Crash Bandicoot Posted April 24, 2015 Share Posted April 24, 2015 (edited) A quick sketch I know but I think all the info needed is there. I've pretty much completed my e36 M3 5 speed gearbox conversion and I have a little fettling to do reguarding the prop shaft, basically the gear selector arms directly beneath the gear stick are JUST touching the prop shaft. My plan is to turn the fixed bearing on the front half of the prop shaft round 180 degrees so it sits the prop lower. However it will throw angles out. The angle of the front half isn't changed too much by doing this but the rear half of the prop angle is changed a bit more. As we know the gearbox output shaft and diff input shaft are on pretty much a horizontal axis... Can anyone with knowledge shed light on wether this is a good idea or not please Edited April 24, 2015 by Crash Bandicoot (see edit history) Quote Link to comment Share on other sites More sharing options...
mattdavies Posted April 24, 2015 Share Posted April 24, 2015 Quote Link to comment Share on other sites More sharing options...
Crash Bandicoot Posted April 24, 2015 Author Share Posted April 24, 2015 Cheers Matt, I have seen that video before. But I'm still a little confuzzled. as the output of the gearbox and the input to the diff are on horizontal angles does that mean as long as the prop shaft fits it will give good drive with minimal vibration? Quote Link to comment Share on other sites More sharing options...
Crash Bandicoot Posted April 24, 2015 Author Share Posted April 24, 2015 What I'm trying to say is the angle out of the gearbox and into the diff are the same so in my head after watching that video it will be ok? Quote Link to comment Share on other sites More sharing options...
Crash Bandicoot Posted April 24, 2015 Author Share Posted April 24, 2015 Plus, that video is of a one piece drive shaft, we have 2 piece drive shafts on supras, I want the front half to stay relatively the same sort of angle as it usually would be on a standard setup but the rear half will be on more of an angle. I'm almost positive it will be ok as the angle of the gearbox and diff are relatively the same Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 24, 2015 Share Posted April 24, 2015 I think you should have a U/J or a C/V joint on the gearbox end of the prop, rubber doughnut couplings do not like misalignment, and I am not sure the present set up will give constant velocity to the shaft. I am no expert though, I would ask a reputable bespoke prop shaft makers, like Reco-Prop. Did the BMW application use *TWO* doughnuts? i suspect if not running two will give annoying wind up, even if a front C/V joint is not deemed NECESSARY. Quote Link to comment Share on other sites More sharing options...
Crash Bandicoot Posted April 24, 2015 Author Share Posted April 24, 2015 It has a doughnut off the gearbox output shaft, and a doughnut off the diff input shaft. The front half of the prop has been cut, welded and balanced, gearbox end being bmw and bearing end being toyota, The rear half of the prop is toyota. So it goes, gearbox-doughnut-front half of prop-bearing-universal joint-rear half of prop-doughnut-diff Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 24, 2015 Share Posted April 24, 2015 Yes, I see that, what I am asking is was the BMW set up one that used TWO doughnuts? I was not aware of any cars using TWO doughnuts. Quote Link to comment Share on other sites More sharing options...
David P Posted April 24, 2015 Share Posted April 24, 2015 (edited) Yes, I see that, what I am asking is was the BMW set up one that used TWO doughnuts? I was not aware of any cars using TWO doughnuts. Aristo's use them shredded wheatnuts front and back and some Lexus models too? Edited April 24, 2015 by David P (see edit history) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 24, 2015 Share Posted April 24, 2015 (edited) OK, it seems the concept is sound, but i would be concerned running them with any real misalignment. I am guessing the normal usage is fixed gearbox (relatively speaking, although the tail shaft will move about a BIT as the engine / gearbox are on flexible mounts), and the relatively fixed differential casing. I believe running them with misaligned drive and driven shafts laterally or vertically, will not be to their liking. They are really for absorbing torsional vibration, and to give torsional cushioning. You definitely need advice from qualified people. Propshaft failure can be extremely nasty and dangerous, take no chances!! Edited April 24, 2015 by Chris Wilson (see edit history) Quote Link to comment Share on other sites More sharing options...
David P Posted April 24, 2015 Share Posted April 24, 2015 (edited) From the Toyota/Lexus model, donuts are used for "straight" connections. Edited April 24, 2015 by David P (see edit history) Quote Link to comment Share on other sites More sharing options...
Crash Bandicoot Posted April 24, 2015 Author Share Posted April 24, 2015 Thanks guys, I think I'll modify the selector shaft instead of turning the bearing round 180 degrees. Angle grinder and welder at the ready! Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 24, 2015 Share Posted April 24, 2015 Yes, that would be my choice if it's feasible. Quote Link to comment Share on other sites More sharing options...
Crash Bandicoot Posted April 24, 2015 Author Share Posted April 24, 2015 I'll make it feasible! Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 3, 2015 Share Posted May 3, 2015 Good practical demo! Quote Link to comment Share on other sites More sharing options...
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