ACTIVA NOSEDIVE

[chrisjvm]

My Activa seems to nosedive under quite modest braking
As if there is a definite bias towards the front brakes.
Any suggestions gents ?

Regards

Chris

[davoxx]

Fluid may be low?

[xantia_v6]

My Activa seems to nosedive under quite modest braking
As if there is a definite bias towards the front brakes.

More likely to be rear bias. The suspension geometry gives anti-dive for the front brakes, but not for the rear braking effort.

Does it have correct spec spheres fitted?

[Mandrake]

Bleed the rear brakes!

"Nose dive" will actually be the rear lifting, which will happen if the rear brakes aren't working.

If bleeding doesn't help you may need to check the rear brake pistons aren't seized and that the rear pads aren't rusted to the callipers.

Had the same problem on my V6 - even slight braking was causing the back to lift right up, it turned out to be all three problems - a couple of pads rusted solid to the calliper, pistons in need of working back and forth to free them up, and air to bleed from the rear brake lines. No more nose dive after that.

[chrisjvm]

Thanks for your suggestions Gents...
Might have to wait till the w/end to check possible causes as work /post work apathy dominates at the moment!
I would really hope its something simple like low fluid level except that might point to a leak somewhere.
Re correct spheres... I would hope they are, I bought the car from Dom on this Forum,he did mention that all the spheres had been regassed. Are they easily identifiable?
I did notice that it doesn't roll very well,when you pull up from low speeds it seems to stop itself with light braking which made me think the brakes may be binding slightly which would point to what Simon ( Mandrake) suggested.
Think it may be a trip to a garage when time/ funds allow.

Regards
Chris

[CitroJim]

Chris, finding a garage anywhere around here (or anywhere for that matter) that will competently understand your issue will be hard. Therefore I've PM'd you a potential lead...

Easy to tell if the rear brakes are not working. The rear discs will be rusty...

[Mandrake]

Personally I wouldn't take a Citroen into a garage for this sort of job, they're likely to be reluctant to do it, wont do it properly, or will charge a lot more than the job is worth, however it's a very easy DIY job that would take maybe half an hour to an hour depending on whether you've done it before.

Apart from usual tools like screw drivers, spanners etc, (8mm ring open ender spanner for the stone cover bolt and bleed nipple) the only special items you might need is a metre long length of clear flexible hose that pushes snugly onto the bleed nipple, and a pair of adjustable pliers for squeezing the pistons in:

http://www.dave-cushman.net/bee/slipjoint.html" onclick="window.open(this.href);return false;

I find these work brilliantly for this job as they allow you to grip firmly and parallel between the tab on the top of each pad and the calliper housing and thus squeeze the pistons right in without even removing the pads.

Some people like to put a few drops of LHM down the side of the piston before working them back and forth but I haven't really found that necessary, you just squeeze each piston right in until its practically flush with the hole that it exits, then press the brake pedal to push them back out, do that 4 or 5 times for each piston and in most cases they will be fully freed up and good as new.

Bleeding the brakes on a Citroen is easier than a conventional car as you don't need to pump the pedal. I put the suspension on high, jack up the rear corner under the suspension sub chassis mounting bolts or under the rear door sill jacking point, remove the one rear wheel, lower the jack a bit to put some of the weight onto the other rear wheel that is still on the ground, (important, otherwise there will be no rear suspension pressure to supply the rear brakes) attach my bleed hose and bottle to the bleed nipple and get the spanner ready, I then use a length of wood between the drivers seat and the brake pedal to keep the brake pedal pressed down hard (electric seats come in handy here ) and leave the engine running.

Then just gently open the bleed nipple and watch the flow of oil for bubbles. I typically fill about a half litre of oil in the collection bottle just to be sure. Once done tighten the bleed nipple, remove the wood from the brake pedal, lift the jack, refit the wheel, pour the collected oil back into the tank (if its clean and green, if not replace with an equal amount of new LHM) and repeat with the other wheel.

Easy peasy!

[CitroJim]

http://www.dave-cushman.net/bee/slipjoint.html" onclick="window.open(this.href);return false;

One of the most useful tools I have. I'd be lost without them... Truly a tool of a thousand uses and possibly more...

[chrisjvm]

Simon and Jim ...
Thank you for your thoughts/ advice.
I think even I could follow those detailed instructions Simon .(Thanks Again)
And im definitely no spannerman!
In fact I'm in the Guinness Book of Records...
4 hours to put a back box on a VW T25!!!
Anyway I'm going to throw myself into it with the confidence and
vigour ...
That Activa had better look out at the w/end...
I'm going to be wielding some spanners... And a long piece of plastic nipple fitting tube!!!

Regards

Chris

PS Weather Permitting !!!

[Old-Guy]

A plastic drinks bottle with a largish cap with 2 holes drilled in the cap that are a tight fit for 2 lengths of plastic bleed pipe (one just through the cap and the other to the bottom of the bottle) makes an ideal bleeding tank; 1L size would be best if you can find one (mine is 330ml). Bottle doubles up for topping up gearbox (you blow hard into the short pipe).

[Citroenmad]

You should be fine bleeding the brakes, its quite an easy job. Activas like a bit of TLC from time to time, so you might get used to doing things with it.

[chrisjvm]

Thanks for the advice "Old Guy" I Will be attempting to make a brake bleed bottle very soon... I think I'm going to have to call on all the skills i acquired watching Blue Peter all those years ago!

Chris ,I appreciate the words of encouragement ...!!!
And I'm looking forward to getting used to doing things to it.

Regards
Chris

[DickieG]

Re bleeding the brakes and further to the above advice, once you've bled off the mucky LHM use clear plastic pipe long enough to run straight back into the LHM tank from the rear calipers and you can bleed literally gallons of fluid through in a closed loop system at no expense (other than petrol), that way you can be sure of removing any air bubbles.

[RichardW]

I would add to Simon's excellend advice...

1. No need to lower- as long it is on high and hasn't been depressured there will be plenty of pressure to bleed to brakes
2. Jam something into the caliper on the side of the disc you are not working on before levering the other piston, otherwise the fluid takes the path of least resistance into the other side of the caliper and the piston can shoot out without you realising
3. Before you get too far in, check the position of the caliper relative to the disc - if no one has been near it in a while (ever?) chances are that the calipers will be twisted outwards by corrosion between them and the arm. This needs to be rectified before new pads will fit, but adds a whole new dimension to the job, and shouldn't be attempted unless you have new caliper bolts to hand - and the means to remove the stubs if you snap them off....

[Mandrake]

I would add to Simon's excellend advice...

1. No need to lower- as long it is on high and hasn't been depressured there will be plenty of pressure to bleed to brakes

That's the theory, it worked on my previous Xantia, but not this one.

Reason being either the manual height override linkage is a bit out of adjustment (haven't checked them yet ) or the height corrector linkages are a bit sticky - which they are.

End result is that even though the height lever is on maximum, if I left both wheels hanging the height corrector won't open - so I had absolutely zero rear brake pressure. The only thing that worked was to let the opposite wheel take some of the body weight thus ensuring that the height corrector opens.

2. Jam something into the caliper on the side of the disc you are not working on before levering the other piston, otherwise the fluid takes the path of least resistance into the other side of the caliper and the piston can shoot out without you realising

Good advice if you push the pistons back with the pads out, however not an issue if you squeeze them back via the pads as I described - one reason I like doing it this way. (The other being if I can be lazy and do it without removing the pads I will )

3. Before you get too far in, check the position of the caliper relative to the disc - if no one has been near it in a while (ever?) chances are that the calipers will be twisted outwards by corrosion between them and the arm. This needs to be rectified before new pads will fit, but adds a whole new dimension to the job, and shouldn't be attempted unless you have new caliper bolts to hand - and the means to remove the stubs if you snap them off....

Yep that job is a whole other ball of wax, and not to be attempted by the timid. I'm pretty confident in most Citroen repairs but I wouldn't be attempting it without a new pair of bolts and a few heavy duty tools like MIG welder to save me if the s**t hits the fan.

While its a waste of time fitting new pads if the calliper alignment is out, that doesn't necessarily mean that the brakes wont work more than adequately after freeing the pistons and bleeding etc - the callipers on my V6 are hideously out of alignment, one nearly touching the disc, yet not only do they seem to work fine, (no nose dive) they passed the MOT without any warning as well... so misaligned callipers are not necessarily doom and gloom unless you have to fit a new set of pads...