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Live Axle and Propshaft Movement
pekwah1 - 1/8/14 at 01:49 PM

Hi Guys,

How much movement should i expect with a live axle striker from the rear axle and the prop shaft?
I have a fairly narrow tunnel, and my prop is currently fouling on the tunnel wall on bumpy roads or hard left corners.

The noticeable point is that my prop is not central down the tunnel, but i'm not sure how i fix this other than "modifying" the tunnel wall with a big hammer as obviously the prop can only fix to the diff, and i can't exactly move the axle left or right.

Again, a bit concerned as i don't really want my prop fouling on the car, so what is reasonable movement, what should i expect?

Sylva Striker
2.0 Blacktop Zetec
5 Spd Type 9
Mk1 Escort live (english) rear axle

Cheers,
Andy

pekwah1 - 1/8/14 at 01:57 PM

A couple of pics:




jeffw - 1/8/14 at 02:00 PM

You need an adjustable Panhard rod. You will be able to get one from Raw or Fury Sportscars. This will allow you to adjust the position of the live axle and stop the rear flange rubbing against the tunnel.

[Edited on 1/8/14 by jeffw]

pekwah1 - 1/8/14 at 02:03 PM

The problem with that though is that my axle is aligned in the middle of the car, if i move the axle, effectively my track will be out. I'll have more offset one side than the other

loggyboy - 1/8/14 at 02:06 PM

Is the track currently spot on dead centre tho?

pekwah1 - 1/8/14 at 02:08 PM

pretty sure it is measuring from front wheels to back....
i'll have another check though.

designer - 1/8/14 at 02:10 PM

In the top picture the yoke seems to be off-centre.

jeffw - 1/8/14 at 02:16 PM

quote:
Originally posted by pekwah1
The problem with that though is that my axle is aligned in the middle of the car, if i move the axle, effectively my track will be out. I'll have more offset one side than the other


When you say 'aligned to the car' which bit. Obviously the axle is offset or it would be hitting one side of the tunnel (either both or none).

twybrow - 1/8/14 at 02:26 PM

My axle rotates ever so slightly (slight play in all the bushes) but it does not move sideways other than by adjusting my panhard rod. It is not central in the tunnel on car as the diff is offset from the centre.

jeffw - 1/8/14 at 02:32 PM

I presume you do not have a Stiker/Phoenix then.

Live Axles in these do move and without it being square in the tunnel they will hit the side.



[Edited on 1/8/14 by jeffw]

blakep82 - 1/8/14 at 02:36 PM

as i understand it, the prop shouldn't be perfectly aligned, the pinion on the diff should always be a little off centre so the bearings in the prop are NEVER perfectly alinged, otherwise they'd wear out pretty quick. the out of alingment makes them last much longer.

you'll notice that the pinion is never centred on the axle either.

the original book locost had a slight widening of the tunnel to accomodate this i think?

is your axle centred correctly?

Sam_68 - 1/8/14 at 02:40 PM

quote:
Originally posted by jeffw
You need an adjustable Panhard rod.


Edited for wrong Edwardian Frenchman.

jeffw - 1/8/14 at 02:41 PM

quote:
Originally posted by Sam_68
quote:
Originally posted by jeffw
You need an adjustable Panhard rod.


Edited for wrong Edwardian Frenchman.


Indeed....brain not engaged

jeffw - 1/8/14 at 02:43 PM

quote:
Originally posted by blakep82
as i understand it, the prop shouldn't be perfectly aligned, the pinion on the diff should always be a little off centre so the bearings in the prop are NEVER perfectly alinged, otherwise they'd wear out pretty quick. the out of alingment makes them last much longer.

you'll notice that the pinion is never centred on the axle either.

the original book locost had a slight widening of the tunnel to accomodate this i think?

is your axle centred correctly?


The Striker/Phoenix Live Axle setup is different to the Book chassis. You can have the necessary mis-alignment vertically rather than horizontal.

pekwah1 - 1/8/14 at 03:32 PM

ok so i've gone and had another look and turns out you lovely people must just be right for a change!
Question is, how do i go about changing the static positioning of a rear axle?

My setup looks something like this drawing an artist did for me:



So i have brackets where the suspension meets the axle, another arm that is connected to the axle on the right side and the chassis on the left, and then four trailing arms (two from suspension mounts to rear chassis, two from hub to centre chassis).

Apologies for my stupidness in advance, i don't know much about axles/suspension etc.

[Edited on 1/8/14 by pekwah1]

loggyboy - 1/8/14 at 03:42 PM

You need to be able to adjust the bar between the 2 V shaped brackets.

I assume something like this?:

http://www.ebay.co.uk/itm/like/131041326537

Edit - maybe not, that looks like a chassis mounted adjustment.

more like this - http://www.rallynuts.com/nissan-micra-k11-suspension/whiteline-panhard-rod-kit-adjustable.html
but to suit the width of yours!

[Edited on 1-8-14 by loggyboy]

pekwah1 - 1/8/14 at 03:48 PM

Awesome, so assuming that by reducing the length of that bar, it will pull the whole axle towards the chassis mounted side of the car.

Sam_68 - 1/8/14 at 07:47 PM

quote:
Originally posted by pekwah1
Awesome, so assuming that by reducing the length of that bar, it will pull the whole axle towards the chassis mounted side of the car.


Yes, that's right. But try to keep the reduction to a minimum, as the shorter the Panhard rod is, the more lateral displacement you'll get as the axle moves up and down (see Jeff's video, above, although what you're seeing there is a combination of lateral deflection due to the Panhard's arc, rotation of the chassis/sprung mass around the roll centre, and some tyre carcass deflection).

Bear in mind that if your current Panhard rod is rubber bushed, you'll also be getting a bit of deflection through the walls of the bushes, so if you change to a rose jointed adjustable Panhard, it will reduce the total deflection a bit, anyway. The downside being that it will increase the stresses on the chassis and axle mounting brackets a bit, and it's not unknown for the Sylva's mounting brackets to crack even when rubber bushed...

Whatever sort of adjustable rod you get, try adjusting it so that it gives the diff. just a small amount of clearance when you move the axle through its working range (with the springs/dampers disconnected). Keep an eye on it, and if you're still getting contact due to things flexing when the axle is under actual cornering loads, adjust it a bit more until the contact ceases.

Incidentally; off-topic, but never fully Rose-joint the longitudinal Watts links on a Sylva live axle set-up. The arrangement relies on some compression through the walls of the bushes to work properly, and fully Rose jointing is inviting a broken link or mounting bracket (not to mention making the axle tube act as a big rear anti-roll bar).

loggyboy - 1/8/14 at 08:21 PM

quote:
Originally posted by pekwah1
Awesome, so assuming that by reducing the length of that bar, it will pull the whole axle towards the chassis mounted side of the car.


Or just move the mounting point over.

Sam_68 - 1/8/14 at 08:34 PM

quote:
Originally posted by loggyboy
Or just move the mounting point over.


Yes, theoretically, this is the better solution, as it doesn't involve shortening the arc of the Panhard rod any.

... but an adjustable Panhard is a bolt-on solution, if you can't be arsed buggering about with cutting and welding mounting brackets, and unless you're chasing the last few hundredths of of a second on a racing lap time, slight shortening of the Panhard won't be a problem.

You pays yer money, and you takes yer choice!

jeffw - 1/8/14 at 09:28 PM

Also remember that Jeremy designed the car to have metalastic bushes. This was to give an element of roll resistance. If you remove them and replace them with rose joints you would need to run an ARB on the rear.

jeffw - 1/8/14 at 09:31 PM

quote:
Originally posted by pekwah1
Awesome, so assuming that by reducing the length of that bar, it will pull the whole axle towards the chassis mounted side of the car.


Just ring Raw or Fury Sportscars and they will be able to supply the correct adjustable length of Panhard rod.

Sam_68 - 1/8/14 at 09:44 PM

quote:
Originally posted by jeffw
Also remember that Jeremy designed the car to have metalastic bushes.


Yes, see my post above... but this applies only to the longitudinal (Watts) links. You can Rose joint the Panhard rod without it affecting the roll stiffness by a noticeable amount.

Also, while fully Rose jointing the longitudinal links is most certainly not a good idea, it won't reduce the rear roll resistance, necessitating an ARB. It'll increase it, because instead of compressing the wall thickness of the nice, squishy rubber in the bushes, the lack of any resilience in the rose joints will mean that the linkages try to twist the axle tube instead.

strikerbird - 2/8/14 at 10:24 AM


I use rose joints at both ends of my panhard rod for adjustment. I do have rose joints on one end of all the other links but use metalastic bushes the other end. I use good quality joints and check axle and chassis brackets for cracks after every event.

bigfoot4616 - 2/8/14 at 03:56 PM

my striker cracked the axle where the panhard bracket is welded to it even though it is fully rubber bushed(normal metalastic bushes on the rear facing arms, not sure what the other bushes are)

that's always put me of the idea of rose jointing even just the panhard rod.