De-Dion rear ends

[rms]

also I think i better clarify things here, I want maximum cornering traction, and if that means losing my anti-squat due to no more torque reaction then so be it

You will not get anymore lateral traction on most circuits or hill climbs with an IRS or De-Dion untill you reach the nth degree.

Lateral grip is about car balance/C of G height/vehicle track/tyres/car weight.

[Billzilla]

Nothing much to add to what has been already.
They are as good as a good live-axle, but as mentioned have a lot less unsprung mass. The Fraser suspension isn't the best though, and so you'd be better off using four trailing arms and have some kind of lateral link.
The Fraser deDion tube is about 75mm diameter. Not sure of the thickness but a few years back they found that they had to go up in wall thickness as the early ones would sometime fail. I'd guess about 2mm or so though.

[MRMOPARMAN]

if your still after inspiration, have a look at volvo 343/360's. they have deDion rear ends. iirc rear mounted gearbox too

[Jayem]

if your still after inspiration, have a look at volvo 343/360's. they have deDion rear ends. iirc rear mounted gearbox too

...and leaf springs too. The most awful POS ever. Dries inspiration out of anybody!

[oldeskewltoy]

mini rant...( sorry Sam for the momentary insanity....)

You are asking waaaay to general a question and expecting waaaay to specific an answer. You spoke of us not assuming it is an AE86... but we don't know what it is..... Each car is different, and as rms pointed out

You will not get anymore lateral traction on most circuits or hill climbs with an IRS or De-Dion untill you reach the nth degree.

Lateral grip is about car balance/C of G height/vehicle track/tyres/car weight.

so I guess a bit more information from you is required for better, more accurate answers......
What is the exact application... any rules you must work within... is this single purpose, or multi role....

I now return you to your thread..........

[The Real Roadrunner]

I want maximum cornering traction, and if that means losing my anti-squat due to no more torque reaction then so be it

this confuses me to a degree, anti-squat increases your drive out of the corner so while you may be 5kph down on the way in you can be more than 15kph up on the way out due to anti-squat loading the tyres better on the way out of the corner,
whats the weight difference between the 2 setups?
does it really offset the sacrifices you will make in doing it?

these are all things that need to be considered b4 making drastic changes to a vehicles geometry/handling.

cheers
linden

[Sam_Q]

oldskewltoy: I hear you but I did mention at the start its for an ae86. The other thing I said was I wanted maximum traction, but that was vauge and misunderstood so I corrected myself. I basicly want the car to have the greatest cornering grip, because right now my problem isnt putting the power down so much as the inertia causing my car to lose traction. But runing the De-Dion I want to have -1 to -1.5 degrees of negative camber to allow for a more flat contact patch on the outside and hence more grip. But as you say I need to consider what I will loose if I no longer have the anti-squat effect.

roadrunner: all fair points, and I have thought about this, ok as I said above its not getting the power down thats the issue so much, basicly I was initually thinking that I wanted more cornering power at the expense or a torque reaction. However now that I think about it whist I dont have much a problem getting the power down now it could be because I am used to the torque reacted anti-squat I dialed into my rear end. I am fairly confident though that the effect of the antisquat is relatively minimal on any decent angle of corner. Now while that is a bold and possibly really ignorant thing to say my reasoning is that the higher the gear the less torque there is to cause the reaction because of the reduction in torque multiplication of the gearing compared to first gear. Ontop of all that the throttle is almost never all the way down exiting a corner, so a reduction in torque there also. Lets say there theoretly was a strong anti-squat effect around a corner, I think that would mean I would have to turn in before the apex and then get flat on the throttle to get the anti-squat happening to keep the weight down on the rear of the car to carry me through the corner, if that was the only factor it would mean lifting the throttle would cause me to suddenly lose traction and have lift off oversteer (something my car doesnt seem to do). However I think the most prominant factor would be power oversteer, this may make me look stupid but I think the effect of power oversteer tottaly nullifies any anti squat effect. My other reasoning is less logical in that when I dialed in more anti-squat into my car I only felt the difference in first gear and before or after I couldnt feel the difference around a corner.


Now to anyone who just read all that, I only woke up a little while ago so sorry if I am total mess in my description. Also my conclusions are a combination of my poor analasis of those books I have been reading and my own personal experience. So if I have made a fool of myself then please gently let me know.

[rms]

Sam,
Sometimes it can be very difficult to see the forest, the tree's get in the way.

The basic question is - what is limiting your cornering/lateral traction ?

What is the car doing on turn in, mid corner, exit ?
If you rarely have full throttle on exit - why not ? if you are power limited.

Answer the basic question from first principles, and then work on how to improve it.

[oldeskewltoy]

so in essense what you are aftyer is a bit of negative camber in the rear wheels???? I can't promise you 1 to 1.5 degrees... but I can promise you some rear camber... and you can stick with the OEM diff and housing! An old Trans Am trick(from the late 60s/early 70s was to move the diff in relation to its mounting. This was how the Mustangs got an advantage over the GM crowd the first few years....

For example, if you were after toe... you'd remove the studs from the case and machine 1 to 2 mm from the housing mounting face(or 1 mm from the housing and 1mm from the diff mounting flange. This would allow a deeper mounting depth and so you would get a bit of rear toe in.

The same thing can be done with a bit of camber.... although it is tougher do to the mounting flange ridge..... In essence to get a bit of negative camber you would mount the diff a bit lower against the housing then it would be stock...

There would be some added wear, but not too excessive *IF* camber or toe is kept to a minimum

[oldcorollas]

For example, if you were after toe... you'd remove the studs from the case and machine 1 to 2 mm from the housing mounting face(or 1 mm from the housing and 1mm from the diff mounting flange. This would allow a deeper mounting depth and so you would get a bit of rear toe in.

The same thing can be done with a bit of camber.... although it is tougher do to the mounting flange ridge..... In essence to get a bit of negative camber you would mount the diff a bit lower against the housing then it would be stock...

so basically it acheives the same effect as bending the housing, except in this case, the bearings at the wheels are still parallel, while the axles are slightly angled, and more likely to wear prematurely than if you bent the housing?

what is track? maybe.. 130cm? so each side 65cm
to get 1deg angle change, you need to machine off a total of about 11mm


as RMS said, you need to work out from first principles why the car is losing traction..

"too much inertia" is usually "going to fast"
bit if it is pushing or oversteering then you can start to think abotu what is failing first.

it is possible to incorporate a CV within the axle housing, either at diff or wheel end, and then you can retain the torque reaction, and have whatever angle for toe and camber you want. you lose any benefit of reduction of unsprung mass but....

[wa5]

same as V8s use ?

[Grega]

I know some of the Alfa guys bend/cut and weld their DeDion frames to achieve desired camber and toe angles. I read on 1 Alfa forum (yeah, I got a Alfa ), 1 guy sugested using a place that does wheel alignments for light trucks because they can litterally bend the front (in the case of a light truck) axle to correct camber angles using special equipment .

most F truck places do this also with the front suspension on F100's ect to sort them out when they bend/skew due to old age.

so in essense what you are aftyer is a bit of negative camber in the rear wheels???? I can't promise you 1 to 1.5 degrees... but I can promise you some rear camber... and you can stick with the OEM diff and housing! An old Trans Am trick(from the late 60s/early 70s was to move the diff in relation to its mounting. This was how the Mustangs got an advantage over the GM crowd the first few years....

that'd be shelby drop. not sure how you'd go figuring out the zact dimensions for the cause here though for sam, and, be accurate enough with it. be interested to know however.

[oldeskewltoy]

so basically it acheives the same effect as bending the housing, except in this case, the bearings at the wheels are still parallel, while the axles are slightly angled, and more likely to wear prematurely than if you bent the housing?

what is track? maybe.. 130cm? so each side 65cm
to get 1deg angle change, you need to machine off a total of about 11mm


as RMS said, you need to work out from first principles why the car is losing traction..

"too much inertia" is usually "going to fast"
bit if it is pushing or oversteering then you can start to think abotu what is failing first.

it is possible to incorporate a CV within the axle housing, either at diff or wheel end, and then you can retain the torque reaction, and have whatever angle for toe and camber you want. you lose any benefit of reduction of unsprung mass but....

actually... the axle bearing rides on the shaft. so it rides in the case on a slight angle, no wear on the axle bearing. The largest wear would occur on the spider gears because the axle would be running on an angle in the diff. Remember these "mods" were performed as "cheats" for the original Trans Am, you weren't allowed to bend the case. I never said a great deal of angle can be achieved... but it can be done. Btw... you sure of your measurements... 11mm to 65mm seems like more than 1 degree....................

[The Real Roadrunner]

actually... the axle bearing rides on the shaft. so it rides in the case on a slight angle, no wear on the axle bearing.

once the backing plate is tightened it will run on an angle compared to the axle thus the bearing will be loaded on an angle so yes it will increase wear, also the affects it would have on the drums/shoes or discs/pads would be bad also as they wont seat correctly therefore uneven wear.

Btw... you sure of your measurements... 11mm to 65mm seems like more than 1 degree....................

basic maths dude 60-1 = 1degree, doesnt matter if its 60mm or 60m it will still be the same so OC is certainly correct and btw he wrote 11mm over 65cm

cheers
linden

[Sam_Q]

funny you guys talk about this I just have been doing a lot of talking on here:

http://www.ae86drivingclub.com.au/bo...howtopic=22891







just for the record this is what I am more leaning towards doing but not too such a high degree (no pun intended!). I am thinking more along the lines -0.5 to -1 degrees, apprently the limit of when you start to wear things out