Blooze Own: An F355 Six Speed N* Build Thread (Page 110/126)
RCR JUL 16, 04:16 PM
You could also use a higher density 2-part foam to make a new impact beam to put over the refashioned bumper.

Bob
Bloozberry JUL 16, 04:35 PM
All great ideas to get me thinking outside the box guys. Thanks! I'm going to let it stew a bit more.


quote
Originally posted by Yarmouth Fiero:
HI Blooz, I am thinking the last option might be the most suitable. For my car, I was expecting to remove the entire trunk structure anyway and open it all up for exhaust, engine and such.



That's certainly a clean option, but I'm wondering if I do that whether I'll kick myself later when I try to design an exhaust system and am missing that extra inch or two from having moved the rear bumper back further than it needed.


quote
Originally posted by Yarmouth Fiero:
In plan view is the transverse curvature of the rear fascia going to cause more problems with interference at the ends of the stock bumper?



The profile on the drawing is located at the worst case location, ie, about in the middle of the two tail lights, so the clearance only gets better (marginally) toward the middle of the car (but I didn't measure by how much).

Yarmouth Fiero JUL 16, 07:55 PM
Just had a look at my chassis and it appears that the lower trunk well is completely independent of the lower frame rails so it would certainly be easy to remove and make way for the bumper. As well, by cutting the lower trunk well just below the transverse frame connecting the two upper frame rails, it would keep all this structure intact above the bumper. I think your suggested option of recessing the stock bumper and retaining the honeycomb crush zone is a viable possibility Blooz. I have been staring at that whole area from strut towers back for weeks now and my reciprocating saw trigger finger is getting mighty itchy.
Jefrysuko JUL 17, 12:07 AM
That's crumple zone area that you would be removing by recessing the bumper. I'd loose the egg crate and reshape the bumper first personally. With some simple calculations you can obtain similar stiffness with a modified bumper.

Edit: I think the egg crate is mostly to satisfy the 5MPH Bumper standards which is related to damage to the vehicle and not safety of the operator. That's why I see more worth in the crumple zone than the egg crate. Like someone else said, you can always make something that replaces the function of the egg crate which matches your body with some 2-part foam.

[This message has been edited by Jefrysuko (edited 07-17-2014).]

86Fieroman AUG 13, 10:06 PM
Very useful information here and great job on the build so far. Any recent progress?

Bump
Lunatic AUG 20, 07:41 PM
Hey Dave. I'm going through the same thing as you are, rusty rear bumper. I drew one up real quick (in SolidWorks) and I've since cut it and formed it on the brake using 1/8" aluminum. Just an idea.














[This message has been edited by Lunatic (edited 08-24-2014).]

Bloozberry AUG 22, 07:29 PM
Thanks everyone for your input. That's a really nice set of bumper bars you've made there Lunatic That's exactly what I have in mind as well except mine will be made of steel.

Since my last post I've decided that I'll recess my rear bumper bar by 50 mm's to retain as much of the crush zone as possible at the expense of less honeycomb material. I believe Jefrysuko is right about the honeycomb being there to meet the 5MPH bumper standard. That bumper standard would work with a flexible fascia but my fiberglass fascia will be hard and brittle so I don't have any qualms about removing the honeycomb altogether, though I'll probably shave it down and stick it on to give a factory appearance for the inspector.

With that decision made, I removed the rear quarter panel once again and got cracking on the underlying metal modifications. First up was to remove the lower half of the trunk to make some room to work:



I was careful to cut it only where necessary in case I wanted to re-use it at some later point, but for now I'm pretty certain the exhaust system will occupy this area when all is said and done. I used a cut-off wheel in my angle grinder to make quick work of the "trunkle-lobotomy". The lower half of the trunk sheet metal isn't attached to anything except the sheet metal trunk walls above it, so there's no need to deal with spot welds. It does come very close to the lower rails though so care is needed not to slice into them.



From this top view you can see why the lower half of the trunk pretty much needs to go to make way for exhaust plumbing. Even though some guys with Northstars in their stock-bodied cars have kept most of the trunk, the difference here is that there's less rear overhang on the F355 than on the Fiero.



How's this for a cool shot?:



Another benefit to removing the trunk is that I'll be able to refinish the inboard side of the frame rails. It also allows me to have a closer look at the inside of the rails. I'm a little concerned with the amount of rust on the floor of the rails.

[This message has been edited by Bloozberry (edited 08-22-2014).]

Yarmouth Fiero AUG 22, 08:11 PM
Looks good Blooz. It certainly changes the look of the chassis when you cut all that extra sheet metal out of the way. Your engine and suspension look fantastic from every angle you shoot pics from. If I didn't know better, I'd think you work on the car in one shop and roll it into another clean shop for photos
Yarmouth Fiero AUG 22, 08:17 PM
Are you planning to leave this area alone ( circled in red ) even though the wheels are much further outward now? I have removed most of mine and once my struts arrive I'll remove the rest with the new strut tower design.
Bloozberry AUG 31, 09:01 PM

quote
Originally posted by Yarmouth Fiero:
If I didn't know better, I'd think you work on the car in one shop and roll it into another clean shop for photos.



LOL. My Shop Vac gets a workout before I start taking pictures.


quote
Originally posted by Yarmouth Fiero:
Are you planning to leave this area alone ( circled in red ) even though the wheels are much further outward now?



I haven't removed it yet simply because I've learned over the years to remove as little as possible until I know for sure that I won't need it. I also wanted to leave as much of the "shelf" as possible to make it easier to attach a new trunk floor later.

As for a (little) more progress, I've taken a bunch of measurements that needed to be taken while the engine was in place, like the planned locations for the engine torque strut mounts, fuel and coolant lines, CAI and air filter box, coil packs, etc. I also fed a video boroscope up the two lower frame rails to have a look at the rust inside on the rail floors. I've pretty much convinced myself that I'm going to replace the rail floors with new metal from the rearmost bumper attachment flange to a foot or so forward of the rear cradle mounts.

With that much decided, I figured it was time to pull the suspension, engine, trans, and cradle back off the car and get busy. One nice thing about having removed the lower half of the trunk is that I didn't need to raise the car anywhere near as high to pull the cradle out:



I'll be able to get to the repairs and other modifications much easier now as well.