Rear clunk FD
12-31-20, 12:47 AM
#1
Junior Member
Thread Starter
Rear clunk FD
So im trying to isolate the rear clunk on my car. Ive read lots of threads and stickies. Consensus is the struts for curing the clunk but im pretty sure mine are fine from wut i can tell driving over bumps and uneven pavement. This instantly led to me believing the pillow ball bushings. But a few days ago, i was talking to a buddy that has owned an FD for a while and he said it was the differential mounts. He asked me if it did it on initial take off and braking to a stop....and that is exactly when it seems to be the most intense and apparent. So im wondering if its best to go back OE bushes or upgrade to Banzai(black, of course)? My car is 99.9% original...figured that is a very important point. And in regards to pillow ball bushings, OE or J-Auto?
12-31-20, 01:56 AM
#2
Newly Rebuilt
Personally I went with the Banzai Black Poly diff mounts and had no issues with them.
I also went with the J-Auto pillow ball kit. Main reasons were they don't require greasing and are very well built. OE Pillow ball kits are also more expensive.
If you're going to remove the diff and rear lower control arms, it might not hurt to consider seeing if any of the other bushings need replacing and also changing or relocating your fuel filter while it's out if you don't know when it was last done.
I also went with the J-Auto pillow ball kit. Main reasons were they don't require greasing and are very well built. OE Pillow ball kits are also more expensive.
If you're going to remove the diff and rear lower control arms, it might not hurt to consider seeing if any of the other bushings need replacing and also changing or relocating your fuel filter while it's out if you don't know when it was last done.
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Jbtsurf (12-31-20)
12-31-20, 02:29 AM
#3
Junior Member
Thread Starter
Personally I went with the Banzai Black Poly diff mounts and had no issues with them.
I also went with the J-Auto pillow ball kit. Main reasons were they don't require greasing and are very well built. OE Pillow ball kits are also more expensive.
If you're going to remove the diff and rear lower control arms, it might not hurt to consider seeing if any of the other bushings need replacing and also changing or relocating your fuel filter while it's out if you don't know when it was last done.
I also went with the J-Auto pillow ball kit. Main reasons were they don't require greasing and are very well built. OE Pillow ball kits are also more expensive.
If you're going to remove the diff and rear lower control arms, it might not hurt to consider seeing if any of the other bushings need replacing and also changing or relocating your fuel filter while it's out if you don't know when it was last done.
thanks so much for the feedback...and esp the foresight on the fuel filter. Ive been anxious to order parts but not to tear down the suspension and replace all the bushes lol. Id like to just do them all while im at it, as long as i can source black poly.
12-31-20, 03:20 AM
#4
Newly Rebuilt
I'm not bothered by it, it's a sports car after all, but I wanted to make it last, but not be stupid harsh like nolethane bushes.
I went all Poly (SuperPro) with the exception of the 2 rear lower inner control arm bushings (MazdaComp bushings).
The colour of the bushes don't really matter as you don't see them when installed anyway (SuperPro are purple) but I think one of the poly kits also available through J-Auto are black poly bushings.
Last edited by Axton; 12-31-20 at 03:23 AM.
12-31-20, 06:13 AM
#5
I’m in a different camp if it’s just a street-driven car.
The FD was criticized for it’s (lack of) ride quality when new. Almost any poly bushing, IMO, usually makes things worse and is not necessarily an “upgrade”.
The stock differential bushings are oil filled. That should be a hint that even MAZDA was trying to reduce drivetrain NVH. Bad diff bushings should be easy to diagnose. Just get under the car with a good flashlight and look up for signs of leakage. You can also source a set of Mazdaspeed diff bushings as an OEM option as I did. If it comes to that check this thread...
https://www.rx7club.com/3rd-generati...hings-1128159/
In my experience though, bad diff bushings did not cause clunking as you’ve described. Just a sort of wallowing feeling and increased nvh. A knocking or clunk (in my experience) is usually pillow ***** but checking the shock mounts (you don’t have “struts”) is also prudent. You usually can’t find the offending pillowball bushings visually. I recommend putting the back of the car in the air, stable but with no load on the suspension. Then grab the control arms, trailing arms etc and shake them with your hands near the bushings. Any slop is amplified, so even a little slop can be significant. And if one is bad, changing all of them is best. That said, I understand a budget. I might at least change the corresponding bushing on the opposite side.
No experience with j-auto’s pillowball bushings but been happy with other purchases from them. You might do a search in the 3rd Gen tech section.
The FD was criticized for it’s (lack of) ride quality when new. Almost any poly bushing, IMO, usually makes things worse and is not necessarily an “upgrade”.
The stock differential bushings are oil filled. That should be a hint that even MAZDA was trying to reduce drivetrain NVH. Bad diff bushings should be easy to diagnose. Just get under the car with a good flashlight and look up for signs of leakage. You can also source a set of Mazdaspeed diff bushings as an OEM option as I did. If it comes to that check this thread...
https://www.rx7club.com/3rd-generati...hings-1128159/
In my experience though, bad diff bushings did not cause clunking as you’ve described. Just a sort of wallowing feeling and increased nvh. A knocking or clunk (in my experience) is usually pillow ***** but checking the shock mounts (you don’t have “struts”) is also prudent. You usually can’t find the offending pillowball bushings visually. I recommend putting the back of the car in the air, stable but with no load on the suspension. Then grab the control arms, trailing arms etc and shake them with your hands near the bushings. Any slop is amplified, so even a little slop can be significant. And if one is bad, changing all of them is best. That said, I understand a budget. I might at least change the corresponding bushing on the opposite side.
No experience with j-auto’s pillowball bushings but been happy with other purchases from them. You might do a search in the 3rd Gen tech section.
Last edited by Sgtblue; 12-31-20 at 11:59 AM.
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Snipe G (01-02-21)
12-31-20, 12:21 PM
#6
Junior Member
Thread Starter
You're welcome, when most people have enquired about bushing replacement, the main question that really comes up is "how sensitive are you to harsh ride, noise and vibration".
I'm not bothered by it, it's a sports car after all, but I wanted to make it last, but not be stupid harsh like nolethane bushes.
I went all Poly (SuperPro) with the exception of the 2 rear lower inner control arm bushings (MazdaComp bushings).
The colour of the bushes don't really matter as you don't see them when installed anyway (SuperPro are purple) but I think one of the poly kits also available through J-Auto are black poly bushings.
I'm not bothered by it, it's a sports car after all, but I wanted to make it last, but not be stupid harsh like nolethane bushes.
I went all Poly (SuperPro) with the exception of the 2 rear lower inner control arm bushings (MazdaComp bushings).
The colour of the bushes don't really matter as you don't see them when installed anyway (SuperPro are purple) but I think one of the poly kits also available through J-Auto are black poly bushings.
12-31-20, 12:58 PM
#7
Junior Member
Thread Starter
I’m in a different camp if it’s just a street-driven car.
The FD was criticized for it’s (lack of) ride quality when new. Almost any poly bushing, IMO, usually makes things worse and is not necessarily an “upgrade”.
The stock differential bushings are oil filled. That should be a hint that even MAZDA was trying to reduce drivetrain NVH. Bad diff bushings should be easy to diagnose. Just get under the car with a good flashlight and look up for signs of leakage. You can also source a set of Mazdaspeed diff bushings as an OEM option as I did. If it comes to that check this thread...
https://www.rx7club.com/3rd-generati...hings-1128159/
In my experience though, bad diff bushings did not cause clunking as you’ve described. Just a sort of wallowing feeling and increased nvh. A knocking or clunk (in my experience) is usually pillow ***** but checking the shock mounts (you don’t have “struts”) is also prudent. You usually can’t find the offending pillowball bushings visually. I recommend putting the back of the car in the air, stable but with no load on the suspension. Then grab the control arms, trailing arms etc and shake them with your hands near the bushings. Any slop is amplified, so even a little slop can be significant. And if one is bad, changing all of them is best. That said, I understand a budget. I might at least change the corresponding bushing on the opposite side.
No experience with j-auto’s pillowball bushings but been happy with other purchases from them. You might do a search in the 3rd Gen tech section.
The FD was criticized for it’s (lack of) ride quality when new. Almost any poly bushing, IMO, usually makes things worse and is not necessarily an “upgrade”.
The stock differential bushings are oil filled. That should be a hint that even MAZDA was trying to reduce drivetrain NVH. Bad diff bushings should be easy to diagnose. Just get under the car with a good flashlight and look up for signs of leakage. You can also source a set of Mazdaspeed diff bushings as an OEM option as I did. If it comes to that check this thread...
https://www.rx7club.com/3rd-generati...hings-1128159/
In my experience though, bad diff bushings did not cause clunking as you’ve described. Just a sort of wallowing feeling and increased nvh. A knocking or clunk (in my experience) is usually pillow ***** but checking the shock mounts (you don’t have “struts”) is also prudent. You usually can’t find the offending pillowball bushings visually. I recommend putting the back of the car in the air, stable but with no load on the suspension. Then grab the control arms, trailing arms etc and shake them with your hands near the bushings. Any slop is amplified, so even a little slop can be significant. And if one is bad, changing all of them is best. That said, I understand a budget. I might at least change the corresponding bushing on the opposite side.
No experience with j-auto’s pillowball bushings but been happy with other purchases from them. You might do a search in the 3rd Gen tech section.
In my experience, most Japanese vehicles have fluid filled rear diff and/or subframe bushes. Nothing appears to be leaking in the rear excpt for the left diff cv shaft output seal. Something i will address while doing the rear suspension refresh. Thanks a million for the link as ive was search for that exact reference material. I have jimlab’s rear suspension bushings ‘how to’ saved and have read it a couple times already. If you know a source or link for the axle seal, that would be amazing!!! Again, im being a lil loose with my technical terminology, youll have to excuse some of it. I couldnt get anything to wiggle or budge when the car was on the rack. But i did notice the holes in the rear control bushing open up while the suspension was in full droop...witch was evidence enough for needing to be replaced.
Not really any budget restraints as the PO gave me a generous discount off our originally agreed upon price to address all minor lil tidbits that i identified.
So are the MAZDASPEED bushing liquid filled too? Curious cuz im a big fan. Ive alway been impressed with their tuned production vehicles...some of the absolute best valued light performance vehicles available on the market when new and still today as used.
Last edited by Jbtsurf; 12-31-20 at 01:01 PM.
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Jbtsurf (01-01-21)
12-31-20, 03:54 PM
#9
The stock pillowball have dust seals that hold grease. The grease is there primarily to seal out dirt and moisture. When the suspension is drooped, its natural for the seal to open a little, especially on the trailing arms. That’s not necessarily an indication they’re shot. Neither is a little grease weeping from them. Hell, I even use a needle fitting on a gun to add a bit of grease once in a while.
Differential side seal...fwiw the details are there but pics apparently are lost and I can’t find them to re-post:
https://www.rx7club.com/3rd-generati...-seals-517073/
The key takeaway there is that you don’t have to pull the half-shaft from the hub. And no wheel alignment is needed. Just disconnect those lower things mentioned and it allows enough room for the half-shaft to be popped out of the diff to replace the seals.
Differential side seal...fwiw the details are there but pics apparently are lost and I can’t find them to re-post:
https://www.rx7club.com/3rd-generati...-seals-517073/
The key takeaway there is that you don’t have to pull the half-shaft from the hub. And no wheel alignment is needed. Just disconnect those lower things mentioned and it allows enough room for the half-shaft to be popped out of the diff to replace the seals.
Last edited by Sgtblue; 12-31-20 at 04:11 PM.
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Jbtsurf (01-01-21)
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Jbtsurf (01-01-21)
01-01-21, 06:15 PM
#11
Junior Member
Thread Starter
The stock pillowball have dust seals that hold grease. The grease is there primarily to seal out dirt and moisture. When the suspension is drooped, its natural for the seal to open a little, especially on the trailing arms. That’s not necessarily an indication they’re shot. Neither is a little grease weeping from them. Hell, I even use a needle fitting on a gun to add a bit of grease once in a while.
Differential side seal...fwiw the details are there but pics apparently are lost and I can’t find them to re-post:
https://www.rx7club.com/3rd-generati...-seals-517073/
The key takeaway there is that you don’t have to pull the half-shaft from the hub. And no wheel alignment is needed. Just disconnect those lower things mentioned and it allows enough room for the half-shaft to be popped out of the diff to replace the seals.
Differential side seal...fwiw the details are there but pics apparently are lost and I can’t find them to re-post:
https://www.rx7club.com/3rd-generati...-seals-517073/
The key takeaway there is that you don’t have to pull the half-shaft from the hub. And no wheel alignment is needed. Just disconnect those lower things mentioned and it allows enough room for the half-shaft to be popped out of the diff to replace the seals.
still trying to track down a light gray OEM rubber alternator cap.
01-01-21, 06:22 PM
#12
Junior Member
Thread Starter
i wish mine was just one clunk/thunk but its several simultaneous and varying sound frequencies. Im very under the impression that lube of any kind won’t bandage the wounds, unfortunately.
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