Guest Z Draci Posted March 7, 2006 Share Posted March 7, 2006 I've tried searching this forum for similar ideas but came up empty. I did find this excellent discussion of curing the weak link in the Nissan front differential mount: here I just tore my rubber diff mount in half while at a dry skidpad. I temporarily fixed it with a spare off a rusty 280Z parts car. This one is already starting to crack so I began to think of a permanent fix. I was thinking about using a standard solid mount from Arizona Z car or MSA. Then, I would use longer bolts so that I can fit two urethane bushes (from sway bar endlinks) to the top of the diff. This way the angle of the differential is not altered. It will be like the picture below but only putting the bushes on top and bolting the solid diff mount to the standard position on the bottom. (pic stolen from Wangsman) I might have to search for the appropriate bolts to do this. But I thought this might provide some dampening from the diff vibrations to the body. I also don't want to go all solid mounts for the diff since it is on road car. I thought this solution might give me urethane dampening on the mustache bar bushings as well as on the front. I already have an R200 in my car and do not plan to run above 250hp in the future. What do you guys think? Do you think it would actually provide sufficient dampening to actually go through with the idea? Do you think I can get enough clearance above the diff to fit the bushings on top? Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted March 7, 2006 Share Posted March 7, 2006 That will work. Have seen similar designs. My favorite diff mount option is the one that cuts the stock mount in half putting one part above crossmember and the other half underneath, then fab up some metal extentions so the two pieces bolt together mid way. Sort of a clam shell approach. I'll bet there are over a dozen different approaches to fixing the front diff mount. Quote Link to comment Share on other sites More sharing options...
evildky Posted March 7, 2006 Share Posted March 7, 2006 I'm no expert but I say that looks like about the best easiest solution I've seen, so those are just endlinks from a sway bar right? I guess they are hardened steel? diff height looks about right on the crossmember but it does look to be back a bit Quote Link to comment Share on other sites More sharing options...
2126 Posted March 7, 2006 Share Posted March 7, 2006 Looks as though it would work just fine. Not likely to fail. However, you may get some vibration transmitted to the chassis, since there is no insurance the through bolts will not be in contact with the diff and crossmember. Maybe some urethane sleeves on the through bolts to isolate them from the diff? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 7, 2006 Share Posted March 7, 2006 I'd be a little wary attaching the diff to the chassis with 3/8" bolts. I'd prefer to see 1/2" bolts. At the very least you should be using Grade 8. Other than that looks cheap and easy to do. Quote Link to comment Share on other sites More sharing options...
zguy36 Posted March 7, 2006 Share Posted March 7, 2006 two 3/8" bolts are more than strong enough. They shouldn't be experiencing any shearing forces, only tensile forces. The proof load for a grade 5 bolt is 6500lbs.... I doubt you are seeing those forces. See this website for bolt strengths. http://www.precisionscrewandbolt.com/strength.htm Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted March 7, 2006 Share Posted March 7, 2006 The bolts have to be stronger than the stock rubber mount it came with. But having said that people (corzette?) have posted picks of metal straps used as diff mounts that snapped with a single launch. The forces are being applied rather abrubtly so static tensile strength can be misleading. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 7, 2006 Share Posted March 7, 2006 I just based my comment on the stock bolts. They're 12mm IIRC. No reason not to drill out the bushings and slide them over a 1/2" bolt. One more thing I was thinking is that it would be pretty easy to shim between the crossmember and the bottom bushing to change pinion angle, which might be really useful for our V8 swap members. Quote Link to comment Share on other sites More sharing options...
evildky Posted March 8, 2006 Share Posted March 8, 2006 keep in mine the bottom end of the stock pinion mount was attached to the cross member by a single stud! with what a 10mm dia.? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 8, 2006 Share Posted March 8, 2006 Plus a strap, right? Quote Link to comment Share on other sites More sharing options...
Clifton Posted March 8, 2006 Share Posted March 8, 2006 The easiest way, if you are just looking for quick and reliable is to weld 2 tabs to the front and rear of the top portion of the mount and run a bolt through the tabs under the crossmember. Leave about 1/8-3/16" between the bolt and crossmember. It will even work with a torn diffmount. It will only transmit noise under heavy torque but you won't hear it as the engine will be making more noise than that at the time. Mines been on for about 2 years and I haven't had any problems with it. Quote Link to comment Share on other sites More sharing options...
Sean73 Posted March 8, 2006 Share Posted March 8, 2006 I like Clifton's setup. Then for another minute of work, you could insert that extra bolt through some old refrigerant hose. Quote Link to comment Share on other sites More sharing options...
theBrit Posted March 11, 2006 Share Posted March 11, 2006 I did the same as clifton except I made a U shaped saddle that bolts on and I put a large flat rubber shim in it. The rubber is just not quite in contact with the bottom of the mount, as the diff rises the saddle support progresivly gets compressed and there is no shock load. Under normal conditions only the stock mount is working so there is no extra harshness. I am very happy with the way it works. Quote Link to comment Share on other sites More sharing options...
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