G'day boys, hope you're all loooving the extra warm weather
it's certainly been a tad warm in the workshop this week
Anyhow, I don't really see taking much more about the brakes as I've covered most of what we've learned already. however I would like to quickly talk about brake servos. I didn't realise that if there was no brake servo (a line from the master cylinder to the air intake using the vacuum created to help pressurise the brake fluid) then it would be virtually impossible to depress the brake pedal hard enough to brake. interesting! In addition the actual length of the pedal is there to ease drivers' effort.... if you think about it it does makes sense as your using torque (leverage + force) to aid the driver
Ok down to the stuff we've been doing this week and I have found it VERY interesting...
STEERING:
This week we mostly been looking at rack and pinion racks
This is a power steering rack (note the metal lines which are for power steering fluid. note also the track rod ends are attached in this photo)
the operation of the steering rack is very, very simple. the 'pinion gear' is what you see coming down in to the rack. when this is spun round (by connection to the steering wheel) this gear moves the ''rack'' gear left or right...this is connected to the hub via the track rod ends and affects its left to right motion by pushing the hub inwards and outwards.
from an alignment point of view it is important to note that in most cases the steering rack is positioned behind the centre point of the hub.... as per my awesome paint picture
......but we'll come nore on to the alignment in a few
Anyhow sadly we weren't allowed to take a rack out of a car
that sucked cos I know that theyre hard to do and I really fancied the challenge. but nevertheless we were tasked woth removing and replacing a track rod end.
jack up, support on stands, remove wheel.
undo the nut securing the track rod end in place. then undo the nut on top of the ball joint and use a ball joint chisel....
....to separate the ball joint and relieve it of its' place in the hub assembly. (chisel is wedge shaped so as you hammer it in, it separates further)
a pic of the balljoint clearly protruding from the steering rack and attaching to the hub assembly...
a pic of the one on the Renault
Migraine Megane that I did...
a pic of the tie rod twisted off and ball joint knocked out (note the pic is of it resting on the control arm in case you're wondering about its' odd orientation. and soz for bad photos
)
before you get to this point you would have held the road wheel (with it attached obviously) and shook it to look for play. if there is any is probably this track rod end. when track rod end off look for cuts in the rubber boot (or gaiter) and press it in and move it around and look for ease of/excessive play. if so REPLACE
We also removed and replaced the gaiters (rubber boots) on the steering rack with them in situ. look for cuts or wear. if needed to replace. not much to say about that really other than use side cutters to break the metal clip and pull gaiter off.
I suppose you should replace the metal securing rings/clips but we used cable ties. is that acceptable in your opinions???as I said I really wish theyd let us actually pull a rack
but now to the fun bit
TOE ALIGNMENT
This, as far as I can work out is specifically the alignment of these track rod ends that attach to the steering rack. note I haven't touched the camber adjustment yet
firstly I need to explain degrees and minutes. you know what a degree is in terms of angles (surely?
). minutes are a fraction of 1 degree and there are 60 minutes in a degree... very small angles i'm sure you'll appreciate. I should also explain that toe out is referred to as ''negative'' toe and toe in is referred to as ''positive'' toe.
ok so generically speaking when talking about what the track rod ends do (at the front of the car)..... RWD cars tend to toe out i.e. when the power comes on they want to push outwards. FWD cars tend to toe in i.e. the wheels wants point inwards. This is reflected in the toe settings...