I use cad for a lot. Doing the design I set up a two dimensional parametric drawing with vector style graphical stress drawings. That way I can grab the suspension with my mouse and watch all the geometry, roll centers, stresses and stress directions change in real time as I move things around. Definitely a fast way to do things.
I really want to use rod ends but one of my design criteria was to use off the shelf common parts from auto parts stores. And I hate the lifespan of rod ends, but they are just such a great design.
How much body roll did you account for in regards to tire deflection for the rear. I got .6 degrees (about 25lb tire pressure on 275 tire).
Aaron, I didn't consider tire deflections in my analysis. I knew what size tires I wanted and figured there wasn't much I could do about changing sidewall stiffness without changing the look.
I got a pleasant surprise email today saying that my wheels had arrived a week earlier than expected! It was a real pain in the derriere to get a Motegi rep to confirm that the front wheels I wanted would have enough clearance depth-wise behind the spokes for the brake calipers. The 7" wide and 48 mm offset front wheels didn't appear as though there would be much room left. In the end it took three weeks of badgering countless people before someone finally said the best they could do was assure me they would fit, however there would still be a no-return policy given the "special-order" nature of the wheels. This, after giving them a scale drawing of my front and rear suspensions complete with every dimension you could imagine. The level of ineptitude is mind-boggling sometimes.
I can happily report that my worrying was for nothing... I ran home with the bare rims to check out the fitment before potentially wasting money mounting the tires... and the fronts cleared everything just fine:
I loaded up the tires and wheels and headed out to the tire shop for mounting those bad-boy rubber shoes...
And getting them balanced...
And finally made my way home to stick them in the fender wells. I'm very happy with the look despite the fact that I have to use my imagination to envision the fiberglass changes that are forthcoming:
Here's the rear quarter view from before, except this time there are wheels attached to those tires!
[This message has been edited by Bloozberry (edited 03-05-2013).]
Well, it's been a while since I updated the thread because I've been busy restoring a customer's '46 Willys Jeep. That's finally out the door and now I can concentrate on the Blooze Own.
I created a pattern for the cuts needed to the 2" X 3" rectangular stock to form the cradle side rails. It starts out as a 1103 mm long tube and ends up being 977 mm long after it's been notched and formed into shape.
I measured twice then marked up one of the tubes in preparation for cutting, then used a die grinder with a cut-off wheel to make the first slice.
The die grinder was just waaay to slow for me so I used an angle grinder to make the largest part of the cuts...
...then used the die grinder with the thinner wheel to make the finish cuts. I was pleasantly surprised at how accurately I could slice out the pie sections with the angle grinder.
Here's one cradle side rail with all five notches. I also bevelled each cut edge to make a vee to increase the surface area of the tube where the welds would be.
I used a crowbar and an adjustable bubble level to bend each section to the correct angle then tack welded the notch in preparation for final welding.
I prefer not to grind the welds flush after they're completed since the extra material adds strength to the area.
Here's the final product: One new modified cradle side rail awaiting it's identical twin (BTW, it's laying on it's side in this picture).
(edited to correct length of tubing required)
[This message has been edited by Bloozberry (edited 04-06-2013).]
That first frame looks great Blooz. You are right about those thin zip wheels, they do a great job in steady hands. I recently got some ultra thin wheels at a trade show just to try them. Wow, they don't last as long but they are like using a surgeons scalpel. I was cutting 2 x 3 x 1/8 twice as fast as my 14" chop saw.
Are you planning to have your final cradle welded completely closed or leave it open on the ends or perhaps some well placed lightening holes? If you leave it open, have you considered having it hot dipped galvanized before you paint it? In Halifax, Argo Protective Coatings does all our shipyard work and they do a nice job. The key is to have openings in every part...... or they'll make them for you.
Thanks Sage, RCR, & Yarmouth! For Yarmouth, I've been thinking about sealing the insides of the tubes but I was only considering primer until you mentioned possibly getting the whole cradle galvanized. I'll have to look into what it would cost. The downside to galvanizing is that once it's done, it makes it a lot more difficult to make any changes that need welding. The galvanized coating makes some pretty noxious gases, not to mention making terrible looking welds unless it gets ground off.
I got the second cradle side rail made up yesterday... I was careful so both are straight as an arrow and are identical measurement-wise. I left both of them several inches too long at the back end so that I could make any adjustments in length later on.
Now to get working on the cradle cross members. Rather than weld the lateral link mounts and the rear cradle mounts on the side rails at this stage, I think it would be better to complete the square box of the cradle first. That will allow any warpage or inaccuracies that creep in as a result of that process to be accounted for when welding on the various mounts later.
I agree with Bob that the rails do look like they are angled to the left in the bottom picture but it appears to be only the angle of the camera that makes it look like that. Threw me the first time I looked as well.....
Looks great except one thing... aren't they supposed to be mirror images of each other? It looks like they are an exact duplicate.
Bob is right... when viewed from the top, the side rails are straight as in the drawing that he reposted. The last photo in my post above does sort of look like they angle off to the left in the background, but as Don said, it's just an illusion. In my second to last photo both are lying flat on their sides on the workbench.
Edit: I've since updated the drawing that RCR quoted above to a later revision. The new revision can be found on page 16 about half way down)
[This message has been edited by Bloozberry (edited 07-26-2013).]
When we get our galvanizing done, we are charged per lb of steel they dip but maybe that is because we are usually getting large structures done. I also don't know if the heat will cause distortion in smaller, lighter parts. They are very knowledgeable though and it might be worth a call atleast. You are right about welding afterwards. Its nasty stuff when it burns. Then you must use cold galvanizing to touch up. While still good, its not as good as hot dipping.
The frames look great. Your welds and material are so clean too. You'll notice that because I work so slowly, my material gets a nice oxide coating by the time I'm done fabricating.
Not a lot of progress to show, but I cut up some more 2" x 3" x 1/8" wall tubing today to form the two cradle cross members:
It's not like it was a difficult task since they're only straight pieces, but I did bring them to my local metal shop for cutting because I wanted the ends to be as perfectly square as possible, and for the lengths to exactly matched. It's hard to do that in a chop saw like mine (cheap made in China), but relatively easy with an automated metal band saw. Once I got the pieces home, I mocked them up to start puzzling out how I'm going to ensure the pieces stay true while I weld them together. I'll probably take it to the professionals where they have nice solid, straight, level welding tables.
Originally posted by RCR: They are mirror images of each other, just depends on the plane you're speaking of. By the looks of the plans, they are straight.
My mistake. I should have looked at the drawings vs. just looking at the photos.
What are you going to do for the suspension now? The mounting points on the cradle have been moved outward by quite a bit, how are you going to accommodate for that? It doesn't look like you need any more track width, so if you plan on shortening the suspension arms, that will really screw with the way your car handles.
For El-Roy, if you go back to page 16 about 1/2 way to 2/3rds down, you'll see that I designed a completely new rear control arm set-up. You're right... they are considerably shorter than the 3" extended arms I bought from HT Motorsports, but my analysis shows that the extended arms actually hurt suspension performance in several key areas. The performance of the new design is shown higher up on the same page in the graphs. The new design follows the reddish brown curves which show an improvement in every area over stock or any other modification I've studied previously, as depicted by the other colored lines in the graphs.
I started looking at my drawings to determine where the cradle cross members should be welded to the side rails when I remembered that I hadn't finalized those dimensions yet. I need to take into consideration what engine and transmission mounts I'm going to use, plus have a general idea what the exhaust system layout will be, to be certain that the cross members are located optimally. So I mocked up the new cradle pieces around the engine/transmission and started figuring out where and how I would mount them to the cradle:
I did a bit of research on the internet to get a better understanding of the considerations that go into the design of modern engine mounts and was sorry I looked! It seems it's an entire field of it's own with designers calculating the engine's CofG, bending and torsional characteristics of the block(!), anticipated stresses in fore and aft, vertical, and torsional planes, vibration characteristics of the engine at various RPM's, the characteristics of the rubber in the mounts, and on and on and on! Then, a whole slew of other factors are considered with transverse engines since all the differential loads are transmitted to the mounts as well. Whew! My head was spinning.
To make things as simple yet effective as possible, I decided that the Cadillac engineers must've done their homework in this area and that I wouldn't reinvent the wheel if I could adapt the OEM Northstar mounts to my new cradle. I don't have much to go by at the moment except for two dogbones and two lower mounts and brackets. One of the lower brackets looks specifically designed to go around the automatic transmission on the aft side of the engine block so I don't know how useful it will be, but the mount and bracket on the forward side of the engine looked promising from the get go:
Once it was bolted in place, I noticed that of the two main rubber mounts I had, one was about a 1/2" taller than the other. I tried test fitting both, but the taller one just wouldn't fit between the underside of the bracket and the top of the new cradle cross member.
I don't have the option of raising the engine any further so notching the cross member would've been the way to go if I had only had the taller style rubber mount. As luck would have it, the shorter mount fit perfectly (good thing too... the taller mount was badly rusted and the rubber had failed).
This view shows that I'll have to slide the forward crossmember backwards some more if I want the mount to bolt directly to the cross member rather than to a bracket welded to it. That won't be a problem either way, so for now I'll look at what the Caddy had for a forward transmission mount before setting the forward cross member location in stone.
For El-Roy, if you go back to page 16 about 1/2 way to 2/3rds down, you'll see that I designed a completely new rear control arm set-up. You're right... they are considerably shorter than the 3" extended arms I bought from HT Motorsports, but my analysis shows that the extended arms actually hurt suspension performance in several key areas. The performance of the new design is shown higher up on the same page in the graphs. The new design follows the reddish brown curves which show an improvement in every area over stock or any other modification I've studied previously, as depicted by the other colored lines in the graphs.
Wow, can't believe I missed that. I've even drooled over those schematics a few times quite a while ago. Was just checkin through a few threads again the other day and didn't quite put the two together I guess. Nice to see some more work go into this car, you've done an amazing job with it so far.
Originally posted by Bloozberry: I did a bit of research on the internet to get a better understanding of the considerations that go into the design of modern engine mounts and was sorry I looked! It seems it's an entire field of it's own with designers calculating the engine's CofG, bending and torsional characteristics of the block(!), anticipated stresses in fore and aft, vertical, and torsional planes, vibration characteristics of the engine at various RPM's, the characteristics of the rubber in the mounts, and on and on and on! Then, a whole slew of other factors are considered with transverse engines since all the differential loads are transmitted to the mounts as well. Whew! My head was spinning.
Well......that's about how some of us here feel after reading/looking over some of your own posts/drawings/plans! That cradle looks incredible, and regardless of how much info is out there pertaining to all the ramifications of ANY install from the mundane to the ethereal, we know that you will get it worked out so that it not only looks great, but functions exactly as it should!
Nice progress, and that mount looks pretty good to me!
You are providing inspiration to more than a few of us.
Thanks el_roy... I've posted so many different versions so far that I don't blame you for not noticing the latest design.
For NoMoreRicers: attention to detail, anal retentive, OCD... either way, it's a curse! Thanks for your kind words nonetheless.
no2pencil: You FORGOT it was an F355 project?! Meh... that's OK...I won't hold it against you.
Sage: LOL... you crack me up.
OK so I posted a tech question in TD&Q looking for anyone with access to the cradle drawing for the Caddy's that used Northstars (Seville, Eldorado, Seville) between 1995 - 1999, but so far no luck. I'll zip on down to the dealership tomorrow to see if they can help me out. I'm not sure how relevent the measurements between the engine and tranny mounts will be, but it's a start.
In the meantime I decided to work on cradle mounts that attach to the cradle side rails. The first stop was to make some more sparks and perform some surgery on the Fiero cradle:
I can't believe how much faster and easier it is to slice through the metal now that I've discovered the super thin cut-off wheels that attach to my angle grinder. I forget exactly how thin they are (something like 3/64") but they work like a hot knife through butter as compared to the 1/8" wheels I was using before. I lopped off both rear mounts taking as much of the stock part as possible.
Next I needed to chop the rear mounts down to get my new cradle to sit 25 mm higher up in the chassis than the stock cradle. Since the lower edges of the mounts were uneven and difficult to get a clean reference line, I turned them upside down and calculated that I needed to mark a line all the way around the mount at a distance of 106 mm up from the table top. Once righted, that line would become the new bottom edge of the mount that would sit on top of the cradle side rail. I could have lopped everything off below that line but I decided to leave a couple legs that hung down to make aligning the mounts to the side rail easier.
Once I remeasured everything twice, I fired up the angle grinder and shortened up the OEM mounts:
The legs that I left on the mounts actually serve two purposes: the first is to add a little reinforcement, but the second is to align the center of the bolt hole to the correct offset (14 mm further inboard than the inner wall of the cradle side rail). The notches are such that when held tight against the vertical wall of the side rail, the bolt hole at the top of the mount is exactly 14 mm further inboard than the wall of the rail. Here's the passenger side rail seen from the inboard side looking out... it's just mocked up and held in place with a magnet.
And here's what it looks like as viewed from the outside of the car looking inwards. Note that they're reversed from the stock Fiero config since the rounded part of the mount now faces inboard.
Great as always. I cannot speak for the Cadillac, but I do have a 96 Aurora cradle, FWIW. I know that there are only two cradle mounts, front and back. The belt side of the engine, and the trans, are mounted directly to the chassis. This is how I installed mine. If there are any measurements you need off of it, let me know.
Thanks Bob... I saw a similar set up while scouring the net (I think it was PFF member Ajxtcman's car). While I thought it was interesting, I don't think I have the room vertically under the lower frame rail for mounts like that, now that I've "raised" the cradle. I'll almost certainly need to use a more traditional mounting system.
Thanks Bob... I saw a similar set up while scouring the net (I think it was PFF member Ajxtcman's car). While I thought it was interesting, I don't think I have the room vertically under the lower frame rail for mounts like that, now that I've "raised" the cradle. I'll almost certainly need to use a more traditional mounting system.
No problem... I'm not suggesting something like mine. I have no idea how it will ultimately workout. I guess what I'm getting at is that most Cadillacs will probably be similar, though. You're doing such a great job, I'm sure you will come up with something. Charlie made some real nice mounts for his Aurora/Isuzu combination. Probably closer to what you will need than mine.
Originally posted by exoticse: You mentioned fiberglass changes, what do you have in mind ??
A whole bunch of stuff really... definitely going to separate the rockers from doors, the fender openings have to be reshaped entirely, the hood needs to be modified for the extended windshield, the belt line needs serious straightening, the tail light valence panel will be replaced with the F1 style mesh, the mirrors will be custom-made carbon fiber, the pop-up headlights will be history, and a few other little changes as well.
PFF member Yarmouth Fiero who lives about 2 hours away, is also building an F355 replica-build with his boys. The two of us plan to use my heavily massaged and modified body to make a new set of molds and recast ourselves each a straight, unmolested body, along with a few select spare parts. His years of experience at a high-end fiberglass boat building shop will be priceless. We're toying with the idea of making several panels out of carbon fiber, painting them body color, but leaving some select areas unpainted like this:
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).]
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).]
Thanks fierogt28 and jb1 for your compliments. The wooden floors are both a blessing and a curse jb1: they're easier on the feet than cement, but I have to be very careful whenever grinding or welding. I make it a rule to stick around for at least a half hour after I do anything that makes sparks, just in case.
Over the last couple days I've been spending a lot of time aligning the cradle to the engine/trans combination to mark the location of the mounting brackets as accurately as possible. I ended up spending a fair bit of time scratching my head trying to figure out why things weren't going quite they way they should according to my drawings. I finally figured out that I made a mistake in the overall length of the transmission. Luckily I had left enough fudge factor in the side rail clearances to compensate for my error and now everything works out just fine.
With that settled, I marked the locations of all three mounting brackets and tacked them into place. In this picture the cradle is upside down and I'm tacking the aft engine mount bracket:
And here's the same bracket only right side up:
And here it is with the rubber mount mocked up for test fitting. The plate on top of the mount is just the lower portion of the brace that will connect the top of the rubber mount to the engine block. I haven't made the rest of the brace yet.
Then I did the same for the transmission mounting bracket which is tacked to the aft cradle cross member:
... and also to the forward engine mounting bracket:
Interestingly enough, when I ordered the rubber mounts from RockAuto, the description indicted that they were "hydraulic" engine mounts (there was an option for solid ones too). I thought to myself "hydraulic?... meh, must be a typo or someone that didn't know what they were writing". Tonight however as I was priming them in preparation for some paint, I heard a "gloog-glug" as I turned them over. Sure enough, there's a liquid inside, making them hydraulic. Just what the principle of operation is or how they're layed out on the inside is still a mystery to me but I think I'll take the cutoff wheel to the worn out one I have sitting on the bench tomorrow and report what I find.
Not a whole lot to post today, though it feels significant to me since the cradle is nearly complete from a construction stand point.
I got the front and rear cradle mounts as well as the two engine and the single transmission mounting brackets welded to the cradle for good:
Now that that's done, I've lowered the engine/trans back onto the cradle and realigned it using the forward engine mount, which is complete, and now I'm working on the two braces that will bridge the gap between the top of the two aft mounts and the engine and transmission. Once those are done, the last thing to complete the cradle will be to fabricate the lateral link mounting ears and weld them to the side rails.
It seems it's an entire field of it's own with designers calculating the engine's CofG, bending and torsional characteristics of the block(!), anticipated stresses in fore and aft, vertical, and torsional planes, vibration characteristics of the engine at various RPM's, the characteristics of the rubber in the mounts, and on and on and on! Then, a whole slew of other factors are considered with transverse engines since all the differential loads are transmitted to the mounts as well. Whew! My head was spinning.
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.
