that would essentially imply that, as a locost has half the weight, it has half the grip, so the wheels spin easier. Fair enough. There is a bit of extra grip applied by squat, dunno how this compares though.
assuming it could handle the power you'd need to get a bespoke/custom porp made up.
Ned.
Yep, it's just the prop that needs making up, but i doubt the escort axle will ever take that amount of power tbh
Interesting one this, I would have thought thet what breaks a prop is torque & the torque on the axle is limited bythe weight on the axle &
the friction between tyre and road. With 1/2 weight you'll have half torque - how could you possibly snap the axle.......??
With more power available you'll produce that torque at higher speeds that's all, nature's own torque limit means your wheel's
spin before you can break a half shaft. Anybody know different????
cheers
Bob
quote:
Originally posted by Bob C
nature's own torque limit means your wheel's spin before you can break a half shaft. Anybody know different????
cheers
Bob
exactly my point - a jeep is 2 tons of car, LOTs of axle breaking torque available there. BTW does it have a centre diff or was this a windup problem
like on the old landies? I was assuming this question pertained to a locost application!
Bob C
I would have thought the torque of the v8 might damage the crown wheel and pinion on the escort axle. I've seen this happen on other
applications.
Ned.
torque is not linked to weight. Under full throttle up a hill in top gear, if you are not accelerating then the full force of the torque is acting on
your transmission.
Accelerating from rest, the full torque does not act on the transmission because the wheels can turn so some torque is taken by the wheels.
I'd better explain myself properly - as soon as enough torque gets fed into the axle the wheels will slip. It matters not what torque the gearbox
can supply, if this torque is exceeded the wheels will slip. You could put the QE2 engine in there but you won't see more torque than it takes to
spin the wheels.
My point was that the locost is half the weight of the ford escort the axle was designed for, so THE AXLE will only ever see half the torque it was
designed for, ergo it should be bomb proof! Irrespective of engine!
However, that maximum torque will be available at much higher speeds which may lead to more heating or lubrication failure in the diff - dunno.
shouldn't snap it though!
Torque applied to driven wheels is obviously limited by the weight on the wheel and the friction to the road surface and the radius of the wheel.
Stop thinking about engine torque here. Max axle torque occurs in LOW gear.
Cheers
Bob
i'll let you off. this once
that would essentially imply that, as a locost has half the weight, it has half the grip, so the wheels spin easier. Fair enough. There is a bit of
extra grip applied by squat, dunno how this compares though.
the half shaft in question is in a cut down jeep 1 ton centre diff running the engine for my locost at the moment
btw the ford rally team never used the std escort diff in competition they always swapped for the baby atlas from a capri
as they never rated the escort diff above 150 bhp reliably
i twisted a escort half shaft in my rs2000 with 130bhp on tap
Tim
[Edited on 16/12/03 by timf]
i thought of another point as well. Not many old escorts actually had enough power to wheelspin on dry tarmac, so the shafts may break before traction is lost anyway.
as well as grip the wheels have a certain amount of rotational inertia. If you dump the clutch the diff / half-shafts will experience more torque than
it would take just to make the wheels slip (they are also accelerating the wheels in their spin)
How much of an effect this would have I'm not sure, but quite significant I expect. With a big enough engine and strong enough prop and clutch
I'm sure you could blow up an escort axle this way.
The diff will not take the torque of the V8, the cross pins will snap when you try and get off the line quickly. If you uprate the diff you then have
problems with the half shafts and you will need uprated ones of those as well.
quote:
btw the ford rally team never used the std escort diff in competition they always swapped for the baby atlas from a capri
This has made me worry if our sierra LSD will take the 230lbft from our vitesse v8..
oh well, one way to find out
blueshift, IMHO the sierra dif should be fine as it was used for the v6's which put out a fair amount of torque and I'm not aware of people
using the turbo technics conversion on the ford v6 ever uprating or suffering from damaged difs.
Ned.
chairs ned. we shall see. those engines may have had muchos bhp but I wonder what their peak torque is.. 230lbft is pretty beefy.
Hi,
To add to the argument about torque versus weight...
Remember that tyres of today are much better than those of the 1970's and on good tarmac (also generally better than the 1970's) you will
get more grip and thus more torque will pass through the diff. Also bear in mind that the Escort diff was designed for road use and would rarely be
blasted away from every junction and roandabout at maximum throttle with wheels spinning. However, with a V8 you will very easily break traction even
when you don't mean to in some cases and will generally be operating the diff at a higher level of stress than a typical Escort would have done.
You are building a sports car after all 
I believe that you could indeed blast away with tyres smoking under V8 power at least once, maybe a dozen or more times but one day it would fail and
most likely within a short space of time. Surely you want more than, say, 3 months out of it before it lets go? This is why motorsport versions are
uprated. Not just because the power is a bit higher or because tyres are stickier or suspension is better but because they will be pushing the
envelope constantly and fatigue failures will result otherwise.
I too will be running a V8 (Rover 3.5 Litre) through a Sierra diff (non-LSD for now) but I'm not too worried for reasons given above. My diff is
actually one of the 7.5" ones which may or may not make it stronger, I'm not sure.
Cheers,
Craig.
I believe the TT Sierra conversions had quite hefty amounts of torque, like over 300lbft easily. I think the Sierra diff is pretty sturdy, but we
should *definately* get a super duper professionally made prop shaft.
[Edited on 19/12/03 by mackie]
Mackie,
I don't know if I told you before but I got a quote from AutopropUK (http://www.autopropuk.co.uk) for a Rover V8 to Sierra propshaft. They quoted
me £96+vat for a brand new unit capable of transferring over 400BHP and with a telescopic section in the middle to take up around 3/4" of
movement. I'll be going for that when the time comes.
Cheers,
Craig.
That sounds perfect, cheers for that! I think I've been to that site before actually but have never enquired. I assume they can make it up to any
length you want.
[Edited on 19/12/03 by mackie]
Yes, all they need to know is what length between flanges and what type of gearbox and diff you are using. When I asked if they had done any RV8 to
Sierra prop's before the guy said "Yes, one or two...hundred!". It was quite obvious from speaking to him that he knows his stuff. By
the way, the telescopic thingy is only there to ensure that no longitudinal stress is placed on the joints so don't use this as an excuse to
lower your accuracy in measuring the flange spacing. Also, try to use the Rover SD1 gearbox mounting plate as it has an extra mounting bolt and bush
arrangement which restricts longitudinal movement of the engine and box. This is important to prevent the gearbox and engine moving around under
braking and acceleration. If you're making up your own mount then at least try to emulate this. I can give you the measurements if you need
them.
Cheers,
Craig.
Yeah, our box didn't have the mount included so either we need to get one or need to fashion one ourselves. I think we need new washers and rubbers for mounting the remote too.
Our Rotary drag racing scene is very large here, and if anyones using strong Live axles, its them. One of the more popular ones is the Toyota Hilux, capable off handling 300+ hp with ease... There are many others of course, Nissan Bluebird TRX axles are apparantly quite sturdy...