Series 3 Wonky chassis

Hi. I have now got my series 3 down to the bare chassis on axle stands. I have spent ages patching, plating, grinding and sorting it. The trouble is in the last few weeks it has become apparant that the previous owner's repairs to the rear crossmember and both dumbirons are not accurately done. It always sat low on the drivers side but so do lots of series 3's. It has had Britpart springs fitted at some time so i'm sure that won't help.Everything is now solid with all rust cut out and repaired and it did have an MOT when I bought it a year ago. I have not had to touch these previous repairs so it must have passed an MOT with them exactly as they currently are. My goal is just to get it back on the road for a few years before I have to bite the bullet and get a new chassis so the big question is just how out of line can a chassis be before it is unsafe or won't pass an MOT. I think it sits 2cm low on the drivers side overall and the passenger dumbiron is about 1cm toe in. It doesn't sound much and maybe i'm just worrying too much but it's visible and I would be really fed up if I get the bugger rebuilt only to have the MOT tester fall about laughing when I drive in. What do you think?

Easier to replace the dumb iron now.
Are the rear spring hangers in the correct position?

I think so but i've really got to get the tape measure out and thoroughly find out properly.

I suspect the mot tester probably wouldn't notice. I'd be more concerned about spring fitting, poor handling and pulling under hard braking. Seems a shame not to cut and weld whilst it's still a bare chassis.

I have now checked the position of the spring mounting points and they are quite accurate. Also i've done lot's of other measuring. Overall I'm starting to think that the chassis is not so bad but if that's the case maybe the springs are just more far gone than I thought.

Don't forget the series 3 springs are HANDED might be that a previous owner forgot that? Certainly would account for its lopsided appearance!

If you download the manuals there is a section in there somewhere about measuring the chassis for errors and the tolerances are quite large! The main things I'd be worried about are the trueness of the axles (centre to centre back to front) so you're not crabbing too much. A bit of lean is sommat and nowt. If the front hangers are out by much it is surprising how easily persuaded they are to move 1/4" to make spring sit nicer!

2cm is bugger all, mines down by about 2" with the sag in the parabolics. Didnt help the previous owner was a larger gentleman who went around on his own in it

Thanks for the advice. This all sounds good. I am pretty sure it's square and that the suspension bushes are correctly placed. But because i'm a shocking fuss arse I have devised a sheet of measurements that I want to check to be sure. Father in law is coming round to hold the other end of the tape measure. He was a pattern maker at Rustons in Lincoln as a young man so is used to ridiculously small tolerances so he might be dissapointed. Personally I will settle for strong, safe and about right +/- 10mm.

Thanks for that. I will give it a try at the weekend.

I have now really thoroughly measured the chassis. I have checked it for squareness as described in the manual above and it's well within the tolerances. I used 2 bottle jacks at the back and a trolley jack at the front so that datum AA is level and the chassis rails are level (within 5 or 6mm) across. Basically it all shows that the original bits are very true and the repaired areas are not far out. It was certainly no craftsman who did the repairs but it has done the job and I believe will continue to do so. One mystery though. I wanted to check the position of the front suspension mounting points. From the diagram this involves using dimension J which is measured from the front face of crossmember 3. Now whenever I measure from that crossmember I end up about 96mm out. A crazy amount that can't be right. If I measure from the rear face of crossmember 3 i'm about cock on. Surely too much of a coincidence? I had only printed out the 88inch diagram to use in the garage so I have been baffled. I came on here tonight to pick your brains and I see that on the long wheelbase diagram dimension J is measured from the back of the crossmember and it is exactly the same as the 88inch at 793.7mm. Just so that I know i'm not going mental can someone check my theory and let me know. Is the 88inch diagram incorrect or am I reading it wrong somehow.