new fed to me questions

[probird]

a few pics now that I have the body and wheels off.
Thoughts?

[rooman]

I would like to see a photo showing the mid plate area before commenting but strictly speaking the forward bay may be non compliant as it appears that the long diagonal is not within 3 tubing diameters of the junction between the intermediate upright and the lower rail which is the normal criteria for a diagonal within a bay. The rear bay is OK because the upper tube makes the configuration a "K" in that bay. The fact that the bend in the upper rail is well behind the forward upright is also a bit of a worry (feel free to jump in here Bruce.  ) but that could be obviated somewhat by adding a diagonal from the top of the intermediate upright to the bottom of the motor upright (one of the reasons that I would like to see that part of the frame) to make an X in that bay. Alternatively that bay could also be converted to a "K" configuration although the lower part of the "K" would be a little shallow.

Roo

[probird]

went out and took a couple mid plate area pics. thanks roo.
Im guessing it was a home built kit as the previous owner didn't know who built it.
looking for 7.50.

[rooman]

Yep!  Just what I thought I would see. Typical of most cars that have had the motor moved forward, the mid plate is out in space (and so are the front motor mounts). Any flex in this area will cause coupler alignment problems. Also the mid plate is no longer acting as a firewall. I can't see from the photos but is the mid plate tabbed to the lower rails?
   When the mid plate is at the motor uprights (as the SFI spec intends) any torque is carried through those uprights to the diagonals/X's/K's in the side bays. As the motor torques up under load it tries to lift the left side and push the right down. In this case the only resistance is provided by the tube diameter and wall thickness rather than the "beam" provided by the braced side bay. Having the front mounts similarly out in space just adds to the problem.
  Worm's Cen-Pen cars seem to get by because the rails are .095 wall but it is not unusual to have problems with a .058 rail chassis if the engine makes plenty of power/torque (ask hotrod316 about that ). The ideal fix is to add an upright at the motor mount but even a diagonal from the original motor upright to the new mid plate location will help (although not with the firewall issue). Also I see that the stepdown in the top rail is behind the mid plate since the change in engine location and even the rule book spec for 10 second and slower calls for it to be at least 2" ahead of the motor upright.

Roo

[probird]

ok. I will bring it back to where it was originally and set the engine high enough for the oil pan on both engine and trans so I can put a catch pan under the engine and seal the driver area with a nice belly pan. its tabbed on the bottom but will be cutting them off anyways. And will add 4 bolt hole mount to the rear end.

[probird]

ok cut the 4 tabs off and pulled the rear end. Going to by two new uprights with bushings.
There a little bent. N&P has them. Replace the rear mounting plates. should line up fine.
The only other issue I have is the frame is bent in the middle. I know.......Buyer beware. but Grapro and I think we should be able to cut and straighten it up. looks like they did a bad job of fitting it up. were thinking cut all 4, sleeve, and weld it up. jig it up to keep it flat and square. I'm guessing the bottom should be fairly flat..... here is a couple pics.
Thoughts?

[rooman]

Looking at the shots from low down I would think that if you straighten that lower rail you will raise the motor quite a bit. Project a line forward from the rear part of the frame and it looks as if it will land well below where the front end is now. Add to that the fact that it is generally a good idea to build a little arch into the frame so that it is straight when under load and you could be opening a whole can of worms. If the car worked OK as it is I would be more inclined to leave it that way.  As the straight edge indicates that the top rail is bowed as well It would pay to add a diagonal in the first open bay to stop that from getting worse.  Or better still, try taking the motor load off the frame (jack or crane) and see if the frame un-bows at all. If it does, add the diagonal to keep it that way. Alternatively, leave the motor in the car, tie/weight the front end down and jack the frame up at the upright where the  frame bows and see if that straightens the top rail and then add the diagonal.
  OR, as you are going to re-mount the rear and and move the motor back to the original location as per the earlier discussion you could modify the frame as you originally suggested and then mount the motor at the correct angle (provided that it will fit with the rails higher in that area).

Roo

[dreracecar]

If you are going to do all that work to repair a saggy front end on the chassis table, do it right and front half the chassis, its about the same amount time, and you will have fresh continuas tubing without splices and interuptions. The back half is where all the work and labor is anyway

[probird]

Thanks for the tips. It was suggested to hilti  the front and back to the floor and Jack the center up and see if it comes back. I'll add the diagonal. If it doesn't ,  I'll redo where the crappy welds are in the middle. The pictures are with the driveline out.

[hemidakota]

This may be wrong but is it the placement of the jack stands where there is no upright causing tube to bow?

[probird]

I don't think so as there's no weight  on it. No motor etc.  She's stripped out.

[Paul New]

Add to that the fact that it is generally a good idea to build a little arch into the frame so that it is straight when under load
Roo

Ok Roo how much of an arc say in a 200" car 1/4"-1/2" I remember hearing about this on the old flexible cars dos not know this was still done? I wish I could afford to come be your apprentice for a year or two!

[dreracecar]

Not against arc, but I dont think its needed on FE dragsters. Never put it in any car I built and they hook up and go straight.

Arc puts the engine on a launching pad to which the engine can rise up easier for weight transfer and then you have to use the wheelie bar to control it.  Not haveing arc makes engine rise harder and the rear tires plant harder trying to get underneath the chassis. Whatever works for your combo

[probird]

Well I have the uprights out an the mount areas cleaned up. Now just need the parts to show up and re install.
quick pic on the mount area and the 2 bent uprights.

[probird]

ok. update:
The good= I have the uprights in and the drive train level and straight. rear end welded up. just need to weld in the uprights fully and paint the rear.

The not so good=The next item is the front. I cut the top rail and it straightened out but in front of the engine upright was still bowed up. I cut the 3/4 upright further ahead and the bottom straightened out! The upright and side diagonal is all messed up. Will refit and make it square. Who ever welded this up before really shouldn't have tried! I'll get it fixed. Glad I'm a tuber/pipefitter lol.
Till next time.