Bushings: Which Rubber and Which Poly to maximize comfort and performance

[Greeko]

hey guys,

 

I am in the process of pulling apart all my lower control arms, steering linkage, rear diff and moustache bar..

I am running a 1JZ with 340whp, an eibach upgrade springs with kyb shocks,

 

 I need to replace all my bushings but am kind of stuck as to which way to go.... Please bear in mind I want this as a daily driver with some track days. I don't want my car to rattle, sqeak and feel its vibrating all the time yet I don't want it to be super sloppy.

 

Has anyone done a hybrid bushing replacement? Like some rubber and some poly?  I would really appreciate some feedback.

 

 

[Miles]

Do all of the bushings with polyurethane except the T/C rod.  Use stock rubber bushings for the T/C rod. Other than the T/C rod do not mix rubber and poly bushings. Search the suspension forum if you need to know why.

 

I did mine over ten years ago along with Tokico blue struts and Arizona Z Car springs (front 180lb/in, rear 200lb/in). Car with SBC 350 sits at stock ride height.  Car is very stable on the street and in the mountains.

 

My poly bushings have never made any noise and the car is very comfortable in traffic and long road trips.

 

Suggest you search the suspension forum for more info and installation instructions.  Many many threads to look at.

 

Ignore all of the drama about noise and harsh rides - most of it is subjective and/or hearsay.

Edited December 31, 2016 by Miles

[z mouse]

I changed all my suspension bushings to poly two years ago. Moustache bar and t/c rods are only rubber bushings left in car.Also put grease fittings everywhere.Big improvement,no squeaks.The poly kit fit and installed great.

[grannyknot]

Rubber bushings get a bad reputation I think because the first time we drove our Z's they handled like mush because of the 40 year old stock bushings in them, new rubber bushings are actually pretty firm and are great for a daily driver.

After wading through most of those many many threads that Miles mentioned, this is the combination I came up with.

An R/T mount for the front of the differential with a poly snubber at the top and stock rubber mount on the bottom,

poly for the moustache bar, poly for all the sway bar mounts and the steering rack mounts, every other bushing is new stock rubber. It works for me, no hash ride or vibrations and crisp handling.

Special note for the T/C rod bushings, I tried poly and the ball and socket and IMHO they are both for track cars. I went back to new rubber and love it.

 

[Greeko]

Thanks so much for the responses guys! I really appreciate the feedback.

There is a LOT of info from guys who heard from someone else. Nice to hear from people who actually installed the product!

Good to see lots of responses from the Canadian guys!

[seattlejester]

Good god I love this forum, I tried to tell someone not to use poly bushings in the TC area and got called all sorts of names.

 

I did poly pretty much everywhere except Gmachine Spherical Bushing kit for the TC rods. Just make sure you grease up the bushings well and you won't encounter any squeaks really.

 

One thing I have been told and tried to adhere to is to match bushings for the drive line. If your front diff mount is rubber then keep the mustache rubber, if you go poly in the rear then make sure to go poly for the front. 

[Greeko]

Good god I love this forum, I tried to tell someone not to use poly bushings in the TC area and got called all sorts of names.

 

I did poly pretty much everywhere except Gmachine Spherical Bushing kit for the TC rods. Just make sure you grease up the bushings well and you won't encounter any squeaks really.

 

One thing I have been told and tried to adhere to is to match bushings for the drive line. If your front diff mount is rubber then keep the mustache rubber, if you go poly in the rear then make sure to go poly for the front. 

 

That Makes sense,

 

I was worried about rubber because I am running well over double the Horsepower. I did not however want to feel EVERYTHING!...

 

I thought you cannot get the forward diff mount in anything but Rubber...

Diff Insulator (55415-N4301)

http://www.ebay.com/itm/1972-1978-Nissan-240Z-260Z-280Z-Rear-Differential-Mount-Insulator-OEM-NEW-/191579574506

 

 

 

Rubber bushings get a bad reputation I think because the first time we drove our Z's they handled like mush because of the 40 year old stock bushings in them, new rubber bushings are actually pretty firm and are great for a daily driver.

After wading through most of those many many threads that Miles mentioned, this is the combination I came up with.

An R/T mount for the front of the differential with a poly snubber at the top and stock rubber mount on the bottom,

poly for the moustache bar, poly for all the sway bar mounts and the steering rack mounts, every other bushing is new stock rubber. It works for me, no hash ride or vibrations and crisp handling.

Special note for the T/C rod bushings, I tried poly and the ball and socket and IMHO they are both for track cars. I went back to new rubber and love it.

I am curious to see what Grannyknot did for the R/T mount for the front of the differential with a poly snubber at the top and stock rubber mount at the bottom....

[seattlejester]

I ran the stock datsun style engine mounts with my 7m which by all accounts according to the internet was pushing 300+hp, they look pretty much brand new still. Avernier I think was saying he solid mounts all of his JZ swaps and barely feels it so I don't know how far that goes.

 

I had poly bushings all around and all the squeaks and rattles were user error, you do have to make sure to loctite/thread lock all the bolts with the stiffer bushings as they seem to like to come undone a bit easier then with rubber bushings. 

 

I went mostly solid rod ends now and I have to say, I feel a little more, but hear a lot less. 

 

For my diff I did poly in the mustache bar and a poly mount using the RT mount and a poly or rubber cone type thing on the bottom on the bottom cross member. Not a nissan part it is an energy suspension shave to desired thickness piece

 

Kind of like the piece below, but much fatter I can't recall the part number or the actual name.

https://www.summitracing.com/parts/ens-9-9101g?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-energy-suspension&gclid=CNvw_tvhptECFcZhfgod_RUCqQ

[Greeko]

I ran the stock datsun style engine mounts with my 7m which by all accounts according to the internet was pushing 300+hp, they look pretty much brand new still. Avernier I think was saying he solid mounts all of his JZ swaps and barely feels it so I don't know how far that goes.

 

I had poly bushings all around and all the squeaks and rattles were user error, you do have to make sure to loctite/thread lock all the bolts with the stiffer bushings as they seem to like to come undone a bit easier then with rubber bushings. 

 

I went mostly solid rod ends now and I have to say, I feel a little more, but hear a lot less. 

 

For my diff I did poly in the mustache bar and a poly mount using the RT mount and a poly or rubber cone type thing on the bottom on the bottom cross member. Not a nissan part it is an energy suspension shave to desired thickness piece

 

Kind of like the piece below, but much fatter I can't recall the part number or the actual name.

https://www.summitracing.com/parts/ens-9-9101g?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-energy-suspension&gclid=CNvw_tvhptECFcZhfgod_RUCqQ

 

Did you use the stock front Diff insulator (55415-N4301) with with poly Mustache bar/bump stops?

 

I really appreciate the feedback. the link didn't work.

If you need any help with the JZ swap let me know, I have her running really well and im just across the border if you need some spare parts.

[NewZed]

It's probably just a bump stop.  The parts store usually have them in on the racks.  They're typically used on the ends of old-timey traction bars.

 

Here's some - https://www.amazon.com/s/ref=nb_sb_noss_2/166-8275892-3179244?url=search-alias%3Dautomotive&field-keywords=Energy+Suspension+bump+stop

 

Here's the GM mount that goes on top of the diff, bolted to the RT mount.  https://www.amazon.com/Energy-Suspension-3-1158G-Transmission-Mount/dp/B008SA69DG

 

Summit links are getting redirected.

[seattlejester]

Hmm, interesting, I'll edit the summit link when I find the actual part number on a different website.

 

For the front of the diff I used the RT mount that has the ES bushing up top the GM transmission mount that holds it from the top. On the bottom cross member that usually harbors the diff insulator, I removed that mount and put in a bump stop type poly bushing. The diff will hold itself up without the bottom support, but I figured while I was there I would capture the diff. 

 

Yes the bump stop that newzed link is similar, I'll have to dig up what it was, but it was recommended to me and I ordered it. I think it had like 4-6 steps when I got it, now it looks like a hockey puck with a divot out of it. Once I made the major cut, I just used a bowl brush to grind away the unwanted material until it hugged the bottom of the diff nicely.

[Evlevo]

My 2 cents would be if its a bushing you can upgrade to poly (except the tension rods) id do it. My old silvia was mostly poly, except the subframe bushings which used lock collars, and coilovers. Still rode super smooth. I had another S13 which had solid engine mounts, which i didnt like. That was a bit too much.

[Greeko]

Hmm, interesting, I'll edit the summit link when I find the actual part number on a different website.

 

For the front of the diff I used the RT mount that has the ES bushing up top the GM transmission mount that holds it from the top. On the bottom cross member that usually harbors the diff insulator, I removed that mount and put in a bump stop type poly bushing. The diff will hold itself up without the bottom support, but I figured while I was there I would capture the diff. 

 

Yes the bump stop that newzed link is similar, I'll have to dig up what it was, but it was recommended to me and I ordered it. I think it had like 4-6 steps when I got it, now it looks like a hockey puck with a divot out of it. Once I made the major cut, I just used a bowl brush to grind away the unwanted material until it hugged the bottom of the diff nicely.

 

So something like this:

http://www.technoversions.com/DiffMountHome.html

[grannyknot]

So something like this:

http://www.technoversions.com/DiffMountHome.html

That is the exact R/Tmount and snubber I used with stock rubber mount underneath.

[seattlejester]

That guy is about 45 minutes away from where I live, my friend worked at a shop near there and picked it up for me so yes, exactly that one lol.

 

I have the red bushing pictured up top with that tiered cake thing on the bottom where the original rubber mount is.

[Greeko]

That is the exact R/Tmount and snubber I used with stock rubber mount underneath.

 

That guy is about 45 minutes away from where I live, my friend worked at a shop near there and picked it up for me so yes, exactly that one lol.

 

I have the red bushing pictured up top with that tiered cake thing on the bottom where the original rubber mount is.

 

Nice!

I was contemplating doing this or using the GM mount and just mounting it from above without using the bottom mount.  He sells a kit for this too.  I wonder if it will make it super stiff though... Any reason you guys didnt go for a single mount point up top without using the bottom insulator?

Edited January 5, 2017 by Greeko

[NewZed]

The bushings on the diff are mainly to avoid or remove the "clunk" during shifting that is common from a loose diff mount.  The ES bushing has interlocking metal pieces inside so the bottom bump stop is not necessary.  The original reason for RT to develop his modified mount was because he kept breaking the stock mount, behind a powerful small block chevy engine.  It's actually "wrong" for an L6 application when used with the overhead GM mount because it lowers the diff nose compared to stock.  It fixes the clunk but probably adds a little drive shaft vibration.  When it's used with a bump stop on the top and the stock mount on the bottom it's essentially just a movement snubber, not really a "mount".

 

The urethane bushings in the mustache bar also help with the clunk removal but are known to transmit diff noise in to the cabin.  Many people go back to rubber due to the extra diff whine they hear after replacing the old worn out rubber.  Beware.

 

Many people go to polyurethane because it's cheaper than the stock rubber.  There's no huge benefit, overall, to converting from rubber to polyurethane.  You might consider evaluating each step individually before going crazy.

[seattlejester]

Hmm I think I will have to disagree on a couple points.

 

I am not sure about the RT mount, but at least the Technoversions style of it doesn't seem to lower the nose of the diff more then stock, I didn't encounter any twisting forces putting the differential in. Drive shaft flange was close to level or within the operating angle range for a driveshaft when I measured mine to get made, although I had my diff installed wrong previously the mounting planes weren't changed with the correction. With the mustache poly bushings it is pretty sensitive to deflections, I had to line up everything and jack it up slowly or it would bind. I suppose if you mounted the mustache the bar itself would be capable of deflecting quite a bit due to its construction.

 

I would say there is a fairly noticeable difference with polyurethane bushings in the mustache bar, I'll look for it, but there is a video of an EVO out there with a camera under the car and you can see the diff move drastically on power and off power, especially on shifts. In the scheme of things probably not a thing most people will notice when just normally driving, but I find that pre-movement a bit nauseating as the force comes a bit after the input. 

 

I did the GM mount up top as the nose wants to come up when you are on the throttle the GM mount is supposed to be mounted to the bottom of a cross member so it is working upside down, while the casting of it kind of supports the tabs being pushed down when it is mounted correctly, mounted upside down the tabs kind of do bend away polyurethane with just gravity. I added the snubbing piece (good name for it) to give support while it is not under load. 

 

I will agree though it would be a waste to poly mount things if NVH is your concern. Newzed is right, the poly kits are popular as replacing with stock bushings can be a real chore requiring quite a bit of press work if you can even find all the rubber bits. I have a mostly stripped interior, 3 inch exhaust with a bullet muffler, and a whiny fuel pump, so I have no reference for hearing diff whine really. I've added some sound deadening since then and I find it acceptable, but I have a daily driver so I don't have to live with the car.

[NewZed]

The lowered nose doesn't seem to cause big problems.  It's just one of those interesting asides.  Here's a couple of links, see #5 in the first one.  Most of the designs were copied directly from RT's first drawings, with minor modification.

 

http://forums.hybridz.org/topic/85384-rt-mounts-are-ready-for-shipping/

 

http://forums.hybridz.org/topic/50209-ron-tyler-style-front-diff-mount/

[seattlejester]

Hmm you are just a wealth of knowledge, that makes sense though if it was originally designed for a transmission that hangs lower or at a different angle.

 

I will say that the Technoversions mount is quite a bit taller. bj has 3.75 on his height while the Technoversions lists 4.9 on his. So maybe it moves it back into an unlowered orientation?

 

Edit:

Also found this little tidbit at the bottom.

Acknowledgements: This style differential mount is based on a design by Ron Tyler, and consequently is often called an R/T Mount or RT Mount. The mount offered here is similar to the original design, but also incorporates some improvements by "Datsun Dave," with further refinement by TechnoVersions.

Edited January 5, 2017 by seattlejester