How much frame flex is normal?

[Guest]

The scene - A TR6 halfway through a rear suspension upgrade.

It's up on jack stands (two on the crossmembers in front of the swingarms) at the rear for the suspension bushing change. Even though I know I have to take it to pieces again to do the U joints and change out one of the hubs, I decide I'm sick of looking at it and put it back together.

As part of this process I have to bleed the brakes. I do it the old fashioned way - by pressing the pedal. The door opens fine, but when I try to close it, the frame flex is such that it won't close. Back down on 4 wheels of course it's all good again.

The chassis *looks* fine - no visible rust or rot anywhere. In fact the whole car is like that. The crossmembers have been lapped at some time, but it looks like a solid job. There is certainly plenty of metal to bolt the swingarms to. Everything else looks original.

So my question is - is this amount of flex considered normal, or did I miss something expensive somewhere?

As always TIA
Alan

 

[swift6]

Not Uncommon, even if it's not rusty the frame can and will fatigue. You should be able to find a sweet spot though and be able to open both doors while all four wheels are off the ground.
/ubbthreads/images/graemlins/cheers.gif

 

[Banjo]

I believe it was B.S. Levy that made my favorite comment about TR frames. He was discussing the handeling charecteristics of race prepped TRs and claimed that "The chassis have the torsional rigidity of a soggy pizza crust"
What you are encountering is totally normal and would even have occoured on the showroom floor had you jacked up one corner.
No problems mate /ubbthreads/images/graemlins/thumbsup.gif

 

[Guest]

I concur. My frame is as solid as they come (how solid is that?) and my doors stick while up in the air on jack stands. That is why when I replace my floor pans I plan on having her down on the tires for the actual tacking.

Bill

 

[vrod]

How is the metal at the bottom of your B posts on both the inside floor area and where it meets your rocker panels, I have found if these areas are weak from rust, that after repairing them with new metal, it will make your door openings stronger and your doors will not stick, also try moving your jack stands on the frame sections further behind the wheels and try opening your doors again.

 

[Alan_Myers]

Hi Alan,

I think everyone is right about this. I can "jam" the doors on my TR4 pretty easily by jacking it up under certain places. That's in spite of various strengthening modifications that have been done to this particular frame *and* the fact that the TR4 ladder frame is a good deal more rigid than the 4A and later frames.

Short of installing a full roll cage, there is no way to eliminate some of the flex.

Cheers!

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L

 

[Guest]

Phew that's a relief.
Thanks all.
/ubbthreads/images/graemlins/smile.gif

 

[vrod]

These frames are only 16 gauge steel, which is very thin compared to american cars of that era. Its not surprising so many of them rusted out where the trailing arm is connected.

 

[sammyb]

You won't find many convertibles made prior to the late 1990s where the doors don't stick (or fail to shut) when on a lift. My '86 Dodge is hysterical -- you can actually break the back window putting the top down if you're parked on uneven pavement. (The frame flexes so badly that it puts the top out of alignment with the edge of the rear seat -- causing the window to catch.)