jammed chain 643

[robmon]

I have a 643 with a broken rear chain, seems to have doubled over and jammed right in the back top corner, thinking I might have to undo bolt holding rear sprocket,left handed thread or right?? any tips ??? seems to be a bugger to access

 

[robmon]

sorry wrong forum , oops

 

[Tazza]

sorry wrong forum , oops

Access is not fun, you need to remove the inspection covers on the top of the chain case. I'm not sure if its possible to remove the sprocket from the front cover.
I'm not sure you will ned to remove the sprocket, you should be able to rotate the axle and get the chain out. Install a new chain with a con-link, no need to remove the sprocket then.

 

[robmon]

Access is not fun, you need to remove the inspection covers on the top of the chain case. I'm not sure if its possible to remove the sprocket from the front cover.
I'm not sure you will ned to remove the sprocket, you should be able to rotate the axle and get the chain out. Install a new chain with a con-link, no need to remove the sprocket then.

The chain was tripled over in back bottom corner, pure ass to get it loose!! have bruising on my upper arm reaching in there!!
In regard to braking discs, do they just float very loosely?? just the blocks on top plate used to center them?? they seem to flap around a fair bit.
Also worried about drive motor play, have about 15mm play on sprokets in and out is this normal, cheers Rob

 

[robmon]

The chain was tripled over in back bottom corner, pure ass to get it loose!! have bruising on my upper arm reaching in there!!
In regard to braking discs, do they just float very loosely?? just the blocks on top plate used to center them?? they seem to flap around a fair bit.
Also worried about drive motor play, have about 15mm play on sprokets in and out is this normal, cheers Rob

ok I have replaced the top plate with brake blocks attached and the discs still seem to flap about, it appears to me that it is possible for the edge of the chain to hit or even catch the edge of the brake disc, maybe this is the clunking i have been hearing , i see a large cir clip on one side of disc but nothing otherside allowing disc to move right over to sprocket edge, if anyone has a diagram in relation to this and can post it here that would be great, cheers Rob.

 

[Tazza]

ok I have replaced the top plate with brake blocks attached and the discs still seem to flap about, it appears to me that it is possible for the edge of the chain to hit or even catch the edge of the brake disc, maybe this is the clunking i have been hearing , i see a large cir clip on one side of disc but nothing otherside allowing disc to move right over to sprocket edge, if anyone has a diagram in relation to this and can post it here that would be great, cheers Rob.

I know the bruised arm situation gaining access..... That chain sure did sound like it was wedged in there good.
The brake discs are correct, they are held on with a snap ring and the top part is held straight by the brass pucks that grab the disc. They may seem to wobble now, but then the plate is back on, they will hold pretty straight.
The noise you heard could have possibly been the chain slapping the bottom of the chain case or the guides that are on teh side of the chaincase?

 

[robmon]

I know the bruised arm situation gaining access..... That chain sure did sound like it was wedged in there good.
The brake discs are correct, they are held on with a snap ring and the top part is held straight by the brass pucks that grab the disc. They may seem to wobble now, but then the plate is back on, they will hold pretty straight.
The noise you heard could have possibly been the chain slapping the bottom of the chain case or the guides that are on teh side of the chaincase?

thanks Tazza , much appreciated, now i am stuck with brake pedal assembly, it has been off machine for ages and cant remember how it goes back together, particuarly the braket with the spring ?? I can see the long rod goes from arm to brake pedal , but how does the bracket with spring fit into the scheme of things??

 

[robmon]

thanks Tazza , much appreciated, now i am stuck with brake pedal assembly, it has been off machine for ages and cant remember how it goes back together, particuarly the braket with the spring ?? I can see the long rod goes from arm to brake pedal , but how does the bracket with spring fit into the scheme of things??

good news , all done, just like a new one, thanks to all for assistance, this forum is gold!!!!!