welderman
|
 posted on 3/3/05 at 11:43 PM |
|
|
Blade starting
Finally after checking wires, fitting new plugs, flushing system with new petrol and generally pissing about. Got it started, great you say. The
propshaft adaptor that i so carefully welded on(which was ever so slightly out of line) seems to make the car shake. Is this normal or is it big
hammer and burning gear job to get it right.
|
|
|
|
|
Hellfire
|
| posted on 4/3/05 at 12:12 AM |
|
|
You welded the propshaft adapter on? 
Couldn't you just use a bolt instead...
UIM (unless I'm mistaken) the engine output shaft is induction hardened to specific hardness and tensile strength to give the required
hardness/toughness. If you have welded directly onto this you will very likely have annealled it (softened) thereby reducing all of it's
critical properties and possibly scrapping the component.
I hope I've misread your posting and you haven't really done this as it could cost many pennies to correct. IMHO the car shaking is the
least of your worries now...
|
|
|
phil_far
|
| posted on 4/3/05 at 07:11 AM |
|
|
I am afraid that Hellfire is right 
This is beside the damage that you might have caused to all the rubber oil seals with the heat generated, and not to mention warpage of the shaft
itself. Sorry
Philip
|
|
|
Peteff
|
| posted on 4/3/05 at 10:55 AM |
|
|
Do you mean you welded your own propshaft end on? If the bike adaptor was splined it couldn't be out of line on the engine output shaft. Is your
engine on a slant and do you have a sliding section in your prop?
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
|
|
|
ChrisGamlin
|
| posted on 4/3/05 at 11:00 AM |
|
|
Ditto the others, although if welded well the heat could be kept fairly localised - although burning it back off certainly won't!
The retaining bolt works fine as long as its threadlocked so see no reason to weld it on unless the splines were damaged or something.
If its an 893 blade then I may know of someone who has a gearbox for sale, this would include the output shaft you'll need if you do decide to
replace it, and will give you a spare box for when you round off the dogs for the first time 
The gearbox swap isnt a huge job, the RGB boys have em down to a fine art.
|
|
|
ChrisGamlin
|
| posted on 4/3/05 at 11:04 AM |
|
|
Ah good point Pete, are we talking about welding the prop adapter to the prop itself rather than using 4 bolts like a conventional prop, or are we
talking welding the flange to the output shaft itself, to negate the need for the single retaining bolt?
If the former then how do you do the bolt up to hold it to the engine? A sliding fit onto the splines is not sufficient even if the flange itself
couldnt slide back off due to the prop holding it on. Ive had my centre bolt come loose once and even though the flange couldnt come off the engine,
it still vibrated like a Rampant Rabbit
[Edited on 4/3/05 by ChrisGamlin]
|
|
|
welderman
|
| posted on 4/3/05 at 11:51 AM |
|
|
Quote.. Do you mean you welded your own propshaft end on?
Yes i welded the prop end back on after i shortened it. And was out of centre by about 0.5 - 0.75mm, which i thought was not too bad, but it seems it
needs to be bob on so to speak. So i am thinking of putting some heat into it to bring it back into alignment. Sorry to be a pain chaps.
Will this be ok?. And also i thought the big rubber bush would have compensated the vibrations.
|
|
|
ChrisGamlin
|
| posted on 4/3/05 at 12:12 PM |
|
|
Ah ok, at least you havent taken the welder to the engine itself
Props are finely balanced on a rig a bit like a wheel balancing machine, mine has little lead weights on one side of it so Id think any deviation from
totally straight that is measurable using conventional equipment would be very noticable and vibrate a fair bit.
|
|
|
ChrisGamlin
|
| posted on 4/3/05 at 01:10 PM |
|
|
I don't want to sound like Im preaching but bear in mind that the prop is only 3" from your legs and if it fails it may get considerably
closer!
Added to that, its rotating around 3.5 times quicker than the wheels, so any small imbalance will be magnified compared to a wheel imbalance.
I would certainly look to getting it balanced and inspected by a professional prop manufacturer if nothing else, and not try straightening it myself.
|
|
|
welderman
|
| posted on 4/3/05 at 01:30 PM |
|
|
Thanks for the replys, will have a good look at it and think about getting it sorted. Ta.
|
|
|
Peteff
|
| posted on 4/3/05 at 01:48 PM |
|
|
I made my own type 9 prop from 2 separate units but it was easy to cut the end off one and knock the other one into it. It was a very tight fit and
worked well. I've made a temporary one for the bike powered car I'm doing now but due to the overall length and sliding joint I'm
going to get one done for running it on the road. I might even run to a cush drive to ease the gearbox strain.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
|
|
|
welderman
|
| posted on 4/3/05 at 02:32 PM |
|
|
Let us know how you get on with cush drive, been quoted 40 - 50 pounds for prop to be balanced
|
|
|
Lightning
|
| posted on 4/3/05 at 05:57 PM |
|
|
On my last kit which had a Xflow, I had a mate weld the prop. When driving the car no noticable vibrations could be felt but the constant
"slight out off balance" caused fatigue in the tail of the gearbox (aluminium) which resulted in failure in the casting. Not realising the
cause I changed the gearbox and suprise suprise it did it again.I bought a balanced prop which stopped the problem.
In short, do not risk it, get the prop dynamically balanced.
Force= angular velocity x radius
The angular velocity is high as Chris stated.
Steve
|
|
|
welderman
|
| posted on 6/3/05 at 02:32 PM |
|
|
Deffo getting prop sorted, shame ive put all inside pannels seats etc in car. But better safe than no legs i say eh.
Thanks again for all your help guys.
|
|
|
kipper
|
| posted on 6/3/05 at 03:21 PM |
|
|
prop balance
When I used to be a skint apprentice I had an old escort which we messed about with and it developed a vibratoy prop,, An old guy who worked at the
local garage told us to clip a jubilee clip onto the shaft and keep moving it round until the vibes stoped......... it took us an afternoon at the
airfield but it worked.
|
|
|
ChrisGamlin
|
| posted on 6/3/05 at 07:46 PM |
|
|
Yeh but the prop in an Escort aint 3" from your feet, if you trust the continuity of your lower limbs to a jubilee clip by all means give it a
go 
|
|
|
welderman
|
| posted on 6/3/05 at 08:28 PM |
|
|
quote:
better safe than no legs i say eh.
|
|
|
ChrisGamlin
|
| posted on 6/3/05 at 08:30 PM |
|
|
Indeed, I wasnt really referring to you giving it a go as I got the impression you'd already decided to get it done properly
[Edited on 6/3/05 by ChrisGamlin]
|
|
|
welderman
|
| posted on 6/3/05 at 08:38 PM |
|
|
Ye going to get it sorted asap thanks. Summer is on its way? soon.....
Phone up local SVA center soon i think, been told you can wait up to 2 months.
|
|
|
welderman
|
| posted on 8/3/05 at 10:13 PM |
|
|
Got the prop soted.
£50.00 all in and hopefully legs will be safe.
|
|
|
