goodall
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| posted on 20/2/07 at 09:32 PM |
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well why do car makers go for split prop shafts?
but i have applied some of my engineering knowledge and i see how different angles would also cause it but i still think its also got something to do
with the shaft twisting
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gazza285
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| posted on 20/2/07 at 10:00 PM |
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quote:
Originally posted by goodall
well why do car makers go for split prop shafts?
Much easier to balance over short lengths, less lash at high rpm, to incorporate a sliding section and to gain ground clearance. Other that that, no
idea.
DO NOT PUT ON KNOB OR BOLLOCKS!
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goodall
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| posted on 20/2/07 at 10:31 PM |
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was a rhetorical question that wasnt ment to be answered because we all know the answer and i was thinking maybe some of those reasons also applied to
the split half shaft in many modern fwd cars
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gazza285
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| posted on 20/2/07 at 10:59 PM |
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I'm sorry then.
Non of those reasons apply to a FWD drive shaft as the FWD driveshaft is running at a lot lower speed, is a lot shorter, the diff is much lower than
the driveshaft and the CV joints do the job of the sliding section.
The only reason I can see for having split FWD driveshafts is to reduce torque steer.
If your FWD driveshafts are suffering from windup them I must congratulate you on having superb grip. Most torque steer is cause by weight transfer
due to poor front geometry or incorrect scrub radius.
I had an Alfa Sprint once.
DO NOT PUT ON KNOB OR BOLLOCKS!
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goodall
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| posted on 20/2/07 at 11:07 PM |
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im not saying the shaft is twisting by a huge amount its just a bit enough to pull one side a greater distance for a short moment causing a turning
motion which then exaggerates this effect, you have to remember that steel has a springing coefficient to it and will change shape, some half shafts
are very long and even at the lower speed it turns at i could imagine it still causing g forces if it was out off balance by abit. as for the sliding
bit i know that done by the cv but remember i said some of the same reasons
anyway this is way of what my question was about i just wanted to know about short V engines nothing more
[Edited on 20/2/07 by goodall]
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Liam
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| posted on 20/2/07 at 11:13 PM |
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Assymetric shaft windup is undoubtedly one of the many factors, but the fact that modern fwd cars with this very transmission layout that you're
criticising dont torque steer in practise, should tell you it isn't a major factor.
Certainly not a main criteria for choosing one donor transmission over another, or a good reason for choosing a tranny that gives you such packaging
problems.
Liam
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goodall
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| posted on 20/2/07 at 11:23 PM |
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but both transmissions would cause packing problems
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gazza285
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| posted on 20/2/07 at 11:24 PM |
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I'll leave this topic alone then because I don't know of any V4 engines that have been fitted to a car in the last 30 years, and I
can't see the point in having a AWD/ 4WD performance car with a thirty year old engine with 80bhp and no tuning potential because it gives you
equal length driveshafts at the end with the least foward grip.
DO NOT PUT ON KNOB OR BOLLOCKS!
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Liam
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| posted on 20/2/07 at 11:33 PM |
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quote:
Originally posted by goodall
but both transmissions would cause packing problems
Well you're the one putting this stuff in a mini!!
But seriously - yeah true, but the ford option wont give you half the headache you're having with this crazy hunt for this magic 10" long
engine that produces power. Did you look at that 4x4 mini site I linked? Even if you can fit audi quattro tranny in a mini, why would you want to
build something with the weight of the engine and box sooooo far forwards? How do you think it'll handle? It'll be front heavy enough
with the ford tranny, but at least you have 2/3 power to the rear for some chance of avoiding understeer. And proper LSDs that you dont have to lock
yourself (assuming you're not considering modern quattro stuff with torsen centre and rear diffs.
Dont think i'm some audi bashing ford fanboy or something - i'm just trying to give you what I think is the best advice. Audi quattro
tranny in a mini just dont work in my mind and your one reason for disregarding the ford tranny isnt really valid.
Liam
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goodall
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| posted on 20/2/07 at 11:48 PM |
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id be going for the audi transmission with a torsen mid diff for sure, i took a look at that web site and it does look good alright, iv never seen a
ford 4x4 gearbox in real life so i dont know what they are like as for weight up front that is a concern but neither transmission really gets away
from that problem.
maybe its just not worth while doing this idea
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smart51
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| posted on 21/2/07 at 08:50 AM |
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Back to the original topic. Why not use a bike V twin. Very short front to back. 2CV engines are also short but you'll need several of them.
What about the VW beetle flat 4? The later brazilian imports had EFI (f you can find one) and were said to be very good engines due to the 50 years
of development they had.
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NS Dev
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| posted on 21/2/07 at 01:40 PM |
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bike twins are short but you are still looking at 400mm ish for my Aprilia twins
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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NS Dev
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| posted on 21/2/07 at 01:47 PM |
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PS current road car is an XR4x4 and i can categorically say the only time you know the front wheels have drive is on ice and snow or gravel, where you
can feel some slight pull at the wheel.
On tarmac, wet or dry, the rear bias of the drive plus the equal length shafts mean you just get grip, and lots of it, together with an excellent rwd
type steering feel.
footnote, my 4x4 is a workhorse, not a preened toy car, and I only like em cos they are totally bulletproof!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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rav
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| posted on 21/2/07 at 03:26 PM |
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Just a thought - if fitting and transmission (Audi or Ford or whatever else) & engine in the front of a mini is troublesome, why put it there?
Theres far more space in the back!
No hassle of working around a tiny engine bay or modifying the scuttle. Then you can choose from all sorts of pokey engines & boxes and as long
as the engine sits right behind the seats it will be mid-engined, probably with a slight rear weight bias. Which means potentially much better
handling than the front heavy sardine tin approach.
If it has to be 4x4 and thats putting you off, I'm pretty sure the Lancia Delta S4/ RS200 style transmission layout is do-able, even on a locost
budget.
Any longitudinal engine and RWD box combo (as long as the box is narrow since its a mini and it has to fit between the seats, or rather the seats have
to fit beside it!) facing the opposite way, a transfer box mounted down near your feet somewhere sending drive front and rear via propshafts on the
passenger side, into a couple of suitable diffs.
All those bits are available, then its just a case of mounting them all and making some propshafts and possibly driveshafts.
It would mean adding a structural framework to carry all those bits, but then if you're going to be driving it hard you'd probably want a
cage anyway....
A type 9 box is 6" wide, as long as that could fit centrally between the seats I think it would be possible.
Alternatively, bike engine mounted behind the seats, chain driving a centre diff. Engine would be on the passenger side, assuming you didn't
flip the diffs, so it would be nicely balanced with the driver on board. Someone must have done that before?
Mark
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goodall
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| posted on 21/2/07 at 11:35 PM |
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nah i to keep it as a four seater so mid engine is a no
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rav
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| posted on 21/2/07 at 11:53 PM |
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Is there something special about the number 4?!
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Liam
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| posted on 22/2/07 at 12:30 AM |
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quote:
Originally posted by goodall
maybe its just not worth while doing this idea
Nah dont give up that easy! You know the ford tranny will go in from that 4x4 mini website. I dont think the quattro will work unless you can find
this crazy short engine but ah well - ford is better anyway with the rear power bias.
Another option is to give yourself a teeny bit more room - what about a pug 205 5-door? Still ultra light and what a sleeper that'd be with 4wd
and a decent amount of power.
Hmmm or what about quattro backwards? You may be able to flip the front diff in the case (not sure but i know you can with a certain similar
transaxle - possibly renault un1 - maybe rav'll remember i'm sure we looked at this once). And turn the rear diff upside down. Ok now
the engine is sticking out the arse of a mini but that's better than the front. You could make the engine cover look like you have a chest of
drawers sticking out boot - would surprise a few at the lights
Liam
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goodall
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| posted on 22/2/07 at 08:10 PM |
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sounds like a nice idea haveing it sticking out of the boot but i want to shock people a little less than that
nah i want it to be a mini for the design its just a little british classic
no the number 4 just happens to be the number of people you can carry in a standard mini
just i was thinking if i could get a 1.3 V4 that give out about 150 bhp at the most i could use two mini subframes and hopefully have more than 8
points (dont have to do a sva) and then just insure it as a standard 1.3 mini and claim to the insurance company if i crash i got the car like that
and since the engine size is right i might just still be insured, unlikely i know but worth a try, anyway im not planing on crashing since i built it
(not that very many people plan on crashing their car anyway)
[Edited on 22/2/07 by goodall]
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locost_bryan
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| posted on 23/2/07 at 02:47 AM |
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Anybody mentioned the Honda 116bhp VF1000 V4? Or the 125bhp Pan European ST1300?
Bryan Miller
Auckland NZ
Bruce McLaren - "Where's my F1 car?"
John Cooper - "In that rack of tubes, son"
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goodall
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| posted on 23/2/07 at 10:40 PM |
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but can you mount them to a normal gearbox with ease?
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