My rear diff mount is shot, some guy told me that if i reaplace it they break ez if am puting down power, he told me the best bet is to weld it. has any one ever herd about that or done it????

 

Solid mount, I wouldn't do it thats rather stupid unless you're in the obscene power range. I don't know where you're at but I doubt many people need anything more than a comp mount.

 

seen it done a few times, might as well do it

 

seen it done a few times, might as well do it how did it work out was the shifting rougher

 

How much power are you making???


-Ted

 

not much now but ill get there soon, so might as well do it. am be around at least 300rwhp as soon as i get the baby tuned

 

i want to weld my diff mount, simply because i dont want to put another rubber mount in there thats going to shear apart. my reasoning is, if Supras can have diffs mounted solidly to the subframe, so can RX7's. the rear diff mounting on RX7's is absolutely homosexual. anything i should look out for when pulling the mount out? i still have a stock Y-pipe, its not going to hinder me, is it?

 

id just put in a competition mount if your putting down 300 to the ground.......thats not THAT much horsepower, shouldn't have any trouble

 

you think a rubber mount is really going to hold up to drifting? i highly doubt it...

I just checked the prices again. stock is $144, comp mount is $111... **** that noise. i will weld mine together for $10.

 

my diff mount use to be welded and trust me it sucks wen you let off the gas,the diff moves up and down(thats wy theres rubber betwen the two pieces) and its gonna start making weird noises,i bought the racing diff mount of mazdatrix its better in construcion that the oem with better and stiffer rubber and doesnt have the counterweitgh

 

I used a few links of chain, loose when under light load and when there is a heavy load the chain keeps the mount in check. Weld the chain in right at the mount.

 

yes, tahts odd... see, my supra, it has a diff that is mounted solidly to the subframe, and it makes no movement, noise or vibration during any sort of driving or throttle modulation. the vibration and noise doesnt come from the diff moving, it comes from the sudden STOP of the diff. if the diff doesn move in the first place, how can it come to a sudden stop? In practice, there has to be an intial action for there to be an equal and opposite reaction. its physics 101.

whether or not the driveline harmonics will be transmitted to the interior is a moot point anyways. considering that 2 of the 3 stock diff mounts are already isolated by rubber bushings, leaves the 3rd/front bushing to question. keeping in mind that the front of the diff is affixed to the forward subframe, and then the subframe is connected to the body via 2 rubber bushings in the same manner as the 2 rear diff mounts, there is going to be minimal increase in NVH. now, since we know that the diff will be affixed to the vehicle by 4 rubber bushings rather than 5 and an elimination of the counter weight which prevents the pinion angle from changing rapidly, there will then be a minimal or negligible reduction in ride quality or driving characteristics. once the front of the diff is mounted solidly to the subframe, the 2 subframe mounts will now shoulder the responsibility of isolating movement and vibration associated with driveline undulation. also, on the same token, since the diff is rigidly affixed to the subframe, the entire subframe assembly will now act as a huge counterweight and reduce the tendancy and degree of pinion angle change during driveline loading and unloading.

if there is slack in the bushngs where the subframe meets the body, then, quite simply, shim the bushings. it is possible to add spacers between the subframe bushing retainers. thusly, when the 21mm subframe nuts are tightened down, the spacers will place more tension on the webbing joining the center sleeve and the body of the bushing pressed into the subframe. it wont necessarily be a solid mount on the subframe bushings, but it will take up the preliminary movement of the subframe so that only huge load changes will force the subframe to move. again, the NVH will increase, but i feel that it will be a negligible amount. moreover, i think that its a moot point when keeping in mind, ride quality and comfort typically have to be sacrificed in favor for better performance.

 

Replace the diff mount and install a pinion snubber. After the second one broke, I installed a snubber and it has kept it in place. A 6puck unsprung and hard launches does it every time.

 

Just an update. i cut the counterweight arm completely off the mount, as well as the lower tab on the flange that bolts to the subframe for ease of installation.

i chopped up the counterweight arm and used as flat-stock to join the mount halves on the top and bottom. i laid the arm across the top and cut it to make a lap joint. its the perfect side to use as a top plate. then with the small triangular piece thats left of the arm, i just cut a small sliver off, about 10mm wide. it basically went across the stamped hole right next to the bolt hole that holdes the counter weight. that piece is the right thickness to be laid between the lower tab and backplate and welded in. the 2 side pieces youll have to come up with. i had a DSM bumper beam laying around and i cut a patch of metal from it. its about 4mm thick as opposed to the 8mm of the flange plates; easier to weld.

i dont have pics of my welded mount, cuz flux core wire yeilds hideous welds... but i doctored a picture to show you what to cut off and what you can reuse for the top and bottom of the mount;

cut the coutnerweight arm off at the red line nearest the mount body. youll end up cutting it on the first bend as the arm comes off the back plate.

then, the next cut on the arm starts at corner and comes out perpendicular to the arm. this makes up one of the flat sides that will yeild your top plate. then, make the next cut at the next red line. measure this distance against your diff mount for "exact" distance.

then, the next cut will be where the Blue line is. this piece will make up the bottom plate to join your mount.

the areas marked with Cyan X's are scrap/waste.

in order to use your new bottom piece, you will have to cut off the lower bump stop on the diff-plate. cut along the Green line. you will have to access the cut-line from the Back of the diff mount, the side that faces the diff itself. you will end up cutting along the bend where it comes off the main plate. basically, envision cutting a straight line between the 2 bolt tabs. when this bump stop is removed, your 2nd piece to join the bottom of the mount will drop in gap between the upper bumpstop and the mount backplate. it will sit in there vertically; the gap between the upper bumpstop and the back plate is almost the same as the plate thickness. so you dont have to lay it across the gap like the upper plate to make a lap joint. the bottom will weld together with a butt-joint.

welding an additonal plate on the side where the counterweight arm used to be is pretty straight forward. just find a piece that is the right size and weld it in. both parts of the backing plates are flat. however, the other side of the mount, which is technically the Rear, is a bit harder. the easiest way i found was to get a plate, and lay it on there. it wont sit level because the diff-side backing plate is curved. so, hold the filler stock so that it sits flat on the subframe-side backing plate, tack both corners there. then, tack the 3rd corner quickly where it touches the diff-side plate. the filler stock should be hot enough to hotform. get a hammer and beat the plate so it bends and conforms to the curvature of the recess on the diff-side plate. should only take 30 seconds of beating. then, run both beads and youre set.

Installation is way easier than removal. hav esomeone pull the subframe down or pry it down, push the diff ALL the way up, and slide the mount onto the 3 studs. then let the mount fall down into the 2 grooves of the subframe. then, get the 3 nuts started on the diff side and tighten them down. then put the locating plate on the 2 mount studs and get the 2 nuts started. start putting the subframe back onto the 2 forward studs, and temporarily install the 2 21mm nuts a few threads to hold the subframe up. use your 17mm short, universal and 20" of extensions to get the 2 subframe nuts. hit it from the back, holding the extensions parallel to the latereral link bar. make sure the diff mount studs are resting on the bottom of the subframe slots by pushing the driveshaft/pinion up and letting it fall down and listen for the audible clunk before tightening all the way. then, put the subframe back together, as this will be the easiest part. re-hang your exhaust if you had to lower it like I did.

btw, if you weld your mount, you wont need a Pinion snubber. as long as the diff mount halves dont separate, the pinion will never pitch up and down. the subframe flange uses that retainer plate with a locating tab bent over the top. so even if the nuts were loose and the plate installed, that tab wont allow the plate to travel upward.

the car is awesome to drive w/o the clunk. there is no real increase in NVH unless you are Under 2500 rpm and "lugging" the motor. the choppy power pulses of the motor are felt more readily though the floor, but any time other than that, i notice no real increase in NVH or decrease in comfort.

i cant wait to go grip driving with it now.

 

nice

 

I've heard that this messes up your camber or something along those lines, but I'm on a pretty small budget, so I might also go this route (at least temporarily). Thanks!

 

No this does not mess up your camber.

If you run a solid front mount you NEED to run solid rear diff and subframe mounts as well or you will rip the diff mount tab off the subframe over time. With all solid mounts you won't break the tab ever.