We own a Foden 4000 series 6x2 tractor unit which often suffers from broken wheel studs on the front axle. The near side hub has no studs older than 6 months so this is not an age related problem. We have super single tyres fitted . Has anyone any ideas on the cause of this.
Probably tightened the nuts with a scaffold tube on the wheel brace and got them too tight 
as above snapped a fair few this way myself being an overkeen new driver when i 1st started out.
Yes over-torquing is one of the most common causes.
It sounds like you are replacing them piecemeal. If one has broken you really need to change the lot as it will have caused the others to become overstressed. It is quite common for one to go, just that one be replaced, then find more go.
Our Foden six and eight wheelers got through front wheel studs. Foden did modify them but they still broke them, I remember travelling empty back from South Wigston with three broken on a front wheel. When we changed them we always hit the others with a hammer and often a couple more would shear off so in the end we changed them all, even when only one was broken. Rear ones were not affected though. Our Sed Ak 400’s rarely snapped any and they were all tightened the same.
Pete.
Be sure the wheel and hub surfaces are clean, smooth and rust free.
Try swapping wheels as you may have a warped one putting uneven load on studs.
Seen this problem on 401 and 411 Seddon Atkinson’s years ago, we could get them in for inspection just tap them with the tapping hammer and they would just fall off and always the N/S/F.
On some we found changing the wheel worked on some, and then changed the brake drum on others and that worked too.
Cheers Welly
welly bobby, we had same on sedd atk , always on front axle, we changed wheels but still did it. got to stage were one had gone every day. in end they reckond bad batch studs cheers Charlie
Not quite the same but similar. I am currently going behind a fairly well known restoration company and putting right their ■■■■ ups on a bus. During the course of their work on the vehicle new front tyres have obviously been fitted. Being nearly 50 years old, the vehicle has old-style left and right hand threaded wheel studs which use a cone seating wheelnut. Unusually the cone is larger than the hexagon (it’s an AEC). Because the front spring shackle hanger plates are carving chunks out of the chassis I needed to remove the front wheels. The nuts had been overtightened, but rather than shearing the studs, four of the wheel nuts broke at the weakest point - where the hexagon meets the cone. This left the wheel secured by about two threads inside the cone. Having overcome the problem, the four stud holes have elongated so the wheel is scrap.
Same here had the same trouble with the Sed Atki 401,s however we noticed that some of the studs were "black " in the middle so we got a couple of new studs and cut them in half and noticed that out of five, one was like this . My brother in law had his own metal casting foundry and we had them tested and found that the ones with the black centres were defective,albit looking ok. We pointed this out to our local agent backed up with a metalurgists report and fair comment Sed Atki followed it up( and although not admitting any liability ) withdrew a batch of studs , howfar this went I dont know I do know we didnt have a prob again. Prior to this we had the same prob with the nearside wheels especialy on the front. With regard studs breaking on single rear wheels if you look at a single wheel ( on the rear of a 3 axle unit ) when it turning tightly it looks as if the tyres trying to leave the rim , many years ago we had ERF with a Southworth conversion it used to break studs on the rear axle we cured it by having twins on the rear , this meant that when turning tightly the twins tended to skip/scrub and it cured it.
Yes there was a bad batch of studs too, but we still had it after that.
But one thing was, out of 30 trucks the 411s was ok, it was the same 401s every time that we had this problem. I would say 4 out of 15 401s were the problem, I will never forget A523PWW was one, ALW908Y, A977ALW MWG911X and the last one is YPH782Y.
This was years ago but I still have the book that I used to write thing down in what and when we did work on the trucks, No computers then Lol.
Cheers Welly
Thank you very much all of you for all your helpful replies, some of which we had already implemented, others to try again on the next break!!