Is the De Dion axle a real improvement over a Live axle??
Discussion
I know it is the more modern alternative but is it a lot better??
Can you convert a live axle Caterham to a De Dion set up?
Also how easy is it to get differentials for the Ford / Marina axles?
Does the Ford Diff fit the Marina axle...i get the impression they are basically one and the same...am i correct or just a Dork?....
(I may be after a 5 speed gearbox and a Diff if they are available!..?)
Mike.
Can you convert a live axle Caterham to a De Dion set up?
Also how easy is it to get differentials for the Ford / Marina axles?
Does the Ford Diff fit the Marina axle...i get the impression they are basically one and the same...am i correct or just a Dork?....
(I may be after a 5 speed gearbox and a Diff if they are available!..?)
Mike.
redmire said:
I know it is the more modern alternative but is it a lot better??
Can you convert a live axle Caterham to a De Dion set up?
Also how easy is it to get differentials for the Ford / Marina axles?
Does the Ford Diff fit the Marina axle...i get the impression they are basically one and the same...am i correct or just a Dork?....
(I may be after a 5 speed gearbox and a Diff if they are available!..?)
Mike.
Ital (Marina) live axles are lighter than the de dion units. They tend to get a bit of bad press because the presumed wisdom is that they are harsh to drive on the road. The only time I have ever noticed a siginificant difference is when going round long fast bends when the road surface isn't too smooth and the live axle car may skip sideways slightly. The de dion car may ride a little more smoothly at this point.Can you convert a live axle Caterham to a De Dion set up?
Also how easy is it to get differentials for the Ford / Marina axles?
Does the Ford Diff fit the Marina axle...i get the impression they are basically one and the same...am i correct or just a Dork?....
(I may be after a 5 speed gearbox and a Diff if they are available!..?)
Mike.
Not sure about the difficulty in getting diffs but I can't re-collect there being a problem. Maybe have a word with Steve Perks at SPC or Phil at Road & Race.
Anything is possible I suppose in converting a chassis but I am sure that Arch won't convert a live axle set up into a de dion one as they carry different chassis numbers and are fundamentally different models. This doesn't mean to say that someone else or you culdn't carry out the work to fix the diff in.
The Ford unit is physically a lot bigger than than Ital version (and heavier) but will take much bigger power outputs (250+ compared to a max of 170 for the Ital unit) and has a different PCD (108mm vrs 3.75") which would either necessitate a change in front hubs to match or putting up with different PCD's on the two axles.
A Ford unit can easily be fitted into an Ital car. The nose of the axle is slightly offset though to the drivers side so a very slight adjustment (with a big hammer...) is called to for as part of the upgrade. You will also need to fabricate a couple of small plates in the tunnel section to fit the different handbrake cable that is needed if you change over. Pretty simple stuff though.
Tango7 said:
redmire said:
I know it is the more modern alternative but is it a lot better??
Can you convert a live axle Caterham to a De Dion set up?
Also how easy is it to get differentials for the Ford / Marina axles?
Does the Ford Diff fit the Marina axle...i get the impression they are basically one and the same...am i correct or just a Dork?....
(I may be after a 5 speed gearbox and a Diff if they are available!..?)
Mike.
Ital (Marina) live axles are lighter than the de dion units. They tend to get a bit of bad press because the presumed wisdom is that they are harsh to drive on the road. The only time I have ever noticed a siginificant difference is when going round long fast bends when the road surface isn't too smooth and the live axle car may skip sideways slightly. The de dion car may ride a little more smoothly at this point.Can you convert a live axle Caterham to a De Dion set up?
Also how easy is it to get differentials for the Ford / Marina axles?
Does the Ford Diff fit the Marina axle...i get the impression they are basically one and the same...am i correct or just a Dork?....
(I may be after a 5 speed gearbox and a Diff if they are available!..?)
Mike.
Not sure about the difficulty in getting diffs but I can't re-collect there being a problem. Maybe have a word with Steve Perks at SPC or Phil at Road & Race.
Anything is possible I suppose in converting a chassis but I am sure that Arch won't convert a live axle set up into a de dion one as they carry different chassis numbers and are fundamentally different models. This doesn't mean to say that someone else or you culdn't carry out the work to fix the diff in.
The Ford unit is physically a lot bigger than than Ital version (and heavier) but will take much bigger power outputs (250+ compared to a max of 170 for the Ital unit) and has a different PCD (108mm vrs 3.75") which would either necessitate a change in front hubs to match or putting up with different PCD's on the two axles.
A Ford unit can easily be fitted into an Ital car. The nose of the axle is slightly offset though to the drivers side so a very slight adjustment (with a big hammer...) is called to for as part of the upgrade. You will also need to fabricate a couple of small plates in the tunnel section to fit the different handbrake cable that is needed if you change over. Pretty simple stuff though.
Does that mean i wouldn't be able to fit a five speed box?
I am buying one with a four speed...do you think that is a problem?
Thanks again.
Mike.
redmire said:
I know it is the more modern alternative but is it a lot better??
Can you convert a live axle Caterham to a De Dion set up?
Also how easy is it to get differentials for the Ford / Marina axles?
Does the Ford Diff fit the Marina axle...i get the impression they are basically one and the same...am i correct or just a Dork?....
(I may be after a 5 speed gearbox and a Diff if they are available!..?)
Mike.
The dedion tube was invented in 1894! Can you convert a live axle Caterham to a De Dion set up?
Also how easy is it to get differentials for the Ford / Marina axles?
Does the Ford Diff fit the Marina axle...i get the impression they are basically one and the same...am i correct or just a Dork?....
(I may be after a 5 speed gearbox and a Diff if they are available!..?)
Mike.
PCD = pitch circle diameter and the distance between the wheel studs. Standard Ford fitment is 108mm or around 4.25". Marina Ital is 3.75".
There sbould be no problem fitting a 5 speed box but you might need a spacer fitted as part of the conversion. Brent Chiswick on Blatchat used to offer them for a small sum of money. Thus saying that, I think you need to give the age of the car/chassis you are thinking of buying in case its an early chassis and a 5 speed box might not physically fit in there.
Mickrick
There sbould be no problem fitting a 5 speed box but you might need a spacer fitted as part of the conversion. Brent Chiswick on Blatchat used to offer them for a small sum of money. Thus saying that, I think you need to give the age of the car/chassis you are thinking of buying in case its an early chassis and a 5 speed box might not physically fit in there.
Mickrick
The Ital will only take about 155 true BHP and struggles with longevity on grippy tyres on track.
As said the Dedion diff will take big HP no problem.
You can mod to take a Ford axle that handles much more power.
I had two live Ital/Marina axled 7's and my current 7 is a Dedion one.
Other things of interest are the adjustable ears (read changeable) from 2.0 deg to 0.5 deg in 0.5 deg steps, for the dedion.
This allows fine tuning to tyres that like more or less camber. Race teams will change according to race rules, slicks use 0.5deg, CR500's etc 1.5deg.
Other big differences are the way the lower damper mount is turned through 90 deg degrees on the Dedion axle.
This means that a single wheel compression (bump in road on one side) allows the axle to move upwards with the bush pivoting on the Dedion. On the live axle the pivot is the other way so it actually bends the damper along its length - not ideal for the rod of the damper to be bent along it's length as it is forced into the damper body!
This means the Dedion can hammer down a bumpy B road a good 10-15mph faster or round that bumpy corner (as already noted without skipping), than the live axle and still feel in control.
I have pics of the dampers on my last live axle car under single wheel load showing exactly this.
The solution to the problem is to fit rose jointed bottom mount dampers - such as Avo do. I did this.
This allows the damper to pivot in all directions and prevents the above bending force.
The live axle car handling on bumpy roads will be significantly improved - I've felt it.
However! BUT! The live axle car is still handicapped as the mass of the entire axle is unsprung weight. Every bump and direction change has to accelerate the entire mass of the whole axle.
Yes, the whole live axle is lighter then the Dedion tube and Sierra diff but the diff is not unsprung so the Dedion tube assembly that is unsprung weight is significantly lighter and thus can move around in a more responsive manner to the forces applied to it. So on a bumpy road the Dedion axle still wins!
As said the Dedion diff will take big HP no problem.
You can mod to take a Ford axle that handles much more power.
I had two live Ital/Marina axled 7's and my current 7 is a Dedion one.
Other things of interest are the adjustable ears (read changeable) from 2.0 deg to 0.5 deg in 0.5 deg steps, for the dedion.
This allows fine tuning to tyres that like more or less camber. Race teams will change according to race rules, slicks use 0.5deg, CR500's etc 1.5deg.
Other big differences are the way the lower damper mount is turned through 90 deg degrees on the Dedion axle.
This means that a single wheel compression (bump in road on one side) allows the axle to move upwards with the bush pivoting on the Dedion. On the live axle the pivot is the other way so it actually bends the damper along its length - not ideal for the rod of the damper to be bent along it's length as it is forced into the damper body!
This means the Dedion can hammer down a bumpy B road a good 10-15mph faster or round that bumpy corner (as already noted without skipping), than the live axle and still feel in control.
I have pics of the dampers on my last live axle car under single wheel load showing exactly this.
The solution to the problem is to fit rose jointed bottom mount dampers - such as Avo do. I did this.
This allows the damper to pivot in all directions and prevents the above bending force.
The live axle car handling on bumpy roads will be significantly improved - I've felt it.
However! BUT! The live axle car is still handicapped as the mass of the entire axle is unsprung weight. Every bump and direction change has to accelerate the entire mass of the whole axle.
Yes, the whole live axle is lighter then the Dedion tube and Sierra diff but the diff is not unsprung so the Dedion tube assembly that is unsprung weight is significantly lighter and thus can move around in a more responsive manner to the forces applied to it. So on a bumpy road the Dedion axle still wins!
Edited by Yellow 7 on Saturday 19th June 21:43
Tango and yellow that is extremely interesting...There are obviously much greater advantages with the De Dion than i thought!...Bummer really as i am probably buying one without!!...
Hope i can get a 5 speed to fit...little lost now, not sure whether to make a De Dion a priority now, or go with my heart (A car i like??...)
mike.
Hope i can get a 5 speed to fit...little lost now, not sure whether to make a De Dion a priority now, or go with my heart (A car i like??...)
mike.
Thanks Yellow, bit concerned that the 2.0 zetec is already putting that out....plus i get itchy fingers to play with cams...or anything tuneable (when i get time)..maybe there is an ital / Ford axle / Diff, that will swap over easily but handle up to 200 bhp..comfortably above anything i would consider!?
Great info on here from some serious guys....hope one day i will be able to help!
Thankyou,
Mike.
Great info on here from some serious guys....hope one day i will be able to help!
Thankyou,
Mike.
redmire said:
Thanks Yellow, bit concerned that the 2.0 zetec is already putting that out....plus i get itchy fingers to play with cams...or anything tuneable (when i get time)..maybe there is an ital / Ford axle / Diff, that will swap over easily but handle up to 200 bhp..comfortably above anything i would consider!?
Great info on here from some serious guys....hope one day i will be able to help!
Thankyou,
Mike.
Don't think there is an Ital fix - the halfshafts work their way out as well!Great info on here from some serious guys....hope one day i will be able to help!
Thankyou,
Mike.
Swap to a ford live and forget the problems. LSD is a must too,
Plenty you *can* do to an Ital.
You can shim the half shaft to stop if moving about, they used to tack weld them in which is no longer recommended I think.
You can fit an LSD.
You can overfill the diff.
You fit an oil seal around where the shafts go through the oil baffles. This stops the problem of all the oil flowing into the end of the diff on long corners and this causing the CWP to get hot and go ping.
I think there was a supply problem with the CWPs, I think Rimmer Bros probably still do them. And there is at least one manufacturer of uprated CWPs.
But at 200bhp and upwards, you may as well fit the English and forget about it.
You can shim the half shaft to stop if moving about, they used to tack weld them in which is no longer recommended I think.
You can fit an LSD.
You can overfill the diff.
You fit an oil seal around where the shafts go through the oil baffles. This stops the problem of all the oil flowing into the end of the diff on long corners and this causing the CWP to get hot and go ping.
I think there was a supply problem with the CWPs, I think Rimmer Bros probably still do them. And there is at least one manufacturer of uprated CWPs.
But at 200bhp and upwards, you may as well fit the English and forget about it.
Yellow 7 said:
The live axle car is still handicapped as the mass of the entire axle is unsprung weight. Every bump and direction change has to accelerate the entire mass of the whole axle.
Yes, the whole live axle is lighter then the Dedion tube and Sierra diff but the diff is not unsprung so the Dedion tube assembly that is unsprung weight is significantly lighter and thus can move around in a more responsive manner to the forces applied to it. So on a bumpy road the Dedion axle still wins!
It's possibly worth adding that the critical factor is the ratio of sprung:unsprung weight; the unsprung mass of a live axle is a very much bigger problem on an ultra-light car like a Seven than it would have on, say, an american sedan.Yes, the whole live axle is lighter then the Dedion tube and Sierra diff but the diff is not unsprung so the Dedion tube assembly that is unsprung weight is significantly lighter and thus can move around in a more responsive manner to the forces applied to it. So on a bumpy road the Dedion axle still wins!
The poor sprung:unsprung weight ratio demands particularly accurate and consistent (read expensive) dampers to minise the shortcomings.
The other problem with live axles that hasn't been touched on yet is the torque reaction... basically the whole axle tries to revolve in the opposite direction around the propshaft, to the detriment of traction, particularly out of tight corners. With a de Dion, this propshaft torque is reacted directly into the chassis by the diff.
The final, obvious problem with a live axle is that it's not so easy (though it is possible to some degree) to adjust the camber and toe on a live axle, whereas with a de Dion it is simply a matter of fitting appropriate shims between the 'ears' of the tube and the hubs.
Don't get me wrong; live axles can be made to work surprisingly well with careful attention to damping and spring rates and the overall weight advantage can allow them to remain competitive on smooth race tracks, but they'll never match a de Dion or a good IRS on the road.
Okay, i have got to forget my 'live axle' car and make a dedion a priority!
I will only regret it otherwise....Bum!
Think i would rather forgo the engine i want, than have a chassis i am not happy with, don't want to spend good money then immediately start work!!
Anybody know of a dedion car with sensible miles and ideally a ford engine but will consider other!??
I will only regret it otherwise....Bum!
Think i would rather forgo the engine i want, than have a chassis i am not happy with, don't want to spend good money then immediately start work!!
Anybody know of a dedion car with sensible miles and ideally a ford engine but will consider other!??
It is all relative, and relative to what you ultimately want. I have had my live axle for many years, and I have never "regretted" it. 10 years of tootling (as much as any 7 tootles, obviously) around with a Crossflow Live Axle were great fun. And my limited abilities meant I never really stressed it out too much, all 7s are a bit skittish due to the lightweight and at my speeds I don't really notice LA vs De Dion.
Then I got into track days and bust the CWP after Brands Hatch GP. And then I drove a James Whiting Fireblade whilst he was fixing my diff.
If you are looking to go the power route, then I think you are right to sort the chassis first. Engines can be swapped and tweaked a lot easier than LA to De Dion.
And if you go with something a little tamer in the front to start with, depending on what you drive now of course, it should be a little while before you need to upgrade. Little crossflows with live axles are still quite quick, even by today's standards
Then I got into track days and bust the CWP after Brands Hatch GP. And then I drove a James Whiting Fireblade whilst he was fixing my diff.
If you are looking to go the power route, then I think you are right to sort the chassis first. Engines can be swapped and tweaked a lot easier than LA to De Dion.
And if you go with something a little tamer in the front to start with, depending on what you drive now of course, it should be a little while before you need to upgrade. Little crossflows with live axles are still quite quick, even by today's standards
Edited by Noger on Sunday 20th June 20:19
redmire said:
Okay, i have got to forget my 'live axle' car and make a dedion a priority!
I will only regret it otherwise....Bum!
Think i would rather forgo the engine i want, than have a chassis i am not happy with, don't want to spend good money then immediately start work!!
Anybody know of a dedion car with sensible miles and ideally a ford engine but will consider other!??
Do you have a budget that you are working to? I know it's quite fashionable to describe the k-series as sI will only regret it otherwise....Bum!
Think i would rather forgo the engine i want, than have a chassis i am not happy with, don't want to spend good money then immediately start work!!
Anybody know of a dedion car with sensible miles and ideally a ford engine but will consider other!??
t these days but...A very sweet entry to caterham ownership is the 1600 supersport in "executive superlight" form. 6 speed, apollo, big brakes, widetrack. Can be had for 10-12k.
Bert
All I can say is my Zetec is still running on an Ital axle, with LSD, and I love it!
I've had the 7 re-chassied and deliberately stayed with the Ital - it's so much more fun to drive than a dedeion, and with the LSD, bearing fix, and overfilled it copes with my engine power no problem.
It's a LOT lighter than the dedeion, and has a better final ratio.
I've not gone for rose-jointed mounts, but do use better bushes than Caterham standard.
But, I don't do any racing - just FAST road use.
I've had the 7 re-chassied and deliberately stayed with the Ital - it's so much more fun to drive than a dedeion, and with the LSD, bearing fix, and overfilled it copes with my engine power no problem.
It's a LOT lighter than the dedeion, and has a better final ratio.
I've not gone for rose-jointed mounts, but do use better bushes than Caterham standard.
But, I don't do any racing - just FAST road use.
Best handling 7 I've ever driven was a live ford, well sorted car lots of fettling with damper & spring rates.
My old Live ford was ok but not as good as that one but still rode fine road & track & I couldnt moan at all & it was bloody light, 557kg with road gear & fueled rady to go & it had a boat anchor Vauxhall XE 2.0, that was not far of superlight weights which had much lighter body work & much lighter k series engines.
My old Live ford was ok but not as good as that one but still rode fine road & track & I couldnt moan at all & it was bloody light, 557kg with road gear & fueled rady to go & it had a boat anchor Vauxhall XE 2.0, that was not far of superlight weights which had much lighter body work & much lighter k series engines.
The Caterham Graduates (Classic Class - 8v Vaux live axle) now run an amended rear axle configuration. Includes new hubs, shafts, bearing, etc. and retains the old (rare!) Ital diff.
Previous years saw failure of half shafts on a racecar with A539 tyres and 100bhp, so far this year zero failures. So far this appears to be the only real method to remove the half shaft failure issue, but the car has not been tested to 'high' horsepower, but having seen the engineering then there is no reason for it to fail and it certainly provides better support at the bearing (where the shaft used to break).
Make contact with the Caterham Graduates - Nick Frost is probably the best starting point - his email can be found on the Graduates website.
Previous years saw failure of half shafts on a racecar with A539 tyres and 100bhp, so far this year zero failures. So far this appears to be the only real method to remove the half shaft failure issue, but the car has not been tested to 'high' horsepower, but having seen the engineering then there is no reason for it to fail and it certainly provides better support at the bearing (where the shaft used to break).
Make contact with the Caterham Graduates - Nick Frost is probably the best starting point - his email can be found on the Graduates website.
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