prop shaft balance

hi, 2 weeks ago my front propshaft joint failed on my landy disco . not knowing they are balanced i took it off without marking the flanges and drove it in diff lock for about 20 miles . i had a new joint put on the prop and fitted it back to the disco and everything seemed ok .

a week later the hole car started to vibrate and i think this is because the rubber douhnut between the rear prop and rear diff has splits in it .

also the front wheel bearings need replacing. on the last 2 mot's they have been advisable to change them .

anyway - how on earth am i going to know which way the front prop should of gone back on when i didnt mark the flangers .

today i have the rear rubber doughnut tofit and 2 front wheel bearings. any1 in the belper/derby not doing anything today are more thank welcome to come and help me. drop me a PM with your phone number and i will ring you straight away.

many thanks matt

not sure if this is right but i have revoved and fitted loads and never really marked them and i aint had a prob with it.
ill prob get shouted at now.....................

I allways mark em with a centre punch but like you have wondered what you do when you buy and fit a new prop???

hence i aint ever botherd marking em.

at the end of the day with it being a rotaional item it must surely be balanced anyway as any variation in weight or shape would act as a fooking big rattle anyway when it was spinning if yer get what i mean??

RAZ8550TDI said:

at the end of the day with it being a rotaional item it must surely be balanced anyway as any variation in weight or shape would act as a fooking big rattle anyway when it was spinning if yer get what i mean??

Click to expand...

Yeh they are balanced!
Totaly agree with you but you read everwhere that you MUST always mark both flanges so you can put it back together reight! Being in Engineering many moons ago I was taught to do this on anything we stripped down but dunt make much sense on a replacable item.

I got a new front one and picked it up by one end so it all fell apart, bollocks I thought then looked reeeeeeeely closely at it an it was allready marked reeeeeeeeely reeeeeeeely faintly . Any how if you can't find the marks an you put it back together anyoldhow make sure the UJs aren't in the same orientation they should be out of kilter with each other.

i always thought prop balance only mattered if you were actually taking the prop itself apart, not just off the motor....i mean how can the drive flanges on the diff/t-case affect the balance? they're symetrical (spellin?).

did my front UJ's last week, just made sure I stuck it back together with the flange at the t-case (short splined bit) end at 90° to the one on the diff end. oh and i made sure that the grease nipples on the new uj's were in the same place as the old ones...didnt bother with making marks on diff/t-case tho...no vibe yet seems fine.

thanks guys it was just worrying me abit.

anyhow - didnt fit the doughnut and front wheel bearings today - doing it tommorow. what you lot doing? any chance of a hand

Jason2 said:

Yeh they are balanced!
Totaly agree with you but you read everwhere that you MUST always mark both flanges so you can put it back together reight! Being in Engineering many moons ago I was taught to do this on anything we stripped down but dunt make much sense on a replacable item.

Click to expand...

cheers jason, wa struggling to explain then!

nah youll be reet mate!

fitted te new rubber doughnut and wheel bearings and it still vibrates and shakes like fuk. well ****ed off with it now. dont know whats wrong with the heap o ****e

hmm any eggs or damaged skins??? maybe the vibration could be somthing that cause yer rubber bush to go?? yer did check the uj's for play while yer was there didnt yer?? warpped disks? just throwing thing in to complicate the matter here arnt i?

Because those UJs are NOT "constant velocity joints", it is important for the long life survival of the entire drive train that the two ends of the prop shaft are aligned in the one way that reduces angular rotational velocity variations to a minimum.

In ONE rev of the propshaft the speed of rotation will change twice like a sine curve and that applies four rising and falling strains per rotation on the whole system, a bit like smooth hammering.

If the ends are well aligned, those variations are nearly but not quite cancelled out and the drive will be smoother.

Line them up boys!

CharlesY

go charles y!!!

CharlesY said:

Because those UJs are NOT "constant velocity joints", it is important for the long life survival of the entire drive train that the two ends of the prop shaft are aligned in the one way that reduces angular rotational velocity variations to a minimum.

In ONE rev of the propshaft the speed of rotation will change twice like a sine curve and that applies four rising and falling strains per rotation on the whole system, a bit like smooth hammering.

If the ends are well aligned, those variations are nearly but not quite cancelled out and the drive will be smoother.

Line them up boys!

CharlesY

Click to expand...

how do i do that then? i didnt mark the flanges - my brain hurts

mattydred said:

how do i do that then? i didnt mark the flanges - my brain hurts

Click to expand...

have a look at your OTHER shaft to see how the two OUTER halves of the yokes lie in relation to EACH OTHER. There aren't that many splines, and it's quite easy to get it right-ish.

It isn't vitally important (no immediate damage will be caused) but in principle and in the long term there's no doubt it's better done right, especially in a vehicle such as a Landy where propshaft angles can be steep.

CharlesY.

CharlesY said:

have a look at your OTHER shaft to see how the two OUTER halves of the yokes lie in relation to EACH OTHER. There aren't that many splines, and it's quite easy to get it right-ish.

It isn't vitally important (no immediate damage will be caused) but in principle and in the long term there's no doubt it's better done right, especially in a vehicle such as a Landy where propshaft angles can be steep.

CharlesY.

Click to expand...

Yeah as charlsey says always re-align the prop itself, just be methodical and fix them as soon as you notice vibe etc, its quite easy for a knackered UJ to take one of your t-case output bearings with it if it is allowed to vibrate for a while without being fixed.