Guest Anonymous Posted July 4, 2001 Share Posted July 4, 2001 My newly acquired V8 Z(please see my 'hello & help' post in Non-Tech for details) has a quirk. The rear end goes "Thunk!" when ever I shift and release the clutch any way other that very softly. If I try to take off too fast from a stop, especially in reverse, the car does not spin tires, it vibrates in a most disturbing manner. All the commotion seems to be coming from the rear axle area, and I have no problems unless I apply too much torque too fast. I am guessing that the differential mount may be shot. Do you agree with diagnosis? If not, what else should I look at? Any help is very much appreciated. Thanks! Quote Link to comment Share on other sites More sharing options...
blueovalz Posted July 4, 2001 Share Posted July 4, 2001 Sounds like a front mount to me. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted July 4, 2001 Share Posted July 4, 2001 Agreed! If you replace it with a stock unit follow the JTR suggestion for wiring it with cable. That shoudl keep it from breaking again. I'm switching to a solid mount myself but others have said it's harsh so that migth not be an option for you... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 4, 2001 Share Posted July 4, 2001 Thanks all! I guessed right for once! For anyone who has done it, how hard is that differential mount to replace? Quote Link to comment Share on other sites More sharing options...
fl327 Posted July 5, 2001 Share Posted July 5, 2001 hey buddy, just fixed that in my z, it may or may not be the front mount, it might be driveshaft to diff flange bolts! i was having those symptoms, and the bolts went and i was stuck in place for like two hours!! check those bolts, and the solid mount is also a very good idea, harsh it may be, but very potent. i bolted one up when i fixed those bolts, and its much stronger, a little noisy at times, but i feel better now i can launch the crap out of my car without fear! Leonard "been there, broke that" Quote Link to comment Share on other sites More sharing options...
jeromio Posted July 5, 2001 Share Posted July 5, 2001 Replacement rubber mount is over $50. Total waste of money in my opinion. It's doomed to fail again. I'd either go solid, or fab a DeGroot mount - I've done the latter. Very happy with the results. http://www.usq.edu.au/users/degroot/240z/pages/diffmount.htm http://240z.jeromio.com/diffmount.html Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted July 5, 2001 Share Posted July 5, 2001 Shouldn't the stock mount hold up if it's wired down though? So long as it can't pull far enough to tear the rubber I'd think it would survive. Maybe not the best for performance but I'd think it would be more streetable. I'm hoping my solid mount doesn't drive me from the car Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 5, 2001 Share Posted July 5, 2001 Both elegant solutions and well executed. Scottie had one I think was even easier as I recall. Just found the photo: Simple, strong. I may try for something like this when I get into mine. Regards, Lone Quote Link to comment Share on other sites More sharing options...
jeromio Posted July 5, 2001 Share Posted July 5, 2001 Scottie's solution is certainly innovative - if you already have a stock rubber mount. My question is, performance-wise, how does this differ from a solid mount? I suppose you could put some bends in that steel piece to allow for some movement. This would reduce the amount of total stress on the rubber while still allowing for some flex - even out the vibrations and such. Would make the rubber last longer. But the way that rubber mount is designed - it's just severely flawed. It's simply some rubber bonded to 2 pieces of steel. Not only is the rubber going to deteriorate, but certainly that "glue" effect can't hold up very long. What I'm saying - if you're starting from a blank slate, seems like you may as well just get the solid mount in the first place. If you've driven it with the diff slapping against the body, the little bit of harshness of the solid mount is just not going to seem like anything comparitively. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 5, 2001 Share Posted July 5, 2001 Sounds like mine. Almost sounds like someone with a ball peen hammer striking the floorboard. I havn't looked yet, but judging by the looks of other bushings back there, I'd guess the mount is toast on mine as well. Those I've taken for a ride are usually quite worried by it (or maybe my driving I donno.. ) and I'll admit its not a good sounding noise. Must fix that soon too. Regards, Lone Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 5, 2001 Share Posted July 5, 2001 True, I suspect also the quieter your rearend is (that sounded funny.. ) the less harsh it would be when mounted solid (I.E. howling rear end solidly mounted = a pack of wolves in your hatch area...). Honestly with the exhaust most have on they're cars its probably not that noticable, and performance often times goes with making some sacrifices. I'm not keen on how the back mustache bar mounts, but assume the bushing go in the end of them? If thats the case perhaps just a solid machined piece of aluminum (or steel or brass, whatever would be appropriate) pressed into the mustache bar ends (making it shorter to raise the rear a bit to get a better pinion angle) and using Scottie's type of mount would effectively give a solid rear end without that billet mount thats being sold? Just a thought... Regards, Lone Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted July 5, 2001 Share Posted July 5, 2001 Lone, you got the idea. The difference between my solution and a solid diff mount is that the stock rubber mount is still in place to absorb vibrations. Since no one else is using it, folks have to take my word for it that there is no vibration or resonance like you get from a solid mount. My Z does not have a radio and those 4-500 mile highway trips lets me hear evey sound in the car and the rear end is not one of them. That was a good point about a bad rear end hightening the problem of a solid diff mount. You could also put in a pair of 2-chamber Flowmasters if the rear end noise bothers you. My apologies (sympathy) to those who have them . Quote Link to comment Share on other sites More sharing options...
pparaska Posted July 5, 2001 Share Posted July 5, 2001 I've ridden in a few Zs (L6 and V8) with solid diff mounts (front) and the sound is objectionable to me. To each his own, but if I want to hear whining, my daughter does a good job, but a blower belt whine would be preferable . Ron Tyler made a diff mount that is pretty cool. It doesn't use the crossmember at all, but it's a big u shaped bent piece of plate that bolts to the diff arrestor strap bracket mounting holes in the tunnel, and goes above the front of the diff. He used interlocking GM transmission mounts (2), on one either side of the diff nose, to pick up all four of the bolt holes. If/when my snugged down diff arrestor strap goes, I'll be making one like Ron's. This is a great way to go, because you can lower the front of the diff a bit to help with driveshaft u-joint angles, you have a compressed instead of stretched set of rubber mounts, and it's super-sano. Again, Ron comes up with a killer mod! Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted July 5, 2001 Share Posted July 5, 2001 Pete, Does Ron have a web site that further explains his diff mount with some pictures. Danno74Z Quote Link to comment Share on other sites More sharing options...
DavyZ Posted July 5, 2001 Share Posted July 5, 2001 Pete, we've seen solid mounts, Scotties mounting solution (love it! ), the JTR cable solution, and the Simon DeGroot mount (beautiful & lotsa work), but I can't really picture Ron Tyler's solution. Does he have a website or pictures? I would be great to see it. So far, I like Scottie's solution for its simplicity, cleanliness, and cost effectiveness. But I'll gladly look at anyone else's! Davy Quote Link to comment Share on other sites More sharing options...
pparaska Posted July 5, 2001 Share Posted July 5, 2001 Ron does not have this one any web site, as I remember it. Think of it this way. Build a squarish box that fits up into the tunnel where the front of the diff mounts (diff out of the car). The box bolts to the tunnel with the two bolts on either side of the tunnel where the arrestor strap brackets would bolt in. Now, cut the bottom, front (side towards the front of the car) and back out of the box - you're left with a bracket that's u-shaped in cross-section. Scarab used to sell something like this that bolted in like that, but solidly contacted the top of the diff. This bracket would go higher in the tunnel, enough to hang two GM transmission isolators from, running lengthwise on either side of the centerline of the diff. The bolt holes in the isolators that would normally mount to the GM transmission tailhousing would instead be bolted to the top of the diff, using the bolting bosses (2 each side aft of the pinion flange) The isolator would be inverted with the stud(s) sticking up into holes in the u-channel bracket described above. I think Ron said the spacing was very close to that of a standard GM trans isolator. Ron has been to this site before, maybe he can sketch something and/or elaborate. Quote Link to comment Share on other sites More sharing options...
DavyZ Posted July 5, 2001 Share Posted July 5, 2001 Thanks for additional information--makes it easier to visualize the schematics. Davy Quote Link to comment Share on other sites More sharing options...
Dave Posted July 6, 2001 Share Posted July 6, 2001 I have a urethane tranny mount that is interlocking. It in made by Energy suspension. You can see a picture of it at suspension.com the part number is 3-1108 the application is Chevelle or Camero, well it really fits all Chevs. It is almost a perfect fit as far as bolting to the two front bolt holes in on the R200. But like Pete said it will have to go on top. Ron Tyler hangs out at Datsuns.com and there is a write up on his car there. Dave... [ July 05, 2001: Message edited by: Dave ] Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted July 7, 2001 Share Posted July 7, 2001 Dave, any chance you could post a pic of that setup? Sounds interesting and a good possible solution using an off the shelf part. Thanks! Quote Link to comment Share on other sites More sharing options...
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