Pyro Posted January 17, 2008 Share Posted January 17, 2008 where does the engine move place the transmission shifter? Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted January 17, 2008 Author Administrators Share Posted January 17, 2008 where does the engine move place the transmission shifter? Here's a picture of my LT1 powered Z, also with a T56, mounted in the standard JTR position... Its a modified Datsun shift lever, oriented so the offset positions the knob rearward. While its not etched in stone, its looking like the trans will be another 3" farther back. Flipping the shift lever around, I should end up with a knob an inch or two father back than the above picture, which I would welcome. Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted January 18, 2008 Share Posted January 18, 2008 Some people aren't convinced 50/50 is 'ideal'... Porsche, Ferrari, myself... True, moving the engine mounting position has nothing to do with weight distribution of the car. Moving the center of mass does. I agree wholeheartedly. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 18, 2008 Share Posted January 18, 2008 To exaggerate, put 20,000 lbs of weight on top of the engine (stock mounted). The suspension will be on its stops and the four vertical bolts through the crossmember will try to tear out (vertically). The lower rail is seeing a lot of focused stress (in tension), but its being held to great degree by the upper rail due to the strut tower. A fairly robust load path. On the other hand, assume the engine is mounted to the lower rail, roughly in the middle. Again, putting the same 20K lbs of weight on the engine. The suspension is still bottomed, but now the lower rail is bowed downward because the only thing attaching it to the upper rail is the inner fender and its not efficiently built for that load. Also, there is no longer ANY stress on the 4 crossmember bolts. In fact, you could remove them and move the crossmember up and down by hand. The load path changed. OK, now I get your point and yes, you are correct in that assesment. Another way to picture it is from above the car. Engine mass loads, when mounted to the crossmember, pass directly to the suspension. The same would be essentially true if the engine mounts were on the frame rail directly above where the crossmember mounts to the frame rail. Moving the engine mounting back on the frame rail makes the frame rail more of a beam connecting the front suspension with the engine mounts. What I've learned by doing a few of these kinds of things (in Miatas, FD RX7s, 240Zs, and E36 BMWs) is that, with proper reinforcement, its really not an issue. For the 240Z, welding the OEM front crossmember in place and reinforcing the frame rails between the TC box and the welded in crossmember adds a lot of support in that area. I also, in the front wheel well, weld in plates that connect the reinforcement where the crossmember mounts to the reinforced area on the wheel well for the strut towers. I did the SR20DET swap on Amir's 260Z about 4 years ago using the reinforcemnt I mentioned above. I saw the car towards the end of last year and the mounting looks good with no bending, cracked paint, etc. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted January 18, 2008 Author Administrators Share Posted January 18, 2008 Engine mass loads, when mounted to the crossmember, pass directly to the suspension. The same would be essentially true if the engine mounts were on the frame rail directly above where the crossmember mounts to the frame rail. Moving the engine mounting back on the frame rail makes the frame rail more of a beam connecting the front suspension with the engine mounts. Perfect! That's exactly it. I need to learn how to write. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted January 19, 2008 Author Administrators Share Posted January 19, 2008 What I've learned by doing a few of these kinds of things (in Miatas, FD RX7s, 240Zs, and E36 BMWs) is that, with proper reinforcement, its really not an issue. For the 240Z, welding the OEM front crossmember in place and reinforcing the frame rails between the TC box and the welded in crossmember adds a lot of support in that area. I also, in the front wheel well, weld in plates that connect the reinforcement where the crossmember mounts to the reinforced area on the wheel well for the strut towers. I agree. If an engine is frame mounted with suitable reinforcement, I can think of no significant drawback. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.