the car was running prior to the conversion with standard running gear all fine and no vibrations...

wouldnt that rule out things like diff, wheels, wheel bearings etc etc?

the only things that have been replaced are motor, gearbox and tailshaft..

thats why im focusing on those 3 things..

and to add to that i know that the motor and gearbox were operational without vibration prior to putting them into my datto ute..

so there for the process of elimination tells me that the only suspect things are the tailshaft itself and the positioning of the motor/gearbox in my ute...

i have pulled the gearbox out... going to try and reduce the angle by getting the gearbox as high as i can... im gonna get the tailshaft balanced and try and source another gearbox to rule out that sloppy output shaft that im not happy with..


fingers crossed

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I would have thought the same but I couldnt feel any play and finally put a dial indicator up to double check, axial play was only 0.002inch mixed with around 0.002inch lateral play. So not a great deal especially in a rally car but enough to cause a very similar vibration whilst on transport stages to what has already been described. I have mentioned this bit of preload advice because I believe it is often overlooked. Thats why it took me so long to eventually find the problem in my rally car. I am not saying that this must be the problem vibration we are all trying to solve but all the symptoms apear to be the same.

"only when not under load..ie if you put the clutch in to change gear.. when accelerating theres no vibration... when coasting in gear theres no vibration.. only for a second when u let go of the accel pedal"

Hey phunks.....basic physics may work...but they need to apply to the problem...

The problem occurs when NOT under load...when the clutch is ENGAGED..

Phunks you may be onto something with the wheels...I spose when under load the "vibration zone" would be passed quite quickly and thus the vibration may be less obvious..I spose this could also explain why you may be right about the unis...

But with the unis...I understood you saying the angle is caused by axle wind up???..if this is your theory then I spose it can't be the unis...this time!!!! as the problem occurs under no load..

nup

fare chance tho as you've tried the diff at different angles with no luck .... shame you've dropped the oil cos i still reckon the hose clamp on the tail shaft would have showed it up more ...

nothing has been done to the diff before or during the conversion... apart from putting in some new oil..

when the old a12 was in there there was no vibration at all...

doesnt anyone think that the play in the output shaft slopping around could be my vibration?

Would not enough pre load on the pinion, show up as forwards and backwards movement in the pinion? Would it be noticable to the hand?

Was anything done to the diff before or during the conversion?

I hope this doesnt come back to bite me but if you tailshaft checks out OK and your uni's joints havent been fitted poorly then I would bet a six pack on it being the wrong pre load on the diff pinion bearing. I suggest whilst its all apart you take the time to have it checked by somebody that has a good understanding of diffs.
I suppose there are quite a few members that would like to know what is causing your vibration. Please tell us all when you eventually find it.

nah didnt try that...

i had a busy arvo but i managed to get it up on stands and dropped the gearbox oil...

tomorrow after work gonna rip it all apart...

good thing about the rotor is that there isnt much less room to work with than the a series engine...

taking the box out is very easy thank goodness for my sake

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why? well;
Basic physics of 2 uni joints on a shaft.
The description given of the angles.
The way the angle changes under load.
The fact it happens around 60 - 70 kph tells me its to do with a part that this speed is specific to. ( A flywheel of which this isnt ) A flywheel vibration would be rpm specific.
Could basically come down to an out of balance wheel. Out of balance wheels cause vibrations at specific speeds, then the vibration will dissappear at other speeds.

My bet is still on the uni's, basically from the description of the angles.

hey ange did you end up trying the hose clamp around the tailshaft ??? if it is play in the output shaft then a hose clamp up the box end of the shaft would really accentuate it ??

you gotta get this fixed soon i'm hanging to come have a look... never been in a rotory and reckon a datto one would be a good way to experience it for the first time