diff mount broke agian
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Rotary Enthusiast
Joined: Dec 2001
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From: oakland Ca
diff mount broke agian
mine just broke again and what kind of diff mount can i buy i had the mazda comp one in there and i have a na i need some thing that will not brake that easy
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Rotary Enthusiast
Joined: Dec 2001
Posts: 865
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From: oakland Ca
i was just driving and i heard that clunk sound i some times launch but that was before when i use to go racing and what can the worn parts be and some times i throw it into 2nd hard and burn rubber
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From: just a bit north of your business
weld the mount like I did and then start tracking down the other mounts that don't like it and immobilize those too. 
you might also be able to put some screws into the rubber. I doubt they'd hold for long though.
and if you do choose to replace the mount with another one get a snubber for the pinion flange.... take the load off that mount
you might also be able to put some screws into the rubber. I doubt they'd hold for long though.
and if you do choose to replace the mount with another one get a snubber for the pinion flange.... take the load off that mount
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From: just a bit north of your business
I didn't take pics of hardly any of my work on the 7.
When you pull the mount out you'll see the closest proximity metal halves are where to tell them to weld. I did the top and bottom, but for maximum strenght you might want to have them add some more plate and weld the verticle sides. (I did use a piece of bar stock to bridge one of the gaps because I trimmed off some excess metal) If I stay up long enough I might doctor up a pic and make it crystal clear for ya, but no guarantees tonight.
When you pull the mount out you'll see the closest proximity metal halves are where to tell them to weld. I did the top and bottom, but for maximum strenght you might want to have them add some more plate and weld the verticle sides. (I did use a piece of bar stock to bridge one of the gaps because I trimmed off some excess metal) If I stay up long enough I might doctor up a pic and make it crystal clear for ya, but no guarantees tonight.
No longer cares
Joined: Apr 2002
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From: just a bit north of your business
Like I said, I did mine on the other edges than what I drew here. This is for maximum strength but I doubt either way would ever pose a problem.
Just be damn sure to get it lined up right if you're welding a broken one. (getting it back in will be a pain if you're sloppy on the alignment)
"Just Looking".......
Joined: Jul 2001
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From: Treasure Coast, FL
I had the clunking shortly after I bought my TII 5 years ago. I ordered the Mazdaspeed mount from www.corksport.com
Still haven't had any problems, but I don't beat the sh*t out of my car off the line either - I'm more of an on-a-roll hunter.
Still haven't had any problems, but I don't beat the sh*t out of my car off the line either - I'm more of an on-a-roll hunter.
Sick & Twisted
Joined: Dec 2001
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From: FT Lauderdale, Fl
Is there something else that could cause the clunking sound? I went to change my mount to notice it was not broken what else could it be the tranny is fine the drive shaft is fine and the diff itself is also fine so it has me a bit puzzled as to what else it could be.
Refined Valley Dude
Joined: Oct 2001
Posts: 2,283
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From: Kitchener, Ontario (Hamilton's armpit)
Originally posted by me, here:
https://www.rx7club.com/forum/showth...hreadid=117194
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https://www.rx7club.com/forum/showth...hreadid=117194
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Originally posted by Amur_
Okay, here's how it works...
Your front diff mount is mounted to the side of the differential housing. From there it goes up to the body of the car.
There is nothing directly above the front end of the differential. Every time you jump on the gas, the diff tries to snap upwards. The front diff mount can only take being pounded this way for so long.
So you install a pinion snubber. It's basically a cylindrical (I think) block that you insert between the top of the diff and the body of the car (it has a stud sticking out of one end.) The pinion snubber acts as a bumper, blocking the differential from snapping upwards and pounding the front diff mount.
The pinion snubber is an aftermarket part that is made to order. Either repair (weld) or replace your front diff mount and then measure the distance from the top of the front of the differential housing to the body of the car. Since you want there to be a teensy bit of play (you don't want the pinion snubber to actually touch the diff) take a couple of c**t hairs off your measurement.
Go to a performance shop and order your pinion snubber using your measurement. When you get it, use it to find and mark where you will be cutting the hole through the body for the stud. The hole will be under & between the rear seats/boxes (depending on what you're driving.)
Cut the hole, install the pinion snubber, and stop worrying about your front diff mount.
Okay, here's how it works...
Your front diff mount is mounted to the side of the differential housing. From there it goes up to the body of the car.
There is nothing directly above the front end of the differential. Every time you jump on the gas, the diff tries to snap upwards. The front diff mount can only take being pounded this way for so long.
So you install a pinion snubber. It's basically a cylindrical (I think) block that you insert between the top of the diff and the body of the car (it has a stud sticking out of one end.) The pinion snubber acts as a bumper, blocking the differential from snapping upwards and pounding the front diff mount.
The pinion snubber is an aftermarket part that is made to order. Either repair (weld) or replace your front diff mount and then measure the distance from the top of the front of the differential housing to the body of the car. Since you want there to be a teensy bit of play (you don't want the pinion snubber to actually touch the diff) take a couple of c**t hairs off your measurement.
Go to a performance shop and order your pinion snubber using your measurement. When you get it, use it to find and mark where you will be cutting the hole through the body for the stud. The hole will be under & between the rear seats/boxes (depending on what you're driving.)
Cut the hole, install the pinion snubber, and stop worrying about your front diff mount.
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Joined: Apr 2002
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From: just a bit north of your business
Or save the time and hasstle and weld the mount.
It would require far more work to get a snubber mounted from below than its worth in a vehicle which sees track or hard street driving. Granted the snubber if correctly tensioned will prevent the mount from breaking again, but if you do that from the bottom side you'll spend hours trying to get the subframe back on because the bolts won't align. If you do it from the top you have to cut a hole in your floor and fabricate some kind of mount for the snubber. All of this takes longer than welding the mount and calling it a day.
I'll admit that welding it is not the absolute perfect solution, because the subframe on my car does move a little due to the solid mount. But for the amount of energy spent and cost involved in replacing the mount and adding a snubber (which are readily availible at muscle car shops in urathane if you do want to go that route) when within 5 mins of having the bad mount out of the car you can be putting it back in welded and never have the problem again.
Most performance cars will blow these isolators. I've welded every car that I've seen (my friends are hard on cars too) with a blown one and its never bit me back. No regrets.
It would require far more work to get a snubber mounted from below than its worth in a vehicle which sees track or hard street driving. Granted the snubber if correctly tensioned will prevent the mount from breaking again, but if you do that from the bottom side you'll spend hours trying to get the subframe back on because the bolts won't align. If you do it from the top you have to cut a hole in your floor and fabricate some kind of mount for the snubber. All of this takes longer than welding the mount and calling it a day.
I'll admit that welding it is not the absolute perfect solution, because the subframe on my car does move a little due to the solid mount. But for the amount of energy spent and cost involved in replacing the mount and adding a snubber (which are readily availible at muscle car shops in urathane if you do want to go that route) when within 5 mins of having the bad mount out of the car you can be putting it back in welded and never have the problem again.
Most performance cars will blow these isolators. I've welded every car that I've seen (my friends are hard on cars too) with a blown one and its never bit me back. No regrets.
Refined Valley Dude
Joined: Oct 2001
Posts: 2,283
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From: Kitchener, Ontario (Hamilton's armpit)
I've smoked two of them. This will be my first pinion snubber (if all goes well I'll be putting it in myself this coming weekend.)
My mechanic (pretty much a 7 guru) got under her about 2 weeks ago and pronounced the mount 'fucked beyond repair.'
I'd consider welding the replacement mount, but I'd rather have a solid rubber bumper in there to absorb all that energy rather than have it thrashing away at my 7's 16-year-old body through a solid (welded) mount.
I understand what you've written and believe it. I'm given to pursuing a 'gentler' route for my 7, so to speak.
Thanks for sharing the info.
My mechanic (pretty much a 7 guru) got under her about 2 weeks ago and pronounced the mount 'fucked beyond repair.'
I'd consider welding the replacement mount, but I'd rather have a solid rubber bumper in there to absorb all that energy rather than have it thrashing away at my 7's 16-year-old body through a solid (welded) mount.
I understand what you've written and believe it. I'm given to pursuing a 'gentler' route for my 7, so to speak.
Thanks for sharing the info.
No longer cares
Joined: Apr 2002
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From: just a bit north of your business
the tranny mount might not hold up being welded unless you switched to solid engine mounts as well. there's a lot of leverage on that one under normal driving.
the front diff mount when welded doesn't impact much more abuse on the chasis than the rubber one because of what you're actually preventing the diff from doing. all the energy of the car being pulled on the rubber mount as the nose of the diff is trying to climb up while the pinion is tugging at the ring gear causes the failure. If you prevent that upward motion it will not cause any more harm to the body or crossmember. it might actually prevent it. the reason that mount is rubber from the factory is to make it quiet and divorce the suspension from the body to limit vibration and road shock from being carried into the passenger compartment.
the front diff mount when welded doesn't impact much more abuse on the chasis than the rubber one because of what you're actually preventing the diff from doing. all the energy of the car being pulled on the rubber mount as the nose of the diff is trying to climb up while the pinion is tugging at the ring gear causes the failure. If you prevent that upward motion it will not cause any more harm to the body or crossmember. it might actually prevent it. the reason that mount is rubber from the factory is to make it quiet and divorce the suspension from the body to limit vibration and road shock from being carried into the passenger compartment.
Refined Valley Dude
Joined: Oct 2001
Posts: 2,283
Likes: 2
From: Kitchener, Ontario (Hamilton's armpit)
Thought you guys (in this thread) might be interested in this:
https://www.rx7club.com/forum/showth...hreadid=164843
https://www.rx7club.com/forum/showth...hreadid=164843
