fatigue in drivers floor

[sii803]

I've been ignoring this problem for a while but it is now in need of attention. I have a crack in the drivers floor. It originates from the right hand side seat mount. The floor will bellow like an oil can, but now also causes seat to lean noticeably.

has anybody else had this problem? Any suggested repairs? I dont want to replace the floor (it is difficult to get such panels in aus) but it is also rust free.

If I just weld up the crack, I'm unsure if the floor will be stiff enough so the seat doesnt move around. Unless I shirnk it with the oxy after mig welding floor?

Any suggestions welcome.

thanks,
Matt

[rayofleamington]

Most likely, a stress crack at the seat mounting bracket is caused because the floor is moving under load - not the other way round. I'm sure the movement is MUCH bigger when it has cracked though ;-)

You can weld the crack up. If it's MIG welded and nothing else then chances are that it will crack adjacent to the weld. If it's gas welded then it will last longer but won't cure the original problem.

First to check is how well the seat meets the floor at the rear. If the seat sits unevenly then when weight is applied (by sitting on it) it will twist and try to bend the floor at the front mountings. If that's the case, make the rear sit square by packing or 'adjusting' the seat frame and that will remove the tendency to bend the floor at the front mounting.

If the floor itself has a wobble when you push on it by hand then there are a few approaches. The wrong way to do it (quickest) is to use a big hammer to reshape the floor so it no longer wobbles. Shrinking it with gas or beating tools is good or with MIG, you can slot the floor with a cutting disk then weld to shrink it.

Just my 2p's worth - but I've seen a few cracked floors and most (all?) have had seats that don't sit evenly at the rear. Some have cracked the front floor and some have cracked the rear floor under 1 side.

[sii803]

Thanks Ray. I'll check the seat out before I get too involved. It certainly does seem the floor has streched, and this movement has lead to the cracking. I havent heard of the idea of shinking with the MIG before, osunds sensible, probably good where you need to remove a bit more metal to. I think I'm more confident to shrink with my oxy though.

Really good to know I dont have a special problem.

Thanks again,
Matt

[chickenjohn]

I'm afraid the only long term fix here is to replace the floor pan, even if rust free. i had to do this on the project convertible.

[rayofleamington]

replace the floor pan, even if rust free.

A rust free floorpan that has cracked at the seat monting because of poor seat alignment, is surely worth saving! If repaired properly it's likely to be stronger and last longer than a replacement floor. Just my opinion though.

[tortron]

according to the manuals i have this is fairly common, it also shows where to put "toe" plates to reinforce these spots

i can probably send you that section if you want?

[leyther8008]

I,ve been told that all post office vans were supplied with those reinforcing plates factory fitted, along with jacking pads under the front suspension arms etc, because the floors cracking and arms twisting under use were such a common problem in vans. whether its true or not is for one of the experts.

[aupickup]

the plates or jacking points on gpo vans werte just that , so the jack would not slip

the rear strengheners on the floor for the rear of the seat were there to stop the rubber mat from wearing through, the plates were actually hard rubber pads