Dbl G, I think everyone in the thread already has that mod.

I've got a Sir Michaels Roll Pan, Deleted Hitch and Spare and
spare tire winch, and Stan's Panhard bar. I'm pretty much with
Tim, I don't see HOW that rear could be twisting much. The front
is another issue though.

I think most of the "weirdness" comes from a high CG vehicle
trying to emulate a race car. < grin >

Cliff

 

Tim,
That's a great picture. Is that Stan's C-Notch because it is seriously heavy duty. I remember one of Stan's posts where he measure flex before and after his C-notch and it was significantly reduced. The weight penalty is 120+pounds. A boxed frame will significantly reduce flex and increase torsional rigidity. I think Ford quotes an improvement of something like 9X. When you look at the new F-150 frame, it is very obvious how much more rigid it is. Obviously, boxing the frame is not an option due to weight but to strategically add (weld/bolt) some bracing should make a difference. I will discuss this with my fabricator next month.

I don't have an X-Factor because it interferes with my twin exit exhaust (both sides). No this is not a weight reduction feeling. The R compound accentuates the flex and torsional instability of the frame because it was never meant to be subjected to these forces. Cliff (SVT KY) has commented on the same issues.

I will have an opinion on a possible fix for this next month but in the meantime, I would welcome others comments on a possible fix. Its relatively easy to add a bunch of metal but the key is to do it where it will be the most effective in order to keep weight down.

TB

 

We installed one of Stans C-Notch In Ayrtons truck and it was amazing the reduction in flex. Another great product from him.

It was straight forward and a nice piece of Engineering.


SVT_KY,

I am glad too hear you have upgraded your rear as well, however some readers may still be on the learning curve my friend..

 

DblG,
Is that the one in the picture? How much weight did it add?

Cliff,
Where do you think the problem is up front? Would it be solved with the X-
Brace?
TB

 

Right at 7 3/4#'s

 

I don't think so, but I'm not 100% sure.

Boxing would also be a nightmare to maintain component accessibility. You would have to drill holes everywhere just to take out bolts for service.

I would start with the flexing addressed by the X-Factor. Tie the four suspension pickups together, and I don't see much of a reason to care about the rest.

I posted on this subject before. I did some calcs for a very thick piece of aluminum to bolt on in place of the bumper for us Sir Mike's guys. The wieght penalty would be minimal, but I also expect the effectiveness to be minimal.

It would not be that difficult to get a large piece of thick aluminum sheet to span the whole area under the frame behind and over the axle. Might have some aero benefits also, as well as a tidy place to mount a diff cooler, tranny fluid reservoir or cooler, etc. How much it would stop flexing, though, is another issue.

It seem to me that the only way to really get at frame flexing is with a through-the-back-window roll cage. If all you are doing is bracing side-to-side, I don't see how that will stop the vertical deflection.

 

Garrett: Thanks for the image resize.

 

I don't know if it stiffens the frame, but I can tell you that when I was rearended last november, the Hitch caused nearly all damage to the frame. As it was pushed down it bent the Frame up just about everywhere it touched. Pretty amazing to see actually he hit me running close to 90, hit dead square in the back, and didn't break a tailight on the truck.

 

Gries'd, so what did you get to replace the truck? Or did you fix it?

 

Tim, you got the shock on the wrong side in the picture.....

 

 

id have to say no,,,,do the lightnings share the same frame as other f trucks????

lots of ford trucks come with no hitch,,,,or a bumper for that mater

you had me thinking

 

I'm not disagreeing with you at all. But the Lightning was touted as a sport truck that could handle. I just figured anything to stiffen the chassis, may have been put in there for dual purpose. to tow, and to stiffen it up a little.

 

It's certainly a subject worth discussing again.

Standing by for TB's ideas . . .

 

With the loss of the rear bumper, I am convinced that we need something back there. (If the hitch wasn't part of the engineers rigidity calculations, the bumper sure was) I invite you to take a look at the Toyota for what was done back there. Nothing groud breaking but apparently it works. I have seen pictures of it but I will stop at a Toyota dealership before the end of the week. Just wonder what the salesmen will think about a guy with a highly modded Lightning looking at an X-Runner Will have to take another car...

How's this for an idea. For those not needing the hitch. Keep the mounting points, brace it in an X format and remove as much metal as possible to hopefully end up at half the weight of the original hitch. Weld or bolt in place. With this brace there would be no need to add a brace where the bumper use to bolt in.

Next add a brace to tie in the four suspension points that works with your mods. Again keep the weight down. At this point, I would consider being done. Weaknesses are addressed and taking this further would add more weight which would take us backwards in terms of building a high performance vehicle.

What do you guys think?

TB