Pinion Snubber & Diff Mount Replacement (Convertible)
#55
Rotary Enthusiast
iTrader: (19)
^ it should be on the diff.
okay i noticed that for my gxl, the NA diff has a lump like RotaryRocket's pics show, on a turboII(10th ae) it doesn't have that lump soo i had to use more shims/washers to have it preloaded, for the most part i dont feel any vibrations or any unusual noises.....im very satisfied with this mod.
okay i noticed that for my gxl, the NA diff has a lump like RotaryRocket's pics show, on a turboII(10th ae) it doesn't have that lump soo i had to use more shims/washers to have it preloaded, for the most part i dont feel any vibrations or any unusual noises.....im very satisfied with this mod.
#57
Full Member
iTrader: (2)
Worn diff mounts = 50 mph rumble?
I tumbled to this 2009 thread while searching for info on the effects of worn out diff mounts. The problem in my '88 vert (178k miles) is similar to 1badgvr4 (12/2009 post). Rumbling and vibration that peaks in intensity at 45 to 50 mph. Maybe related - driver's side sits about 1/2 inch lower at wheel well than passenger side.
Changed to RB sway bar & springs with Tokico blues, installed Mazdatrix 'rear steer' eliminator and replaced nearly all of the suspension links. Wheel bearings seemed fine. All good mods...but did not eliminate the rumble. Could worn diff mounts be the problem?
#59
S5 T2
iTrader: (6)
Hey, RR88 - I know it's an old thread but great write up. Thanks.
I tumbled to this 2009 thread while searching for info on the effects of worn out diff mounts. The problem in my '88 vert (178k miles) is similar to 1badgvr4 (12/2009 post). Rumbling and vibration that peaks in intensity at 45 to 50 mph. Maybe related - driver's side sits about 1/2 inch lower at wheel well than passenger side.
Changed to RB sway bar & springs with Tokico blues, installed Mazdatrix 'rear steer' eliminator and replaced nearly all of the suspension links. Wheel bearings seemed fine. All good mods...but did not eliminate the rumble. Could worn diff mounts be the problem?
I tumbled to this 2009 thread while searching for info on the effects of worn out diff mounts. The problem in my '88 vert (178k miles) is similar to 1badgvr4 (12/2009 post). Rumbling and vibration that peaks in intensity at 45 to 50 mph. Maybe related - driver's side sits about 1/2 inch lower at wheel well than passenger side.
Changed to RB sway bar & springs with Tokico blues, installed Mazdatrix 'rear steer' eliminator and replaced nearly all of the suspension links. Wheel bearings seemed fine. All good mods...but did not eliminate the rumble. Could worn diff mounts be the problem?
I'd also look at the trans "y-blocks" and the crossmember bushing. The blocks will begin to sag, and the center bolt on the crossmember will push through the bushing.
#63
Full Member
iTrader: (2)
50 mph rear end rumble
Could be the diff mounts. A more certain way to tell is if you get clunks when shifting. If it does, then your front mount is most likely toast. Did you happen to get a good look at the rear mounts while you were doing all the suspension work?
I'd also look at the trans "y-blocks" and the crossmember bushing. The blocks will begin to sag, and the center bolt on the crossmember will push through the bushing.
I'd also look at the trans "y-blocks" and the crossmember bushing. The blocks will begin to sag, and the center bolt on the crossmember will push through the bushing.
I didn't inspect the front diff mount too closely. But no clunking going on...just rumble and frame vibration coming from the back end. When the car is on stands supporting the sub-frame (diff, axles, wheels hanging from the shocks), there is a noticeable gap at the top of the rear diff mount rubber - maybe 1/8th inch. I'll try to get my head in there to check with all the weight on them.
#64
RobblyWally, I don't think the front diff mount could cause your issue. With mine sheared, there was no such vibration at any speed. Typically vibration like that is going to be caused by something that rotates (ie wheel bearings or driveshaft u-joints). But I'm not sure how the rear end would behave if the rear diff mounts were shot/loose. It isn't too hard to check them out.
http://www.mazdatrix.com/g2.htm
http://www.mazdatrix.com/g2.htm
#65
Lots of rotors
iTrader: (33)
Thanks for this helpful write up, I just did this today. I was originally just going to replace the front mount but after seeing how cheap the stubbers were I ordered one and waited an extra week to tackle this.
Time wise, I spent an hour Friday evening getting the car securely off of the ground and removing the rear wheels. I went ahead and completely removed the rear link to swap in my adjustable one (the top bolt was a bitch, I ended up using +2' of extensions and a swivel 14mm). Saturday took around 6 hours since I took my time removing my RB Y-pipe. It's a true dual system so removing those 2 center bolts on the plate between the presilencer and Y pipe were a pain. The only problem bolt on the front diff mount itself was the front one on the diff nose. I used a 1' extension to get to the 2 bolts that mount it to the subframe, a 17mm ratcheting wrench for the 2 rear bolts on the back of the diff mount, and a regular basic 11/16" wrench for the front one (all I had that would fit in the tight space...). A 2' steel pipe cheater bar worked very, very well
For installing the snubber, I ended up using 4 washers on the bottom of the floor and 1 up top. I got them at home depot for $.25 each, they were 1-1/2" OD, 3/8" ID fender washers. It ended up with the snubber very slightly preloaded.
My one question- with the front mount that I used (it was a spare I had in the shed from an early 86 GXL), it had no front arm and weight. It doesn't look like any arm was ever there... Anyone know if that was another quirky early 86 deal? Just curious.
Thanks again for the write up.
Time wise, I spent an hour Friday evening getting the car securely off of the ground and removing the rear wheels. I went ahead and completely removed the rear link to swap in my adjustable one (the top bolt was a bitch, I ended up using +2' of extensions and a swivel 14mm). Saturday took around 6 hours since I took my time removing my RB Y-pipe. It's a true dual system so removing those 2 center bolts on the plate between the presilencer and Y pipe were a pain. The only problem bolt on the front diff mount itself was the front one on the diff nose. I used a 1' extension to get to the 2 bolts that mount it to the subframe, a 17mm ratcheting wrench for the 2 rear bolts on the back of the diff mount, and a regular basic 11/16" wrench for the front one (all I had that would fit in the tight space...). A 2' steel pipe cheater bar worked very, very well
For installing the snubber, I ended up using 4 washers on the bottom of the floor and 1 up top. I got them at home depot for $.25 each, they were 1-1/2" OD, 3/8" ID fender washers. It ended up with the snubber very slightly preloaded.
My one question- with the front mount that I used (it was a spare I had in the shed from an early 86 GXL), it had no front arm and weight. It doesn't look like any arm was ever there... Anyone know if that was another quirky early 86 deal? Just curious.
Thanks again for the write up.
#68
Driving RX7's since 1979
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Bumping this excellent information up for a question.
I needed to crank down my adjustible centerlink to the maximum to get my negative camber within reasonable daily driving specs. I've replaced every rubber anything that mounts to the 3rd member and I still get the occasional "thunk" when shifting from a stop in my S4 TurboVert. So I'm looking to do this as a final tweak to make the thunking noise go away.
My question, has anyone who has also tilted their sub-frame to the max had any trouble fitting the snubber in?
I needed to crank down my adjustible centerlink to the maximum to get my negative camber within reasonable daily driving specs. I've replaced every rubber anything that mounts to the 3rd member and I still get the occasional "thunk" when shifting from a stop in my S4 TurboVert. So I'm looking to do this as a final tweak to make the thunking noise go away.
My question, has anyone who has also tilted their sub-frame to the max had any trouble fitting the snubber in?
#69
Senior Member
iTrader: (3)
Bumping this excellent information up for a question.
I needed to crank down my adjustible centerlink to the maximum to get my negative camber within reasonable daily driving specs. I've replaced every rubber anything that mounts to the 3rd member and I still get the occasional "thunk" when shifting from a stop in my S4 TurboVert. So I'm looking to do this as a final tweak to make the thunking noise go away.
My question, has anyone who has also tilted their sub-frame to the max had any trouble fitting the snubber in?
I needed to crank down my adjustible centerlink to the maximum to get my negative camber within reasonable daily driving specs. I've replaced every rubber anything that mounts to the 3rd member and I still get the occasional "thunk" when shifting from a stop in my S4 TurboVert. So I'm looking to do this as a final tweak to make the thunking noise go away.
My question, has anyone who has also tilted their sub-frame to the max had any trouble fitting the snubber in?
When I had to replace the diff mount from too many drag launches, I didn't want to do it again to so instead of replacing JUST the diff mount (comp mount), I added a snubber with it. It's been 10+ yrears of occasional hard launches and never a thump.
Your occasional thump *could* be from a broken bracket the diff mount bolts to.
You'll have more than enough room if you loosen the 2 bolts for the rear sub frame and loosen the sublink. Put a floor jack there and lower it.
The indentation on the rear hump is right between the hand brake cables .
I had mine adjusted to sit on the diff .
I'd get the polyurethane one.
#70
Driving RX7's since 1979
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When I had to replace the diff mount from too many drag launches, I didn't want to do it again to so instead of replacing JUST the diff mount (comp mount), I added a snubber with it. It's been 10+ yrears of occasional hard launches and never a thump.
Your occasional thump *could* be from a broken bracket the diff mount bolts to.
You'll have more than enough room if you loosen the 2 bolts for the rear sub frame and loosen the sublink. Put a floor jack there and lower it.
The indentation on the rear hump is right between the hand brake cables .
I had mine adjusted to sit on the diff .
I'd get the polyurethane one.
Your occasional thump *could* be from a broken bracket the diff mount bolts to.
You'll have more than enough room if you loosen the 2 bolts for the rear sub frame and loosen the sublink. Put a floor jack there and lower it.
The indentation on the rear hump is right between the hand brake cables .
I had mine adjusted to sit on the diff .
I'd get the polyurethane one.
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