QWKDTSN Posted November 17, 2006 Share Posted November 17, 2006 Pyro, Zleep, I love it. I think I'm going to give this a try to replace the standard mount. This will make taking the diff apart much easier and looks like an elegant solution. The overhead Ron Tyler mount will be my backup idea if I don't like the swaybar bushing mount. How did you mark the holes in the crossmember? Drop a pen or scribe through the holes in the diff? Also, do the bolts fit precisely through the holes in the diff or are they just 'close enough'? I'm not sure that it matters much because most of the force will be along the length of the bolt but finding bolts with standard threads will probably be a lot easier than finding metric bolts that fit flush inside the bores. Quote Link to comment Share on other sites More sharing options...
briann510 Posted November 18, 2006 Share Posted November 18, 2006 Finally finished up the R200 4.38 LSD tonight, and went for a spin thinking the solid diff mount was gonna be some horrible sounding noise and we would have to go home and take it off. Didnt even notice anything much different as it was before noise wise with stock mount. The car is so loud anyway I doubted we would hear it anyway. So im happy as can be with the solid mount and it will stay. Quote Link to comment Share on other sites More sharing options...
bjhines Posted November 18, 2006 Share Posted November 18, 2006 The solid mounts using the stock mustache bar(poly ends or not) will crack the differential mount x-member... The mustache bar is a spring... it cannot be made solid enough... the front billet mount is rock solid... the differential housing is rock solid.. the crossmember is FORCED to FLEX.. it will fatigue and literally FALL APART in a few seasons of use... I personally think that the people who sell those mounts should be shot.. it is a stupid design.. guaranteed to cause failure unless the rear of the diff is solidly mounted as well... Those billet mounts were never intended to be used on a car with a stock mustache bar(regardless of the eye mounts).. they were developed for use along with custom rear uprights and rear mount reinforcement that ENTIRELY REPLACED the mustache bar. Quote Link to comment Share on other sites More sharing options...
briann510 Posted November 18, 2006 Share Posted November 18, 2006 Ah, I wasnt seeing the whole picture of the negative effects other than noise on running a solid mount. Im gonna start looking for some ways to remedy the flexing stress of the X-member. The above pictures and posts give me some ideas. Pisses me off I didnt really look at this post when I had the R200 out and could have whipped up a custom mount on the bench. Thanks Quote Link to comment Share on other sites More sharing options...
QWKDTSN Posted November 18, 2006 Share Posted November 18, 2006 Does the ArizonaZCar billet setup eliminate the spring action of the mustache bar? Just curious, I prefer having some flex, I'm staying far away from solid mounted anything. Quote Link to comment Share on other sites More sharing options...
bjhines Posted November 18, 2006 Share Posted November 18, 2006 What happened to the idea of the Ron Tyler style mount??? or the other swaybar bushing method mentioned just a few posts up???... Or the cable over the nose of the diff???... Or the bracket and bolt welded under the original mount???... or any other number of good approaches that allow driveline angle changes to suit any custom driveline???... The billet front diff mount would go well in tandem with the Arizona Z-car billet rear differential mount if you want it solid.... they are both solid... so it works fine... I think that Dave at Arizona Z-car will custom drill the holes to suit your needs... there is a thread named "Ron Tyler style differential mount"... Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted November 18, 2006 Share Posted November 18, 2006 there is a thread named "Ron Tyler style differential mount"... Actually I linked to that thread on the first page. http://forums.hybridz.org/showthread.php?t=115905 Excellent write up, worthy of sticky status. Has the same info as Pete's page with some additional info. Actually I was always critical of the Ron Tyler mount thinking a more simple solution would be better. Once I got the car apart and actually saw how easy it is to do, I was sold. It took maybe half a day to make. The other thing to keep in mind is the R180 front crossmember is no where near as heavy or strong as the R200 units. Something to think about before you start drilling holes or go to a solid mount. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 19, 2006 Share Posted November 19, 2006 The billet front diff mount would go well in tandem with the Arizona Z-car billet rear differential mount if you want it solid.... they are both solid... so it works fine... I think that Dave at Arizona Z-car will custom drill the holes to suit your needs... Just a clarification. The billet mustache bar is meant to be used with poly bushings. Yeah... I know... You'd have to make aluminum bushings to go into the mustache bar to solidly mount the diff. Quote Link to comment Share on other sites More sharing options...
bjhines Posted November 19, 2006 Share Posted November 19, 2006 You know what.... the solid design of this bar might be stiff enough even with poly bushings installed... Quote Link to comment Share on other sites More sharing options...
Clifton Posted November 19, 2006 Share Posted November 19, 2006 The twisting of the diff pivots where the axles are. The rear mustache bar is mainly just there to hold the diff up. Under load it will see some downward force but not much as the majority of the load is on the front mount as it is further away from the axle centerline. It's spring steel so it can twist with the diff movement. If the front cannot lift it wouldn't matter if the rear mount is solid of flexable. I don't plan to change my diff limiter anytime soon as it works fine, but the sway bar bushing idea is pretty good and simple. Is it as quite as stock? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 20, 2006 Share Posted November 20, 2006 The twisting of the diff pivots where the axles are. The rear mustache bar is mainly just there to hold the diff up. Under load it will see some downward force but not much as the majority of the load is on the front mount as it is further away from the axle centerline. It's spring steel so it can twist with the diff movement. If the front cannot lift it wouldn't matter if the rear mount is solid of flexable. I don't plan to change my diff limiter anytime soon as it works fine, but the sway bar bushing idea is pretty good and simple. Is it as quite as stock? I'm not following you. You're saying that the diff pivots where the axles are? That would mean the case bends. I've seen several Z's where the front diff mount went, the strap snapped, and the front of the diff lifted up far enough that the driveshaft U-joint started beating the ebrake and the trans tunnel. I'm pretty sure the diff pivots at the mustache bar and the axles are just along for the ride. The mustache bar's purpose is to transmit all of the torque from the driveline into the chassis. That's why it is anchored to those 2 huge bolts that come straight down through the frame rails. It does matter if the mustache bar bushings are solid or flexible, especially with a solid front mount. bjhines has posted pictures of a front diff crossmember that was literally TORN by the torque from the driveline. Making the mustache bar so wide and strong makes it a good way to transmit torque to the frame. The solid front mount alone is not a good way to do it. If the rear bushings are still flexible (even poly) you'll still have some twist going to the front mount. If you're going to solid mount it, solid mount it. Solid bushings in the back coupled with a solid front diff mount means that all three bushing locations handle the torque together, and that's the way it should be done in my opinion. Quote Link to comment Share on other sites More sharing options...
Clifton Posted November 20, 2006 Share Posted November 20, 2006 The diffs rotational force begins were the torque is being transmitted, the half shafts. That is were the twisting is centered. If there were no mounts the diff would rotate around were the half shafts are. The front of the diff is farther from that center and has more leverage than the moustache bar that is very close to the center. There just isn't much leverage on something (M bar) that close to the center. Not saying there isn't, just not much. The front of the diff is much further from center and it has alot more leverage. The S30's M bar is flexible only because there is so much front movement. I't can't be small and rigid or it would fatigue and break from constatly flexing. Don't know why S30's mounts are so far apart though, maybe because the subframe is right there and it's a convenient mounting point. Z31's use a very narrow rear diff mount as the torque isn't transmitted lateraly. I do know the front of the diff has alot of force. Mine without a limiter and bad leather strap did hit my parking brake with the rear u-joint load. Thought my car was comming apart. Then went in a solild mount like I've had in my 71' for the last 10 or so years. Don't really notice noise in a track car, sure do in a street car. That came out an hour later and my limiter and stock mount has been in since. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 20, 2006 Share Posted November 20, 2006 I think we agree that the front diff mount is better positioned to control the front of the diff lifting. You can stop a lifting force with a narrow mount fairly easily because it is meant to take a vertical load. The torque on the other hand requires a different type of mount. That is the reason why the mustache bar attachment points are spread out. Even on the later models the mounts are much wider and farther apart than the front diff mount bolt holes. You wouldn't want one motor mount that attached directly to the bottom of the oil pan, right? Quote Link to comment Share on other sites More sharing options...
Clifton Posted November 20, 2006 Share Posted November 20, 2006 I think we agree that the front diff mount is better positioned to control the front of the diff lifting. You can stop a lifting force with a narrow mount fairly easily because it is meant to take a vertical load. The torque on the other hand requires a different type of mount. That is the reason why the mustache bar attachment points are spread out. Even on the later models the mounts are much wider and farther apart than the front diff mount bolt holes. You wouldn't want one motor mount that attached directly to the bottom of the oil pan, right? The verticle load is the torque. It does not see torque side to side. Just as engine does not see it front to back. The moustache bar could be 4" wide and it wouldn't make a diffeence so long as it didn't need to flex due to the excessive front movement. The moustache bar only sees downward force/torque, not twisting side to side. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted November 20, 2006 Share Posted November 20, 2006 The moustache bar only sees downward force/torque, not twisting side to side.Let's try a mental experiment: take a diff with half shafts attached and place it on the floor. Have 2 guys, one on each side, hold the outer ends of the half shafts. Let's assume they can hold them perfectly still so they can't rotate at all. They are only holding the flange so the u-joints (or CV) are free to move in all axis. Now have a third person turn the input flange in the same direction the transmission would. The nose is going to lift. Now hold the nose down to prevent it from going up any further, and the case will now try to twist as well. In fact, the nose will not go straight up, but will try to rotate in an arc. This is because there is torque acting on the diff in 2 axis (fore/aft and side/side). Here's another mental experiment: consider the force exerted by the torque from the drive shaft (driven of course by the engine) when you start to let the clutch out in 1st gear with the parking brake set. In order for everything to stay in one piece, there has to be an equal and opposite force to counter act it (otherwise things would move to the point they broke). Besides the diff, what else in the rear end could possibly exert the opposite force? There is nothing. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 20, 2006 Share Posted November 20, 2006 Thanks for the help Zmanco. Here is another way to say it: The rotation of the driveshaft is perpendicular to the centerline of the car. So that is a side to side torque. The ring and pinion convert that torque to be on the fore/aft plane instead of the side/side plane. With me so far? When there is a lot of resistance in this conversion process, the byproduct is torque. Without resistance, you have no torque, right? So the torque on the driveshaft makes the differential case want to spin. The mustache bar keeps the diff from just doing a barrel roll under the car. Once that rotational torque has been handled, then the next one is at the ring and pinion. The pinion wants to crawl up the ring gear rather then move the car forward. Hold the nose of the diff down limits the loss of torque thru the lifting of the diff and now the power HAS to go thru the gears and out to the axles and will actually drive the car. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted November 20, 2006 Share Posted November 20, 2006 The moustache bar only sees downward force/torque, not twisting side to side. If the engine is rotating in one direction, the diff will try to rotate in the opposite direction. That is why a solid rear axle car will try to lift one wheel. Noticed Jon just beat me to it. Quote Link to comment Share on other sites More sharing options...
Clifton Posted November 20, 2006 Share Posted November 20, 2006 The diff will not barrel roll. Look at an S130 mount it is one bolt, not a 3' wide mustache bar. The diff will rotate opposite of the torque that is being transmitted which is the halfshafts. There is a ring and pinion that transmitts the torque THROUGH the diff. If you were to stop the transmission of torque through the diff and have it be applied to the diff itself, maybe from a catastrofic ring and pinion failure or welding the pinion flange to the diff itself, then the diff would be recieving the transmitted torque. In that case, yes it would want to roll and twist the directing of the driveshaft. If it were as many on here believe, high torque solid axle vehicles would have zero traction on the right rear tire. It's just not the case. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted November 20, 2006 Administrators Share Posted November 20, 2006 The diff will not barrel roll. Look at an S130 mount it is one bolt, not a 3' wide mustache bar. Thats because the nose of the diff is solid mounted to the subframe. In other words, the subframe now does the job the mustache bar used to. Quote Link to comment Share on other sites More sharing options...
Clifton Posted November 20, 2006 Share Posted November 20, 2006 I give 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.