Reliability issues with solid transmission mounts

[NRXRaptor]

I'd really like to get solid or stiffer transmission mounts/supports because the whine I've heard in some youtube videos is really appealing to me. My question is: Are there any risks in adding a solid transmission mount without installing anything else? I've read in other places that the housing or casing might break, but that was in a forum for a different car. I'm also strongly considering getting the STI engine mounts as well. Any feedback is appreciated and pardon me if there is already a thread with this information, as I'm not very good at navigating forums.

[gramicci101]

I don't think there are actually solid mounts. They might be stiffer rubber or urethane, but they still have compliance.

Get:
Whiteline transmission mount insert
Whiteline diff carrier bushing inserts
Whiteline subframe insert
Some brand of upgraded rear shifter bushing. Energy suspension is pretty inexpensive.

You'll have all the gear whine you might want. And you'll also take a lot of slop out of the drivetrain. While you're installing everything, replace the OEM shift springs with MTEC shift springs. Doesn't increase gear whine, but it makes the shifter feel better.

[nikitopo]

Are you building a dedicated track setup? Do you have plans to FI the engine? Why to change the transmission or engine mounts? For a road based car, only the rear subframe inserts are nice to have. There are also some bigger bolts that will stiffen the subframe a bit more. That's all.

[Turdinator]

I have the TRD motor and gearbox mounts. The certainly reduce the movement but there is only a small increase in noise. 90% of the time you wouldn't even know I had them. Since you are looking for the noise I'd suggest you find urethane mounts or maybe the cusco mounts as I've heard they increase the NVH a lot. I also suggest you do the two motor mounts with the transmission one as the motor and trans move as one under load.

[NRXRaptor]

Thanks for the replies everyone. If you search solid transmission mount frs on youtube the first video by AMBus Drift demonstrates his install of solid purple transmission mounts by Sideways Fab. He removed the oem transmission mount in order to do so. His car is a dedicated drift car and I understand (loosely) that solid transmission mounts can help with some of his technique. His car's interior is gutted, but in other videos where users install solid transmission mounts the whine is still there.

With my amateur research I thought that it would be a good idea to get firmer engine mounts at the same time as solid transmission mounts and I am glad you guys have confirmed my suspicions. Maybe even get the engine mounts first because the engine is what is causing the rotation in the first place.

I know some people don't like it when people put race car upgrades on their not race car but I really like walking up to my car and going, "That's a cool car!"

Again, thanks for the tips!

[nikitopo]

Originally Posted by NRXRaptor

His car is a dedicated drift car and I understand (loosely) that solid transmission mounts can help with some of his technique.

Can help to slide and as you said this was a dedicated drift car.

Originally Posted by NRXRaptor

I know some people don't like it when people put race car upgrades on their not race car but I really like walking up to my car and going, "That's a cool car!"

First of all you should have a safe car. Do you want to have a "cool car" and drive as a chicken, because it'll slide even in cases you don't want it?

As said earlier, going too stiff is not optimal for a road car.

[gramicci101]

Sliding out has nothing to do with how stiff the drivetrain mounts are. That's purely suspension. If you throw 12K springs and massive swaybars on there, then yes. The suspension can't flex and the tires will break loose. If you put solid drivetrain bushings everywhere and leave the suspension alone, all that'll happen is you'll take all of the compliance out of the drivetrain and greatly increase NVH. You may increase wear on actual drivetrain components because the housings can no longer move under load and all the stress goes on the components themselves. You might chirp the tires if you shift like a gorilla, because the drivetrain can't flex to absorb the shock of a rough shift.

Op, the second two letters of NVH are vibration and harshness. The engine moves around a lot. Putting it on sort of stiffer mounts such as Perrin or STI will minimize its movement at the cost of increased noise, vibration, and harshness being transmitted to the rest of the car. If you go with much stiffer mounts such as Cusco, it can quickly become intolerable. A lot of people who initially went with Cusco shortly downgraded to Perrin, STI, or OEM. Most people have only done engine mounts if they've installed an aftermarket header and overpipe and the pipes are hitting the subframe when the engine flexes.

The transmission is connected to the engine, yes. So I wouldn't do solid mounts on anything. You want a little bit of compliance in the system to account for shock to the drivetrain, occasional clumsy shifting, normal movement under load, etc... OEM drivetrain bushings are very soft because they're a tradeoff between effectively transmitting power to the wheels and making too much NVH for the occupants. It's up to you to decide if that line is drawn in the correct place for your own preferences. For me, it isn't. When the engine twists under load I can feel it in the shifter. When I shift I can feel the diff move around. I don't like that. The Whiteline transmission bushing insert (there are others, that's just the one I bought) fixed the first issue. The transmission can still move, it just takes more effort to do so. More power gets sent to the diff instead of being used to move the transmission around. I also threw in an Energy Suspension rear shifter bushing, because it's $20 and I was already under the car. I can't even say if it helped with shifter feel or not. It's stiffer than OEM, but how much did that part really move anyways?

For the diff, I went with the diff carrier inserts, but not the subframe inserts. Either one will reduce, but not eliminate, the OEM bushing compliance. Watch the below video; it's what convinced me to go with the diff carrier inserts. It's officially for Whiteline's subframe bushing inserts. Watch how the subframe mounting points move before and after bushing install. It didn't move a lot to begin with and now it moves less. Still moves, just not as much. Then look at the two big vertical bushings in the middle of the subframe behind the swaybar. Those things flop around like professional soccer players. Those two bushings and two smaller bushings at the front of the diff are the diff carrier bushings. If you shift heavily and you hear a clunk from the rear of your car, you're hearing the diff flop around on those bushings. Whiteline's inserts remove a lot of that compliance, but not all of it. Putting power down to the wheels has gotten much smoother since installing those bushings, at the cost of a little gear whine at low speeds. At high speeds road noise covers the whine. I didn't do both sets of bushings because I specifically wanted to leave a little compliance in the system and not significantly increase NVH.

[ame]https://m.youtube.com/watch?v=IDfJ_zYFPcs[/ame]

If you're after that super loud mechanical whine that you hear from actual race cars; what you're hearing are straight cut gears in the transmission meshing. Most consumer cars have helical cut gears. Straight cut gears are much stronger and can take a lot more abuse, which is why they're in race cars. They don't care if it's super loud and harsh, because performance comes before comfort. In consumer cars, it doesn't. Very few people would buy a street car that sounded like that from the factory.

[NRXRaptor]

Thanks for the info dump Gramicci101. Tons of useful info. I have definitely heard the differential make that clunking noise around corners, especially bumpy ones, though that might just be the differential doing its job cutting power to the inside wheel as it bounces up. Watching the shifter wiggle around is pretty annoying, too.

Honestly I'll probably copy your setup if you'll let me. I've also come across posts and videos of people regretting putting very stiff or solid engine mounts in their car, convincing me to get the STI engine mounts if I upgrade them at all. From what I gather they are a smallish but significant improvement from OEM. I wish I had the skill to do stuff to my car like you do, but at least I managed to replace my fog lights and do a bit of wiring (barely) for some new brake lights.

Thanks again

[nikitopo]

Originally Posted by gramicci101

Sliding out has nothing to do with how stiff the drivetrain mounts are. That's purely suspension. If you throw 12K springs and massive swaybars on there, then yes. The suspension can't flex and the tires will break loose.

Suspension should be considered as a complete system. Tires play a role in the equation, the same holds for bushings. Think about handling on an uneven road especially at the rear. If you have stiff tire sidewalls or stiff bushings, then it is not optimal. Our cars are pretty light at the rear and lifting of the ground can happen pretty regularly (i.e. losing grip).

Whiteline provided this video years ago and there is considerable flex in the bushings when cornering. This is another evidence that handling is not purely a suspension thing.

[gramicci101]

Originally Posted by NRXRaptor

Honestly I'll probably copy your setup if you'll let me.

Hahaha, what am I going to do, tell you no?
For drivetrain mods I have:
Whiteline diff carrier bushing inserts
Whiteline transmission insert
Energy Suspension rear shifter bushing
MTEC shift springs (very highly recommend these. It strengthens the shifter's return to center.)

If you're after gear whine, do the diff bushing inserts. If you like those but you'd like a little more, then do the subframe inserts.

Originally Posted by NRXRaptor

I wish I had the skill to do stuff to my car like you do..

I can do a bit of maintenance in my garage, but nothing like some of these guys. None of those mods were difficult, so if you have the space it's a great way to learn. There's a lot of good info in the DIY section. If you're looking for a shop around LA, go to CounterSpace Garage. They are awesome. They're also a very active vendor on here.

[gramicci101]

Originally Posted by nikitopo

Whiteline provided this video years ago and there is considerable flex in the bushings when cornering. This is another evidence that handling is not purely a suspension thing.

No, it's evidence that the designers engineered compliance into the system to reduce NVH and stress. Plenty of sports cars, and probably most race cars, have their diffs bolted to the chassis, either directly or with very minimal bushings. Beatrush and Cusco don't even bother reinforcing those bushings; they just give you a metal bar to bolt across them and bolt to the subframe. CSG has a package that replaces every rubber bushing in your suspension with a pillow ball mount. Camber plates replace the flexible rubber top mount with a metal plate. The only things that *need* to flex when the suspension cycles are the springs and swaybars. Struts compress and extend; they don't flex. Control arms rotate around fixed points. There's no performance reason for those points to flex. Suspension bushings are definitely a part of the suspension system as a whole, because of the compliance they introduce into the system. But they're for reducing NVH, not for performance. That's why pillow ball LCAs aren't allowed in lower SCCA Autocross classes. Drivetrain bushings are not a part of the suspension system. They're for buffering the drivetrain against shock and for reducing NVH.

[NRXRaptor]

Maybe I'll work up the courage to do so then if it is simple like you say. Would I need a torque wrench to do so? I've been strongly considering getting a torque wrench because I want to be able to replace my headers, front pipe and over pipe myself. Exhaust is literally remove and replace. I can't hardly mess that up lol.

In the meantime I'll have to take the front bumper off to install the new headlights I ordered.

Thanks again

[gramicci101]

You definitely need a torque wrench and metric socket set. The MTEC springs require a specific socket and some extensions and u-joints. People have messed up the threads on that one, so maybe leave it for later.

You need a jack and jack stands if you want to get under the car. Once the car is up you'll need the jack to support the front of the diff while you unbolt it. I did my diff one bolt at a time and never completely unbolted it.

Read the DIYs and the instructions that come with the parts a few times before starting, take your time, and don't stress. If you don't understand a step, ask about it before you start.

[nikitopo]

Originally Posted by gramicci101

No, it's evidence that the designers engineered compliance into the system to reduce NVH and stress. Plenty of sports cars, and probably most race cars, have their diffs bolted to the chassis, either directly or with very minimal bushings. Beatrush and Cusco don't even bother reinforcing those bushings; they just give you a metal bar to bolt across them and bolt to the subframe. CSG has a package that replaces every rubber bushing in your suspension with a pillow ball mount. Camber plates replace the flexible rubber top mount with a metal plate. The only things that *need* to flex when the suspension cycles are the springs and swaybars. Struts compress and extend; they don't flex. Control arms rotate around fixed points. There's no performance reason for those points to flex. Suspension bushings are definitely a part of the suspension system as a whole, because the compliance they introduce into the system. But they're for reducing NVH, not for performance. That's why pillow ball LCAs aren't allowed in lower SCCA Autocross classes. Drivetrain bushings are not a part of the suspension system. They're for buffering the drivetrain against shock and for reducing NVH.

All the things you mentioned are perfect for auto-x or track usage. For road usage, such setups are more dangerous depending how extreme a user will go.

Check here a video I was watching yesterday about tire sidewall size. It is related with your statement I made in bold. They were checking tires of same compound and width but different sidewall on 17", 18" and 19" rims. On a dry track the 17" tires perform worse and the 19" perform best. However, on a wet track it was the other way around and the 17" tires outperformed the other ones. Even the reviewer didn't expect this result. One argument was that the 17" tire had more flex and could pump out the water from the contact patch better. The other argument was that the more tire flex helped with the slippery conditions. You can imagine a wet track to have similar properties with a bad quality road pavement. Same slippery situations. It should be clear that the designers engineered the car as is not only for compliance into the system and to reduce NVH or stress. It was engineered like this also for better road performance.


[ame="https://www.youtube.com/watch?v=mPyg3ilw3KU"]The differences between 17, 18 and 19 inch tyres tested and explained - YouTube[/ame]