The front cradle mounts were the next thing that needed attention. I bought some DOM steel tubing that was 0.840" OD X 0.54" ID to make the sleeves that are welded to the front of the cradle. I marked where the through-holes needed to be for the sleeves and drilled them out after painstakingly aligning my drill press. Even so, I didn't want to chance it so I drilled the holes on each side separately rather than going through all the way:



I cut two pieces of the tubing that were 66 mm long and slipped them into the holes. I'll only weld them after I get the entire cradle aligned and mocked up in the car:



Then it was time to slip the side rails under the car and pin them loosely in place using the front mounting holes (here you can see how the extra 3 inch stretch was compensated for by the addition of a 4" X 4" square tube extending the chassis mounts further back):



At this stage, the rear cradle mounts aren't welded to the side rails because I wanted to dry fit everything to double check my measurements. I bolted the rear mounts up to the lower frame rail using the witch-hat nuts, and then swung the cradle side rail up until it mated with the rear mount. I was then able to mark where the rear mounts will be welded to the side rails.



Here's an overview of the new cradle mocked up with wooden blocks. I still haven't decided on the location of the rear cross member yet since I'm still researching engine/tranny mounts, which will impact where the rear cross member will end up.

[This message has been edited by Bloozberry (edited 04-17-2013).]

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we're in desperate need of a little more religion to nurse your god-like point of view...

Built not bought... Because bolt-ons don't.

http://www.fiero.nl/forum/Forum2/HTML/119122.html

Thanks ericjon... one disadvantage to documenting everything is the amount of time it takes. Hopefully it will pay dividends when I go to have the car mechanically inspected by a provincial engineer.

JHarvey: I hummed and hawed about buying the Motegi's for the longest time simply because I didn't like the red stripe either. But then I saw on one site where they could be ordered with a machined and polished stripe instead so that was the clincher for me. Having them repainted isn't impossible it's just that it's extra cost and hassle that if you can avoid, so much the better!

Back to the build: In my last post I indcated that I wasn't sure where the best place to locate the rear cradle cross member would be, given that I hadn't done much research on engine and transmission mounts yet. I put out a question in TD&Q to see if anybody had the dimensions of the stock Deville, Seville, or Eldorado cradle for comparison's sake and PFF member IXSLR8 found a partial answer. He provided me with the following from his Service Manuals:



It didn't include the dimensions for the engine and transmission mount locations but it certainly helped me triangulate them with better accuracy once I realized I'd have to measure them from under an actual car. One of my car storage customer's daily drivers is a '97 Deville so he graciously let me borrow the car for a couple hours to measure things out. Surprisingly, the Northstar and automatic transmission are held in place by only three lower mounts and two torque struts highlighted in green in this drawing:



Since I wanted to mimick the OEM mounting system as much as possible to avoid unnecessary vibrations and misaligned strains on the powertrain and cradle, I plotted out where the various Caddy mounts would end up on my custom cradle, then moved the rear cross member to accommodate the aft mount as best as possible:



So from the above drawing, starting across the top, you'll see that I was able to keep the two stock torque struts at exactly the same location as the Caddy. As shown earlier, I was also able to keep the forward engine mount in the same location except that I had to swap part numbers to get the correct height on the mount. The fore and aft Caddy engine mounts are identical except for the height of the bases which have about a 20 mm difference. I used the shorter part number (Caddy aft mount) in all of my locations.

Moving on to the bottom of the drawing, the main difference between my set up and the Caddy one is that I've used two rear mounts where the Caddy uses one at the rear, and one at the driver's end of the transmission. I couldn't transfer the rear Caddy location directly onto my cradle since it wasn't ideal for several reasons. The first is that it wouldn't fall at the strongest part of the cradle where the side rail and the aft cross member meet. The second problem is that the mount only lined up with a single tapped hole in the engine block to secure the upper half of the mount to. In the stock Caddy configuration, the bracket that connects the block to the mount also picks up two mounting bosses on the long snout of the automatic transmission, giving three points of contact for the bracket. In my case with the F40, no such snout exists. Leaving the mount in the stock Caddy location wasn't really an option. I moved it to the right of the drawing where both conditions were satisfied: the lower part of the mount would be located at the strongest part of the cradle, which also aligned the upper half of the mount within reach of three threaded holes in the engine block. I will need to fabricate a custom mount bracket but that should be no problem. Here's what I envision for the RH aft mounting bracket:



With the aft mount no longer centered very well on the engine, and with no mount to counteract the torque of the transmission, I needed another aft mount specifically for the transmission differential. I used Fieroguru's transmission mounting bracket on his LS4/F40 project for inspiration on the shape of the bracket, but essentially it was a no-brainer to come up with the location and design of the mounting system for the differential. This is the same view as the last drawing except that I've omitted the RH aft mount for clarity:



Lastly, the stock Caddy mounting system includes a mount on the LH cradle side rail to support the end of the transmission (see LH side of first drawing in this post). The stock Caddy location for that mount falls short of the side rail on my new cradle, it doesn't align very well with the side rail either, falling on the zig-zag, and it doesn't align well with the tail mounts on the F40 transmission. I've drawn it in green in the drawing below where I think I would put it, if I decide to use it, though I'm not convinced it's necessary yet. I'll probably wait until the other mounts are installed to make my final decision:



Now that I've settled on a mounting system for the engine, I can proceed with finalizing the cradle.

(Edited to update engine and transmission mount locations to "as-built" configuration.)

[This message has been edited by Bloozberry (edited 07-26-2013).]

Squaring up the side rails with the cross members of the cradle so that everything was level and within tolerances was a time-consuming task. I used some long pipe clamps to hold the cross members sandwiched between the rails, then slowly tapped one way or another until the cradle pieces were perfectly lined up, then tacked-welded the parts together. My welder was acting up so I took the cradle to my local welding shop for final welding. Even then, we spent another hour fidgeting with perfect alignment before committing to the final welds. Here's what it looked like back on my workbench.



By the time I took the picture above, I had already mocked the cradle back up under the car using the front mounts only, and aligned it side to side within the engine bay. Then I bolted the rear upright cradle mounts (which still hadn't been welded to the cradle) to the lower frame rail. With the cradle centered, and the rear mounts in place, I then tacked the rear mounts to the cradle to assure that all the bolt holes will line up:



After that exercise, I decided I wasn't going to fool around with the witch-hat nuts spinning on themselves so I dug them out of the frame and welded ears on them.



A week earlier I had done some research to locate the two extra Caddy engine mounts I wanted. My first stop was the dealership (just for laughs) where they quoted me $130 each before taxes. So then I checked out the local NAPA store where they said they'd have to come from the States and would be $80 each, plus $30 shipping, and it would take between 2-3 weeks for delivery... better, but still hardly the level of service I expect in today's global economy. Finally, I checked out RockAuto online where I found the same part number that NAPA was offering, except that they were a whopping $16 each!! Even after factoring in the shipping costs of $32 and taxes, I got both mounts for a total of $75 within a week of ordering. Now that's the power of the internet.



With the rubber mounts on hand, I started work on the brackets that are needed to weld to the cradle to bolt the mounts to. I bought some 4" wide X 3/16" thick steel bar and got busy cutting out the patterns I'd made on the computer.



I had originally intended for the side braces of the mounting brackets to be angled at 45 degrees so I cut the metal with that in mind.



But after sticking them in my 12 ton hydraulic press and bending them, I decided they looked rather big and heavy with the "wings", and besides, the forces being generated by the engine didn't need the mounts to be stabilized side to side, so I bent the wings up at 90 degrees and trimmed them accordingly. Here they are after sandblasting:



Next up was to mock up the engine on the cradle to double check the location of the new engine mount brackets on the cradle. I have my drawings for planning and all, but nothing beats a clear visual with the actual parts, so I hooked up the engine/transmission to the hoist and got it off the workbench for the first time in about a year. Luckily it hadn't grown any roots!



Just as a temporary measure, I set the cradle and engine on top of a couple 8 X 8's so that I could get the crane's legs to clear the underside of the cradle. Now I can clearly see where my engine mounting brackets will need to go and can tack weld them into place. That's the next step.

[This message has been edited by Bloozberry (edited 05-11-2013).]

Blooze, me likes your skills !!

Nice work.

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fierogt28

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

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87 GT
series 1 3800sc (7.597 @88.53 1.579 60ft)
(series II swap in progress)
85GT Northstar
86GT 3800 n/a