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4wd rear axles
chrisg - 8/8/03 at 09:03 PM

I've been thinking(I know)

I was following a VW golf 4motion and thinking about modern 4 wheel drive hatches and saloons.

Would the back axles be any use for Locost purposes?

The ones I can think of are The Golf, Cavaliers, Mondeo & Jaguars, Audis, subaru.

Any more, and can anyone tell me why it wouldn't work?

Cheers

Chris

JoelP - 8/8/03 at 09:23 PM

well, IMHO if it turns the right way, and has the right ratio, it should be fine, though if i had a powerful 4x4 id be sorely tempted to use all of the drivetrain. I suppose RWD is more fun than AWD though, but youd need a new g box to make it RWD i guess, which would make it a trifle wasteful only using the back end. Plus golf 4motions are a trifle expensive to massacre! however, i suppose from a scrappers it could be a good option. Most would be IRS wouldn't they?

trifle trifle bloody trifle.... gotta stop saying that.

i'll be getting fat...
[Edited on 8/8/03 by JoelP]

[Edited on 8/8/03 by JoelP]

Peteff - 8/8/03 at 10:16 PM

What about these then
Nuff said.

yours, Pete.

andyps - 9/8/03 at 11:27 AM

I guess the potential problem with some of them would be that they typically work on a front biased power ratio (things like golf, cavalier, audi etc.) which may mean that the rear axle components are not designed for continuous application of the full amount of power their respective engines generate. e.g. Cavalier 4x4 had about 130bhp, would generally only put 60 through rear, probable max through rear in short bursts no more than 100bhp.

Putting all the power through them may lead to shorter than expected life if you have decent engine power. Otherwise, no reason why they wouldn't work.

Rick - 9/8/03 at 12:05 PM

I understand what you are saying about the back axles maybe not good for the power.
But most live axle Locost's have Escort or Cortina type axles that weren't designed for lots of power either and seem to cope quite well with double what they were originaly working with.
I am sure that these axles could cope with quite a lot more power. (but I could be wrong, and often am )

A good idea in the first place, since donor axles are getting harder to find.

Rick

theconrodkid - 9/8/03 at 12:15 PM

how bout BMW,millions of them about and bomb proof as well

ChrisW - 9/8/03 at 12:23 PM

Heard rumours of these RWD Mondeos. Apparently it's the same running gear as the back of an RS2000 4x4 but I've never managed to find out which model Mondeo to look out for. Any clues?

Chris

Stu16v - 9/8/03 at 01:08 PM

A lot of Westfield BEC's use Landrover Freelander rear diffs, which are originally 4X4.

HTH Stu.

blueshift - 9/8/03 at 01:25 PM

We're going to be using the rear diff and gubbins off a sierra 4x4 - afaik similar to the normal rwd sort in size of casing etc, but limited slip. front end is going to be rover v8 and gearbox.

I think craig1401 is doing that too.. If it can't handle the torque I'll let you know

[Edited on 9/8/03 by blueshift]

JoelP - 9/8/03 at 01:34 PM

dont take this as fact, but someone told me that the 4x4 drivetrain on sierras breaks all the time, can take the 2.9 power... they said a relative had had it fixed several times. maybe they were just a poo driver!

Rick - 9/8/03 at 02:18 PM

The reason they use the Freelander diff is because they are half the weight of almost anything else, my uncle has one on he's Megabusa, no probs with power on these

Rick

andyps - 9/8/03 at 08:06 PM

quote:
Originally posted by ChrisW
Heard rumours of these RWD Mondeos. Apparently it's the same running gear as the back of an RS2000 4x4 but I've never managed to find out which model Mondeo to look out for. Any clues?

Chris


The only RWD Mondeos were the early BTCC race cars - Ford took advantage of a rule which meant that the race cars had to use standard components from road cars so they used the RWD bits from the 4x4 mondeos and forgot about the connections to the front wheels.

There wern't many (if any) 4x4 Mondeos sold in the UK though as far as I remember.

JoelP - 9/8/03 at 10:07 PM

my neighbour used to have a 2.0 4x4.... at least thats what it said on the side!

chrisg - 9/8/03 at 10:38 PM

There were some 4WD mondeos

Dont have any production figures.

Have a look Here

Cheers

Chris

[Edited on 9/8/03 by chrisg]

andyps - 10/8/03 at 06:07 PM

My comment was only personal observation! I havn't seen many at all, but maybe the badges were discreet!

Noodle - 10/8/03 at 06:54 PM

quote:
Originally posted by chrisg
There were some 4WD mondeos

They're called X-Types

MK9R - 11/8/03 at 09:15 AM

Noodle, beat me too it!!

mranlet - 11/8/03 at 03:23 PM

Any of the Nissan Skylines, All AWD Audis but the TT, All Subarus are RWD biased. Rear differentials receive 100% of the power under normal driving, so you'd be safe to plug a lot of power through them.

I think that rear ends that weren't designed for high power will work alright due to the greatly reduced weight.

Imagine trying to lift a rock with a stick: Trying to lift a big rock with a small stick will break the stick, but if you use the same stick on a small rock it will work fine, regardless of how much input force you give it...

If you're trying to use a full-time AWD system rather than an on-demand 4x4 system, the rear end should not matter, as long as you have the right sensors and such. This is not true for all cases, but for the majority it is. A RWD Dastun differential will work with a Pulsar GTi-R AWD system (and is a fairly common setup from what I understand) as long as the slip sensors and drive/propshafts fit.

What is your AWD or 4x4 plan?
-MR

ijohnston99 - 11/8/03 at 05:25 PM

quote:

All Subarus are RWD biased


Not all, I believe UK spec turbos are 50/50 hence the understeer probs. Some jap cars are 40/60 to compensate for the understeer probs, although you can get around it in the 50/50 cars by messing about with suspension geometry!

My ha'pennies worth,
Ian

mranlet - 11/8/03 at 08:27 PM

Hmmn... I believe that understeer is partially from weight distribution, partially from the the AWD system's propensity to want to deliver power to the front.

If the biasing were 50/50 all the time, it would make the fuel economy suck hardcore - known as 4x4. Therein lies the beauty of AWD, power going only where it can be applied.

The vast majority of AWD systems used in road cars (and race cars for that matter) are descendant from the Audi Quattro AWD system first found in the WRC Coupes of the 80's. The 50/50, 40/60/ or 70/30 ratios are often used to describe how much power CAN be alloted to the respective sides. Subarus mostly have up to 50% front under extreme slip, while Skylines will only direct 30% of the power to the fronts even if the rear wheels are smoking madly.

Something else that occured to me is the use of Porsche rears - 944 or 911's can be found on Ebay quite often or at the junkyard/breakers yard.

-MR

Liam - 20/8/03 at 11:20 PM

quote:
The 50/50, 40/60/ or 70/30 ratios are often used to describe how much power CAN be alloted to the respective sides.


Nooo...

Quoted torque splits like these for 4WD cars are always refering to the static torque split - i.e. the split under normal conditions of no wheel slip. For example, when pootling round town, a Sierra 4x4 sends 33% to the front and 66% to the rear. Most Subaru's are 50/50, up until recently all Audi quattros have been 50/50, etc etc. Of course you're right about the Skyline being 100% RWD under normal conditions.

It's when wheels start to slip that the splits start to change. Centre diff's lock up and torque splits can go all the way to 100% being delivered to the non-slipping axle depending on the diff-locking method in the centre diff (most centre diffs are viscous or torsen lsd's and can only lock around 80%).

quote:
If the biasing were 50/50 all the time, it would make the fuel economy suck hardcore - known as 4x4


I think you are refering to the reputation of old 4x4 jeeps and such (e.g. old landrovers) as having poor fuel economy and tyre wear which is wrongly associated with modern AWD cars. Old 4x4's of this type had no centre differential and so in 4WD mode the front and rear axles would be locked at the same speed - so when you go round a corner the tyres scrub themselves to bits and your fuel economy is cack.

All modern 4WD's regardless of torque split will of course have slightly worse fuel economy than 2WD's cos of the losses in the extra diffs/clutches/shafts/etc, but a 50/50 split is no different to any other.

*****

Oh yeah - the topic...

As I said above any 4x4 system (even a FWD based one such as the Cav) will take most of the engine's torque on one axle if the other slips (depending on how much the centre diff/coupling can lock up), so will be appropriately rated.

The modern Golf (also Audi A3 and TT) 4-motion system has the centre 'diff' (a multiplate clutch) lumped in with the rear diff - so not much use to locosters.

Cavalier/Calibra 4x4 has IRS and uses some beefy holden sourced rear diff. It looks exactly like a Carlton diff and probably is. It isn't an LSD either. Possible locost option but may as well use a sierra diff.

Escort 4x4 has IRS and the rear diff is non-LSD (not all that good since it's a permanent 4WD system). I think it's the same as the diff's used in later (bug-eyed) scorps. At least it looks like it from what I've seen - has removable cover on bottom instead of back. Ok unless you want an lsd.

Mondeo 4x4 is same as 'scort (but didn't even have a centre lsd - 3 open diffs using braking to limit slip - uuuurgghhh!).

Dunno bout the x-type but probably slightly fettled ford.

Audi quattro rear diff's are Torsens - mmmmmmm. Quite 'agriculturally' sized though. Celica GT4's and Lancia Integrales are another source of Torsen diffs - mmmmm.

Scooby WRX's have viscous lsd's and they seem to look quite nice and compact. Quite nice.

Old Beemer 3-series look quite nice too - that's what we'll all probably have to use anyway when the Sierra's all dissapear like the MK2 escorts have.

Hope that helps.

Liam

Rorty - 21/8/03 at 03:21 AM

Liam:

quote:

Audi quattro rear diff's are Torsens
Actually the Torsen diffs in Audis are in the centre, not the rear.
BMW Z3s have a Torsen diff in the rear, as do the MX5, RX7 and a lot of Toyotas.
Incidently, the Rover 600 and 800 Ti Coupes have Torsen diffs in their FWD set ups. Possible contenders for mid-mounting?

Noodle - 21/8/03 at 06:02 AM

quote:
Originally posted by Rorty
Incidently, the Rover 600 and 800 Ti Coupes have Torsen diffs in their FWD set ups. Possible contenders for mid-mounting?
As does the 200 Turbo Coupe. A guy who worked with Tony Pond on chassis development for these things told me they could cause serious handling problems in the FWD motor. Apparently Mr. P could replicate the car losing control at a certain speed round a certain bend again and again. He intimated that this caused their demise (litigation fears).
True or not? Dunno.

Neil.

Liam - 21/8/03 at 12:49 PM

quote:
Actually the Torsen diffs in Audis are in the centre, not the rear.


Oh yeah - right you are. I thought I might get a little bit mixed up tryin to remember all that. Some of the bigger quattros (A8's/V8's) also have a rear Torsen, but in most models the side to side torque distribution is handled by the traction control.

Incidentally, it's Audi centre torsen diffs that are used in the bike engined Formula SAE student series. They can be plucked out of the audi gearbox and chain driven - a nice cheap alternative to quaiffe units.

Liam

greggors84 - 22/8/03 at 11:18 AM

I know thats what Oxford brookes are using in their car.
Its powered by a CBR 600 and has a full carbon tub. Its got a silly power to weight ratio. The competion was on last month. Dunno how brookes got on though.

JoelP - 22/8/03 at 09:04 PM

quote:
Apparently Mr. P could replicate the car losing control at a certain speed round a certain bend again and again. He intimated that this caused their demise (litigation fears).
True or not? Dunno.

Neil.


Never felt that myself in a selection of 600 and 800 turbos, the worst thing i found were terrible torque steer, appalling ABS, too much length in the 800s and weak power steering pumps. Use to love setting wheels spinning on roundabouts! And sometimes the 800 would overboost and run the injectors out of fuel.

Brilliant engines in my books though, that will definitely be the donor for the next proj! Midmounted...

Chris7 - 12/9/03 at 08:21 AM

I have the chance of obtaining a jag backk axle of XJ40 1991 not sure if they are live axle if they are has anybody ever fitted one building book built chassis with ZX-9R Engine .

Thanks Chris B