W202 Propshaft Flexi Discs

[alan1304]

Hi guys.
Just a quick one.
I have got to change the propshaft centre bearing on my 1998 C180 Esprit Auto. I went to North Wales and back a month ago (nearly 1000 miles in a week) with no problems whatsoever. I checked the flexi discs before I went and they were fine but there is some wear in the centre bearing. My question is, being that I am going to have to drop the rear of the prop to change the centre bearing do have to replace the bolts in the rear flexi as I will not be replacing that and it only involves undoing three of the bolts. I have dropped propshafts on many different cars in the past and always re-used the bolts with no adverse effects. I only ask because I have read on different sites posts where people are saying you "Must fit new bolts".
Many thanks in advance.
Alan.

 

[grober]

Its important to mark the exact position where the centre bearing support bracket bolts to the underbody before removing it and likewise mark all the propeller shaft components where they mate together so you can re-assemble them correctly to retain the balance of the entire assembly. I expect the bolts will be reuseable if their heads are not mangled but I would deffo renew the locking retaining nuts. Any bolt with low recommended torque figures can usefully be re-used but once you get into high torque figures you enter the realm of "bolt stretch" where new bolts are often advisable.

 

[Bellow]

As a generality, bolts used in shear can easily be re-used but bolts used to clamp if torqued-to-yield need to be replaced. (The bolts in question are in shear).
As per Grober's post, locking nuts should not be re-used - unless with a locking compound.

 

[alan1304]

Hi Grober, and thanks for the quick reply.
It all makes sense now. I don't suppose you get much more torque on a car of this size than at the joint between the prop and diff, (although I have been told the the auto's are easier on their flexi couplings). I think I'll just change the bolts anyway. In actual fact I am now wondering whether it might just be worth changing the flexi discs as well, gets it all out of the way at the same time.

 

[Druk]

As a generality, bolts used in shear can easily be re-used but bolts used to clamp if torqued-to-yield need to be replaced. (The bolts in question are in shear).
As per Grober's post, locking nuts should not be re-used - unless with a locking compound.

Actually, they're not in shear. The flex discs have little extensions on the through sleeves that engage into recesses in the coupling flanges and transmit the drive from one to another. The bolts act only in a clamping sense, however, as Graeme suggests, they're not torqued to anything like a stretch scenario so if you were fussy I would replace the nuts only. iirc they are the squashed locking type and don't work so well after first use, although again...Loktite would do perfectly well imho. Must say, I've never replaced a coupling nut but always used Loktite and never had one undo.




.

 

[Druk]

Also to note. I've never worked on a 202 but if they're the same as most others of this era there will be a large nut just in front of the centre bearing to slacken and allow the two shaft halves to concertina. Without this it will be almost impossible to get the rear end to part from its coupling. Similarly it must be done up tight on reassembly as it clamps the sliding splines together.