fl327 Posted March 13, 2002 Share Posted March 13, 2002 ok here goes, after making everything stiff and getting my car to hook good and run well, making adjustments to timing, fuel pressure,jets, etc etc. i went out "jogging" three nights in a row hard to see how it hangs with imports and domestics old and new 1. 88-91honda civic dohc+turbo yellow with either carbon fiber or black painted hood- used to have trouble out the gate with them, hooked and all i could hear in the background was vtec, blow off, and a second and third gear chirp, far far away 2. a 240z blue with a white stripe down the middle, its too bad he gave up in second, he had a nice car. 3.1999? green new style z28 with a 6speed- first time against one of newer fbodies, beat em, beat em good. raced a 01 ss a while back and bearly edged out, novice drivers us both, ill try the SS again 4.2nd gen mr2red with modena kit turbo- go back to autofreak 5. 80s monte carlo ss black, with a 10-1 350 2004r from a roll on the freeway 6.supratt red with veilside kit and large exhaust-nothing but hook baby, he was was coming back for my ass in third, but these streets arent long enough for his top end advantage. 7.240sx turbo and a primered del sol with open pipes at the same time!!! (refer to 1) yeah im spouting off im happy im finallly gettting the power to the ground, trust me its been a long time coming and i didnt realize before how much of a difference in power and traction can be made without buying bolt on speed parts, all tuning and structural modifications, remember im on unemployment insurance right now. heres the tragic end for the time being. a while back i shattered the diff mount insulator piece in half, right after the flange and the mustache bar gave up on me, i have replaced all and welded and reinforced the crossmember. i broke the insulator again and put in a new mount and reinforced it again with sheetmetal, welds, and the jtr recommended 3/8 steel cable that ties the insulator to the crossmember, they said to wrap it three times, i wrapped it eight times, and i added a racheting nylon strap to reinforce the arrestor rubber strap and wraped that around the crossmember. man, i just snapped the crossmember do you guys think its from putting all the torque loads on it, does this piece weaken after time, did welding it weaken it? halfshaft u joints and driveshaft are good. i understand that people are getting away with even leaving this piece stock and running some really fast times, times i cant match, im thinking of getting a new x member and welding box steel to it? maybe it was too rigid and that caused the break? if that is the case should i go and get a new rubber insulator from nissan and then strap it down? man im almost done with all mechanical and ready to go body, and i know i put a lot of abuse on my car, but man it busted up in one week and it lasted two years before!! any suggestions would be greatly appreciated, very appreciated, man i just started to get this power to the ground and im hooked, just need a little more reliability with it. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 13, 2002 Share Posted March 13, 2002 too much welding maybe the culprit. Quote Link to comment Share on other sites More sharing options...
Guest kc6wfs Posted March 13, 2002 Share Posted March 13, 2002 Currious, How much squat do you have? Wonder is thats whats taring it up? I have little WOT at idle. 13.7@100 1/4 mile . I am running ~250hp and have not had any problems(yet) But I did not even do the cable wrap that JTR recomended. It's on jack stands now as my rear gave up the ghost at the track. (loud whine) I'm still running the stock diff mounts and all and R180 3:54. What HP is your motor at and what trans are u running? I have yet had much keep up with me (import wise) but going to do major cam/converter/supercharger(700R4.. 3500 stall) very soon. I'm going to drop in a R200/4.11(I hope) and don't want any problems... What do you sugest?? Thanks. Dave Quote Link to comment Share on other sites More sharing options...
fl327 Posted March 13, 2002 Author Share Posted March 13, 2002 running a m21. maybe 250-275 max hp no squat, running eibach/kyb/tokiko coilovers 3.54 r200. r200 is all good, its just the mount thats bugging me, maybe its the violence of the manual trans? ive heard that with an auto the r180 and mounts last longer. Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 14, 2002 Share Posted March 14, 2002 I just installed a diff mount that goes ABOVE the front of the diff and does away with the OE diff mount. The guy who made it for me had me swear I wouldn't reveal his name. But it's simple to make. It's three lengths of 3"x1/4" bar stock (steel) that form sort of a squared off U inverted and bolted into the tunnel using the bolts that originally hold the diff strap. The ends of the U have short (~3/4"x3.5"x1/4") steel welded to the ends to make up the distance between the bolt holes, as 3" is not enough). I have pics I will post. The top horizontal length of 3x1/4" steel is just below the parking brake U that holds the cable. A GM tranny mount is attached to this horizontal piece, with the stud of the mount going through a hole in the horizontal steel piece of the U. Two 3/8" bolts come up through the diff mount lugs on the diff and into the two holes on the GM tranny mount. A bonus is that the front of the diff is lowered and now I have 1 degree vertical u-joint angles! Torquing the pinion flange back onto the diff really showed me what's happening graphically. I was only putting 120 ft-lbs on the pinion nut and it was compressing the rubber mount (the GM tranny mount, which is soft) more than 3/8". But that mount is being COMPRESSED and it appeared to stop compressing after about 100 ft lbs. But it's not in tension being torn in two like the clueless Datsun designers did with the OE diff mount. BTW, you can just cut the center section of the diff crossmember out and leave the parts that hold the front control arm bushings to the unibody if you do this diff mount design. I will get some pics up of this over the weekend. Remind me if I forget! Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted March 14, 2002 Share Posted March 14, 2002 Bad news for you regarding auto trannies and 180's I ripped my 180 a new one on first run at the track. So r200 is the way to go. And yes the auto is easier on car that manual tranny. Had both in my Z, first was a b/w super t10,cool tranny but no o.d was not cool. Now run a 700r4 but do miss hammering gears. zfan..Mike Quote Link to comment Share on other sites More sharing options...
jeromio Posted March 14, 2002 Share Posted March 14, 2002 That diffmount design sounds very intriguing, Pete. I'm anxious to see the pictures. I think my DeGroot mount is bullet-proof, but it sounds like this U mount might be easier to construct. As to the Nissan design, completely stupid. I mean, it's design incorporates a freaking rubber band! Quote Link to comment Share on other sites More sharing options...
blueovalz Posted March 14, 2002 Share Posted March 14, 2002 If it took two years to break this crossmember, then consider replacing it and look forward to another 2 years of abuse. Just change it out with every tire change (ha ha) Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted March 24, 2002 Share Posted March 24, 2002 hmm all this talk of rubber mounts...I went solid for my diff.. My tranny and motor mounts are still rubber..(modified tho..) I broke 2 mounts with my race prepped l28 The diff is a bit noisier in the cabin..but it sure worked.. no more breaking.. Quote Link to comment Share on other sites More sharing options...
Guest Fast Frog Posted March 28, 2002 Share Posted March 28, 2002 Hey Pete: Your 'lil blue Z looks pretty good!! Hope you get running soon! Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 29, 2002 Share Posted March 29, 2002 Thanks Rick! I hope to get it running again this weekend. Been tied up with life in general lately. I hope to post pics of the diff mount this weekend. Quote Link to comment Share on other sites More sharing options...
fl327 Posted March 29, 2002 Author Share Posted March 29, 2002 ok we done again, lets do it again! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 29, 2002 Share Posted March 29, 2002 I learned a lesson the hard way years ago when I had a mount keep breaking on a Nova I had. I would weld it up and it would break again in a week. Finally I realized that it was not a good idea to quench it with water after welding because this made the metal harder and more brittle. Letting it cool down slowly after welding helped cure the problem. Agreed that the M21 is part of the problem also. Very high shock loads on driveline parts. My 69 SS 396 Chevelle with M21 twisted the solid tranny spline, the driveshaft, axles, and broke all the wheel studs off and jammed the tire up into the wheel well. Fun though! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 30, 2002 Share Posted March 30, 2002 Quench in Water! Ouch to the steel. Plain steel and High carbon steel is not capable of getting any harder at a little over 1500 degrees and is more brittle than a cheap file. Molecule destruction slowly begins after 2000 degrees and that is why welding can be damaging to steel's integrity. Steel does not get flowing into a hard state until after 1200 degrees and over 1500 degress is critical for most steel. Alloy steels are slightly higher at 1800 to 1900 degrees for maximum hardness and aound 1400 degress for molecules to start flowing and attracting to each other. The little fire demons begin their work! A long full heat oven soak of around 400 degrees will bring high carbon steel to a long wearing cutting edge with ability to flex slightly without breaking. I used to make knives. When welding a critical piece, the fabricator can use a rose bud torch to heat the welded piece to a slight and very dull red and then turn the oxygen off and black coat the welded piece with the gas only. The black sooty piece then can be buried in ashes to anneal (soften) slowly. The black soot will also be absorbed into the surface giving the welded piece high carbon steel qualities of toughness. Quote Link to comment Share on other sites More sharing options...
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