Weird handling after strut top replacement XM

[bump_draft]

I replaced the front control arms and strut tops on my 1990 xm

Now when I accelerate in low gears, the front end pitches up quite a lot, even under moderate throttle. When this happens the car pulls to the right quite a bit, like it's torque steering. My guess is the pitching is causing weird toe movement. But why is it pitching?

Toe is zero, I measured it twice. It tracks straight when cruising. Hydraulic fluid levels are correct.

I don't understand why it's pitching up and down so much now? Is this is a hydraulic issue? Maybe one side isn't getting fluid or something? I'm baffled. How do I check hydraulic performance of individual corners?

[Armidillo]

Better put this question on Club Xm as well - Dieselman might have some ideas.

Don't have a clue about the torque steer, but it might be worth bleeding the system to make sure you get all air out. Make sure the regulator pressure release screw is properly tightened, put the car on High, then bleed the brakes (the only bleed points). Would also be worth looking in the LHM reservoir (with the engine running and car at normal height) to see if you can see bubbles. A lot of fine bubbles might indicate one of the spheres has just chosen this moment to rupture and feed it's nitrogen into the LHM.

I presume the best order for bleeding is same for LHD and RHD cars. Looking forward, I believe you do the LH rear first, then the RH rear before the LH and RH fronts.

[Stickyfinger]

Bleed it by setting LOW/High a few times and Turn the wheel left/right (but do NOT hold) a few times...

Did you only tighten up the lower arm rear bushes AFTER the car was down on its wheels ?

[xantia_v6]

Are you absolutely sure that the correct sphere(s) was fitted in the right place? An accumulator sphere on a front strut would cause the pitching that you described.
Less likely, but was the replacement strut mount the correct specification for the car?

[bump_draft]

Ah, I didn't know the system had to be bled. That makes sense.

Definitely the right spheres as I did one side at a time, so there was only ever one sphere off at a time. I still haven't gotten around to the accumulator...this car is a handful

[Hell Razor5543]

I do not know if this will help, but when I replaced the accumulator on a Xantia what I did was to drop the suspension to its' lowest position, turn off the engine, and then locate the pressure bolt on the accumulator block. Loosen this off a couple of turns (NO MORE than that; there is a small ball bearing providing the seal, and if the bolt is removed that ball bearing will make a very determined (and probably successful) attempt to escape!), and you should then hear a whistling noise. Once this has stopped I would wait for a couple of minutes (just to make sure there was no pressure in the system), put a cheap washing up bowl underneath (to catch any spillages), and then replace the accumulator sphere (making sure not to pinch the seal between the sphere and the accumulator block). Start the engine up, and leave it running for a couple of minutes (this should help circulate any air back into the reservoir), and then tighten up the pressure bolt. Wait a minute or two more, and then raise the suspension to normal height. Remove the washing up bowl, and then perform a Citrobics session.

It is possible that the accumulator sphere may not want to come off the accumulator block (fortunately this did not happen to me), so you would need to remove the whole assembly. I do not know what is involved in this, but I know that there will be the information you require here on the Forum.

[xantia_v6]

Bleeding of XM / Xantia suspension is relatively simple.

The pump to regulator circuit is self bleeding. Putting the suspension on high for the time it takes to rise + 30 seconds, fills the spheres with LHM and pushes any air into the spares, but due to the pressure, the air takes up very little space. Putting the suspension to low releases most of the LHM and most of the air into the return line to the tank. It is important to leave the suspension at low for about a minute to allow the sphere diaphragms to push out all of the LHM.
It is probably slightly more effective to perform the bleeding procedure immediately after a run on some rough surfaces, so that any trapped air has been broken into microbubbles (foam) and is carried more effectively in the LHM flow.

With regard to your suspension behaviour, how is it with the suspension in firm mode? How does it feel if you manually bounce the front suspension by pressing on the bumper?

[bump_draft]

I don't have a firm mode, it's unfortunately a non-hydractive model.

[xantia_v6]

OK, that reduces the list of possible failures...

If you bounce the front corners of the car, do they seem to have the same damping?

A long-shot, but easy test would be to swap the left and right spheres and see if the problem moves.