JMortensen Posted March 12, 2014 Share Posted March 12, 2014 I am making motor mounts and second guessing myself. I've got limited clearance around the steering shaft, so the motor mount has to fit above it, and the engine can't come up and down vertically very much due to the cage members in the engine compartment, so this is what I came up with. I've got a plate with a section of square tube welded on as a clevis which holds a generic urethane bushing setup. There will be a section of 1.5 x .095 tube that runs out above the frame rail, and this will weld to a 2" tall section of 1.5 x .095 which will bolt to the rail. The rail will be reinforced with a piece of 1.5 x .120 angle, and it will have a nut welded to the bottom side for the bolt to catch. Essentially this is similar in effect to the Trans Dapt mounts, but the Trans Dapt doesn't bolt on at the frame end, it welds directly to the frame. http://www.jegs.com/i/Trans+Dapt/969/4501/10002/-1 There will be a slight downward angle to the tube that goes to the frame rail. I dunno why it's bothering me, but it is. Am I being paranoid? Quote Link to comment Share on other sites More sharing options...
seattlejester Posted March 12, 2014 Share Posted March 12, 2014 (edited) As long as the connecting tube doesn't kink it looks pretty sound. I would want to run a gusset underneath the tube to the bottom portion of the angle iron, but as noted the steering column would get in the way. The only concern I would have is the 0.095 tube seems a bit on the thinner side. If you wanted over kill you could raise the post in the engine bay and triangulate to the engine, but all that would do is add stress to the weld between the vertical tube and the angle iron as well as give the engine a bit of leverage to tear the post off of the frame rail. If you can get the angle on the tube, I can ask a friend to run stress analysis if he has time. Edited March 12, 2014 by seattlejester Quote Link to comment Share on other sites More sharing options...
hwvigo Posted March 12, 2014 Share Posted March 12, 2014 The over all design looks very sound, I am with Seattle on the thinness of the tube I would say use 120 wall dom. but i'm all about over building. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 12, 2014 Author Share Posted March 12, 2014 (edited) Angle on the tube will be about 18 degrees as close as I can estimate it, and thanks in advance. The tube is DOM, FWIW. Edited March 12, 2014 by JMortensen Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted March 12, 2014 Share Posted March 12, 2014 (edited) Jon, You are essentially building a race car. Why are you not using a front plate / mid-plate to mount the engine? I love mine. The front plate essentially ties the strut towers together and helps stiffen the chassis, and the lack of the motor mounts on the side of the block creates a bunch of space for headers. Edited March 12, 2014 by 74_5.0L_Z Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 12, 2014 Author Share Posted March 12, 2014 Two reasons Dan: I don't have the rest of the drivetrain hard mounted and don't want to go to the hassle at this point, and the oil pump is under the timing cover on the LS engine. I know it can be done, but it's a bit more tricky than a SBF or SBC. Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted March 12, 2014 Share Posted March 12, 2014 Ah, I see. I'm obviously not LS savvy. I am still in the dark ages with my Windsor based Ford. Carry on... Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 13, 2014 Author Share Posted March 13, 2014 This might help to visualize what I'm doing. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 13, 2014 Author Share Posted March 13, 2014 This might help to visualize what I'm doing. Quote Link to comment Share on other sites More sharing options...
LLave Posted March 13, 2014 Share Posted March 13, 2014 Jon, What exactly are you worried about? You are worried the tubing will fail? Quote Link to comment Share on other sites More sharing options...
seattlejester Posted March 13, 2014 Share Posted March 13, 2014 I'd be worried about the welded angle iron pulling out the spot welds between the frame rail and the inner fender more than the bar kinking. I'll ask my friend about the analysis this weekend. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 13, 2014 Author Share Posted March 13, 2014 I'd be worried about the welded angle iron pulling out the spot welds between the frame rail and the inner fender more than the bar kinking. I'll ask my friend about the analysis this weekend. That is what I'm worried about. I don't have an inner fender anymore, but I'm worried about tearing the frame up. Quote Link to comment Share on other sites More sharing options...
heavy85 Posted March 14, 2014 Share Posted March 14, 2014 Jon - I wouldnt do that as its a hella load on that bolted joint to the frame rails. It may or may not break but it sure wouldnt be very stiff. If you think about load path, the load from the tires goes into the crossmember (plus a little into the TC buckets) and then to the frame. I strongly believe this is why its best to mount the engine to the crossmember. This way the body only has to move itself around in reaction to tire input and doesnt even know the engine is there. For this same reason the crossmember is only mounted with 4 small bolts as it only sees the load from the mass of the body which is pretty small in the front. Cameron Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 14, 2014 Author Share Posted March 14, 2014 The steering is REALLY in the way of mounting to the crossmember. I do have the xmember welded in and I've welded the crossmember to the TC buckets, essentially making it a welded in K member. So far my thoughts are: Do it and see what happens, or reinforce the top and both sides of the frame rail, which wouldn't be hard at this point. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted March 14, 2014 Share Posted March 14, 2014 What if you mounted solidly to the engine side and built a flat-head style rubber mount on the chassis side? You are putting all the twist on the thin "frame rail" by pivoting at the engine end of that lever. What about going solid with no rubber in the mounts? Not like a little vibration is gonna bother you in that beast. Have you seen MiKelly's version? Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted March 14, 2014 Share Posted March 14, 2014 For reference: Heres my drivers side mount. My only question is: As much of the car as you've removed, why not just replace the factory rails with something with a little beef? Just a question. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 14, 2014 Author Share Posted March 14, 2014 (edited) What if you mounted solidly to the engine side and built a flat-head style rubber mount on the chassis side? You are putting all the twist on the thin "frame rail" by pivoting at the engine end of that lever. What about going solid with no rubber in the mounts? Not like a little vibration is gonna bother you in that beast. Have you seen MiKelly's version? I was going to do solid mounts but I think it's best if you're going to solid mount the drivetrain that the ENTIRE drivetrain be solid mounted. I've got poly everywhere else and it would add a considerable amount of time and effort to change it out, so I figured easier to make this poly than make everything else solid. Besides, gotta leave a few projects for later, right? EDIT--Did take a look at Mike's mounts, that looks like a good solution, just running the reinforcement across the whole top and down a bit on the sides. Sunny, didn't plan on going this far when I started or I might have cut the whole front end off. Ended up here though. Beefing up a short section of the rail might be the answer though. Looks like yours is essentially the same thing but welded at both ends. I would weld mine in but I am pretty limited in how high I can lift the motor. I am thinking though if yours is holding down 600hp, I should be alright with me 350 or so... Edited March 14, 2014 by JMortensen Quote Link to comment Share on other sites More sharing options...
rags Posted March 14, 2014 Share Posted March 14, 2014 A beefed up rail is only as strong as it's weakest point, which is not very strong. Ever see a sway bar mount get pulled through the rail? With all of the cutting you have done to the inner fender, IMO not to use the crossmember as a mounting point or replacing the Datsun rail altogether is going to be a recipe for disaster. Again, just my opinion. Quote Link to comment Share on other sites More sharing options...
johnc Posted March 14, 2014 Share Posted March 14, 2014 It looks fine to me but if you're concerned add a second tube from the engine bracket to the frame rail making a "Y". The frame gets the two legs and the engine gets the one leg of the "Y". Sorry for the late reply. Quote Link to comment Share on other sites More sharing options...
m1ghtymaxXx Posted March 17, 2014 Share Posted March 17, 2014 Any possibility of being able to run the steering shaft through the mount? A friend of a friend was doing a turbocharging an E36 and in order to solve a exhaust to motor mount interference, made a new motor mount with a section of heavy wall pipe in the middle, big enough for the exhaust to pass through. Unfortunately I can't find a picture, but perhaps just an outside-the-box idea to play with. Unfortunately it seems it's the u-joint that's in the way though. Quote Link to comment Share on other sites More sharing options...
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