ayoungman
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| posted on 2/2/07 at 06:13 PM |
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sierra prop shaft
Ok I'm confused ! I've seen a big pile of sierra prop shafts in my local scrapy. I don't know which parts of the prop shaft I need .
also, most seem to have a big connector on the gearbox end. I intend to cut the shaft down, sleeve it and get it rewelded/balanced locally. Help
please, cos I'm feeling a numpty
"just like that !"
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James
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| posted on 2/2/07 at 06:15 PM |
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Just phone up a proper prop place and get one made!
£100-120 for mine 2/3 years ago. Saves a load of hassle, it looks pretty, and it ain;t as likely to chop my leg off!
Cheers,
James
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"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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tks
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| posted on 2/2/07 at 06:34 PM |
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yeah!!
a prop is a very important thing..
not something you trow at a yard and then regrab it to balance!!
if the engine side brakes then your own weight energy forces the prop to do nasty things!!
think twice!! how do you feel if it broke when you use the car on the moment when it didn“t need to brake?
yeah then you shout and say f***k wy i didn“t spent it on the prop!
Tks
The above comments are always meant to be from the above persons perspective.
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JB
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| posted on 2/2/07 at 07:00 PM |
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Props
Basically you require an end that fits the gearbox and an end that fits the diff. One end needs enough tube to go between the diff and gearbox.
Somewhere there must be a slider, normally at the gearbox end (it slides in and out of the gearbox)
Now take the whole lot to a prop firm and let them do the job, all of the job.
I worked in props and built 1,000`s and to build a prop you need a lathe. (OK you can do some without)
Alternatively nearly all the bits for new props are available off the shelf. Dunning and Fairbank are good for props.
John
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John Bonnett
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| posted on 2/2/07 at 07:09 PM |
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I've shortened a number of propshafts and I've never had a problem and never needed one to be balanced. You do however need access to a
lathe. First mark the relative positions of the UJs by scribing and be very careful to reassemble in the correct position. The front UJ is on a spigot
which slides inside the tube. You can cut the tube beyond the weld and remove the UJ. The weld and residual tube can be turned off and cleaned up on
the lathe. Take the rear part of the prop, cut to length and tap the front UJ into the tube checking UJ relative positions. Make sure that the
finished length is correct by ensuring that there is free movement of the prop on the gearbox output spline. Weld up and Bob's your uncle. Trust
me it really is that simple.
John.jpg)
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MikeRJ
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| posted on 2/2/07 at 08:21 PM |
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The sierra prop does not have a suitable front UJ with splined section as it uses a very large cush drive which is unlikely to fit into a locost
tunnel. This is definately one part of the build it's not worth scrimping on.
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ayoungman
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| posted on 2/2/07 at 08:21 PM |
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Cheers John, I've got access to Lathes, so will do as suggest. First step is to get the prop tho'
"just like that !"
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JB
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| posted on 2/2/07 at 09:10 PM |
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Prop Shortening
quote:
Originally posted by John Bonnett
I've shortened a number of propshafts and I've never had a problem and never needed one to be balanced. You do however need access to a
lathe. First mark the relative positions of the UJs by scribing and be very careful to reassemble in the correct position. The front UJ is on a spigot
which slides inside the tube. You can cut the tube beyond the weld and remove the UJ. The weld and residual tube can be turned off and cleaned up on
the lathe. Take the rear part of the prop, cut to length and tap the front UJ into the tube checking UJ relative positions. Make sure that the
finished length is correct by ensuring that there is free movement of the prop on the gearbox output spline. Weld up and Bob's your uncle. Trust
me it really is that simple.
John
There is more to it than that. What you describe is correct but you MUST "clock" the shaft with a DTI to get it running without run out.
Tack it in 4 places then weld. You must be damn lucky to not require a "clock" or balance and for the prop to run true.
When I was building props about 1 in 50 I built would not require clocking. If the fit of the stub is correct into the tube then 90% would be OK for
machinery, but not perfect for cars without a balance. We would never supply a car shaft without balancing.
You can actually do all the above without a lathe. Carefully grind the weld out / off, holding the tube yoke into the tube. Cut the tube down as
square as possible, insert the tube yoke (stub) into the tube then fit the prop to the vehicle and clock it on the vehicle, tack and weld. If total
tube run out after welding is less than 0.01mm you will probably OK without a balance.
Unless you are 100% confident in doing your own prop I would leave it to the proffesionals.
John
[Edited on 2/2/07 by JB]
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ayoungman
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| posted on 2/2/07 at 10:03 PM |
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cheers for the offer Stuart. I think I can get hold of a prop locally to me. If I have any trouble, I'll u2u if thats alright.
"just like that !"
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goodguydrew
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| posted on 2/2/07 at 10:20 PM |
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So if the std Sierra front UJ is not suitable for the locost book chassis, what do you use?
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ProjectX
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| posted on 2/2/07 at 10:45 PM |
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Why isn't the front sierra UJ suitable? Thats what im using. MT75 fits no probs?
I know it has a big rubbery thing there for shock/movement but it does fit?
J
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tks
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| posted on 3/2/07 at 03:00 PM |
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yeah
it just fits..
but not by much..
(an old user of the donut) now has a bailey morris in it)
Tks
The above comments are always meant to be from the above persons perspective.
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