:{THC}:YosamiteSam
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| posted on 3/8/09 at 08:37 PM |
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trying to trace a vibration
im getting a bad vibration from my megabusa
when on track going over 100mph is nigh impossible due to the vibrations
i still have to get the wheels double checked for balance - if its those - rear - front isnt transmitting thro the steering
feels like the rear end through the floor or possibly propshaft - transmission
1 question - iv noticed play in the gearbox output shaft - if you rotate the flange by hand how much free play is normal?
my own feeling is prop balance or wheel bearing / wheel balance.. just going through the cheapest, quickest and easy options first
any ideas?
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Guinness
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| posted on 3/8/09 at 08:43 PM |
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Can you get easy access to the propshaft / driveshafts?
Someone mentioned using jubilee clips as balance weights?
Mike
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:{THC}:YosamiteSam
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| posted on 3/8/09 at 08:47 PM |
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quote:
Originally posted by Guinness
Can you get easy access to the propshaft / driveshafts?
Someone mentioned using jubilee clips as balance weights?
Mike
yea - easy to get at most things but how would you know where to put the weight? - thats a real critical thing to get wrong!
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MakeEverything
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| posted on 3/8/09 at 08:54 PM |
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Check your tyre pressures. Youll be surprised at the difference this makes.
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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eznfrank
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| posted on 3/8/09 at 08:59 PM |
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Are you running a reverse box?
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r1bob
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| posted on 3/8/09 at 09:11 PM |
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also check your prop alignment, first half of prop from gearbox should be square off the gear box flange (90degree's horizontal looking
sideway's and 90 degree's looking down at it off flange) if it is in 2 halves ,the rear half can go off at an angle to the diff,
the gear box flange should have minimal up and down play.
had 2 prop's overhauled for me in the last 6 month's for myself and a mate, cost around £50 each including new splines and balancing,so
not the end of the world
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:{THC}:YosamiteSam
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| posted on 3/8/09 at 09:21 PM |
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quote:
Originally posted by MakeEverything
Check your tyre pressures. Youll be surprised at the difference this makes.
and this would put them out of balance? they would have to rotate on the rim to do so - i run the front at 14psi - rear 16psi dont think they have
slipped round the rim but as i say thats my next call - also have a small grease gun - going to re grease prop joints
quote:
Originally posted by eznfrank
Are you running a reverse box?
yea - westfields own - i know its not the best and it is the most expensive - i would love to change to an electric reverse tbh but cash isnt fluid..
lol
quote:
Originally posted by r1bob
also check your prop alignment, first half of prop from gearbox should be square off the gear box flange (90degree's horizontal looking
sideway's and 90 degree's looking down at it off flange) if it is in 2 halves ,the rear half can go off at an angle to the diff,
the gear box flange should have minimal up and down play.
had 2 prop's overhauled for me in the last 6 month's for myself and a mate, cost around £50 each including new splines and balancing,so
not the end of the world
i havnt noticed any up and down movement but did wonder about output shaft possible wear - without knowing what other busa freeplay is i wouldnt know
- probably around 5-10mm play i have
i do have a diff output seal (lhs) with an oil leak but the diff is fully loaded - i wonder if the bearing is on its way - leaking thro that.. testing
just give it a good 'yark' lol - see if it moves up n down or rattles... lol?????? 
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02GF74
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| posted on 3/8/09 at 09:34 PM |
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quote:
Originally posted by :{THC}:YosamiteSam
quote:
Originally posted by Guinness
Can you get easy access to the propshaft / driveshafts?
Someone mentioned using jubilee clips as balance weights?
Mike
yea - easy to get at most things but how would you know where to put the weight? - thats a real critical thing to get wrong!
I'd be very surprised if a jubilee clip in the wrong place is that critical.
find track or stretch of road and drive car at certain rpm and speed.
fit clip, and compare with above.
if better, job done.
if same the problem lies elsewhere.
if worse, rotate clip 180 degrees and repeat.
obviously you would not drive at same speed if the vibration is really bad so there is some common sense involved - hence why I said the fitment is
not critical .... no doubt someone will come along and prove me wrong, which is fine since this is my theory as opposed to anything I have tried. 
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MakeEverything
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| posted on 3/8/09 at 09:37 PM |
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quote:
Originally posted by :{THC}:YosamiteSam
quote:
Originally posted by MakeEverything
Check your tyre pressures. Youll be surprised at the difference this makes.
and this would put them out of balance? they would have to rotate on the rim to do so - i run the front at 14psi - rear 16psi dont think they have
slipped round the rim but as i say thats my next call - also have a small grease gun - going to re grease prop joints
quote:
Generally, tyres dont rotate around the rim, but if the pressures are different particularly each side it will affect the harmonics of the car, cause
vibration, and pull to one side - including under braking.
When the tyre pressures are lower than designed, the tyres respond in differing ways causing them to re-form or mis shape slightly which would cause
the vibration that you mention.
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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austin man
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| posted on 3/8/09 at 09:44 PM |
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I once hasd a tyre that was twisted that really caused a bad vibration, play in the input shaft could be a cause, as could the diff or prop. Have you
had the wheels off recently ?? I have also come across a problem with the wheel not sitting on the hub flat due to rust or a dirt at the rear of the
wheel.
Life is like a bowl of fruit, funny how all the weird looking ones are left alone
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:{THC}:YosamiteSam
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| posted on 3/8/09 at 10:12 PM |
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quote:
Originally posted by 02GF74
quote:
Originally posted by :{THC}:YosamiteSam
quote:
Originally posted by Guinness
Can you get easy access to the propshaft / driveshafts?
Someone mentioned using jubilee clips as balance weights?
Mike
yea - easy to get at most things but how would you know where to put the weight? - thats a real critical thing to get wrong!
I'd be very surprised if a jubilee clip in the wrong place is that critical.
find track or stretch of road and drive car at certain rpm and speed.
fit clip, and compare with above.
if better, job done.
if same the problem lies elsewhere.
if worse, rotate clip 180 degrees and repeat.
obviously you would not drive at same speed if the vibration is really bad so there is some common sense involved - hence why I said the fitment is
not critical .... no doubt someone will come along and prove me wrong, which is fine since this is my theory as opposed to anything I have tried.
no disrespect but a prop spinning that close to my hips / legs and passengers isnt getting a jubillee clip on - a prop not balanced correctly is a
lethal weapon - it should be ONLY done right - by people who have the right gear - no other way.
i would guess its gotta come off and be measured
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:{THC}:YosamiteSam
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| posted on 3/8/09 at 10:15 PM |
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quote:
Originally posted by MakeEverything
quote:
Originally posted by :{THC}:YosamiteSam
quote:
Originally posted by MakeEverything
Check your tyre pressures. Youll be surprised at the difference this makes.
and this would put them out of balance? they would have to rotate on the rim to do so - i run the front at 14psi - rear 16psi dont think they have
slipped round the rim but as i say thats my next call - also have a small grease gun - going to re grease prop joints
quote:
Generally, tyres dont rotate around the rim, but if the pressures are different particularly each side it will affect the harmonics of the car, cause
vibration, and pull to one side - including under braking.
When the tyre pressures are lower than designed, the tyres respond in differing ways causing them to re-form or mis shape slightly which would cause
the vibration that you mention.
tyres can slip on the rim due to the soap used during mounting the tyre on
famous example is the mansell vs prost british GP where he had to pull in due to tyre balance being that bad - he braked hard the grip slipped the
tyre round the rim
we use at work a test for that - a simple painted yellow dot on the tyre - a red dot on the rim - it has to be within 35mm of each other after testing
otherwise weight position goes out
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r1bob
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| posted on 3/8/09 at 10:16 PM |
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you always get a bit of back lash,rocking the prop to and throw, but you should have minimal up and down movement where they go into the bushes, if
you have, the spigots could be worn or the bushes, alot of up and down movement will cause bad vibration,,,, double check prop alignment as this can
be critical as i found out.
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:{THC}:YosamiteSam
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| posted on 3/8/09 at 10:17 PM |
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quote:
Originally posted by austin man
I once hasd a tyre that was twisted that really caused a bad vibration, play in the input shaft could be a cause, as could the diff or prop. Have you
had the wheels off recently ?? I have also come across a problem with the wheel not sitting on the hub flat due to rust or a dirt at the rear of the
wheel.
yes i have had the wheels off too - theres no dirt or rust but it wont hurt to relook and make sure
when i take the tyres down to be rebalance checked i want to watch the tyre spin
you cant check it on the car because there might be bent suspension parts
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:{THC}:YosamiteSam
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| posted on 3/8/09 at 10:23 PM |
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quote:
Originally posted by r1bob
you always get a bit of back lash,rocking the prop to and throw, but you should have minimal up and down movement where they go into the bushes, if
you have, the spigots could be worn or the bushes, alot of up and down movement will cause bad vibration,,,, double check prop alignment as this can
be critical as i found out.
yea - will look at that - what a loverly place to try and get at tho - lol - luckily the top tunnel cover is just bolted down
i need to remove it to regrease the uj's
if i had to put money on it it feels like tyre distortion or balance
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miikae
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| posted on 3/8/09 at 10:34 PM |
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If you feel it may be tyres just check that there is no water in them due to bad air line water filters , i had this problem a while ago , it was only
discovered when as a last resort they took the tyres off the rims.
Mike
If it can be done it i will be done .
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Russ-Turner
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| posted on 4/8/09 at 06:20 AM |
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quote:
Originally posted by Guinness
Someone mentioned using jubilee clips as balance weights?
Mike
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mad4x4
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| posted on 4/8/09 at 09:13 AM |
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quote:
Originally posted by :{THC}:YosamiteSam
quote:
Originally posted by 02GF74
quote:
Originally posted by :{THC}:YosamiteSam
quote:
Originally posted by Guinness
Can you get easy access to the propshaft / driveshafts?
Someone mentioned using jubilee clips as balance weights?
Mike
yea - easy to get at most things but how would you know where to put the weight? - thats a real critical thing to get wrong!
I'd be very surprised if a jubilee clip in the wrong place is that critical.
find track or stretch of road and drive car at certain rpm and speed.
fit clip, and compare with above.
if better, job done.
if same the problem lies elsewhere.
if worse, rotate clip 180 degrees and repeat.
obviously you would not drive at same speed if the vibration is really bad so there is some common sense involved - hence why I said the fitment is
not critical .... no doubt someone will come along and prove me wrong, which is fine since this is my theory as opposed to anything I have tried.
no disrespect but a prop spinning that close to my hips / legs and passengers isnt getting a jubillee clip on - a prop not balanced correctly is a
lethal weapon - it should be ONLY done right - by people who have the right gear - no other way.
i would guess its gotta come off and be measured
My prop was out of balance and destroyed the Engine Mounts and cracked the bell housing and tore off one of the engine block lugs. ..... (all in
about 18miles)
And that was all due to vibration only luckily Prop stayed put. EnDed up buying a New Prop that was true balanced.
Scot's do it better in Kilts.
MK INDY's Don't Self Centre Regardless of MK Setting !
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SJL
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| posted on 4/8/09 at 09:18 AM |
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You need to find a tyre shop with a Road Force balancing type machine.
We have one at work and rather than just balancing the wheel/tyre it applies a measured load to the tyre and tells you if the tyre is any good.
Even when we have fitted new tyres this machine has found faults,it then allows you to correct this by trying to match the tyre to the rim.
Its from these people http://www.beissbarth.co.uk/ so it might be worth giving them a call and seeing if they have supplied one to someone local to
you.
I have to be honest though its probably the reverse box as everything I have read about them indicates they have problems
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:{THC}:YosamiteSam
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| posted on 4/8/09 at 10:09 AM |
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quote:
My prop was out of balance and destroyed the Engine Mounts and cracked the bell housing and tore off one of the engine block lugs. ..... (all in
about 18miles)
And that was all due to vibration only luckily Prop stayed put. EnDed up buying a New Prop that was true balanced.
i could well believe that but wow that must of been a long way out.. props really can be underestimated to the damage they can do.
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:{THC}:YosamiteSam
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| posted on 5/8/09 at 07:20 AM |
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think i might of sussed it.. The reverse box.. The 2 sets of prop bolts were loose.. Finger tight.! Just got to test it to see what its like..
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:{THC}:YosamiteSam
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| posted on 9/8/09 at 09:28 PM |
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well i stripped it down.. Again.. Reverse box drive flange nut was loose on both sides of the box.. Got about 1 turn on the nut.. Just need to finish
rebuilding and give a test.. Fingers crossed..
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