools to pinpoint the problem. Also sending you away with 75g on such a wheel and you still have a complaint means their initial work was not 100%. Actually this is a warranty issue even if it is your tyre or rim not sold by them that has the initial problem. I hope to hear from you how it went.

 

[CapitanXeon]

Yeah it shouldn't be that way. It may cost money but those balancing prices are flat. That you happen to have a rim with something going on, they should try to fix that for the same price. This is because people that want balanced their wheels can't help it if something is wrong with the wheel in the first place, they have the tools to pinpoint the problem. Also sending you away with 75g on such a wheel and you still have a complaint means their initial work was not 100%. Actually this is a warranty issue even if it is your tyre or rim not sold by them that has the initial problem. I hope to hear from you how it went.

I've replaced my tyres and the issue has gone away completely, so it may have just been some kind of flat spot...god knows, they weren't good tyres tbh. Sorry about the late response but that's how it goes, until i didn't have the money to replace the tyres i couldn't confirm this.