240RR Posted July 11, 2011 Share Posted July 11, 2011 OK...building a tube chassis 240z using a Q45 diff, Q45 axles and 350Z hubs, spindles and control arms. Also a VQ35dE engine and 6 speed. I measured the angles of the halfshafts off a G35 and they were about 3+ degrees sloping up to the diff. I set the diff in a fixture that gives the proper angles for the halfshafts. MY QUESTION IS HOW IMPORTANT IS THE ANGLE OF THE DRIVESHAFT GOING TO BE? The driveshaft is going to run uphill to the diff...not sure of the angle yet but looks like maybe a couple inches.... Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted July 11, 2011 Share Posted July 11, 2011 The CV halfshaft angles are not important as long as they are kept in a reasonable range (<10 degrees). If it were me then I would lower the differential as far as possible with respect to ground clearance. I just lowered the mounting of my differential by one inch relative to the body for three reasons: First, I wanted to minimize my drive shaft angle. The driveshaft was running uphill from the transmission to the pinion, but now it is level in the horizontal plane. Second, I wanted the halfshafts to be at their minimum length at full droop. The reason for this is that I use 300ZX turbo halfshafts with the Modern Motorsports adapters. These axles were close bottoming during suspension motion when the axles were straight. By lowering the differential, the axles are always angled up toward the wheels even at full droop. I only have 2 inches of droop travel in my suspension. Third, the R200 is heavy (and the R230 is really heavy) and should be mounted as low as possible to keep the CG as low as possible. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 11, 2011 Share Posted July 11, 2011 (edited) Second, I wanted the halfshafts to be at their minimum length at full droop. The reason for this is that I use 300ZX turbo halfshafts with the Modern Motorsports adapters. These axles were close bottoming during suspension motion when the axles were straight. By lowering the differential, the axles are always angled up toward the wheels even at full droop. I only have 2 inches of droop travel in my suspension. Just FYI Dan, I just did some measuring on my car and found that the CV axles changed 3/8" from full droop to full bump and were shortest at full droop, and that's with the diff in the stock location. For the OP, I'd consider using a different differential. I've been waiting for someone to do a Ford 8.8 IRS. The diffs are cheap and plentiful, there are lots of options for gear ratios and limited slips and lockers, and they're tough. Some come with aluminum housings, so I believe they would be lighter than an R200 or 230. I've found weight for the aluminum version quoted at 65 lbs but haven't verified it myself. Edited July 11, 2011 by JMortensen Quote Link to comment Share on other sites More sharing options...
Neverdone Posted July 11, 2011 Share Posted July 11, 2011 The Q45 difff is a viscous setup aswell. I don't know how much power you can really grab out of both wheels. Meanwhile, in the junkyard, there is probably several Thunderbirds and Lincoln Mk VIII's who have a damn near bulletproof diff and a decent enough entire irs. The Factory 5 guys use them all the time, so I imagine it would be fine for a Z. Quote Link to comment Share on other sites More sharing options...
240RR Posted July 11, 2011 Author Share Posted July 11, 2011 The CV halfshaft angles are not important as long as they are kept in a reasonable range (<10 degrees). If it were me then I would lower the differential as far as possible with respect to ground clearance. I just lowered the mounting of my differential by one inch relative to the body for three reasons: First, I wanted to minimize my drive shaft angle. The driveshaft was running uphill from the transmission to the pinion, but now it is level in the horizontal plane. Second, I wanted the halfshafts to be at their minimum length at full droop. The reason for this is that I use 300ZX turbo halfshafts with the Modern Motorsports adapters. These axles were close bottoming during suspension motion when the axles were straight. By lowering the differential, the axles are always angled up toward the wheels even at full droop. I only have 2 inches of droop travel in my suspension. Third, the R200 is heavy (and the R230 is really heavy) and should be mounted as low as possible to keep the CG as low as possible. OK...so then I should lower the diff...what is ideal angle for the driveshaft? I assume it should have some angle and not zero? Slight angle down towards the diff? So the halfshaft angle is not really that important as long as they are within 10degrees? If I lower the diff about an inch it would be close to zero angle for the halfshafts and anything lower will have the halfshafts running downhill to the diff? Also the driveshaft would start running downhill to the diff...which is good I think? I know I have to allow for bump with the halfshafts...and plunge with bump and droop. I see you worked with minimum length at full droop. If I lowered the diff a couple inches that would put the halfshafts approximately 3 degrees downhill to the diff and probably have the driveshaft down slightly to the diff....is that a good comprimise?? I am shooting for around 3 to 3-1/2" ground clearance....this is a flat bottom underslung rail chassis so the chassis/undertray will be the lowest point. Quote Link to comment Share on other sites More sharing options...
240RR Posted July 11, 2011 Author Share Posted July 11, 2011 (edited) Just FYI Dan, I just did some measuring on my car and found that the CV axles changed 3/8" from full droop to full bump and were shortest at full droop, and that's with the diff in the stock location. For the OP, I'd consider using a different differential. I've been waiting for someone to do a Ford 8.8 IRS. The diffs are cheap and plentiful, there are lots of options for gear ratios and limited slips and lockers, and they're tough. Some come with aluminum housings, so I believe they would be lighter than an R200 or 230. I've found weight for the aluminum version quoted at 65 lbs but haven't verified it myself. So what designation is this Q45 diff...it is the 5 bolt flange one...R200 or R230 or other? I picked it up for $40 and it only has 40k miles on it. I figure this car is going to hover around 2000lbs finished and the diff is good weight in the rear and relatively low. I should have tried out that multiquote.....I think I got lucky with the setup and swap as the Q45 axles work with the 350Z hubs and this was huge! I am altering the width of the body to fit the final width so was not concerned with track width with the component selection. I do have to figure out what to use for front suspension yet...leaning towards late Supra so I can stick with the same wheel bolt pattern easily. Was going to use 350z but the swan neck on the spindle would stick through the fender! Edited July 11, 2011 by 240RR Quote Link to comment Share on other sites More sharing options...
johnc Posted July 11, 2011 Share Posted July 11, 2011 I've been waiting for someone to do a Ford 8.8 IRS. Does the Ford 8.8 in an E36 BMW count? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 11, 2011 Share Posted July 11, 2011 I'd put that sumbitch in everything! Quote Link to comment Share on other sites More sharing options...
johnc Posted July 11, 2011 Share Posted July 11, 2011 I figure this car is going to hover around 2000lbs finished and the diff is good weight in the rear and relatively low. There's no such thing as "good" weight. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 11, 2011 Share Posted July 11, 2011 There's no such thing as "good" weight. I don't want to sidetrack too much, but was that Toby's car and do you know the weight of the diff? Quote Link to comment Share on other sites More sharing options...
johnc Posted July 11, 2011 Share Posted July 11, 2011 I don't want to sidetrack too much, but was that Toby's car and do you know the weight of the diff? No it was another customer BMW and the fully loaded diff (AL housing, cover, and girdle, 4.11R&P, Auburn LSD, fluid) was 54 lbs. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 11, 2011 Share Posted July 11, 2011 Thank you. If memory serves, the longnose R200 weighs ~100 with a Nissan LSD. I believe the shortnose that the OP is looking at is right around the same. Quote Link to comment Share on other sites More sharing options...
Neverdone Posted July 11, 2011 Share Posted July 11, 2011 I've yanked a diff out of a Q45, and I remember it being a heavy son of a *****. Also, I dunno if anyone answered his original question yet, but the angle of the driveshaft is very important. Quote Link to comment Share on other sites More sharing options...
240RR Posted July 11, 2011 Author Share Posted July 11, 2011 (edited) I've yanked a diff out of a Q45, and I remember it being a heavy son of a *****. Also, I dunno if anyone answered his original question yet, but the angle of the driveshaft is very important. Yeah...I kinda figured it was at least to some extent. SO...more help please on half shaft and drive shaft angles from above post number 5 Oh...and yes I know weight is not good but for what I am doing with the car...mostly street driven I am not concerned about the diff being a few pounds heavier. If it was dangling off the front of the car I might be a little more concerned. Edited July 12, 2011 by 240RR Quote Link to comment Share on other sites More sharing options...
240RR Posted July 12, 2011 Author Share Posted July 12, 2011 (edited) OK...so then I should lower the diff...what is ideal angle for the driveshaft? I assume it should have some angle and not zero? Slight angle down towards the diff? So the halfshaft angle is not really that important as long as they are within 10degrees? If I lower the diff about an inch it would be close to zero angle (not good?!) for the halfshafts. Dropping the diff a couple inches or more lower will have the halfshafts running downhill to the diff. Also the driveshaft would start running downhill to the diff...which is good I think? I know I have to allow for bump with the halfshafts...and plunge with bump and droop. I see you worked with minimum length at full droop. If I lowered the diff a couple inches that would put the halfshafts approximately 3 degrees downhill to the diff and probably have the driveshaft down slightly to the diff....is that a good comprimise?? How much angle do I want to try to get out of the driveshaft? I am shooting for around 3 to 3-1/2" ground clearance....this is a flat bottom underslung rail chassis so the chassis/undertray will be the lowest point. I will maintain OEM suspension mounting points. Also...does the diff need about 3 degrees pinion angle? I also believe the engine is also supposed to be set in with 3 degree angle down at the rear? Edited July 12, 2011 by 240RR Quote Link to comment Share on other sites More sharing options...
johnc Posted July 12, 2011 Share Posted July 12, 2011 You really should be searching this site. All this has been discussed before. Check the FAQs and the Driveline section. Quote Link to comment Share on other sites More sharing options...
240RR Posted July 12, 2011 Author Share Posted July 12, 2011 You really should be searching this site. All this has been discussed before. Check the FAQs and the Driveline section. I did a little...most info appears to be related to swapping diffs in stock locations and not utilizing a tube chassis from scratch build. I would think this would be pretty standard issue info and maybe if I searched more I would find more info but humor me a little with my somewhat specific project and components and help me out please. I am trying to locate a shop that does custom half shafts to pick their brain but for some reason that is proving to be not easy either. Quote Link to comment Share on other sites More sharing options...
johnc Posted July 12, 2011 Share Posted July 12, 2011 Driveline angles are universal. It doesn't matter if its an OEM install or a custom tube frame chassis. Its all on here or on the internet. Quote Link to comment Share on other sites More sharing options...
johnc Posted July 12, 2011 Share Posted July 12, 2011 Thank you. If memory serves, the longnose R200 weighs ~100 with a Nissan LSD. I believe the shortnose that the OP is looking at is right around the same. Its exactly 83 lbs. for the long nose with a CLSD, a front diff mount, the 300ZX Turbo bigger rear cover, and no fluids. I just put that combo on the scale in my shop. Quote Link to comment Share on other sites More sharing options...
240RR Posted July 12, 2011 Author Share Posted July 12, 2011 (edited) dang...I have been looking and have not found it yet. If it is so universal and easy to find why can't you just rattle it off to me? Not making me feel very welcome! I know what OEM is supposed to be on the half shafts and driveshaft but it is not that simple as the drive shaft then is out of whack if I run the halfshafts to the OEM angle. I know I am a new guy here and lots of people get on these forums and look for the easy answer and don't want to do their own research...I am not one of those guys! I am not doubting it is on this forum somewhere...just not found it yet. I have spent a lot of time trying to research and have fallen short...shoot me! If I find this forum helpful I would like to continue on with posting and updating the project build. I think I just have to find a happy medium with the halfshaft angles and the driveshaft angles...most importantly if the halfshafts can run downhill to the diff? Obviously consideration needs to be given to bump and rebound and not binding up the halfshafts. I assume they don't care if they run uphill or downhill but just wanting confirmation if this. Edited July 12, 2011 by 240RR Quote Link to comment Share on other sites More sharing options...
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