Just a curious question regarding shock mounting point size, I have just got hold of this project and just going over it to see what's what, and noticed the hangers for the shocks are quite big 15mm it's been powder coated by previous owner and looks like a collar has been left on all the mounts? Can anyone tell me what size they should be before curiosity gets the better of me

I am not sure which model Ossa you have there, my bike is an 1981 gripper 250cc. The top of the shock goes between two plates either side of the frame and then uses an M8 alan head bolt, but the bottom is different. The gripper swinging arm has  a horn and a single sided boss with a thread inside. The outer diameter is 15mm so I push out the inner metal bush on the end of the shock and with the shock rubber  warm (soaked in hot water) and plenty of waterproof grease I pull the shock on to the boss using a G clamp. Its a 8ugger first few times but they get easier.

The threaded bolt I think bottoms out in the swinging arm boss  and I use a big washer to hold the shock on, check them for tightness after a short ride one side can loosen with use.

 

                        Steve.

MK1 and MK2 MAR had different size shock mounts top and bottom.

 

Bottom is 12mm.

 

Top mount is 14mm (maybe 15mm, can't remember)

 

Sounds as though someone has left the metal inserts to the bottom bushes on the swingarm mounts. Not uncommon if they rust on and then when the shock is removed they get left behind.

 

MK3 MAR onwards they changed the top mount to 12mm

many thanks Steve and Woody for the information,I have cleaned all the paint off the swing arm mount and managed to get the collar off brilliant.

You'll no doubt discover the mounting bolts are M7's.

 

So save your money if you're thinking of fitting those clever, countersunk, shock fitting kits!

They always come with M6's and I've yet to find a countersunk M7.

I think they are only M7 on later bikes, all of my early MARs have been M6. Fork pinch bolts and bar clamps are M7 which is a pain

Hi yes the mounting bolts are M6 It's a mkii mar