James
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 posted on 28/11/02 at 11:08 AM |
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Sierra Gearbox Doughnut
I've just been putting in the transmission tunnel and I was really pleased at how far back I'd managed to get the gearbox/bellhousing and still have
a modicum of foot/pedal space.
Anyway, I've done the tunnel 140mm wide as I believe is standard(?) but now I've actually managed to get the gearbox to the chassis I've found that
the poxy rubber dougnut-propshaft thing is so wide I'm gonna have to have a transmission tunnel 'power bulge' to fit it in!
So, do I widen the tunnel (and therefore reduce space for seats etc. Which I don't want to have to do.
Or, is there some way of ditching the doughnut?
Presumably you do *have* to have it don't you?
I know someone said something about using one off a LDV van? But I'd need more details about model etc. as know nothing about vans!
Please help!
Thanks,
James
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David Jenkins
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| posted on 28/11/02 at 12:01 PM |
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Are you using a Sierra diff? If not (i.e. using a live axle) then you don't want the rubber thing anyway - it will split fairly qickly as it isn't
meant to bend much. It's a 'take the shocks out of the transmission' device, not a UJ.
...but you probably know that anyway ...just ignore my drivellings... 
cheers,
David
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scutter
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| posted on 28/11/02 at 12:10 PM |
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James ,
Seem to recall that the 2.8 capri that donated it's back axle to the cause had a type 9 gear box which had a normal UJ joint at the front of the
prop-shaft,
This may be of some use unless someone else proves me wrong.
Take care Dan.
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James
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| posted on 28/11/02 at 02:10 PM |
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quote:
Originally posted by David Jenkins
Are you using a Sierra diff? If not (i.e. using a live axle) then you don't want the rubber thing anyway - it will split fairly qickly as it isn't
meant to bend much. It's a 'take the shocks out of the transmission' device, not a UJ.
...but you probably know that anyway ...just ignore my drivellings...
cheers,
David
Hi David,
Sorry, should have said- yes I'm using the Sierra diff.
Dan,
I think the Capri doesn't have the donut as it's not IRS. (Stress the 'think'  )
Perhaps I should describe it better:
There is a splined (output?) shaft that sticks out about 10mm from the back of the Type 9. Over this slides the 'female' equivalent of the shaft a
tube which has at the back of it a 3 pointed star.
The dougnut had six holes around the outside and bolts to the three pointed star with three bolts.
The prop starts with another three pointed star which bolts to the other three holes of the doughnut.
I presume there's no way I can just ditch the doughnut and attach the two 3 pointed stars together? There would be a large shearing force on the
bolts and also any diff' shock would travel straight to the gearbox. So I need to come up with something else.
Thanks,
James
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Viper
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| posted on 28/11/02 at 02:17 PM |
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the donut is there as a cush drive a comfort thing if you like also it reduces sudden loads to the diff when you nail it..you dont need it and surely
you will be having a prop made to suit the new length? so you won't need to bolt them together you will have a 1 piece prop...
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scutter
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| posted on 28/11/02 at 06:01 PM |
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James
If you're going to make up your own prop-shaft, then if it fits use the front and smaller capri UJ and mate it up to the sierra rear shaft. job
jobbed.
Take care Dan.
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Viper
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| posted on 28/11/02 at 06:05 PM |
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unless you have a way of balancing the shaft, your best bet would be someone like reco prop, at least you know it won't shake itself to bits when you
get going...
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James
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| posted on 28/11/02 at 06:15 PM |
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Have a nasty feeling I'm hijacking my own post here but anyway:
Not sure about the prop shaft yet (whether I'll do it or get it made). My welding instructor says he's been making them for racing for years and
hasn't had a problem and reckons I should make it but get it professionally balanced.
What diameter tube have people used? The Sierra prop seems to be about 3" diameter and that would seem to be overkill. The book says use 16swg tube
but doesn't state diameter (that I could spot).
Cheers,
James
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geoff shep
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| posted on 28/11/02 at 06:25 PM |
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Ditch the donut
On the sierra, the rubber coupling is for noise and vibration damping. The prop goes from the gearbox to a fixed bearing before going to the first
UJ. Unless you get the run absolutely straight the rubber coupling will be flexing on every rotation and even a new one can fail - with dire
consequences at a couple of thousand rpm.
There's lots of history of it on the monocoque robin hoods where the advice is definitely to get rid of it. There have been many cases of the thing
letting go and bashing the transmission tunnel into a circular cross section - right next to your thigh!
I've got a RH with sierra set up - have the prop shortened with a UJ where the rubber goes.
This is from the robin hood club forums:
Don't Let the cost bother you, take it from someone who learned the hard way, my propshaft let go on the motorway last week, and the
damage was incredible, I now need a set of new tunnel panels (because the broken end of the shaft Cut through in to the passenger compartment), and a
new gearbox which was shattered and unrepairable, along with a new propshaft.
[Edited on 28/11/02 by geoff shep]
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stephen_gusterson
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| posted on 28/11/02 at 07:47 PM |
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i bought my prop made to measure brand new with all the right fittings from the type 9 to the diff.
160 quid all in.
I dont need to worrry if it fits, if my welding is good, if its gonna vibrate like hell, or if the donut is gonna give and tear me out a second
as&&ole.
I agonised over this, and combined with the fact you need a prop end from a transit - like big van with the prop under the car and buried in mud -
that the only sane thing to do was buy.
atb
steve
PS - the big diameter of the shaft is due to the fact you are putting a lot of power and torque through it. The rear drive shafts are SOLID hardened
steel.
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jollygreengiant
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| posted on 28/11/02 at 08:48 PM |
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Sierra gearbox doughnut
Ok here we go.
Sierra's (Ford) used 3 (yes THREE) type of front prop joint. In order of priority of use (depending on availbility from suppliers/at assembly)
Rubber doughnut
Spicer joint (UJ)
CV Joint (Ultra Very scarce)
Gearbox output splines should be the same for sierra, granada, cortina, capri, but might be differnt sizes for smaller 1.6, 1.3 units and yes beware
there were a few 1.3 pinto engines fitted to base sierra's.(dog Sh*t slow but 50 to gallon).
Making prop is quite easy if you think about it sensibly. Get U.J. spline end prop and put light chissel mark in tube side of u.j. carrier adjacent to
one of the yokes. Then move to other end of tube that you will be fixing to diff and mark tube in line with first mark.
Cut prop front joint of tube about 4/5 inches back u.j. rear yoke face. Then carfully grind/cut weld down to sleeve face & remove waste piece of prop
shaft, fit front joint to gearbox (about 3/4 on)
Fit prop to diff (in normaly ride height if live axle)and mark prop where you need to cut it to join on sleeve of front joint.
Remove both items, cut propshaft squarely to length, and deep chamfer outer joint edge of tube. Fit both parts together and align indents. tack weld
at three points (lightly) check alignment then if OK fully weld.
A Good commercial truck depot might be able to balance prop ( Billows in Kettering used to be able to do it)
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jollygreengiant
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 posted on 28/11/02 at 08:52 PM |
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Sierra gearbox doughnut
Ok so your nowhere near Kettering but you get the Idea.
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paulf
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| posted on 29/11/02 at 09:54 PM |
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quote:
Originally posted by jollygreengiant
Ok so your nowhere near Kettering but you get the Idea.
So are you in or near Kettering?. I am from Rothwell.
Paul.
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stephen_gusterson
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| posted on 29/11/02 at 10:55 PM |
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i am in kettering and I have a propshaft.
do i get a prize?
atb
steve
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jollygreengiant
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| posted on 1/12/02 at 12:25 PM |
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Rushden
Now yer know
nuff said
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James
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| posted on 2/12/02 at 05:41 PM |
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Thanks!
Thanks for all the replies guys, guess I'll go the following route:
splined propshaft 'socket' welded to 1st UJ, then main body of propshaft welded to another UJ to join onto the diff.
Sound OK?
Whether I make it myself of course is another matter!
All I can say is this:
pity I chopped out my tranny tunnel before reading these posts!!! 
Thanks again!
James
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stephen_gusterson
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| posted on 2/12/02 at 07:00 PM |
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what do you mean by welded to UJ?
atb
steve
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