Quote:
Originally Posted by ShakotanRon
I do understand that the system is pretty reliable.
A brand new unit would hopefully last 150k to 200k.
I am faced with the necessity to buy a new driveshaft.
And it is unlikely that I will even get this much mileage out of the rest of the car. However I do not like the non serviceability of the units. And once the u joint begins to fail, it starts to take the rest of the driveline with it.
I would greatly prefer a serviceable unit especially considering who even knows if I will be able to find one for the car if it does last until the next drive shaft.
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I don't quite understand what you mean by serviceable.
The flex discs are (as far as I know) easy to find and replace. The centre drive shaft bearing and the carrier is also quite easy to find and change.
Even the original unit with the single UJ can be replaced - take it to a machine shop.
On the whole, however, my experiences of the W123 and W201 chassis (which has the same design requirements as your W115) have shown that you can get a perfectly nice drive line from a propshaft with a notchy UJ. I know it isn't ideal but the problems materialise when the propshaft isn't straight =>
There needs to be a straight line (think of the cross hairs of a gun along the length of the vehicle) from the front pulley on the crank - to the output shaft on the transmission / gearbox - to the centre propshaft bearing - to the input shaft on the differential. So long as you've got everything lined up the notchy-ness of the UJ doesn't matter.
To do this you need good motor mounts + a good transmission mount + good subframe mounts (at the front of subframe) + good "third" subframe mount / differential mount.
If you get these bits right and everything lined up the system works.
If one bit (or more) isn't straight then you get movement in your notchy UJ as well as the inherent vibration problems in a single universal joint.
Sure in some respects a double UJ system might seem like a good solution - but most of these double UJ designs need to have a large angle in the drive line (a difference in heights) so that the joint remains healthy and notch free.
In a Mercedes drive line (like the ones we are discussing) you could end up with two notchy UJs which might actually be worse than the system you have - you'd have to check with "lang" owners to see if that is true though!