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Mazdacomp differential bushings?
Getting ready to replace my original set after one started leaking. Searched but didn’t find a picture or much information on how the Mazdacomp version differs from stock. Are they oil filled? All rubber? Urethane? Anyone have first-hand feedback? Thanks, Jim |
https://cimg8.ibsrv.net/gimg/www.rx7...d94beec17.jpeghttps://cimg7.ibsrv.net/gimg/www.rx7...16b93bbb6.jpeg https://cimg6.ibsrv.net/gimg/www.rx7...488480dc4.jpeg I bought a set and installed em in the horn in May. They’re oil filled rubber OEM mounts but the rubber is 40% stiffer than stock. Seems like a good compromise between poly and OEM if you’re looking for comfort but slightly more aggression. I have not hung the diff on them yet nor driven the car since I’ve been waiting almost two months for an LCA bushings that finally came in yesterday. Matt |
Thanks Matt. Pics were welcomed as well. And yeah, I was looking for a little more firmness but was concerned about nvh. The Pettit Racing street bushings generally got good reviews but (like most things) it wasn’t universal. |
I put poly diff bushings in my car. You can feel a little bit more vibration at idle but it isn't bad. I have stock motor mounts on the car right now (will eventually be IR mounts) so that will add to the vibration a bit.
The stock diff bushings do have a lot of slop. That and the trailing arm bushings in the rear are tops on my list for doing bushings, doing those will tighten up things nicely without a big impact to NVH. I also like to do poly steering rack mounts, they wrap around the stock steering rack. Little to no NVH there and the stock ones can tear/fail over time. Dale |
I was talking with Chris Ott about this very subject yesterday. He's a fan of Delrin bushings. Not has loud as solid aluminum but he says not bad. I'm really not concerned about NVH in my RX-7 or any car for that matter. I'm actually more comfortable in the RX-7 for long road trips than I am in our Honda CR-V. When I finally dump the OEM bushings on my diff I'll likely be going with Delrin.
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I have both bushings that the OP is inquiring about and the Irperformance mounts that Dale is planning on getting. I can say that stiffening up the drivetrain with these two components adds stiffening to not only your driving (coupled with good coilovers like ohlins) but it also firms up the transition between shifting gears and banging through all 4 quickly and confidently.
I also have mazda competition bushings for all of my suspension components I.e upper and lower control arms front/back. It really makes the car feel more responsive with a bit of vibration but still having that new car feel with a planted and responsive experience. Now I did have that infamous clunk and replaced the arms with the battles that J-Auto sells and the metal bushings. He had great customer service skills which really impressed during our 60 minute conversation, spending the time to make sure my needs met his product. All in all, it’s worth replacing those high mileage, in my case, or old rubber bushings with mazdacompetition, Irperformance motor mounts( mazda competition mm are 400 a piece I think), and J-autos battles and metal ba arm bushings. |
F128-39-040 - Mount, Engine #1 - $435.00 F128-39-050A - Mount, Engine #2 - $359.75 If your car has the later mounts (both steel, vs DS aluminum) then something like the Banzai mounts that just replace the buffer material would be a less expensive though more labor intensive alternative. Because I had engine mounts on the brain, I looked up the wrong damn part. Sorry for any confusion. |
Appreciate the posts but interested in user info and feedback on Mazdacomp Differential bushings (i.e. nvh, movement etc) compared to stock or any aftermarket. |
I currently have powerflex diff bushings on my FD and I will be putting in mazdacomp diff bushing in the next week or so. I will give you some feedback after.
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Originally Posted by dfwrx7
(Post 12287806)
I was talking with Chris Ott about this very subject yesterday. He's a fan of Delrin bushings. Not has loud as solid aluminum but he says not bad. I'm really not concerned about NVH in my RX-7 or any car for that matter. I'm actually more comfortable in the RX-7 for long road trips than I am in our Honda CR-V. When I finally dump the OEM bushings on my diff I'll likely be going with Delrin.
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Originally Posted by Narfle
(Post 12287853)
Don't do delrin anything. It's an awful bushing material for any car you actually drive farther than a hot lap. Get polyurethane, if you're dead set on some under-engineered aftermaket nonsense.
I'm always open to more options and direct feedback. What's your weapon of choice? |
OK, now that I'm looking up the CORRECT part number (F128-28-890) the Mazda Comp diff mounts are $92.21 from Mazda, $96.50 from Racing Beat.
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Just to update. Finally got around to this job over the winter.... *I went with the MAZDACOMP bushings. Visually there was no difference that I could see. *In other threads guys seemed to have some difficulty breaking the hanger arm bolts loose from the top of the diff housing. They have factory thread-lock on them and torqued down pretty good. I found my Craftsman 1/2" drive flex-head ratchet with a short 17mm socket worked like a champ. It's long like a breaker-bar with great leverage and I could tilt the handle down and get a couple of 'clicks" on it at a time to get them loose. I reached all four bolts and worked great for reinstall too. Side-note: My arm was looking a little scabby after 26+ years. Cleaned it with reducer to remove oil. POR-15 and a throw-away brush made it look like new again. https://i1126.photobucket.com/albums...psj3c1nzsn.png http://i1126.photobucket.com/albums/...pshgykqmer.png *And I used a 12 ton HF press I bought that removed the old ones and pressed the new ones in without too much trouble. Just like MrMatt3465's pictures above. The only issue was getting the new bushings started evenly. I ended up using a big blunt brass punch I have to tap it into the arm ~ 1/16 inch evenly so that when I put it on the press it went in straight. Just like Matt, I used the sleeve from a HF ball-joint press I had to receive the old bushings when I pushed them out, but used a 1 1/3" socket on the bushing itself. Piece of cake. *Even though it only had maybe 10k or 12k on it, I used the opportunity to change out the fuel filter while I had things out of the way. And I noticed that when I had the diff hanging down the pinion drooped quite a bit. That caused the drive-shaft snout to pull in and out of the transmission every time I moved the differential. I decided as a precaution to change out the rear transmission seal. It's not expensive and a lot easier to do at this point if the old seal started to leak from the activity. http://i1126.photobucket.com/albums/...ps3gde4dha.jpg http://i1126.photobucket.com/albums/...psni3zb4rr.png . |
Glad you got it done!
Any reason you didn't remove the whole diff from the car? I've found it's much easier to tackle all those jobs with the diff out and on the ground. You do have to take more stuff off (PPF for one) but the better access is well worth it. Dale |
I did pull the PPF and cat-back. And was prepared to disconnect the lower suspension points so I could swing the rear hubs up and pop out the axles. I just didn’t feel the need once I tried that big flex-head ratchet on those hanger nuts. Plus I don’t (yet) have a transmission jack and working alone it would’ve been tricky for this old guy to hoist that pumpkin up 6’ off the floor and bolt it back in. No draining the diff either. |
Just in case anyone is curious to know what a really shot OEM differential bushing looks like...http://i1126.photobucket.com/albums/...psilkcmeju.png |
Originally Posted by Sgtblue
(Post 12331047)
Just in case anyone is curious to know what a really shot OEM differential bushing looks like...http://i1126.photobucket.com/albums/...psilkcmeju.png https://cimg3.ibsrv.net/gimg/www.rx7...891076676.jpeg Matt |
I recently put in poly differential bushings when I had the diff out of the car thinking "what harm can poly do, the diff doesn't move much."
Well, I picked up a more pronounced thump through the chassis when changing lanes over the bots dots. Makes sense in retrospect the way the diff is hanging weight on the subframe. Interested to hear back on how the Mazdaspeed mounts are. |
I had the Delrin bushings on my last FD. They made a great (desirable) difference on mine. It felt like the car was putting down the power that went through the drive train in a solid manner. The slop in the drive train was also greatly reduced. And just to clarify, the slop I refer to is when you go from being ON the power to taking your foot OFF the throttle. It's that momentary spot before the engine catches, compresses the soft bits like bushings, and finally starts slowing the vehicle down. Combine new bushings with new motor mounts and you've REALLY got a solid drive line and it will completely change how you feel about the car! :D
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For anyone looking to order Mazda Comp diff bushings, they are back ordered. Was told by Mazda Motorsports that a conservative timeline of having them in stock ready to ship is May. Just passing some information.
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Vibra-techincs is an alternative to MS I guess...they are not poly or derlin...so I assume they are not bad for NVH. https://www.vibra-technics.co.uk/maz...ounting_bushes |
Originally Posted by Spalato
(Post 12331249)
Vibra-techincs is an alternative to MS I guess...they are not poly or derlin...so I assume they are not bad for NVH. https://www.vibra-technics.co.uk/maz...ounting_bushes
Originally Posted by BLUE TII
(Post 12331072)
….Interested to hear back on how the Mazdaspeed mounts are.
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About 10" of snow on the ground here...with 5" to 10" more on the way. I'll update when I can. I don't have a technical background and don't know how the different materials behave in cold. I wonder if the reason MAZDA used oil-filled bushings is to keep NVH low over a wider temp range? Keep yourself and your FD safe. Temperature is an interesting variable for many systems of the car. I had some Stance coilovers once on my TII and I swear they didn't have a proper temperature compensation circuit in the piston or it was mis-calibrated because they were remarkably stiff in cold weather - just what you don't want... However; for the diff busings/mounts, I was thinking the oil filled bushing was so the bushing actually acts as a damper (like the oil filled bumpstops that were the old classic Mini "shocks"). To damp the motion of the heavy differential over sharp bumps. Of course I only came to this conclusion once I put in the poly diff bushings/mounts and heard the thump reverberate through the chassis going over the bots dots. A little late... |
Was there ever any real consensus on which bushings to go with for a primarily street driven FD? I have done the occasion auto-cross, hit the 1/4" mile a few times as well, just to safely experience what the was made for. I may even take it to an HPDE this year. I had a Banzai brace but there a little too much NVH transmitted for my liking. So I am back to leaky worn out OE bushings for now. It looks like the MComp bushings are back in stock, but they cost 3 times what the SuperPro bushings would be. I am willing to drop the extra money if anyone has a compelling reason to go MazdaComp in this case. Mazda stock replacement are $57ea.
Thanks for any additional input. |
I've been running poly diff mounts for years. You can feel the engine and vibration more in the cabin, but it's not terrible. You also don't have to worry about it leaking out over time :).
A friend of mine YEARS ago (like 15-20 years) had Mazdacomp diff mounts and I remember just sitting in his car at idle it was rougher/more vibration. But, that was so long ago I don't think it should count for anything. Personally I'd get the poly mounts. I don't think they're so aggressive that they are obnoxious. Dale |
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