One for Harvey - BW35 output flange.

#1
Hi Harvey,
I’ve been chasing my drivetrain clonk over the years and the list was to check the output flange was not loose. i thought it may have been as my speedo wavered all over the place. Well I have checked the flange and the nut is very tight and I can’t move it. But, does move in and out of the box maybe 1/8”. Is this normal and if not what could be the cause.

Many thanks.
ps speedo somewhat cured by lubricating the drive cable.
 

harveyp6

Well-Known Member
#2
Because the flange butts up against the speedo drive gear, which in turn sits against a step in the shaft, even if the flange bolt is tight it won't stop any end float on the shaft because the whole assembly is moving forwards/backwards. There is a torrington race between the rear of the gearset and the front of the output shaft, and a problem with that could cause excess endfloat and possibly cause a clonk especially when shuttling between "D" and "R". There's always some endfloat though as I don't remember any varying sized shims to take it up, those are at the front end behind the pump.
 
#3
Because the flange butts up against the speedo drive gear, which in turn sits against a step in the shaft, even if the flange bolt is tight it won't stop any end float on the shaft because the whole assembly is moving forwards/backwards. There is a torrington race between the rear of the gearset and the front of the output shaft, and a problem with that could cause excess endfloat and possibly cause a clonk especially when shuttling between "D" and "R". There's always some endfloat though as I don't remember any varying sized shims to take it up, those are at the front end behind the pump.
Thanks Harvey,
I'll measure the exact end float and maybe you can tell me if thats good/bad. By the way when I do get a back change up or down sometimes the "clonk" is right under the transmission tunnel.

Craig
 
#4
Thanks Harvey,
I'll measure the exact end float and maybe you can tell me if thats good/bad. By the way when I do get a back change up or down sometimes the "clonk" is right under the transmission tunnel.

Craig
Hi Harvey,
Endplay is approximately 1.0mm.. Good, bad or no worries.
thanks Craig
 

cobraboy

Well-Known Member
#6
Thanks Harvey,
I'll measure the exact end float and maybe you can tell me if thats good/bad. By the way when I do get a back change up or down sometimes the "clonk" is right under the transmission tunnel.

Craig
I had a car with a driveline clonk right under the trans tunnel, it was a worn gearbox tailshaft bushing. Grab hold of the propshaft where it comes out of the box and see if there is any up/down/side/side movement.
I don't know if the 35 has a bush at the back end, its just a thought.
 
#9
Thanks both,
Having spend much time under the car last night trying to get the verniers in a suitable position for measurement I can say that there is no up/down side/side movement in the output shaft. I'll strike this off my list of possible causes now. Having investigated and eliminated most common "clonk" causes I am leaning towards the differential itself as having too much play.

Regards,
Craig
 
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