Guest Zyoul8r Posted February 2, 2005 Share Posted February 2, 2005 I have a 1971 240z with a 350 and 200-4R Tranny connected to the R200 Diff. I just purchased the front "Solid Differential Mount" from the Z Store (See link: http://www.zcarparts.com/store/merchant.mvc?Screen=CTGY&Category_Code=PRC02B ) If anyone has installed this before, how much more noise can I anticipate? and I was thinking of putting a thin rubber strip on each side of the mount prior to installing to try and reduce noise? If anyone has attempted this or has any input, please let me know as I will be doing this over the weekend. Thanks! Quote Link to comment Share on other sites More sharing options...
jt1 Posted February 2, 2005 Share Posted February 2, 2005 Noise is kind of a subjective thing; the solid mount is going to transmit more noise to the interior, but whether it's enough to make a difference is up to the individual. I would try putting some rubber in if possible. Welcome to HybridZ John Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted February 2, 2005 Share Posted February 2, 2005 Well, it will depend on the condition of your rear end, driveshaft, transmission, driveshaft angle, etc and whether you have cv's or u-joint axles... My former 240z had u-joints and a rather loud r200, and I could definately hear a droning as I went down the road (especially highway). My 280z turbo has an LSD w/ cv's and was not loud at all (comparitively) until recently when my tranny started making noise... That sound too is transfered through the solid diff mount... Quote Link to comment Share on other sites More sharing options...
Guest Zyoul8r Posted February 3, 2005 Share Posted February 3, 2005 Thanks for the information, and the welcome!! What a great site!! I just got off the phone with the guy from Arizona Z Car (http://www.arizonazcar.com/diffmount.html) and explained that I already purchased the Solid front diff mount prior to me being aware of his website and the billet mount.... Anyway, I did order his Alluminum Mustache Bar and will have that this weekend. He told me to put a piece of radiator hose rubber on one side of the front diff mount, and that will eliminate the noise. He has done quite a few this way. So that is my plan... (6061 T-6 Alluminum Mustache Bar and a Solid Steel Front Differential Mount w/ a slice of radiator hose between mount and frame connector) I will let you know how it works out. I am only getting around 375hp out of the engine so this should work great for me (crossing fingers) Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted February 3, 2005 Share Posted February 3, 2005 It must depend heavily on the condition of the rear diff. When I put one on my Z it was so loud at highway speeds I literally felt sick afterwards. It was unbelievable. Had it on a total of 15 minutes before it came off again. Quite a few other guys have had a less extreme experience. But there must be a reason there are so many modified diff mounts being made, otherwise everyone would run a solid mount. If the guy at Arizona Z says a rubber hose will work, then he would know better than I do. But I would think the bolts would transfer the sound right around the rubber. There is still steel on steel contact there. Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted February 3, 2005 Share Posted February 3, 2005 Run a search on "Ron Tyler front diff mount". This is the type I'm using. I'm convinced that it is the best solution for us V8 guys as it lets you lower the nose of the diff more that other types for better u-joint angles as well as solving the torn mount problem and it totally rubber isolates your diff. Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted February 3, 2005 Share Posted February 3, 2005 I just made my own solid mount with the help from a goood friend of mine Galen. I have not had noise problems with mine. I am using a1987 300ZXT LSD rear end in mine and with a sbc 383 that runs traction limited low 11's I have had no problems except for half shaft u-joints...imagine that! Mike Quote Link to comment Share on other sites More sharing options...
Forrest Posted February 4, 2005 Share Posted February 4, 2005 I replaced a regular rubber mount with a mount that was welded into a solid mount, on a Quaife-equipped R200. Honestly, I couldn't tell the difference. Ho ho ho, I kill myself. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 4, 2005 Share Posted February 4, 2005 I don't wanna get sucked into this too far, but I'll throw this hypothetical question out there to all of you solid mount proponents and maybe get the ball rolling: If you've solid mounted JUST the front diff mount, what part of the driveline or frame takes the load when the engine and transmission want to torque over to one side??? OK, OK, just a couple more: If the front of the diff is SOLIDLY mounted, why have bushings in the mustache bar??? What do they do, other than isolate all of the stress onto the front mount? What problems could this cause? Quote Link to comment Share on other sites More sharing options...
Guest Zyoul8r Posted February 4, 2005 Share Posted February 4, 2005 My Rear Diff is in excellent condition and teh 200-R4 was just rebuilt by a local speed shop. No noise out of either unit so I think it should be a good match. Plus there seems to be an even mix of pro's and con's on the solid mount. I'll let you all know the results next week. I will not get the mustache bar until tuesday... so I will try and change in the evening during the week. I am getting prety anxious. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted February 4, 2005 Share Posted February 4, 2005 Jon, you beat me to it. My opinion is either all solid, or all flexible, but no mixing. Can you imagine using motor mounts in which one side is solid, but the other mount is flexible? Guess which will fail. Quote Link to comment Share on other sites More sharing options...
260DET Posted February 4, 2005 Share Posted February 4, 2005 The other point is that completely solid mounting the diff turns it into a structural part of the car, which it was not designed for, nor were the bits its attached to. May not cause a problem but why take the risk when there are several better alternatives Quote Link to comment Share on other sites More sharing options...
Guest Zyoul8r Posted February 5, 2005 Share Posted February 5, 2005 Well... The moustache bar is mounted using urethane bushing and only holds the differential in place. It is not designed to control twist or lift of the differential. The solid front diff mount's pupose is to prevent the lifting or twisting of the differential. So technically as long as the front diff mount does its job, it dosen't matter what material (Steel, Aluminum, Wood) you make the mustache bar out of.... because if that front diff dosent work you are S.O.L. anyway. Therefore I feel very comfortable going with the solid steel front diff. mount since that is where the pressure is applied. As far as the Mustache bar... It is a nicely engineered piece that is strong and light with a nice set of bushings.... nothing wrong with that. Thanks again all for the input. Quote Link to comment Share on other sites More sharing options...
Guest Zyoul8r Posted February 5, 2005 Share Posted February 5, 2005 Jon, you beat me to it. My opinion is either all solid, or all flexible, but no mixing. Can you imagine using motor mounts in which one side is solid, but the other mount is flexible? Guess which will fail. Well, now you are comparing apples and oranges. Unlike the rear differential, BOTH motor mounts help control twist of the engine. On the rear diff the mustache bar is primarily a support bar while the front diff mount controls 90% of the twist or lift. The rear mustache bar is also closer to the center of the gear carrier than the front diff mount which also eliminates the stress put on it. Quote Link to comment Share on other sites More sharing options...
Guest Zyoul8r Posted February 5, 2005 Share Posted February 5, 2005 Oh yeah, Blueovalz. That is a sweet looking car you have! Here is my car.... http://album.hybridz.org/showgallery.php?cat=500&ppuser=12136 Quote Link to comment Share on other sites More sharing options...
blueovalz Posted February 5, 2005 Share Posted February 5, 2005 Zyoul8r; Thanks for the compliment on the car. You've got a sharp looking Z as well! In regards to the mustache bar's function, I must respectfully disagree. Engage the emergency brake of any Z and apply engine torque (while in gear) and watch the dynamics of the differential. One reason the mustache bar is designed like it is (extended arms with bushings at the ends), is to offer improved lever moment to resist torque. The long arms on the bar provide this function. The bushings on the bar are designed to provide a "ramped" counterforce against the movement up or down (the sawtooth pattern of the bushing's engaged surface) which controls both up and down concerted movement, but also twisting as well. The front mount will provide a good deal of up/down counterforce but is not designed to resist any twisting (look how narrow the mount is). The mustache bar takes care of the right angle forces that the front mount cannot. This is why you will hear of instances where the mustache bar gets broken occasionally (rarely, and with large torque motors), and why an OEM strap over the top of the differential's nose helps keep the tension forces from exceeding the OEM mount's limits. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 5, 2005 Share Posted February 5, 2005 Follow me here: If you had no motor mounts at all, that torque wouldn't drive the car forward, it would spin the motor instead. Now you add motor mounts and the engine moves say 1" or 1 1/2" when you rev the motor. Further down the line the transmission has one mount, so it helps a little to control the twisting, but not too much. Further along is the front diff mount, also a single mount that isn't going to help too much. Last you've got the big wide mustache bar with bushings on both ends. It would have been a lot easier to put a single stud in the back of the diff cover and run that straight up to the frame rail, but Nissan didn't do that, because the mustache bar IS responsible for controlling the twist. When you just put a solid front mount on, all the twisting stress goes straight to the front diff crossmember. None is carried by the mustache bar, and that twist goes to the front diff mount BEFORE the motor mounts. The most likely piece in there that is going to fail is the driveshaft. Next most likely is the differential crossmember. You could take the load off the front crossmember by adding solid bushings in the mustache bar, but that still wouldn't fix the driveshaft issue. I've had this discussion before, and bottom line was some (mostly ITS guys) ran their cars like this for years with no problems. Some others had problems including driveshaft U-joints exploding and the front diff crossmember actually tearing. I would expect that a V8 conversion is going to produce more torque than an ITS motor, and have much larger U-joints. Where that will leave you as far as failures I can't say. May be that your driveshaft is big enough to take the strain. Maybe not... Quote Link to comment Share on other sites More sharing options...
Guest Zyoul8r Posted February 5, 2005 Share Posted February 5, 2005 1st BlueOval I do agree with your assesment. My point is that the force the mustache bar takes is minimal when compared to the forces on the front diff mount and that the Aluminum Mustache bar should be more than adequate. I do not know the exact ratio... but as I earlier stated my estimate would be about 90% of the lift of the rear diff is controlled by the front diff mount. 2nd jmortensen I follow your logic, and I agree with that as well. But again, by the time we are that far back in the drive train, plus take into mind the initial design of the suspension. I find it hard to believe that a solid front diff mount will cause a problem with that aluminum mustache bar. If the original kit fron ArizonaZCar comes with a "solid" front diff mount, why does it matter if its aluminum or steel.... its still solid, right?. I'm just tired of breaking these weak original mounts. I'll be the guinea pig and let you all know FOR SURE how this works with my car... 1971 240z 375HP SB Chevy Pro-Built 200-4R Tranny R200 Rear Diff w/3.9 Final Drive Tires are 205/60-15's Again -- All.... Thanks for the input, it really does help with the decision making process. Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted February 5, 2005 Share Posted February 5, 2005 Actually, Leonard (FL327) was the first guinea pig. With his 327 V8 (and his rambuctious right foot) he tore his diff crossmember in half with the combo of a solid front mount and bushings in the back. Another note: it's not the material the moustach bar is made of so much as whether or not you use bushing with it. Aluminum or steel neither is going to flex in the vertical (twisting) axis. I believe it depends on how hard you push your car and how much torque you have, and how sensative to NV&H issues you are, as to whether you will have problems mixing solid and flex mounts. Obviously there are several testimonials here from credible people who are mixing mounts without problems. And there are good logical arguments for not mixing, as well as at least one recorded failure from mixing. Choose for yourself how you want to go and let us know your results. Quote Link to comment Share on other sites More sharing options...
Guest Zyoul8r Posted February 5, 2005 Share Posted February 5, 2005 Thanks for the FL327 reference. I will see if I can find any of his threads on this site. If this dosen't work for me, I will try that "Tyler" mount... that looks like a really nice set-up. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.