Diagnosing body shake

Area Discussion Cheshire and North Wales
2

I’ve moved up to a Mk3 1.8 and have an irritating shake/wobble/vibe. I’m finding it hard to describe what it is.

I feel it through my backside, the wheel and the body. The passenger can also feel it.

Following general actions I have fitted new tyres had them balanced and tracking done (it was well out).

The rear tyres required a lot of balance, 40gram(IIRC).

Current garage feeling is I should replace the rear rims.

I’m not 100% convinced and would like it confirming.

Is there anyone in the N/W area (St Helens) that would be able to meet me and compare the drive to their car ?

Would anyone be happy to do a temp wheel swap to see if that cures it ? (If it did I would happily buy new ones.)

Basically, I don;t mind spending the money if it defo needs it.

3

Hi YTC1,
At the risk of stating the obvious, have you actually checked the tyres for roundness and wobble when fitted? They should be true within about 2mm when spun up off the ground. If they need a lot of balance from new it indicates they may not be centrally seated on the rims.
Are you sure the vibration is coming from the rears?
If you can feel it through the steering wheel, it could be the fronts as well…

Are the rims original 16inch Mazdas? It’s not unknown for aftermarket wheels to be some way out of round - I had occasion to get one set re-machined to actually true them up to the wheel fixings and spigot. Admittedly a few years ago, but there are some dodgy ones about.
Again, at the risk of ‘teaching Granny to suck eggs’, it’s worth checking the security of the propshaft UJ’s and torque tube if the wheels prove OK.

My NC 2.0 Sport is a bit noisy from the rear, (they all can be with hood up) but smooth as a baby’s bot - as they should be.

Good Luck
Aldi

4

 

The issue existed prior to new tyres, a (very) small bulge was seen on the fronts and another on the rear. So I had all four tyres done.

The garage has checked and re-balanced since.

I didn’t measure the trueness of the rears, the mechanic commented it was worse than normal.

Nope, not sure it is from the rears (or even the wheels). But it is not as I would normally expect wheel balance issues to be.

It is there all the time,actually feels smoothest around 85.

I was on the back roads over the from Brough to Newcastle yesterday and it felt very shaky as I swung in and out of the bends.

Sometimes I would say it feels like running over rumble strips… constantly.

Pretty sure they are standard rims. They look like others I have seen.

All the above reasons are why I would like a 2nd opinion from someone with more experience of the MK3.

Garage say no noticeable issues with the prop shaft.

Now I will ask what is a torque tube ?

5

Torque tube is probably a bit of a misnomer…it’s an old-fashioned term.
I mean the diff mounting plate which extends forward to the body and forms a reaction point for the differential. Not unknown for them to get loose, particularly if they have been taken off at any point.
Other possibility is rear drive shafts…do they feel smooth when rotated - any clonking?
Did they actually check the UJ bolts for tightness; and propshaft for runout?

If the tyre fitter/mechanic picked up the out of roundness then it must be there, and will for sure give you a lumpy ride at best.
My car has 17 inch rims, so can’t really offer a comparison.
Sorry…

Aldi

6

You may have checked already for correct tyre pressures but it’s suprising how many report terrible handling/ride problems and it turns out to be over inflated tyres. Even new cars or cars that have had a tyre change, just my thoughts, ignore it’s that’s not the case.

7

I had a Mk2 “shaker”.  New wheels and tyres sorted it.

When I finally took the old wheels off - they were aftermarket ones - I noticed that there was one spigot ring missing. That might or might not have been a factor, there were also three different brands of tyre on it!

Might be worth checking, if your existing wheels are aftermarket ones with centre bores bigger than the spigots.

8

It does sound like out of true or out of balance rear wheels, especially as you say the mechanic commented on it.  One easy check is to swap the front and rear wheels and see if the problem goes away or moves to the other end of the car.

 

JS

9

 

It’s not a tyre pressure issue :frowning:

 

10

 

At least I am not the 1st to experience it :-).

I’m thinking of the ones from mx5parts.co.uk

11

For some reason I had ruled out doing that (must have had a brain freeze).

I’ll borrow a trolley jack off a neighbour.

12

Had a similar issue on a MK2.5 a few years back, turned out to be a slightly bent rear hub assembly from where the car had previously been in an impact with a kerb or something

Changed the hub and all was well

Im not saying this is your problem, but it was checked by lifting the car, removing the wheel and spinning the hub with a gauge against it

13

Swapped the wheels from front to back, and … errrr… no difference :frowning:

I reckon the key is the “rumble strip” feeling, it is as if something kicks off the suspension ?

Yet when I do a “bounce test” that all seems ok.

Totally doing my head in.

14

While it was jackedup did you try spinning the wheels (easier with the fronts!) and wath them carefully to see if they ran true?

15

No, I found it hard enough crawling around doing this as it was.

I really don’t think this is a wheel issue. Zero difference. Steering wheel fine at all speeds.

16

many many many years ago, I had a UV joint fail on a prop shaft.

I never noticed any build up to it failing, but then again, I was only a kid, so probably wouldn’t have paid any attention.

I believe that prop shafts are balanced, maybe related ?

I think a temporary wheel swap would be a good idea, maybe someone has a spare set with winter tyres on ?

17

 

I’ll get it back to the garage to re-check joints etc, but they are usually spot on with seeing this sort of stuff.

I’ve heard of the prop shaft rumour, and have not found anywhere local (NW) that could fulfill that quickly (North West Propshafts in Chorly seems to be the nearest , any one any experience of them ??).

 

Swapping he front and rear was as good as borrowing a set. Zero change, therefore not a wheel/rim issue.

18

…many many years ago I had this problem on a Triumph GT6…turned out to be the prop shaft. Somebody at the time suggested putting a jubilee clip around it and rotate it till it got better. Never tried this as I sold the car and went back to two wheels for a another few years…

19

That reminds me… I had exactly the same problem on a Triumph Spitfire in the 1970s.  A propshaft UJ had been replaced by the previous owner who had turned one of the yokes through 180 degrees when reassembling the joint.  Took me a while to find that problem. 

JS  

 

20

 

Ok, all checked over (again). Nothing the garage can see (joints, bushes etc yadda yadda).

Found a nice MX5 person who let swap wheels today.

I’d say it improved, but there was still something there. Now thinking multiple issue (maybe the fact I have noticed 1 rear suspension has been changed and is not a Mazda one) and one problem leads to another.

 

So, going to splurge out on wheels (bye bye £400+).

Only question remains, get the standard 110 (ET55) or one of the various ones that are ET45 ??? Thoughts ?