pparaska Posted March 30, 2002 Share Posted March 30, 2002 ...I got permission though. You may have seen this before. The owner didn't mind me copying the idea for a one-off for my car, so I have the same setup now: (Larger version click here) (Larger version click here) (Larger version click here) This mount does two things: (1) Lowers the front of the diff, making the u-joint angles smaller (mine are now 1 degree front and rear in the vertical direction) (2) Puts the rubber mount ABOVE the differential snout, reacting against the "axle windup" with the mount in compression instead of in tension like the goofy Nissan setup. The only drawback is there's little room above this bracket for the parking brake mechanism. I used an extra spring that holds the u-shaped part of the parking brake cable to the body. I bolted one end of this spring underneath the head of one of the bolts that holds the parking brake levers above the front of the differential and looped the other end of the spring around the rod that connects the U shaped bracket for the cable to the levers there. This holds the linkage above the new differential mount bracket so that it won't rattle against the bracket. I'm anxious to see if I have created a driveline that's truly free of the dreaded V8Z driveline vibration problem. I have an extensive write-up of all my driveline mounting modifications at: http://mywebpages.comcast.net/pparaska/drivelinemods.htm Quote Link to comment Share on other sites More sharing options...
Guest Thurem Posted March 30, 2002 Share Posted March 30, 2002 I stole an Idea for a Front Differential Mounting Scheme And here I was thinking you talking 4WD. Thure Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 30, 2002 Share Posted March 30, 2002 Hey pete is that just in the picture, or did you have it cad plated? I tell ya, your car is so clean, it makes me want to go burn mine. Regards, Lone Quote Link to comment Share on other sites More sharing options...
z ya Posted March 30, 2002 Share Posted March 30, 2002 ARE THEY FOR SALE? Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted March 30, 2002 Share Posted March 30, 2002 Pete this is beautiful. By far the best idea yet for this problem. Thank you very much for sharing with us. Yes, I'll buy one too. Or, can you provide drawings so I can make my own? I mean, why not? You already work your butt off providing us with invaluable info for FREE! jk Quote Link to comment Share on other sites More sharing options...
383 240z Posted March 31, 2002 Share Posted March 31, 2002 Hey Pete nice mod! Just do me a favor, put a pinion nut on there before you bolt up a drive shaft!!!! Keith Quote Link to comment Share on other sites More sharing options...
jeromio Posted March 31, 2002 Share Posted March 31, 2002 Definately the right way to go. You end up not even really needing that front crossmember piece anymore either. It really would be key for people to be able to buy these. Maybe work some arrangement with Mike or Ross? (Of course, I don't need one ) Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 31, 2002 Author Share Posted March 31, 2002 Lone, thanks for the comps. You've had your Z for less than 2 years, and I've been tinkering with mine for over 10 years and poured way too much dough into it. Personally, I'd like to have a rougher V8Z as well, so I would have to hold my breathe while working on it! And no, it's not cad plated - I just drew yellow lines on the digital photo to show the outline of the mount - it's actually POR-15 black. Oh, and Keith, thanks for the heads up - I torqued a nut onto the pinion flange (120ftlb) and installed the driveshaft. Guys, I've let the original designer of this setup know there are customers. He may want to make/sell them, I'm not sure. I'm not really set up to do it. If he's not interested in making them and doesn't mind me passing the dimensions along, I'll do that. I'm not trying to be difficult guys, just not step on the original designer's toes. I agree it's a great solution - wish it had been my idea! Thanks for all the nice words, Quote Link to comment Share on other sites More sharing options...
pparaska Posted April 1, 2002 Author Share Posted April 1, 2002 Well, I really hate driveline vibration into the cabin. The solid front diff mount that Jim Cook racing, AZ Z car and others sell CAN cause alot of interior noise - I've witnessed this in a few V8Z's that had the stock front rubber mount and the JTR cable wrap and then put in that solid front mount. Then, I hear people say that there's no more noise in their experience. Well, that wasn't a gamble I was willing to play with. If my car was a race car, I wouldn't care. But the noise I've experienced in other V8Z's with a solid front but urethane mustache bar mounts was unacceptable to me. Second, with the high placement that the front mount scheme below the differential nose gives (with the exception of Simon Degroot's [& someone else did the same mod, cant remember who,] and Bryan Little's mount) causes large u-joint angles. This mount I show above makes it easy to lower the front ot the diff to lessen those angles - in fact it's a given that the front of the diff will be lower due to the GM mount height. The high nose of the OE setup is another reason for V8Z (JTR especially) drive train vibration and possibly u-joint wear and breakage, although I haven't heard of the latter. To me this mod cures both the probable solid front diff mount noise problem and lowers the u-joint angles to optimal. Plus it's just more elegant, since you are compressing the mount under load instead of trying to rip it apart. I doubt you could fail the system I showed above even if doing a reverse burnout. And if you did, the front of the diff case would simply fall down less than a 1/2" onto the diff crossmember. That's acceptable to me. I really see few drawbacks to this setup. As Terry pointed out, there's alot of sheetmetal in the area, and alot of it is doubled and connected to the bulkhead forward of the package shelf. Sure, I guess if I had lots of torque and traction and I was drag racing turning 9's I'd beef it up there. But I'd have other worries then. The other thing to realize is this mount is wedge shaped and the tunnel is tapered. It's not going to move up easily at all. I doubt that good welds n 1/4" mild steel in this design is going to be a problem either, but I could be wrong. I haven't run the calcs, but I'd bet that this steel design is in the infinite fatigue limit range. It's darned beefy. If it were aluminum, it might fatigue at some point, but I'm not a weight savings freak so I think steel is the better choice. The weight of the front of the diff when it's in this lower nose position is very little - less than 20 pounds. That's alot less than the load on it in the upward direction when any appreciable amount of torque's being transmitted to the rear tires! If it fails, I'll figure something else out I guess. But I have faith in this design. Cheers, Quote Link to comment Share on other sites More sharing options...
Guest 1fastz Posted April 1, 2002 Share Posted April 1, 2002 why dont you guys just put in solid aluminum mounts? it totaly fixes the problem for 60 bucks from im cook raceing? and the harshness isnt bad at all. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted April 1, 2002 Share Posted April 1, 2002 From my point of view I see several ways to look at this unique approach to the front mount. First, you maintain the OEM buffer on the differential nose without the worry of a tension failure due to hard launches, BUT, if you do have a failure in time (all the front diff weight is now in tensional load), theres nothing to hold up the nose (add a strap to the bottom now?). Also, will the thin sheet tunnel be able to adaquately distribute the shock loads? There's a lot of area there to distribute these loads, so that may not be a factor. 327's recent failure of the OEM crossmember shows that even that is not bullet-proof, but he had a solid mount up front, but (I hope I'm correct here) not in the back. Which brings your question up about the aluminum solid front mount. Unless you also make the rear mounts solid, either the aluminum or the steel is eventually going to fatique, and then fail. I like the design, with some reservations. Quote Link to comment Share on other sites More sharing options...
awd92gsx Posted April 2, 2002 Share Posted April 2, 2002 Just make sure that the driveline angles don't dissapear altogether...which would be bad...very very bad... Quote Link to comment Share on other sites More sharing options...
pparaska Posted April 2, 2002 Author Share Posted April 2, 2002 Good point. But with the differential off to one side by 3/4" or so, and with the height of the pinion, it'd be hard to get 0 degrees. I have 1 degree in the vertical plane, not sure how much in the horizontal, as that's not as easy to measure. BTW, the originator of this idea is Ron Tyler. He let me let the cat out of the bag. Ron has some really neat fabrication projects on his web site. I only wish I could do the stuff he does! His site is: http://rontyler.com Scroll down and you'll see "Diff Mount Mod". Click that link and you'll see a few of my pics and his drawings! He said he could make them for people, but his schedule for the rest of the year is very tied up with that V6 510! Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted April 3, 2002 Share Posted April 3, 2002 Thanks Pete, and Ron! Can't get Ron's site to come up from your link. I really want those drawings. Got another way in? Quote Link to comment Share on other sites More sharing options...
pparaska Posted April 3, 2002 Author Share Posted April 3, 2002 Yeah, that link works one hour, not the next for me. Try this: http://www.home.earthlink.net/~rontyler/rontyler.html Quote Link to comment Share on other sites More sharing options...
DavyZ Posted April 3, 2002 Share Posted April 3, 2002 Man, he is a master fabricator--with a good eye for making things look like art!! He's also really cool for allowing us to see the diagrams of that mount Thanks, Ron!! Davy Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted April 3, 2002 Share Posted April 3, 2002 Pete, I too really like this setup/idea. In looking at the design, I see a potential weakness in that there is only one relatively small bolt holding up the front of the differential and a spinning drive shaft. From the pictures on Tyler's site it "appears" that the OEM front differential mount does not support the front if of the differential anymore. I am probably wrong on this but can you add any additional information since you already have it installed. Thanks, Danno74Z Quote Link to comment Share on other sites More sharing options...
pparaska Posted April 3, 2002 Author Share Posted April 3, 2002 Danno, you are correct, the front of the diff is only attached vertically by the stud in the GM tranny mount (as well as the bolts through the GM tranny mount to the diff). The mustache bar attachment has a large role in holding the front of the diff. (For you Mech Eng types, the mustache bar attachement provides for some level of fixity or clamped support, so that the differential is somewhat cantilevered by the mustache bar mounting. The urethane mustache bar bushings enhance the stiffness (and strength) of this cantilever effect, causing higher fixity.) With the front mount out of the car, the front of the diff was suspended only a half inch to an inch below it's current position with the front mount in there. I agree the spinning driveshaft will add some more loads to the front of the diff (dead weight, imbalance loads, lateral loads due to non-zero u-joint angles during torque transfer). But the major load is the upward vertical load that is the reaction to acceleration torques that cause an "axle windup" type of situation. I don't think the vertical downward loads mentioned above are anything to be concerned about as far as pulling the GM tranny mount apart in tension. There might be some merit in providing som sort of additional lateral support, as this is tending to shear the GM tranny mount sideways. The front of the diff moves left and right even if I just slowly turn the tires with the car off the ground. Again, I doubt that's needed either. Either way, if the GM tranny mount fails, the diff is not going anywhere, unless the mustache bar breaks. I still have the OE front crossmember that the OE front diff mount bolts to in there. Ron actually cut the ends off of his and left the center of this crossmember out to enable better exhaust system fitment. I'm just going to leave mine alone as I already made accomodations for duals in my front crossmember. Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted April 3, 2002 Share Posted April 3, 2002 Pete, Thank you for the further explanation. Like I said, I really like this idea but I also like your idea of still using the front diff mount. I may also tinker around with some additional support. Perhaps overkill on my part but I'm a bit paranoid when it comes to new mechanical stuff. Danno74Z Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted April 4, 2002 Share Posted April 4, 2002 Pete, thanks for the new link. It worked! I printed out the drawing before anything else happened. I'm going to make this piece before I do my diff swap (180 to 200). I've been thinking of doing the "U" in one bent piece rather than 5 welded ones though. When I do I will modify it to make more room for the e-brake cable assembly. Seems like you could drop that area down a bit since the diff nose is offset to the passenger side. What do you think? Quote Link to comment Share on other sites More sharing options...
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