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Bad Vibration
amalyos - 3/4/11 at 07:11 PM

I'm getting a really bad vibration through the chassis, that is at it's worse in top gear, at high revs.
The cars not been on the road yet, as I'ts only for the track, but it was noticed on the rolling road, and over the last few days, I've been trying several things.
The Prop was checked for balance, and was ok, although it wobbles like some of the other posts over the last few months.
The diffs been changed.
The wheels removed and run up without them on, still vibrating!!!

Even though the probs in balance, could it cause vibration if it's running out of true?

Any ideas welcome.


rusty nuts - 3/4/11 at 07:14 PM

Bent drive shaft ??


johny p - 3/4/11 at 07:14 PM

have you checked the prop adapter flange bolt... common prob with cbr engine mate....


blakep82 - 3/4/11 at 07:15 PM

quote:
Originally posted by amalyos
I'm getting a really bad vibration through the chassis, that is at it's worse in top gear, at high revs.
The cars not been on the road yet, as I'ts only for the track, but it was noticed on the rolling road, and over the last few days, I've been trying several things.
The Prop was checked for balance, and was ok, although it wobbles like some of the other posts over the last few months.
The diffs been changed.
The wheels removed and run up without them on, still vibrating!!!

Even though the probs in balance, could it cause vibration if it's running out of true?

Any ideas welcome.


erm, mystery solved then? the prop wobles, thats where the vibration comes from. being a BEC, is it a sliding prop? is it the one that was made for that particulare engine? is it on full extension? because it shouldn't be fully extended, as it offers itself less support that way

and who checked for balance? did they tak eit off and check it at the correct extention?

[Edited on 3/4/11 by blakep82]


jacko - 3/4/11 at 07:15 PM

Drive shafts ?


RichardK - 3/4/11 at 07:16 PM

A prop shouldn't wobble in my opinion, where did you take it to to get checked?, take it somewhere else, how many uj's does it have, are they supported anywhere along the prop?

Pictures maybe useful or even a movie of the wobble.

Cheers

Rich


amalyos - 3/4/11 at 07:17 PM

quote:
Originally posted by johny p
have you checked the prop adapter flange bolt... common prob with cbr engine mate....


Tell me more? what to check?


johny p - 3/4/11 at 07:26 PM

yes a prop will wobble if its not running true.. it only takes a small amount to be out of line for it to make a considerable vibration... i found this out through a bad experianceof my own... the prop was out of line that much that it shook the adapter bolt loose causing the prop adapter to shear off causing quite a bit of damage to the engine... check the prop for alignment mate and the adapter bolt is tight...


Ben_Copeland - 3/4/11 at 07:36 PM

Another vote for wobbly prop = bad !


Agriv8 - 3/4/11 at 08:08 PM

prop lost a balance weight tunnel off.

or have you split the prop on the splines.

regards agriv8


amalyos - 3/4/11 at 08:41 PM

No, checked the balance,, that's ok, but the prop wobbles really bad at speed.
Damion had to pull himself out of the seat on the rolling road, the vibration was so bad.


blakep82 - 3/4/11 at 08:58 PM

the prop should not wobble at all. at any speed. thats your problem right there.


watsonpj - 3/4/11 at 09:19 PM

Steve
I agree prop shouldn't wobble, I had a bearing start to breakdown on my quaife reverse (only a small amount of play) but you could feel that, the prop was fine but the prop could whirl around at the end. Have you checked the mating flanges to see if they have any play on them and also removed the prop and turned them to see if they runout through a revolution?

Pete


Johneturbo - 3/4/11 at 09:25 PM

check a thread i started a few weeks ago, i also posted a video on youtube

the main problem for me was the slider was at its max length, so sent it off to D&F they added 30mm and changed couple of UJ's and center bearing

but i seem to still have a slight wobble, not as bad as before, i did drive it for the first time on friday, only upto to 6,000 rpm 60mph and seemed fine.


is your wobble as bad as in the videos i posted?


amalyos - 4/4/11 at 06:06 AM

Yes, saw your thread, and mine is as bad, although mine gets bad after 6k, so you may want to run yours up further to check. Did MNR provide your DIFF?


Johneturbo - 4/4/11 at 10:09 PM

No i've fitted a few different diffs. running lsd now.

the slight wobble on mine is the front section between center bearing and front UJ. i guess i need to run it to a higher road speed and see how it is

thinking about it the engine rpm has no relevance to the prop speed