rear springs removal and body floor

[sparkeysprite]

I've just ordered some new rear springs for my '31 Boat Tail tourer to correct it's rather saggy back end.  They'll hopefully arrive this weekend and I'm starting to plan the job.  I'm aware of the "loosen bolts and find a rough track" advice to help free things off and intend to do that (although it all seems pretty clean so I'm hoping the old springs haven't been in there for 90 years...).  
My question is, having loosened the u bolt and through bolt, how do I get the bolts out - their upper surfaces are pretty much flush against the floor of the body - do I need to take the body off (!).  I've had a quick search on the forum, but can't see anything relating to this - perhaps my car should have an access hatch, but may have had new floors at some time and the hatch hasn't been put back in?

If the body must come off then so be it, but I'm wary of doing that as it's then likely to turn into a full restoration which I don't really want to start as the car doesn't really need it.  I know from previous experience on other types of old cars that once you get to the body off stage there are always things that can be found that are worth doing whilst it's off, but these little jobs can quickly snowball..

Any thoughts or advice appreciated.
Steve

[Steve Jones]

Careful measurement and a suitable hole saw will solve your through bolt problem. As long as the U bolts are loose, they shouldn't need to be removed.

Steve

["Slack Alice" Simon]

Not had to do this myself, one car has removable floors, and on the other, someone has bashed holes through with a cold chisel.

If I had to do it, I would see if I could get an indication of the position of the bolt by putting some upwards pressure on the bolt - using a jack - and gently tapping around with a light hammer, to see if I could get an outlne of the bolt head.

If so, a sharp cold chisel  will do the job.   Ideally, one ground to the width of a flat on the bolt.

If not, I might drill some exploratory small holes, and once the bolt position is found, carry on and maybe join the holes up with a chisel.

[Malcolm Parker]

That's exactly what I did when doing the Ulster rep.  When finished I covered the holes with black gaffer tape.

[Robert Leigh]

On my Ulster rep I used the cold chisel method. The heads are now exposed which will make it easy if I ever decide to do it again.

[sparkeysprite]

It seems that cutting is the answer. I'll probably try measuring and using a hole saw so I can fill the hole with a rubber grommet.
I was going to replace the u-bolts, but unless I damage them whilst removing the springs I'll just leave them in an re-use them.

Thanks all.
Steve

[JonE]

don't the holes generally match the hexagon-planed bolt faces quite neatly? and the top of the bolt sit at the same level as the floor? Would be nice to try and recreate as was rather than just a round 'ole. Dremel type circular saw cutter?

[Hedd_Jones]

If the floor is as it left the factory it will have 2 holes in the floor for the 1/2 bolts to come out of. 

That is there should be a hole in the floor directly above the bolt

Dependant on who put the body on, and how, you might need to cut the felt between the body and floor

You dont need to remove the U bolts.

[JonE]

but are they round or are they stamped hexagonal? I thought I'd seen the latter...

[Chris KC]

Like others, I drove the bolt upward just sufficiently to make its whereabouts known on the floor from above, & marked a centre. I then raised the body just enough to permit use of a hole saw without touching the chassis - no need to take it off. After de-burring the holes I suggest to seal them with rubber blanking grommets.