Topic

IIRC the original rivets are an aluminium alloy, cold swaged. When swaged they expand evenly into the rivet holes centralising themselves to fill any discrepancies in size & shape, providing the gaps are even & not excessive.
If using an undersized screw fixing concerns you, you might look for a slightly over non metric screw, opening your holes accordingly into a snug fit.
I haven’t had look but my guess is you’ll find a UNF close enough to do the job, which should allay your worries. Have a look, it’s all on the internet.
M

Nearest UNF is 3/8 which fits a 9.6mm hole. If you have riveted as many mower sections to cutterbar mowers then you would just get the 8mm rivets, these days they use nuts and bolts.

Airportable wrote:

IIRC the original rivets are an aluminium alloy, cold swaged. When swaged they expand evenly into the rivet holes centralising themselves to fill any discrepancies in size & shape, providing the gaps are even & not excessive.
If using an undersized screw fixing concerns you, you might look for a slightly over non metric screw, opening your holes accordingly into a snug fit.
I haven’t had look but my guess is you’ll find a UNF close enough to do the job, which should allay your worries. Have a look, it’s all on the internet.
M

Alloy rivets into a mild steel wishbone ?? I don't think that is correct . Aluminium and steel react badly when in close proximity. I used to work briefly for Dennis Trucks and they had Stainless steel cabs on refuse work . Mild steel and Stainless was bad enough trying to get things free but I don't think I would trust aluminium rivets in a steel wishbone , especially with all the muck and bullets thrown at them .

John

Obviously I didn’t recall correctly & having spent so many years with Land Rover I should have known better. Corrosion cells would form quite quickly with only the slightest amount of electrolyte. So I’m sorry about that but what is the alloy that allows that amount of swagging when cold or are they put in hot & use mild steel?
Neither control arms on my car have rivets, both having been bought with bolted on joints so I can’t go & run a file across one.
Thank you John for the correction.
M

On cutterbar mowers they were (mild?) steel, when you lost a knife section due to a stone caught between the fingers you simply knocked the old rivets out and put new rivets through the new knife section and gave the top of the rivets a couple of good blows with a hammer. If you were really conscientious you would use a tool with a domed impression to get a nice rounded top but if you were doing it for the third or fourth time in a day beauty came as a second priority. It's difficult to believe that it's about fifty years ago since I last did it.

Something doesn't sound right here. There should be no movement in the lower ball joint once the bolts are fitted, even before tightening up the bolts.

Mark, Delcourt says that the holes in his wishbone are about 8.5mm hence reason that he has some movement. I have no idea if that is “normal “ or not hence reason for me saying put it in the halfway position. All the other bits about measurements were to reassure him that you need substantial fore and aft movement to be one degree out. I also added that MG gave a plus or minus one degree in the alignment specs. We just have to remember that the subframes are ordinary Metro ones dating from 1980 and are not that accurately constructed due to wear in the jigs.