tonycharger72 Posted April 11, 2009 Share Posted April 11, 2009 Just curious about what others have done when fabricating their own engine mounts and how they have lined up the driveline? I have tried two seperate methods both with different "straight-lines" to line up the driveline, Firstly, I have gotten the car level, front to back, and then found a centre point at the front of the car radiator support panel and used plumb-bob's at the front and off the diff to create a centreline and gone from there, And then, I put a laser plumb-bob on the diff face (gives me a horizontal and vertical laser line) and got a line that pointed up and off towards the passenger side (drivers side for US), I have looked through lots of engine conversion pics of various different engines from LS1s to SR20s and most seem to just line the engine up straight in the engine bay, is my laser plumb-bob lying ? Just curious as to what other methodologies people have used when mounting various engines in their Z's and what they have aligned their engines up to in order to get the driveline "straight"!!! Quote Link to comment Share on other sites More sharing options...
jt1 Posted April 11, 2009 Share Posted April 11, 2009 There are lots of methods, but there are a few important things to remember whichever method you choose. Most V8 conversions offset the engine to the pass side about an inch, to give more header clearance at the steering shaft. Relocating the steering shaft is a major pita, and the offset to the right helps the weight distribution of the car. The diff is not centered in the chassis. Based on my attempts to measure it, it varies some, but seems to be about an inch to the pass side. It may not be parallel to the CL of the chassis, due to the condition of the front rubber mount and the mustache bar. The CL of the crank and the CL of the pinion need to be parallel as installed, so you have an equal operating angle for each of the driveshaft u joints. This is very important to avoid driveshaft vibrations. Remember you are working with a 30+ yr old chassis that was mass produced and has a lot of unknown history. Perfect just doesn't happen in my experience. EDIT: Crap, I just realized you are working with a RHD. You can probably disregard everything I just posted. I will shut up now. jt Quote Link to comment Share on other sites More sharing options...
kiwi303 Posted April 11, 2009 Share Posted April 11, 2009 thats why theres joints in the drive shaft, close enough is good enough, the joints take out the variation. it just can't be TOO great. Quote Link to comment Share on other sites More sharing options...
tonycharger72 Posted April 12, 2009 Author Share Posted April 12, 2009 Most V8 conversions offset the engine to the pass side about an inch, to give more header clearance at the steering shaft. Relocating the steering shaft is a major pita, and the offset to the right helps the weight distribution of the car. I was going to offset mine to the passenger side (driver for US) for the same reason - but also, when I put the laser plumb-bob on the diff the diff appears to be angled back - so the driveline if looked at from the front slopes back and angles off towards the passenger side (drivers side for US) - kinda weird, would mean that if I aligned the driveline perfectly with the diff it would be way of towards the passenger side and angled really steeply back!!! I basically picked an arbitary point at the front of the car, which offset the engine to give my steering shaft clearance and put a plumb-bob on the diff and made a line, Quote Link to comment Share on other sites More sharing options...
rp975 Posted April 12, 2009 Share Posted April 12, 2009 Hi Tony, I put a laser pointer on the front bracket that is in the center of the front valance with the radiator out and used a spacer until it lined up with the center of the crank pulley on the original L6. Then when I positioned the VQ30det in, I also lined up the center of the pulley with the laser, then at the back I had a short section of the new tailshaft on the back of the transmission. Inside this I rigged up the laser in the center pointing towards the diff, and kept moving and checking front and back until I had both lined up. From there I made the mounts, I haven't had my car running yet so I can't vouch for it's accuracy. cheers Rob Quote Link to comment Share on other sites More sharing options...
jt1 Posted April 12, 2009 Share Posted April 12, 2009 The laser method is the easiest I've seen. Remember you don't want the crank/trans CL pointing directly at the pinion flange, you want them parallel, so the u joint angles will be the same. When I did my car, it fell into place almost perfectly. All I did was tweak the trans mount a bit. I helped another fellow on a V8 conversion, and it took a lot of work. The nose of the diff was high and pointing to the drivers side. There was no obvious wreck repair, but it took a lot of shimming on the diff and relocating the trans mount to get the vibration out of the driveshaft. jt Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted April 15, 2009 Share Posted April 15, 2009 I don't have my time machine working for me to go back 9 years, but this is what I can recall. When installing my VG30ET with matching t5 tranny into my 78 280, We removed everything from the engine bay (left the diff in), and placed the engine/tranny into the car. We then grabbed a scrapo driveshaft and I think we cut it to a length that would fit (I needed a custom driveshaft made afterwards) and moved it all over the place (fore, aft, left/right, up/down) until we got the engine sitting where I wanted, the gear shifter where I needed it, AND the driveshaft lined up with minimal angles. It was a game of give and take, as I could not get every measurement that I wanted (I wanted the engine futher back and down) but was not possible to maintain clearances and driveline geometry. To make it short we used eyeballs to get it close and measured angles (angle finder/protractor, tape measure, and a med sized level) to get the best compromise for all of the requirements that I listed above. Once in position, carboard templates were made to fit, and then recreated from mild steel. As stated above 30+ year old cars with questionable known history, close is about as good as you will get. A laser pointer is great, but if it is not locked down precisely, all measurements could be affected. Edit* That was 9 years ago, and I have had zero issues due to the install/physical layout of the driveline, and I had zero information regarding previous swaps like mine (I'm sure I wasn't the first, but maybe the first to put it on the internet) Good luck with your install! Scott. Quote Link to comment Share on other sites More sharing options...
240hoke Posted April 15, 2009 Share Posted April 15, 2009 When I made my engine mount for my VQ 240z, I really only had one choice due to the size of hte tranmission. I Put the transmission as high as I could which was 1/4" from the top of the tunnel and I centered it which probably gave me about a 1/4" on each side of the tranmission at the critical places like sensors. I used lasers to attempt to align everything but it wasnt much use. I ended up just centering everything and it worked out really well, I dont have excess driveshaft angles...I havent had a chance to give my car a good wringing out (around 200 miles so far), and havent had it into the triple digit (I dont think anyway, speedo would help) Anyway I agree with the close is close enough theory. Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted April 15, 2009 Share Posted April 15, 2009 Tony, You are correct. Don't use the rear end as your guide. On my swap (77 280Z) I measured the stock driveline to various points of the body before I remove it. To be exact, the center of the crank is 3/4" offset to the right side (US passenger) and 3/4" above the frame rails. Now for the tail end. From the hand brake shaft to the bottom of the driveshaft is 3 3/4". On the right (US passenger) side of the tunnel there is a bulge area. From there to the right side of the driveshaft is 1". I put my driveline as close as possible to these measurements and it seems like the rear end is crooked and angled down at the back. I attempted to use the laser as well but before you use make sure the laser is centered. I bought a few laser points and put them in a tube and spin them and they draw a circle on my wall instead of a dot. GL V. Quote Link to comment Share on other sites More sharing options...
Mike Mileski Posted April 16, 2009 Share Posted April 16, 2009 Perfect alignment in this case isn't good. U-joints don't only have a maximum angle of operation but also a minimal angle. You need a small amount of misalignment to aid in lubrication. Check out some of the mechanical engineering forums and you'll see. Mike Mileski Tucson, AZ Quote Link to comment Share on other sites More sharing options...
Mike Mileski Posted April 16, 2009 Share Posted April 16, 2009 Perfect alignment in this case isn't good. U-joints don't only have a maximum angle of operation but also a minimal angle. You need a small amount of misalignment to aid in lubrication. Check out some of the mechanical engineering forums and you'll see. Mike Mileski Tucson, AZ Quote Link to comment Share on other sites More sharing options...
johnc Posted April 16, 2009 Share Posted April 16, 2009 A lot depends on your expected driveshaft rpm. The smaller the angularity difference the faster you can spin the driveshaft without developing vibration. Generally I try to make the engine/trans center line parallel with the pinion shaft with as little offset as possible. Vertically I also try to get the pinion flange and tailshaft flange/output parallel. Its generally +/- .5 degree. I've heard the arguement that there needs to be some variance in the angles but I've learned the smaller variance, the faster you can spin the driveshaft. On my old racer the driveshaft spun at 8,240 rpm at top speed and there was very little vibration at that rpm. Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted April 16, 2009 Share Posted April 16, 2009 I have no experience in this what so ever. But as i was reading this I had an idea. Why not do the laser idea but put it in the crank shaft pilot bearing recess. Then it would be able to get it to be inline and make it have very little angle to the diff. make sense? Quote Link to comment Share on other sites More sharing options...
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