Megane II rear axle defects

[Logic28]

Renault are notorious for rear axle asymmetric designs since the times of the R4 with the rear torsion bars necessitating the N/S rear to be positioned forward with respect of the O/S

I also know that we cannot expect the best precision from a pressed and welded steel rear axle but I would have thought that a decent jig would have delivered a minimum standard for the Megane rear axle.

According to most threads here and on other Renault related forums, the rear end of our Maggies suffer from rear suspension out of tolerance manufacture problems.

I didn’t need to do any reading in order to discover this as, having driven a 2003 1.5 model with knackered rear shocks for a while,I can tell you that the change in rear toe at every road imperfection would produce a noticeable bump steer towards the outside as opposed to the inside (as per toe-in specs).

Now, having carried out a geometry check on my other 2007 megane privilege (I have 2 Maggies now) I see that, despite the correct front alignment and parallelism in respect to the rear wheels, the car is moderately crabbing, hanging the rear to the left as I expected, having found the rear right mildly towing in and the left with no toe whatsoever.

Not sure if the rear axle rubber support are to be blamed for this but I strongly suspect that I am experiencing one of those defective rear axle unit and wonder if someone else in the forum can confirm the same.

One way to resolve the problem would be to fit a pair of eccentric rear mounts in order to equally distribute the native axle toe between the two wheels and also possibly bend the axle itself if the toe in was found to be insufficient.

Any thoughts ?

[robbie1003]

Depends on how far out it is, not many cars are spot on and there is a allowance for thrust line to be out. Just had to do a fix on rear camber and toe on my x type at the rear, all I did was elongate the mounting holes in the subframe to allow movement inbound, larger thicker washers fitted to the bolts and makesure they were tight, geo is spot on now. Any way you could elongate the axel mounts and do similar?

[Logic28]

Yes, I was just about to do that or even better design and fit an eccentric mount.
I know the N/S rear is not much out ( about 10' . . .or better still not enough IN) but is having an effect that requires readjusting the front (re-centring) in order to keep the steering wheel in the right position.
Again even that is only about 1º to 2º at the wheel . . .

it's all very didactical considering that even the best Porsche (I used to race prepare them back in the 80s) is hard to get dad straight especially the rear where the camber adjustment affects the toe and vice versa . . . . .

[robbie1003]

There's not many road cars that are spot on or have the adjustment, the european cars I will say are the worst at being out especially at the rear,Fiat 500 and the ka on my system never seem right at the front. If your on roads and not race track then most cases are fine, I find BMW are a pain for needing ballast for a geo check but yet only carry 1bloke in a white shirt all the time.