10 x 125

The bolts that hold the spring locators are, as previously mentioned, 'captive'in that the heads are welded in place inside a box=section of the chassis---very difficult to get at.The easiest way to get the nut off is by using (VERY carefully) a 'power-file'---these have narrow belt-sanders on them. File away one side of the nut until you JUST see the thread of the bolt. If the bolt's thread is only damaged over a very short section you (a) might find that running a die over it will clean it up enough or, (b) as there is a fair length of spare thread, you can put a spacer over the damaged section when refitting the spring which will cover the damaged thread and put the new nut onto clean thread. Whatever method you use to remove the nut, be very, very careful because replacing the bolt is NOT an easy task!

Thanks for advice everyone, in the garage after breakfast to give it a go, will keep you informed.

You could measure the diameter of the stud. I think but don’t quote me on this that they should be 10mm or M10. I know they are fine pitch which would make it M10 x 1.25. Another give away is the size of the nut AF. If you use a 17mm socket this would be M10, 19mm socket is M12. Sorry I’m in Italy at the moment so trying to remember off top of my head. If I was in the UK I’d just pop into the garage and confirm

I use a long 17mm socket to do/undo the spring-seat nuts---that would make them 10mm bolts----enjoy your holiday Damian. I will be in Misano over the weekend 15th/16th Sept for the BIG Raduno--possibly between 400/500 Cinquecentos! i am going with my friend from Senegalia in his (suicide door) 500--for all 3 days.

It's M10. Just removed nut using a multi tool and two cuts. Didn't damage thread getting it off but you can see its stripped. There's enough length to put on a flat nut and then a lock nut so I think that will do the trick.
Now for the hard bit getting the new Spring on. ��

stocky said:

It's M10. Just removed nut using a multi tool and two cuts. Didn't damage thread getting it off but you can see its stripped. There's enough length to put on a flat nut and then a lock nut so I think that will do the trick.
Now for the hard bit getting the new Spring on. ��

Click to expand...

I did one side at a time, using a stand to hold one side up while I bolted the other I made a timelapse video that you can stop and start to see what I did

See
https://www.fiatforum.com/500-classic/461000-changing-front-rear-springs-lowering.html

I had to replace mine on the right side but there was a hole already opened.
https://www.fiatforum.com/500-classic/456552-help-leafspring-attachment-studs.html

New locknuts arrived today so I finished the job. I'm pleased with the result, I packed the stripped part of the thread with washers and it nipped up ok. Gone for a ride and steering is straight with hands off and steering wheel straight. Haven't checked but wheel angles look as they were so I'm wondering if I've been very lucky with this new Spring?
Post some photos.

Another photo I can't load more than one at a time?

Another

Last one

well done---did you check your spring to make sure that they were even side-to-side as per my earlier suggestion?

Yes they we're within a few millimetres so I chanced it. I fitted the outer Spring bolts first then the wishbone to kingpin bolts, made sure steering wheel was straight and then bolted the two Spring mounting pads. I used two jacks under the outer springs to push up and just lift the body off the axle stands.

Been for a long drive this morning and no banging now when going over speed bumps so problem solved, everything sweet.