Is it Ok to Swap Crownwheel like for like?

[SweetBadger 94]

Hi, planning a gearbox swap at the weekend.

 

The box coming off and the one going on both have a 4.4 cwp.

 

Anyone know whether I’m ok to keep the crown wheel currently attached to the diff and use it in the new box? Or should I keep the each crownwheel paired up with its corresponding pinion?

 

Obviously it’ll work, but is it best practice to keep them paired up - I.e do they wear / bed-in together?

 

[Biggles 65]

For what it's worth, I had a worn diff pin cause the planet gears to fail (quite impressively) on a BH3/5 'box (as fitted to the first 1360cc 205 with the XY engine) and swapped it out for a different CWP/diff assembly.  Ran it for years with no issues.  However, it should be noted that in that design, the crownwheel is integral with one end of the diff casing and the choice was either 'mismatched' crownwheel & pinion or 'mismatched' diff casing halves.  If it's a BE 'box, why not just swap the crownwheel over ?

[Tom Fenton 1,541]

If for example you’d smashed a load of teeth off one crownwheel at a race meeting, I’d say absolutely try another crownwheel with the existing pinion. However if you have the matching crownwheel for the pinion then it’s just laziness not to swap it over! 

The pair of gears will have worn with each other. Swapping a mis matched gear in there is asking for the point loading to move on the tooth profile, probably to a place you don’t want it! The casualty will usually be the higher loaded pinion. 

In summary, it’s a last ditch get you out of jail manoeuvre. For what you describe 100% keep them matched.

[brumster 135 1 Cars]

What he said ^ don't wreck my old gearbox

[SweetBadger 94]

Haha, don’t worry the gearbox is in safe hands (well until my teammate gets behind the wheel anyway). I won’t take a short cut!

 

I only asked as I’m not sure if I’m going to get hold of some new crownwheel bolts by the weekend, and the little buggers have a nasty habit of stripping when they come out.

 

If that happens then i’ll Just have to wait till the next opportunity to get in the garage to put it all back together (these days it could be another month!)

[SweetBadger 94]

All done, crownwheel swapped, and none of the bolts stripped when removing the old one. 

 

Didn't break my back getting the box on either which is a bonus, although I did manage to nick a hole in the rad so a new one is now on order . I'd forgotten what a pita it is to swap a box single-handedly! 

 

Oddly the new box had a mix of clutch-arm bushes (one yellow one white) - looked like it would have worked fine, but I don't think you're supposed to mix them (5mm offset difference) so I swapped to the bushes and arm from the old box.

[jackherer 543]

There is a company on Ebay that incorrectly supplies a clutch arm kit with mixed bushes for some unknown reason.

 

https://www.ebay.co.uk/itm/253908419057

 

Actually I think it might even be the manufacturer (Topran) that is doing it. Were the bushes definitely offset differently? Genuine Peugeot ones do have the offset represented by colour (yellow or white) but that doesn't mean Topran understood that so they might have got the offset right but the colours wrong?

[SweetBadger 94]

Yeah, bushes definitely had a different offset.

 

Clutch arm on the box had 80mm forks (so required the yellow bushes), but one white and one yellow bush. Had to chop it in half to get it out as the pin wasn't budging!

 

The one I replaced it with had 75mm forks and two white bushes.