barraw
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 posted on 21/4/05 at 11:11 AM |
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Converting LiveAxle Westfield to Independant rear suspension
Hi, I have a 1990 Live Axle Westfield. Is it possible to convert it to independant rear suspension? has anyone done it, and what parts would I need?
Would the chassis need modifying?
thanks
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phelpsa
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| posted on 21/4/05 at 11:24 AM |
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You could do it but it might be easier / cheaper to sell it and build an MK or Stuart Taylor.
Adam
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Surrey Dave
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| posted on 21/4/05 at 11:28 AM |
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You could convert to the GTS tuning , dedion setup quite easily
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NS Dev
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| posted on 21/4/05 at 12:28 PM |
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.................and I think that would be my setup of choice anyway, certainly the lightest setup you can have.
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andylancaster3000
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| posted on 21/4/05 at 04:24 PM |
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NS Dev: Do you mean that the de-dion is the lightest setup or the live axle?
Andy
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MikeR
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| posted on 21/4/05 at 04:49 PM |
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de0dion is the best compromise, lower unsprung weight than live axle but a little heavier.
It all depends what you want the car for and why do you want to convert from live axle?
In fact, why do you want to convert from live axle?
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barraw
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| posted on 21/4/05 at 05:08 PM |
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The only reason I want to convert, is that on bumpy A and B roads, the car jumps around a lot and infact, seem to rarely touch the floor - like a
speedboat jump across the top of waves :-)
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MikeR
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| posted on 21/4/05 at 05:12 PM |
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have you looked at changing the damping / shocks / springs?
I've no idea here but other people should be able to comment.
At a guess, weaker spring, bit less damping (and drive slower).
That might help and save you a lot of money / hassle.
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want2race
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| posted on 21/4/05 at 06:33 PM |
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I have done the math, and I have done ALL the math!
DO NOT BOTHER!
The added advantages of IRS are as follows:
Greater wheel control, greater unsprung weight, greater angle of rotation.
BUT the disadvantages are :
Its heavier! YES IT IS! It requires more structural tubing, Live axle can be set up to handle like hell on wheels! Ive seen live axles rotate like
greesed weasel Sh1t..
I would not do it. In fact I am upset that I made my car IRS, it wasnt worth the trouble!
~Jonathan
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Marcus
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| posted on 21/4/05 at 07:08 PM |
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Have to agree with Jonathan, stick to live axle, and play with damper / spring ratio. I run GAZ shocks with the damping only 2 clicks off minimum and
150lb rear springs and 225lb fronts. Handles all I throw at it with little or no bounce.
Marcus
Marcus
Because kits are for girls!!
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britishtrident
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| posted on 21/4/05 at 07:24 PM |
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quote:
Originally posted by Marcus
Have to agree with Jonathan, stick to live axle, and play with damper / spring ratio. I run GAZ shocks with the damping only 2 clicks off minimum and
150lb rear springs and 225lb fronts. Handles all I throw at it with little or no bounce.
Marcus
Good point easy to forget how light these cars are ---- make the damping too tight and the car handles great until you blink and the car has snapped
sideways.
With Spax I would start at about 4 or 5 clicks.
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barraw
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| posted on 21/4/05 at 10:23 PM |
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thanks, that sounds like good advice. I will try softening the settings. I have SPAX dampers, but don't know the spring LB.
I will have a play and post a followup - once I get the car back on the road (as an alternator bracket bolt has snapped in the block so I have some
drilling and tapping to do )
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NS Dev
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| posted on 22/4/05 at 12:31 PM |
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Right, well, depends on your point of view then!!!!!!
I would go for the de-dion setup every time myself! I love live axles (even though I am building a wishbone IRS car!) but they do reach limitations,
no matter what you do about damping, on rough roads.
This is simple fact, on a light car, the ratio of sprung to unsprung weight is a prime factor in traction, and on the back of a live axle 7, the ratio
is not good!
A live axle car will be the lightest car, but a de-dion will retain the roll control of a live axle without the massive unsprung weight.
De-dion would be my choice if I hadn't bought a chassis that wasn't available in that format!
I have a long involvement with rallying and road rallying, and traction is ALWAYS limited by axle hop on a live axled car, even with properly set up
dampers costing up to £1000 per corner.
Look at one of the most successful manta rally cars around, (I am into Mantas, hence the live axle knowledge) Jon Ballinger's 16v. He converted
that to de-dion and then wiped the floor with the opposition due to the traction advantage.
Where it won't help much is on a race track, which is smooth enough for damping to affect traction to a much lesser degree.
One of the replies above, I am afraid to say, is total crap.
By all means, try altering your dampers, but for ones that make any major improvement you need to spend more than what a GTS de-dion kit will cost
you!
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NS Dev
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| posted on 22/4/05 at 12:41 PM |
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quote:
Originally posted by want2race
I have done the math, and I have done ALL the math!
DO NOT BOTHER!
The added advantages of IRS are as follows:
Greater wheel control, greater unsprung weight, greater angle of rotation.
BUT the disadvantages are :
Its heavier! YES IT IS! It requires more structural tubing, Live axle can be set up to handle like hell on wheels! Ive seen live axles rotate like
greesed weasel Sh1t..
I would not do it. In fact I am upset that I made my car IRS, it wasnt worth the trouble!
~Jonathan
Sorry, but some of this is utter crap!
"more structural tubing"....................where? The de-dion setup uses the same mountings as the live axle..................
"Live axle can be set up to handle like hell on wheels!"..................whatever that means................simple "math"
will tell you that on a live axle car, the axle weighs a similar amount to the area of chassis it is attached to. This means that no matter how you
connect the two together, both will always "bounce".
I really can't be bothered to go into it further, but suffice to say, the original question was asked for good reason and I think if the
conversion is done, a big improvement in rough road driveability will be experienced!!
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clbarclay
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| posted on 22/4/05 at 12:54 PM |
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NS Dev, GTS dedion axle cost £150, sierra diff plus halfshafts etc costs ££, moddified prop to fit sierra diff (might not be needed if you lucky) and
brakets to fit sierra diff.
Just what cost(s) are you putting on setting up shock abosrbers, which will probably need doing for a dedion anyway?
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kb58
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| posted on 22/4/05 at 02:33 PM |
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Bottom line, in a light car, every ounce of unsprung weight matters.
Having IRS on a Ford Mustang doesn't do much since the decrease in unsprung weight is nill compared to the huge mass of the car. But put a Ford
9" rear axle under a Seven to see why a small unsprung mass is so important.
Example. If the unsprung weight of a live axle is 1/4 the sprung weight on a Seven, when it hits a 1" pothole, the car will move 1/4".
Now, if IRS is fitted that has 1/6 the sprung weight, the same bump will displace the car 1/6". So it's all by degree...
I read people saying the advantage of IRS is minimal on a racetrack, or that since IRS is really for racecars, and since they don't drive on a
track, they don't need it. That's exactly backwards, they need IRS on the street MORE then on the track. Why? Where does the car hit
potholes, driveways, railroad tracks and cracked cement? Where does the driver care about a nice ride? On the street, where unsprung weight makes
all the difference.
Now if a de Dion's unsprung weight can be made nearly that of an IRS, then yes, it accomplishes the same goal with a simpler set up. Regardless
of how it's achieved, unsprung weight is a big deal. It can be ignored, but the driver will be reminded of it every single time he hits a bump
or has the car leap sideways in a corner.
[Edited on 4/22/05 by kb58]
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want2race
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| posted on 22/4/05 at 02:45 PM |
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quote:
Originally posted by NS Dev
quote:
Originally posted by want2race
I have done the math, and I have done ALL the math!
DO NOT BOTHER!
The added advantages of IRS are as follows:
Greater wheel control, greater unsprung weight, greater angle of rotation.
BUT the disadvantages are :
Its heavier! YES IT IS! It requires more structural tubing, Live axle can be set up to handle like hell on wheels! Ive seen live axles rotate like
greesed weasel Sh1t..
I would not do it. In fact I am upset that I made my car IRS, it wasnt worth the trouble!
~Jonathan
Sorry, but some of this is utter crap!
"more structural tubing"....................where? The de-dion setup uses the same mountings as the live axle..................
"Live axle can be set up to handle like hell on wheels!"..................whatever that means................simple "math"
will tell you that on a live axle car, the axle weighs a similar amount to the area of chassis it is attached to. This means that no matter how you
connect the two together, both will always "bounce".
I really can't be bothered to go into it further, but suffice to say, the original question was asked for good reason and I think if the
conversion is done, a big improvement in rough road driveability will be experienced!!
You need to go back and read what I said again and again.
I made not a single mention of the de-dion system. I have never seen one in person nor have I analysed its effects. I simply havent bothered!
I made all comments in reference to the IRS vs Pan Hard rears.
The IRS requires additional tubing because it needs attachment points and bracing for the differential casing and the wishbones both bottom and
upper.
My points are valid and my reasoning is sound..
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NS Dev
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| posted on 23/4/05 at 08:42 AM |
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quote:
Originally posted by kb58
Bottom line, in a light car, every ounce of unsprung weight matters.
Having IRS on a Ford Mustang doesn't do much since the decrease in unsprung weight is nill compared to the huge mass of the car. But put a Ford
9" rear axle under a Seven to see why a small unsprung mass is so important.
Example. If the unsprung weight of a live axle is 1/4 the sprung weight on a Seven, when it hits a 1" pothole, the car will move 1/4".
Now, if IRS is fitted that has 1/6 the sprung weight, the same bump will displace the car 1/6". So it's all by degree...
I read people saying the advantage of IRS is minimal on a racetrack, or that since IRS is really for racecars, and since they don't drive on a
track, they don't need it. That's exactly backwards, they need IRS on the street MORE then on the track. Why? Where does the car hit
potholes, driveways, railroad tracks and cracked cement? Where does the driver care about a nice ride? On the street, where unsprung weight makes
all the difference.
Now if a de Dion's unsprung weight can be made nearly that of an IRS, then yes, it accomplishes the same goal with a simpler set up. Regardless
of how it's achieved, unsprung weight is a big deal. It can be ignored, but the driver will be reminded of it every single time he hits a bump
or has the car leap sideways in a corner.
[Edited on 4/22/05 by kb58]
You have hit the nail on the head here. 100% correct, unsprung weight is more critical on bumpy surfaces than on the track (as I said before!)
It is quite easy to get the dedion weight down to that of other systems, in fact I would argue that it can be made lighter than any other system ona
seven, but that depends on components used.
Certainly a dedion 7 chassis just needs two brackets to mount the diff, in addition to the std live axle bracketry. The two brackets weigh very
little. The dedion tube itself is lighter than a live axle casing less diff (or should be if designed well) so that just leaves the diff, and yes,
the sierra one is not light, but if weight is the main issue then there are others such as the freelander diff etc. I see no reason why a de-dion
(semi IRS) car cannot be made as light as a live axled car, and certainly lighter than a wishbone IRS car.
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NS Dev
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| posted on 23/4/05 at 08:46 AM |
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quote:
Originally posted by clbarclay
NS Dev, GTS dedion axle cost £150, sierra diff plus halfshafts etc costs ££, moddified prop to fit sierra diff (might not be needed if you lucky) and
brakets to fit sierra diff.
Just what cost(s) are you putting on setting up shock abosrbers, which will probably need doing for a dedion anyway?
I wasn't referring to setting up the shocks, but actually buying decent ones to start with!
On rough roads, the budget end of the shockabsorber market, when fitted to a live axle in a 7, will be sadly lacking! On our mk2 escort tarmac rally
cars, we had to gradually up the shocker budget until we got to Proflex, which then worked!!! Price...............well, multiply Ron Champion's
entire car budget by 3 or 4 and that buys one shocker!!
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MikeR
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| posted on 23/4/05 at 08:52 AM |
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Just as a side point....... a heavy diff in a de-dion seven might be an advantage!
(this is all my micky mouse science here so ignore me)
The heavy unsprung seirra diff in the seven will have an advantage, it will help increase the unsprung to sprung weight balance in the car and help
balance its nose heavy design.
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NS Dev
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| posted on 23/4/05 at 08:57 AM |
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That is not at all wrong Mike! You meant "sprung" sierra diff not "unsprung" but I know what you meant!
Certainly, if you take the rest of the car as it is (i.e. assume you can't get other weight further back) then yes, is should help with
traction.
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MikeR
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| posted on 23/4/05 at 09:18 AM |
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aaah, come on, its early, i was close enough 
(yeah, ok that is what i meant)
All this talk of de-dion is making me think of converting my car ......
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britishtrident
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| posted on 23/4/05 at 09:25 AM |
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Equally important to overall low unsprung weight is the fact the de dion dosen't have have the large mass of the diff in the centre, with a de
dion (as with full irs) what little unsprung mass there is concentrated close to the wheels. This becomes advantageous in the single wheel bump
situation.
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barraw
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| posted on 23/4/05 at 10:51 AM |
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MikeR - to comment on the nose heavy design, I recently parked my car on a public weighbridge, and found the front to weigh 300kg and the rear 250kg -
without me in it, but if you add 2/3 of my body weight to the front/rear ratio you get an almost perfect 50/50 split.
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gazza285
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| posted on 23/4/05 at 01:07 PM |
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quote:
The dedion tube itself is lighter than a live axle casing less diff (or should be if designed well) so that just leaves the diff
And not forgetting that you have to include the addition of four CV joints to the weight. I think that you would struggle to make a Dedion lighter
than a live axle.
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