Blooze Own: An F355 Six Speed N* Build Thread (Page 111/126)
Yarmouth Fiero SEP 01, 12:01 PM
Looks good Blooz. Your engine and transmission look great on that custom cradle. On that note, I have been mulling over my rear lower frames and rear strut tower shift and I pretty much have myself convinced that I am going to remove the lower frame rails and replace them with 4" x 1 1/2" x 1/8" HSS that run straight back from the firewall to the rear bumper. This will make them match up with the widened strut towers and give me a little more room for my SBC. Therefore I will have a set of lower frame rails that are pretty darn clean if you are interested in splicing them on to your chassis as you had indicated.
Bloozberry SEP 01, 01:55 PM
That does sound like an interesting proposition. I would certainly take your rails and see how I could make use of them. I'm sure that would be easier than forming new ones.

If you're looking at replacing the rails entirely, then you should consider going longitudinally. Seriously.
Yarmouth Fiero SEP 01, 02:09 PM
I don't see how I can keep the same wheelbase going longitudinally. Dumb question perhaps but what gearbox would keep wheels in the same position with a SBC? The other builds all do a longer chassis stretch than 3".

edit: to complete my thought

edit x 2: sorry, I'll do an email so I don't muddy your thread.

[This message has been edited by Yarmouth Fiero (edited 09-01-2014).]

Bloozberry SEP 07, 08:07 PM
Well today Yarmouth Fiero dropped by with his sawn-off lower rear frame rails for me. He's decided to make custom rear lower rails to suit his small block V8 installation. So much the better for me because I was getting ready to hammer-form new floor sections for my rails but this is going to be much easier. Even though his frame is an '85, the rails are identical to the '88's except for a clearance notch for the early suspension rear tie rods. The notch is only in the weld flange so it's not like there's a structural impact. Check out how pristine these things are!:



Before I tackled my lower frame rails, I took a short interlude and wire-wheeled the two rear door frame structures (lower extension to the B-pillars), and the rear upper cross member. They weren't rusty but the original paint was flaking off here and there so I wanted a good surface for my primer to adhere to:



I primed the bare metal and was ready to start on the lower rails. This is what originally caused me to suspect that there was hidden structural damage due to rust on the inside of my rails. Notice the pinholes here and there around the rear cradle mount... not good:



Peering down the inside of the rails with my video boroscope confirmed there was more damage than could be ignored. Here's a frame shot as the camera was just entering the frame horn:



Having Yarmouth Fiero's rails on hand made it very simple for me to decide just how much of my own I should replace. So today I got busy with a center punch, 1/8" drill bit, 21/64" drill bit, a metal chisel, and a hammer. Given that the frame rail is formed from two "Z" sections spot welded together, all I needed to do was drill out the 30 or so spot welds holding the two halves together and slice up vertically to remove the entire inner wall and floor section in one fell swoop:



The photo above is after I'd cleaned up the rust with a wire wheel. The outside wall is pitted somewhat but not badly enough to make me want to replace it. On the other hand, here's the inboard wall and floor section:



And remember this pinhole around the cradle mount?



... well this is a close up of the area inside the rail... just a mess of rust between the mount doubler and the sheet metal of the Z section:



Here's another shot showing the difficult-to-repair area:



Wholesale replacement is the easiest option for those of us who live in the rust belt.
fierogt28 SEP 07, 08:37 PM
Ohh, man. Those rails are really...well, new.

Nice to see that Yarmouth Fiero had a really clean / rust free car. Unbelieveable.

Good thinking Blooze on showing us the rails inside on how they can become rusted for
fiero owners. Every Canadian fiero owners nightmare to see.

I like the way your doing everything to strip the old paint, and prep for primer, then new paint.

Thanks for sharing.

------------------

fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. Beechwood interior, All original.

Yarmouth Fiero SEP 07, 09:28 PM
Thanks for posting the pics of the inside of the frames, showing the degree of deterioration of the chassis. The scary part is that almost 30 years later, vehicle are still rusting out in the same way. My Grand Caravan was only 6 years old when I traded it last year and the rockers were totally rusted out. It was quite shocking but apparently it was quite common for these vans. So much for advances in paint technology. The reality is that winters with salt on the roads will destroy a vehicle..period.
LornesGT SEP 08, 09:24 PM
My Fiero metal looks better than my 2008 Avalanche and it has a coating that is suppose to protect it.
Bloozberry SEP 09, 10:07 PM

quote
Originally posted by fierogt28:
I like the way your doing everything to strip the old paint, and prep for primer, then new paint.



Thanks! It just seems like it would be a horribly missed opportunity not to strip, prime and repaint at this stage. It does delay the project completion date but if I were try to correct the rust issues after the body was put on, it would be three times the work.


quote
Originally posted by Yarmouth Fiero:
Thanks for... showing the degree of deterioration of the chassis. The scary part is that almost 30 years later, vehicle are still rusting out in the same way.



Very true. Although the cars that get undercoated yearly seem to do quite well. I just wouldn't want to be the guy welding up a new suspension 30 years from now when all that undercoating they spray inside the frame rails catches fire!

Carrying on with the lower frame rail repair: I separated the two halves of Yarmouth Fiero's rails since I only wanted the portion that formed the lower floor and the inboard wall. I did it by first center-punching each spot weld, drilling a 1/8" pilot hole, then drilling out each weld with a 21/64" drill bit (one size larger than 5/16"). I needed to wedge a small cold chisel in between the two sides of the weld flange to pop each of the drilled out spot welds. Each spot weld literally "popped" apart as I made my way along the weld flange. It was much easier than I expected.



Here's what one of the new rails looked like after separating the two pieces. Interestingly enough it appears that GM used some kind of sealant between the two halves to keep moisture out of the crack. The sealant had long ago dried up though:



Not wanting to give up the opportunity to really protect this area, I decided to strip the OEM paint off the new rails since there were many small pencil eraser sized spots where the paint was flaking off here and there. I used a gnarly wire wheel on my angle grinder so it went pretty fast... 45 mins per rail half.



Then I primed them inside and out. For all the rust belt PFF'ers who've only ever seen the factory rear cradle mounts after they've been ravaged by weather, here's a close up of what the witch-hat nut and cage assembly looks like (until now I'd only ever seen rusted out bits and pieces of the cage). Notice the frame stiffener too.



I did the same to the rail halves that stayed attached to the car too... priming them with a self etching primer.



Time to decide on a colour for these pieces now since I won't be able to reach inside the frame once they're welded back together. Hmmmm... silver? Gun-metal?
Yarmouth Fiero SEP 10, 07:17 AM
Very interesting perspective to see the frame rails open like that. I was a little worried even those clean frame rails would have some rust inside.

As for color, I've always been partial to royal blue frame rails with a pink firewall.

Bloozberry SEP 17, 10:22 AM
I think I'll stick with metallics... but only because Airforce tartan would be just too much work.

Over the last couple days I've been trimming and fitting the new rail halves so they'll fit correctly and get the rear cradle mount properly located. Luckily it wasn't as difficult as one might think. There is some misalignment tolerated in the side-to-side and fore-and-aft directions by the fact that the cradle mount is a captured nut with about 5 mm's of play in all directions except vertically. The vertical alignment was a piece of cake though because there's a stamped groove that runs most of the length of the inboard wall of the rail about an inch below the top. That groove forms a ledge on the inside of the rail that butts up against the "ceiling" of the rail half still attached to the chassis. Confused yet? A picture says a 1000 words... here's the new rail half from Yarmouth Fiero's '85 mocked up:



Once the alignment was checked and then double-checked, I took the rail half off again and painted the inside silver with a hammered finish to look like galvanized steel.



Having seen the ravages of rust on cradle nut "cages" and after having struggled with cradle bolt removal in the past, I decided to take extra steps to protect the area from rusting up and seizing. I just sucked up some anti-seize compound into a syringe and squirted into the cage from the top and bottom until it was good and goopy... perhaps I put too much because I was fighting with the stuff dripping out the bottom.



I made a 3" long splice out of some rectangular tubing (1/8" wall thickness) and buried it halfway into the rail on the chassis. I had drilled a series of 5/16" holes in the rail itself to rosette-weld the splice in place. I also needed a small thin doubler at the top to compensate for thickness of an OEM doubler that only ran partway up the inside wall. It looks nasty but that's just the paint that's flaking off due to the heat:



The splice is as much for strength as it is a backboard for welding up the vertical seam since it was difficult to get a really tight fitting butt joint with all the alignment steps. Here the new rail half has been clamped in place and is ready for final welding. Notice the six 5/16" holes in the rail at the seam for rosette-welding. There are two more on the bottom side.



Once the seam was welded up, it was just a matter of welding in the drilled out spot welds along the top and bottom flanges. The job was made easy because the drilled out spot-welds were in different locations between the '85 and '88 rails. That meant that behind every hole in the '85 rail half, there was solid metal behind it on the '88 half of the rail. It also led me to wonder why they would have changed the program for the welding robots on the production line. That's when I discovered that over the span that I'm working on, the '85 rails had 13 spot-welds whereas the '88's had 18 spot-welds. No wonder they didn't line up! Makes you wonder what prompted them to add the extra strength.



And finally, a peek down the inside of the LH lower frame rail... nice and clean... well except for the anti-seize compound oozing out everywhere!



Now onto the RH rail.