4.8240z Posted November 24, 2015 Share Posted November 24, 2015 Hello all my name is Cass and this is my first post ever on this forum. I have been lurking for some time now and gathering information on a project I am now underway in. The chasis is a 71 240z the engine will be a fi 4.8l Ls engine with a t56 magnum and r200 to start. Now to my question. I am in the process of mounting the car on my frame jig which is perfectly level. But when I have the rockers perfectly level the passenger side engine bay frame rail is about 3/4 of a inch higher than the drivers side, this would lead me to believe it needs to be pulled down which wouldn't be surprising since the floor pan was gone as well with the TV rod box support. But the strange part is that the passenger side transmission mount is about 3/4" higher as well. At this point I'm thinking about just taking it to a frame shop but I have a tremendous amount of time into fabricating this jig and don't want to see it go to waste. Any opinions or options are helpful thank you. Quote Link to comment Share on other sites More sharing options...
johnc Posted November 24, 2015 Share Posted November 24, 2015 If those two points are the only ones out of alignment then I would just pull then into position. The FSM has a chassis diagram that shows where everything should be. I used the top of the rockets for for and aft leveling and the top of the rear deck behind the seats fot side to side leveling. Quote Link to comment Share on other sites More sharing options...
4.8240z Posted November 24, 2015 Author Share Posted November 24, 2015 Thank you for you fast reply John I really appreciate it. I am not familiar with what FSM is, where would I go about finding these measurements? So I guess what this leaves me wondering if I level the car side to side from the location you speak of behind the seats should the transmission mounts and the front crossmember mounts be level side to side in unison as well? I would assume the front crossmember would but one transmission mount appears to be offset closer to the rocker on the side where the starter is located so I'm not sure if it is supposed to be high as well. Also when I level the rockers front to back my engine bay frame rails are angled slightly downhill as well so should those be level in unison with the rockers? Quote Link to comment Share on other sites More sharing options...
LLave Posted November 24, 2015 Share Posted November 24, 2015 This might be helpful http://www.xenonzcar.com/s30/reference.html Quote Link to comment Share on other sites More sharing options...
Trevor Posted November 25, 2015 Share Posted November 25, 2015 FSM = Factory Service Manual Quote Link to comment Share on other sites More sharing options...
seattlejester Posted November 25, 2015 Share Posted November 25, 2015 Pulled straight from the FSM The frame rail should be level when the rockers are level. On the 71, the trans mount I believe is level. Some pictures would help to determine maybe a source of impact and help predict where everything shifted to if you can manage. Quote Link to comment Share on other sites More sharing options...
4.8240z Posted December 8, 2015 Author Share Posted December 8, 2015 Thank you seattlejester for the measurement sheet that will definitely come in handy. After some careful measurements I found that my driver side tc box was over 1/2" lower than the passenger side. Since the car was already on the jig j was able to fabricate some supports and use shims to drive the box up to the correct height. I will be printing off the fsm measurement sheet tonight and will make sure that I drove it up to the correct height. But as of now the chassis is perfectly level from side to side at both crossmember a and trans mount. As for front to back I ended up taking measurements off the bottom of the pinch welds and got all those measurements perfectly even as well. For some reason leveling off the tops of the rockers in the door will never appeared to be accurate with everything else. But once I measured off the pinch welds and got those even and pushed the tc rod box up everything else fell into place. My computer is not doing so hot now but once I have access I will post up some pictures. Thank you all for the help. Quote Link to comment Share on other sites More sharing options...
4.8240z Posted December 15, 2015 Author Share Posted December 15, 2015 (edited) Alright guys so after putting my car on the frame jig and trying to level it for quite some time i discovered that the driver side tc rod box was a little over 1/2" lower than the passenger, probably related the the minor bump the car received in the rear passenger bumper mount location.. So to resolve the problem i built some supports for the tc rod boxes and drove the driver side up till both sides were evenly spaced off the jig as well as level. In order to push the tc rod box up i simply used door shims from home depot and drove them in will a hammer. As of now all the the pinch welds front and back are within 1/16 of 5 7/8 off of the jig. All of the cross member mounting locations are level side to side, and the engine bay frame rails are level as well. I'm hoping this will ensure a straight chassis after i do all of my rust repairs and ensure a true perfect alignment. Anyways enough with the boring stuff lets get to the pictures. Edited December 15, 2015 by 4.8240z Quote Link to comment Share on other sites More sharing options...
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