Hi,
please see this pic attached and tell me if we can put a bike engine maximum far right, to use in a LHD car, and put some angle in those U-joints?
is there some danger in broke propshafts or U-joints at high rpm?
thks
Amadeu
Rescued attachment new-2.jpg
IIRC props work best with a slight angle on the joints and cant go wrong if you run it absolutely straight. Not sure where I remember that from!!!!
A UJ is designed to run with an angle so no fear of problems here. They are made to run with a (IIRC) 5 degree minimum.
Your engine has no effect on the speed of rotation of the propshaft, it's dictated by the speed of the wheel/differential ratio. You won't
break a properly designed propshaft on a slightly modified seven (read - PROPERLY). The se7en weight is almost half it was originally designed for.
Steve
I'm not sure about having the angle between the engine/prop adaptor to the prop - I would of thought that it would be a lot better if those
mating faces were at 90degrees to each other?
I am only going from what I think, not from proven fact so maybe someone else on here can confirm/deny.
the mid bend in the prop is more than fine, it can be angled a lot further than that, as mine is already!
hth
cheers,
Steve.
[Edited on 21/3/07 by worX]
Allways wondered how the BEC get way with it. The yokes should be phased at 90 degrees (in theory) and outputs shafts at each end should be in parall,
but offset to allow the UJ's to work otherwise you wear flats in the bearings..
Would like to hear what others think about this..
Cheers
Dan
[Edited on 21/3/07 by Bluemoon]
quote:
Originally posted by xico_ze54
Hi,
please see this pic attached and tell me if we can put a bike engine maximum far right, to use in a LHD car, and put some angle in those U-joints?
is there some danger in broke propshafts or U-joints at high rpm?
thks
Amadeu
hmmm .... I always thought the important bit was to have the drive flange (on engine) parallel to the driven flange (axle) and the angle does not
matter too much providing it is not more than the UJ can take.
if you angled your engine so the drive flange was in vertical plane, then I would have no problems but like you have it, not sure.
read all about propshaft angles here
02GF74, yep that's what I was trying to get at...
Dan
so... what´s the best solution? bearing in mind the driver will sit on left and the problems of much weight on left side. plus the steering column
have to have room to pass though, gives no other chance than put that engine some distance to the right side.
can anyone sketch over my sketch an ideal solution to this problem?
Rescued attachment new-3.jpg
You'll need a sliding joint in the front section where it connects to the engine or it will shake the joint to bits. Prop suppliers have these.
As others have said, the two flanges should ideally be parallel, and as I mentioned in another thread recently, don't forget to consider VERTICAL
angles as well as the horizontal ones you're looking at here, i.e. if the output shaft is vertically higher / lower than the diff flange, you
have an angle there as well.
Im not sure about it shaking the joint to bits without a slider though Pete, all live axle BECs have to have the slider in the rear half for obvious
reasons and Ive never heard of any trouble at all with the front UJ.
In fact, I would actually suggest the slider on the rear with a fixed length at the engine end, because if your prop flange on the engine ever comes
loose (and they do - mine did), with a slider on the front the prop is able to disengage from the engine and potentially cause serious injury, with
the slider on the rear half it will simply cause some extra vibration but won't be able to escape off the output splines.
cheers
Chris
[Edited on 21/3/07 by ChrisGamlin]
Chris,
just finished to see one of the pics you show in your archive (named: R1 Prop angle) and it's like I have talked first.
in that photo your sprocket isn't in the centerline of the car, making an some angle with the first shaft, the same with centre bearing.
do you want to coment that?
the two prop mating faces need to be parallel because a u/j isnt a constant velocity joint, if they arent square you get a pulsing of motion rather
than constant at both ends. The worse the angle the more the drivetrain gets abused. I have no idea how badly this will affect it, but thats the
theory. However, the engine can happily be off the centreline.
If i was building a LHD bec, i would leave the feet areas out until the engine was being positioned, and balance them around each other. You can take
a chunk out of the passanger (right hand side) footwell to allow the engine further over.
quote:
Originally posted by xico_ze54
Chris,
just finished to see one of the pics you show in your archive (named: R1 Prop angle) and it's like I have talked first.
in that photo your sprocket isn't in the centerline of the car, making an some angle with the first shaft, the same with centre bearing.
do you want to coment that?
Chris,
thanks for the modified pic to observe the explanation.
so the 'receipt' to a good job is to put diff & sprocket flanges paralel. I see.
3 simple options:
1) find an engine which has the prop coming out of the other end. That is a bike with a sprocket on the left.
2) move to England and build it RHD.
3) chop your legs off.
No no no, there is no need to thank me.
Matt
quote:
Originally posted by matt_gsxr
1) find an engine which has the prop coming out of the other end. That is a bike with a sprocket on the left.
Take a look at this LHD BEC to see what he has done:
Left hand drive R1 BEC
I don't think the Isonblade has, I'm sure his is in the front. The centre bearing mount has enough flex to cover live axle movement, same
setup,Transits, Marinas and plastic pigs with 2 piece prop didn't have a sliding joint in the rear only the slider at the gearbox end.
if your prop flange on the engine ever comes loose (and they do - mine did)
Ever thought why this happened?
[Edited on 22/3/07 by Peteff]
Hi Pete
I guess there probably would be enough flex in the centre bearing to cope with a live axle moving at the rear, but if thats the case there's
certainly enough to accomodate any movement on the engine end.
FWIW my bolt loosened itself a bit despite being correctly torqued / threadlocked. I caught it in time after I noticed the vibration, but the flange
couldnt come off anyway because of the fixed prop length, had it been a slider its possible it could have sheared the bolt head off even if it hadnt
come fully undone, which is what appeared to happen to a car on the Yahoo list a while back (I forget who).
Hopefully not such a problem on the R1 though as they have tabbed washers to hold the nut as well as copious amounts of threadlock, but I can't
see a lot of point in tempting fate by putting the slider at the front if you have the choice.
cheers
Chris
If it had been a slider it wouldn't have happened. A slider would be engaged by at least 50mm so if it disengages your engine has fallen out.
Guess all you like about the centre bearing, Ford have been doing it like that for years and they don't guess. 
Pete, I used the word "guess" as a figure of speech which I'm sure most people picked up on without too much bother, I could have just
as easily used "can see", or "accept". You obviously failed to recognise that though judging by the slightly patronising tone to
your reply.
quote:
If it had been a slider it wouldn't have happened.
quote:
A slider would be engaged by at least 50mm so if it disengages your engine has fallen out.
No that was sarcasm Chris, I knew it wouldn't be long before you replied.
My point was that if there'd been a slider on there would have been no stress on the nut and it wouldn't have come loose in the first
place.
Your go, I've done now.
Pete
You're still making statements as fact without actually saying why, if you're going to argue against it then why not explain why you believe
a fixed length prop puts stress on the engine UJ / flange?
As you've said yourself, the centre bearing has enough movement in it to allow a live axle to move at the rear, so how does this suddenly become
non applicable when discussing the comparatively fixed span of engine to centre bearing?
If your engine is moving fore/aft more than your live axle, you have some serious problems that a prop slider isn't going to fix! 
Chris
BTW, I really don't want to turn this into a slanging match but you're seemingly writing in a condescending manner without realising!
Sarcasm by definition has an element of humour / wittyness / irony about it, saying "Guess all you like..." in reply to something I said is
a plain attempt at a put down, suggesting you believe you're knowledge is superior. This makes the comment patronising, not sarcastic.
[Edited on 25/3/07 by ChrisGamlin]
Unlike your prop, the angles on his will not cancel each other out. The rear is straight and the front is angled so the prop will pulse or phase as
the prop turns as Joel said. As it is the front which is at an angle and the rear is straight he will need the slider in the front as I will with mine
and Jon does in his. I have consulted with a manufacturer and his suggestion was a slider in the front and a torque tube in the rear for my
application which is like xico's but angled to the other side. As he says, the ideal would be to mount the engine with the joints parallel but
it's not always practical.
I'm sorry that I couldn't let it go but why should I not take my position in this and only see yours, you mentioned my name in your post
prompting me to retaliate Chris. Why is it only condescending or patronising when I say it?
Im not sure about it shaking the joint to bits without a slider though Pete, all live axle BECs have to have the slider in the rear half for
obvious reasons and Ive never heard of any trouble at all with the front UJ.
Does this sound a touch condescending as well, it does to me. I can't see the reason for a slider in the rear however obvious it is to you and
you have made no effort to explain to me just told me I am wrong and put me in a negative frame of mind. I would not resort to name calling and
insults on a forum any more than anywhere else,
"In fact, I would actually suggest the slider on the rear" sounded to me that you were calling my suggestion wrong implying that I do
not know what I am talking about and causing me to take umbrage.
[Edited on 26/3/07 by Peteff]
If you have 2 UJs on a propshaft, with parallel end flanges, then the non-linear transfer angles can cancel out. But on a BEC split prop you have 3 so
it won't. It can only possibly cancel if one of the joints is straight (which will wear it out quickly due to 'brinelling'
I'd say use a doughnut for the straightest of the joints - cheaper than a TRT (but a bit tricky to fit in a locost tunnel), soaks up minor length
variations and every sierra prop comes with one built in!
cheers
Bob
are you sure you're right there bob, as far as i can see if the ends are parallel then it doesnt matter what happens in the middle. Shame i dont
have lego any more to test it!
How fast would brinneling realistically were the joint out? Is it a real problem in anticipated kit car mileage?
Hi Pete
If the fact that the flanges are not parallel really is your reasoning, why did you not at any point simply say "you'll need it in the front
if your prop flanges aren't parallel", and why argue that its the reason my bolt came loose when you know my flanges ARE parallel?
I apologise if you think my initial comment was patronising, it certainly wasnt intentional which I hoped was obvious given my second reply to you
which was plainly written in a non confrontational way, despite what I thought was a fairly abrupt reply from you.
quote:
I can't see the reason for a slider in the rear however obvious it is to you and you have made no effort to explain to me just told me I am wrong and put me in a negative frame of mind
With 2 UJs you have to line up the yokes on the middle section. Which bits would you line up with 3??? 'cos if you line up both middle sections
the end ones would end up at 90degrees, which would be totally wrong if the middle joint were straight & the other 2 at an angle - it just
don't work with 3 UJs!!
I think the "wearing straight" thing is not too important - at worst you end up with a tiny bit of backlash, nothing compared to the diff
& CVs on the driveshafts! I've seen it on an aincient prop (off a spit I think) - the joint seemed to 'click into position' in the
straight ahead state.
ATB
Bob
Because that was the obvious point of his question as illustrated by his diagram. I didn't therefore think it necessary.
I could have just as easily used "can see", or "accept". which would have worked better. The only reason you gave for putting it
in the rear was because it might let go at the front which just illustrates a lack of confidence in the prop.
The link in 02G2s post illustrates prop principle and the reason the sliding joint is needed in the front is to allow the prop some movement when the
knuckle of the centre uj is on the inside of the centre angle pushing the front of the prop towards the engine and pulling it on the outside. I think
Bob is using the same logic as me in saying that the centre angle cannot be cancelled out on a two piece prop, the joint is phasing. The slider is a
bodge to allow this movement to go somewhere other than back into the engine end of the prop.
According to the vibrate website
On vehicles with two piece propshafts there is an odd joint. The working angle of the odd joint should be kept below 1/2 degree and above zero
degrees. This is because there is not a companion U-joint. Think of the front piece of a two piece propshaft as being an extension of the transmission
output shaft.
1/2° is not practical in my application so now I may have to rethink the engine position
The designer will have specified a material rigid enough to stop the prop from whirling like a skipping rope which is why it is made in two pieces to
keep the thickness down, not to get round a corner like we use it on a Locost, so the movement will be translated into fore and aft and be operating
at an angle to the centre bearing.
Rescued attachment propphase.jpg
I forgot to tell you I'll use a Sierra 3.15 fixed diff.
the discussion is very nice indeed, great theories but no unanimous conclusions at all.
so what kind of way must I follow?
cheers
Amadeu
Pete - there is no axial movement as a UJ rotates, the vibration is purely rotational. (provided the 2 rotational axes of the spider intersect, which
they always do in a prop, sometimes don't in a socket set!).
cheers
Bob
quote:
Originally posted by Peteff
Because that was the obvious point of his question as illustrated by his diagram. I didn't therefore think it necessary.
I could have just as easily used "can see", or "accept". which would have worked better. The only reason you gave for putting it in the rear was because it might let go at the front which just illustrates a lack of confidence in the prop.
Amadeu
As you can probably guess, its quite a complicated subject if you want to get everything "textbook". In reality most installs are a
compromise of some sort but what's been discussed about balancing two of the UJ angles and keeping one almost straight is a good starting
point, so either like mine (with the rear UJ almost straight) or with the front UJ almost straight with the rear two cancelling each other out should
give acceptable results. If you want to look further into the technical stuff, have a look
here.
As for the slider, you've seen the arguments for and against positioning it at the front so I'll leave that one for you to decide on.
cheers
Chris
so, I have to ask this.. why not use a cv joint instead of a universal?
From what I understand, its very hard to make / find a CV joint thats capable of rotating at ~7k rpm, obviously as a driveshaft they are rotating at 1/3 to 1/4 that speed.
Quite a few cars do use a CV in the prop, I know rover SDI did for example. Also the later front engined single seaters used CVs because of the
extreme prop joint angles needed to negotiate the driver's arse (the rzeppa joints from mini driveshafts)
I'd recommend a sierra donut for the straightish joint - then you won't need a TRT. Why has no-one else done this, it works a treat!
Bob
Bob
quote:
Originally posted by Bob C
TRT. Why has no-one else done this, it works a treat!
Bob
Bob
Is it not too big to fit in some transmission tunnels?
To be fair, looking at the top pic, I think it would be a lot easier to route the steering column differently than the propshaft?
Many have router the column around a V8 so dont see a Bike engine could be harder?
quote:
Originally posted by G.Man
To be fair, looking at the top pic, I think it would be a lot easier to route the steering column differently than the propshaft?
Many have router the column around a V8 so dont see a Bike engine could be harder?