fl327 Posted March 13, 2002 Share Posted March 13, 2002 hey ive completely sheared the diff crossmember in half. has anyone beefed up this piece, modified it by welding plates it? ive taken care of the lift of the nose caused by hard acceleration and shock loads, but i think i did it too good and shattered the x member. my rear is holding up well, i do plan an r230 one of these days, but would like to know more about reinforcing the rear end mounts,being that the main reason i want to do the swap is for the lsd and the cv-but what good is any of that if i keep shattering mounts??? any advice is great hope i can help you out one of these days aswell. Quote Link to comment Share on other sites More sharing options...
Tony240ZT Posted March 13, 2002 Share Posted March 13, 2002 What is it that you did to take care of the lift under hard exceleration? Was the the diff solidly mounted? Did it break at one of the ends, where the lift is for the exhaust, or where else? I'd just make one out of some 1/4" steel with quality welds. Making sure to box it up for strength. Quote Link to comment Share on other sites More sharing options...
fl327 Posted March 13, 2002 Author Share Posted March 13, 2002 the x member sheared on the drivers side, what i did to try and hinder the diff lift was wrap almost six feet of 3/8 plastic coated steel cable around the diff mount and the xmember, and i used nylon cable with the rachet fastener around the arrestor strap and cinched that around the xmember as well, i am running a solid mount as well. maybe it was too rigid? right before it broke the car was performing better than it ever has before, and then snap. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted March 13, 2002 Share Posted March 13, 2002 You answered one question (solid front mount). Just curious, how did you mount the rear of the differential though. This may be a key point. Quote Link to comment Share on other sites More sharing options...
johnc Posted March 13, 2002 Share Posted March 13, 2002 If the moustache bar was not solidly mounted then I bet you got a fatigue failure on the front crosssmember. Try replacing the rubber/poly moustache bar mounts with a solid bar of aluminum, drilled and turned down appropriately. Quote Link to comment Share on other sites More sharing options...
fl327 Posted March 13, 2002 Author Share Posted March 13, 2002 sounds like it may it, the freakin mustache bar, its the soft link in the rear end right now, it wasnt solidly mounted,im running poly bushings in it, and maybe that was hurting the front mount? i remember the first time i went solid i broke the mustache bar in half, it was pretty old and weak do you think if i go with new nissan front mounts, a reinforced cross member, and strap it down the whole system would have enough give to not snap from fatigue loads? Quote Link to comment Share on other sites More sharing options...
blueovalz Posted March 13, 2002 Share Posted March 13, 2002 A while back I had posted concerns about solid mounting only one end of the diff. It's kinda like using a solid engine mount on one side, and a flexible one on the other side. The engine will still move around (although somewhat restricted). The solid mount of this type of set-up will be minutely, but constantly flexed, and eventually fatigue, and then break, or tear out the material around it. Just like a wire that gets bent back and forth enough times. Either go full flexble mounts, or full solid. I have run solid mounts now for nearly 10 years with no failure using the OEM crossmember. In your case the solid mount was stronger than the crossmember was, so much so, that instead of it fatiquing to the point of failure, the stresses or flexing was passed on to the surrounding material that flexed into oblivion. You will most likely, even with poly mounts all the way around, not ever tear the crossmember ever again. Will the new mount hold up to whatever load you're putting on it? Don't know, but a stop (poly, rubber, etc)just over the top of the nose is a real good idea. One just high enough to not make contact in normal driving, but close enough to back up (restrict additional movement or tension loads) the mount when extreme loads are thrown to it. Quote Link to comment Share on other sites More sharing options...
fl327 Posted March 14, 2002 Author Share Posted March 14, 2002 thanks everybody, im going to ditch this solid mount and use a new rubber one i think, get a crossmember, brush myself off, and try again.... Quote Link to comment Share on other sites More sharing options...
260DET Posted March 14, 2002 Share Posted March 14, 2002 What blueovalz said about solid front/flexible rear diff mounts. Agree, it's a no no. My '77 had a stronger diff front Xmember than earlier 240's I've seen BTW. Quote Link to comment Share on other sites More sharing options...
fl327 Posted March 16, 2002 Author Share Posted March 16, 2002 is the r200 rear x member bigger/stronger? going to jy this weekend to get the xmembers, maybe ill just get a couple to see if its different. Quote Link to comment Share on other sites More sharing options...
260DET Posted March 18, 2002 Share Posted March 18, 2002 The '77 when I got it was an auto with a R180 diff but it has a stronger Xmember. It's an 8/77 to be precise. Quote Link to comment Share on other sites More sharing options...
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