ICSA
I now get your point fully, and can grasp that the twisting motion on the subframe mountings would be far higher than Jaguar envisaged. Could you please explain to me, as I cannot visualise the V8 installation, as it is beneficial to move the motor rearwards, would your recommended position for the motor mounts mean fabricating brackets and fixing them more to the front of the V8 block than standard? Am I correct in presuming that Fast40, in his current projected mounting system is forced to make those rearwards extensions to the subframe by the V8 mounting points on his engine?
If this is the case, and he did fabricate mounting brackets onto his V8 nearer the front of the block, then I suppose that the gearbox mount would be supporting quite a bit more weight than OEM; but as his tunnel brackets looked strong, this would not be a problem?
Finally, Fast40, can you explain how those large pear-shaped thick pieces of ally that carry the motor mounts are actually fixed to the subframe?
Thanks to all,

 

Yes, the cantilever or extension should be on the engine side, so making brackets that mount to the block and extend forward to the location of the OE subframe mount is the best approach. As for the transmission mount bearing more weight, it's an interesting consideration to ponder. I can confirm 100% that the AJ16 is almost balanced and will teeter around its mounting mounts. Manual or Auto the engine can be rocked up and down by hand when supported by the modest spring that acts as a mount for the OE setup. This suggests that there is very modest weigh on the transmission mount in the AJ16's OE configuration. Installing a V8 and getting it further back would surely result in more weight on the transmission mount and by extension the center of the vehicle. In this case a proper mount of sufficient strength would be required and just about any name brand GM transmission mount would suffice for street use. This may explain why these v8 conversions handle as well at they do. Basically creating a front-mid engine setup with the Center of mass closer to the driver and center point of the vehicle. Having the mass point close to the driver makes for more driving clarity. Having the COG centered the chassis also better distributes dynamic loads more evenly across all 4 tires which results in lower individual sidewall loads which results in better road going dynamics.

I can tell you from experience a GM style energy suspension mount wont last for track duty. I had to switch to a 2001 Camaro GM mount that had hard limits. This mount shown below survived many track days at the back of the 406 SBC, a short live 700 HP turbo project and supports the 5 speed on the current 405HP LS with no signs of giving up yet. Energy Suspension mount survived 1 track day before partially separating.

Notice how the mount is hard limited with tabs.

 

Greg in France - yes, but I cannot sum up the stress loads for you. The 1" plates are clamped to the flanges of the subframe, with 3/4 x 3/4 steel bars, radiused to match the subframe. Bolts are SHCS, 1/4 20, drilled and countersunk in the steel clamping bars, through the flanges, tapped at 100% thread into the plates. At 200 in lbs of torque, clamping load is about 3200 lbs per bolt. 5 bolts in front, 2 in back, so initial preload is 16,000 lbs force in front, 6400 lbs force in the back. Next attachments are four angle brackets cut from extruded aluminum tubing, nominally 1/4" thick. They are secured to the plates by total of 12 SHCS, with grade 8 SAE washers, 5/16" 18, load per bolt is 4720 lbs force.. The brackets are about 3" long at the bend radius, so about 0.75 sq inches, 6061 T651, so about 32,000 psi yield strength, or 24,000 lbs, times 40% (de-rate for the formed angle), is about 9600 lbs per bracket, for a total of close to 40,000 lbs to yield. Brackets pick up the three rack mount bolts, the one unused rack bolt hole (for RHD, and one additional hole on each bracket. 5/15 18, so clamp load is 4720 lbs per bolt, or 14160 lbs clamp load per bracket, times 0.61 (friction coefficient, steel on aluminum) is 8600 lbs per bracket, or 34,500 lbs for all brackets. Pretty well balances out, call it 8000 lbs per bracket. Then there are the tension members running down from the original motor mount pads. 3/16" plate, 3" wide at smallest portion, so about 18,000 lbs in tension. Bottom bolts on those are 3/8" 16 SHCS, 4 each, 7000 lbs clamping, Al on Al is about 1.1, so the joint would hold 7700 lbs. Weaker part here is the top attachment, 4 5/16" 24, 5220 lbs per bolt, times 0.61, steel on aluminum, is 12,600 lbs for the four of them. Of course this is at an angle, approx 40 degrees, so that 300 lb load (engine plus partial transmission, one side, static) would actually exert about 468 lbs tension on that member..

There are two flies in the ointment. The first is that, with multiple load paths provided to resolve the .engine downward load into the subframe, they are not strictly additive - the stiffest - most likely the tension strap - will absorb all of the load, unless, of course, it deforms to the point that something else picks up the load. This is the prefered loading path - in the end we are applying a torque to the subframe crossmember, and are doing so via a rearward "pull" at the top, and a forward "push" at the bottom - about as much separation as is possible.

The other is that the subframe itself must be able to handle the applied forces. From the spring c/l, the engine mount moment arm is roughly (within an inch) equal to that of the subframe forward bushing, almost a see-saw, so the upward load on the subframe bushing (additional to that of the car front end itself) will be roughly equal to the downward load on the engine mount, or about 300 lbs static.I have very little doubt that as designed, the back subframe mounts carry the majority of the car weight load, while the front bushings deal primarily with the dynamic road loadings, and more importantly, keep the rear subframe mounts from experiencing much shear loading.

There is quite a bit more going on dynamically, but overall, I am quite confident that my "Add on" pieces would not be a failure point. Bolt pre-loads given are at a customary 75% of yield, and are far in excess of any anticipated loads - further, extreme load reversals are not anticipated, and creep not a likely issue. The initial failure point, in my view, would be the compression buckling on the bottom of the forward extensions of the subframe. There are outturned flane stiffeners in this are, but I may partially box this area.

Incidentally, for anyone doing a swap, there is a fair amount of flex in the aft subframe mounts between the loaded and unloaded conditions - wise to check engine clearances both with the subframe hanging, and with the car supported by the subframe as in normal operation.

Hope this at least partially answers your question

Mike

 

I am still working toward other parts of the swap, cooling system is also underway. I have vivid memories of the car getting a little warm in traffic in Salt Lake City traffic, on a hot afternoon - this after new water pump, all hoses, t stat, radiator out and cleaned, both fans working - didn't actually overheat, but nudging that way. So, biggest core area I could get. I bought a "Be Cool " LS swap radiator, model 35224, overall size 31 1/2" wide and 17" high. I tacked a couple of 3/8" plate washers over the stock mounting holes, cut a piece of AL square 2" tubing down to a channel, mounted a couple of tapped blocks inside, and bolted to the plate washers. The channel fits inside the channel already on the bottom of the radiator

Channel and plate washers. I did have to trim the couple of gussets at the lower corners by about 3/8", will weld in reinforcement later.

Channel in place.

I bought a "Grand Prix" shroud and 2 14" fans from "Monster Cooling" on e-bay - probably overpaid a little, but was able to get it to work.


Shroud and fans on radiator. Rubber glued in radiator bottom channel. Only temporary fasteners.


Sitting in place

I added a top piece of flat bar to the radiator, to support the top of the shroud, and also, will hold a couple of studs to connect with the OEM top radiator mounts.


From front, with stock top plate in place. Rivinuts should be here tomorrow, so I can semi-finish.

 

Thanks Mike. Have you a close-up shot of the attachment points to the subframe flanges, please?

 

i just started reading these posts!
all i can say is fast40 is very good engineer/ fabricator, thinker!
typical of Nrth/ west americans! maybe something to do with from eastern/mid American thinkers!
different longitudel lines, can produce different mind development!
this abstract thinkin shows up more when someone is from S, Latitude ,comes up (like Austraila,NZ, compared to Northern countries).
sorry i'm rabbilin !

 

This is just a quick post, while I have a couple of minutes. NO, the project is not dead, and their actually is some reasonable progress to report. There is also a bit of a drawback. While welding in a couple of patches in the front of the transmission tunnel, despite some fairly heavy old turbo blankets on the inside, I managed to catch the body seam filler on fire, which in turn got the insulation on the under dash right side wiring harness burning. Didn't look THAT bad, so I extinguished with water - I did have a dry chemical extinguisher handy, but not a Halon bottle. Thought it was out, but a few minutes later, still had heat and smoke from the driver's side defrost vent - so a little more water than I would have liked was used..
Car was insured by Hagerty, claim process pretty easy, adjuster was a great guy, all fine until I hit the desk of an Erica Potter, who wanted to communicate via phone. Played tag for a couple of weeks, until I left a nastygram at the front office number, then I quickly got a call back. They wanted to total the car - had pretty well agreed on that with the adjuster, as with the dash still in, we were not sure as to possible damage.. No issue there, my questions were related to future insurability if I kept the car and repaired - and inspection requirements to prove repairs of the damage. Turned out that the coverage would actually not stop, and the vehicle is still insured while being repaired, with no issues.
Found a right side fuse box with no issue, got a pristine looking '94 heater assembly for pretty reasonable - it is an "AB", rather than the "AC" used in the '95, but guessing it is pretty close. icsamerica was kind enough to sell me a nice dash pad - I think mine will clean, but if it doesn't, the one he sold me was just as nice. Still have not pulled the dash to check damage - think I may be able to tomorrow.
Reasons for no posts - had to go to me daughter's in Denver, do a little work on her house, trip to St. George for fun, the aforementioned fire, then needed to build a new aviary for the baby Doves - they are after all the money source. Plus a few Dove Releases, and need to run back to Denver ln a weeks or so, to pick up some more Doves, to expand our gene pool.

So, will try to get caught up on posts, and hopefully can get back to working on it pretty soon - although my wife was making noises about summer coming, and the Red Boat needing work.

Mike

 

Right (Passenger) side under the dash before starting

OK, this is untouched from fire, except that I did dispose of a couple of pieces of turbo blanket so the adjuster could get some pictures.

Column, gauge cluster, dash pad removed

Pulled the wheel, column, gauge cluster, and dash pad. The dash pad was a bit of a bother - I had not done this before. Three bolts were easy, quite evident. The fourth, in inboard one on the passenger side, there was quite a bit of melted plastic and wiring harness in the way - I could not find the nut. Finally wedged the dash pad out a ways, got up inside and pulled the airbag cover from the dash pad, then - gingerly - the airbag itself, then was able to see that Jaguar had been nice, and installed a 3" long nut for easy access on that stud - thats why I could not find it by feel up against the underside of the dash pad.

With most of the yuck unbolted.

HVAC unit, right side blower, ducting, fuse panel were all literally toast. Got the nasty stuff out of the way, then hit ebay. I had already looked for a harness - didn;t find one, neither did the adjuster, or Hagerty, so I had bought a fuse block, and was resigned to re-building it. Then, today, a '94 in seemingly great condition showed up - bought it, a blower unit, the right side ducting pieces today. I had already bought a dash pad from icsamerica, and an HVAC unit from a guy in Portland, so that is the major pieces to repair.
Guessing I will try soda blasting to clean it up before re-paint - never been a big fan, it always seems slow and expensive, but it might be perfect for this.
Probably back to the dove loft tomorrow, but it was great to get to work on it a little today.