Engine mounts, Transmission bushing/ support mount
 

Hello everyone and greeting from Cyprus!

I'm new to this forum, and I'm quite glad to be here.

I tried searching for some answers to my issue but there are so many topics that i got lost over and over.

If this topic already exists, by all means you can close this one and maybe guide me to the where i need to be.

Basically we all know how harsh 2nd and 3rd gearing can be on these cars when stock. At least on pre-facelift models.

In my case I own a 2015 GT86 for almost 2 years and really wanted to smoothen out the shifting of those 2 gears.

I found various solutions online such as change to motul oil, mtec spring, rear shifter bushing, engine mounts, transmission bushing, transmission support mount etc. etc.

The ones that I've done so far are the motul oil and the perrin rear shifter bushing which does help but not that much. So i decided to buy the Cusco engine mounts, the perrin transmission support mount and the whiteline transmission bushing. I did get warned that there would be some vibrations in the cabin of the car but upon finishing installation yesterday, much to my surprise those vibrations are not "some", it feels like I'm driving a truck and since this is my daily driver i cannot tolerate all this noise and vibrations.

I would be really glad to know if i remove any of these 3 components if the vibrations will be gone. Should i remove the mounts and keep the support mount and bushing? should i remove the bushing only? or take everything out and put stock ones back on?

I would highly appreciate any input here.

Thanks in advance guys.

Regards
Giannis K.

those Engine mounts create a ton of NVH. Trans will add some too.
Harder mounts for a daily is not ideal. I ran some on my integra and learned that lesson.

Go back to stock mounts or go STi for OEM plus . They're stiffer without being harsh.

The engine mounts are causing all the NVH, the increase in NVH from the other two is almost negligible. I would recommend STI mounts. I have the Perrin mounts and they still produce a significant amount of NVH compared to stock, especially at idle.

Having said that, in regards to smooth shifting, I've done all of the mods you've done which never helped, however fitting a one piece (aluminium) driveshaft made shifting smooth. It no longer grinds or catches, just shifts smoothly and precisely.

Ditto on the mounts, at this point I would goto STi mounts, no point in going to OEM when you have everything else.

Mtec shifter springs, Shifter bushing, Whiteline transmission insert, and most importantly, whiteline diff inserts. I put all of these in and the shifter feel is absolutely night and day difference. Even in the cold brutal cold (-15C) the shifter is smooth after one or two shifts. I noticed the biggest difference in the diff inserts, trans mount insert and the Mtec shifter springs.

What are you running for transmission oil? Last time it was changed?

Also recommend the one piece drive shaft

Sent from my ONEPLUS A5010 using Tapatalk

Maybe a good carbon one, otherwise hell no. Even the DSS carbon has issues because of it's diameter to weight. My DSS aluminum one has terrible vibration even after being rebalanced. I am going to put a stocker in the car and cut this one up so it can't hurt anyone again.

which point(s) in the rpm range are you getting vibrations at? Mine starts at 140km/h (87 mph)

At first it was around that same speed, around 90mph. I used some weighted tape about a third of the way from the transmission output and it went up to around 100mph before it would start vibrating. Rebalancing got it up to around 105mph. It is speed related(or more the RPM of the driveshaft). There is a thread on here somewhere discussing wall thickness, and critical speed attributing to it.

Weighted tape, interesting! Never heard of it before. Which kind is it specifically and how much of it did you use? May try it myself. Thanks in advance.

I used this.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Clean the driveshaft very well and make sure you wrap it in the proper direction. Warm it up a bit and roll some out ahead of time, the foil is very thick and if you are not careful you can cause a crease in it. Then it will not lay down evenly. It is quite a bit easier to do with the driveshaft out of the car. Run it in bands about a 1/3 away from one end of the shaft, I don't believe which end matters too much. I can't remember how many wraps I did, it was a while ago. This was suggested to me by a gentleman who I met at a track day that was an engineer for Boeing, specifically in harmonics and vibration damping. With some experimenting I am sure you could get better results then I did. I just got tired of messing with it.

OMG guys so many responses in such little time.
You guys are amazing.

From all the answers i've read the most common answer i see is go for STi mounts.

As for the mtec shifter spring i will definitely get that since it was also recommended from other forums and groups that i've read on.

I already have the perrin rear shifter bushing and whiteline transmission bushing installed on the car, oil was changed 2 weeks ago but i honestly cant remember the oil brand need to ask my mechanic.

As for the vibration i mostly get them on low rpms between 1k to 2.5k. Most of the vibrations are while i'm starting to accelerate from idle. Don't get me wrong the feel it gives that you are connected to the car is amazing but still the car has become quite harsh to drive for a daily. It also happens if lets say I brake while in 3rd to get past a bump and don't downshift to 2nd which drops the RPMs to around 2K so yet again those ranges of RPMs. If i'm cruising on the freeway at 3k rpms then its all fine.

As for the differential inserts am i looking at the right thing here?
There's mount bushing and outrigger bushing which one are you talking about @RayRay88

https://ukwhitelineperformance.com/p...23-bushing-kit
https://ukwhitelineperformance.com/p...25-bushing-kit

Thanks once again guys for the info, highly appreciated.

Oil makes a good bit of difference in shifting, especially cold. I like Redline MT-90, some others are running a variety of oils with good results, Pennzoil Synchromesh, Motul Gear 300.

KD 925, Inserts. :thumbup:

Hey can I ask a few questions? I drive a 2014 BRZ A/T, only bolt on mods and a tune, nothing crazy. (Front pipe, EL catless header, Exhaust, drop in filter) nothing crazy. I need new motor mounts. I've done some research on these forums and it seems that:

-If you have some mods, you shouldn't replace your mounts with another set of OEM mounts, is that right?
-Cusco and Perrin add a lot of NVH which is something I do not want because this is my daily.
STI mounts add very little NVH, but they are still recommended for a car with some mods. They are almost like OEM+, so it seems like this is the route I should go with correct?

Now with the transmission mount. You don't actually need to replace the entire thing, just the rubber insert is that correct? Does it matter if I have an A/T? I'm considering getting the Whiteline insert. But will that add any NVH? I'm not clear on that for the transmission mount.

Thanks for your help, I just want to make sure I buy the best thing for my preference. Sorry if these are silly questions, I'm just not 100% clear.

Don't let the car go below 2k unless it is in neutral. And in 5th and 6th keep it above 2.5k. Every one of these sounds like a farm tractor at those low revs.

It really is personal preference. The best way is to find someone local to you with those motor mounts and get a ride. The firmer it is, the more NVH you will experience. There is no way around that.

Thanks everyone once again for your time and effort :)

Appreciated.

I found all the answers i was looking for.

I'm about ready to install the DSS Aluminum Driveshaft. Do you know if I should change the output carrier bearing on the tranny too so it'll probably get a better seal? I don't want gear oil leaking everywhere.

I never did, just give it an inspection at least and replace as needed.

Thank you! :party0030:

I'm thinking about doing the Sti engine mounts, Whiteline Trans Insert Bushing, Perrin Support Mount, Perrin Shifter Mount Bushing, Whiteline Positive Traction kit, and Whiteline Support Outrigger Insert too as a daily. Let me know how the NVH is once you put in the STI mounts.

Ive heard the Perrin Trans Support Mount is the 2nd most NVH, and Whiteline Support Outrigger is 3rd out of what you have done. I've also heard that the STI Trans Mount does the same as the Perrin Support Mount, but doesn't increase NVH.

I have the sti engine mounts, sti trans mount, perrin shifter bushing, whiteline front + rear diff bushing inserts (outrigger) kit (kdt925), and the whiteline positive traction kit (rear subframe bushing inserts, kdt922). Of these, the most severe was the rear subframe bushing inserts, surprisingly. nvh increased moderately, but worse of all it made the rear of the car substantially stiffer. I installed HKS SP coilovers before the inserts (8k square), and the inserts made the rear stiffer than the coilovers themselves. everything else increased the NVH just slightly, and cumulatively, and absolutely transformed the car. It is the PERFECT balance, not too harsh but also you get enough feeling and feedback like a racecar. Could not be happier.

Also STI trans mount is better than perrin support mount + whiteline bushing for transmission. does a better job and is less harsh.

Do you recommend both diff bushing sets 925 and 922? or just the 925 if the 922 makes the rear end too stiff?

I honestly don't think the 925's do that much. They take up some windup in the drivetrain, but moneywise, not the biggest bang for the buck in the amount of work you need to do to install them. The factory bushings are pretty stiff and if you look at the distance between the outrigger mounts, and the amount of deflection in the stock bushings, I don't really feel you are gaining that much.

I have had my car with solid subframe mounts and the 925's, then traded diffs and am back on stock bushings, can't tell that much of a difference.

I don't recommend the Perrin transmission mount 'bushing' bolt thing.
It adds a stupid amount of NVH for probably very little benefit. I'm going to remove mine when I get a chance and just leave the Whiteline bushing insert.

Yup, I took out my Perrin tranny mount. Awful amount of NVH. I run their shifter bushing with Whiteline trans mount.

I have both. At present, only the 925s are installed. I'm a little leery of increasing NVH to an intolerable level and decided to take it in stages. The 925s reduce drive train wind-up and seem to make shifts a lit more responsive. It's a hard call on the degree to which they add to NHV. At roughly the same time I installed them I did a pretty thorough sound deadening project in the trunk and the car is substantially quieter from that. All in all, if given the choice, I'd do the 925s again.

The 925 and 922 do very different things. The 925 removes slack from the drivetrain, making power delivery more immediate/responsive. The 922 makes the rear feel more connected to the ground, helps with problems like wheel hop, but it also makes it substantially stiffer. It is impressive how much slack the stock rubber subframe bushings absorb, they were really well designed to make the car street friendly. I don't regret it, but I do wonder how much more stress I'm adding to the chassis by removing that slack, especially in the unforgiving city roads. Control of the rear is even easier now due to better feel and no wheel hop.

The 925 is much, much easier to install than the 922, and I would still install it again. 922 is much trickier because you want to make sure the subframe doesn't drop on your head or that you don't strip the subframe bolts. It took me awhile to get the guts to install it to be honest. I would probably still do it again, but think about what you want your car to feel like after everything is said and done.

Putting my experience in, I have a 130k mile car that I've been more slowly refreshing. A few years ago I started getting so much drivetrain lash that it was difficult to shift from 1st-2nd, the transmission would bash into the engine, so I put in the "positive shift kit" and it did a lot of good for the car.

Then after a year or so I started noticing stuff like my rear-end taking longer to settle after corners or changing lanes at speed, and also felt like my driveshaft or subframe twisted a bit under hard acceleration and having one tire grip more than the other. I procrastinated on it, but finally this week took the "positive traction kit" and did a partial install, first installed the subframe bushings. This made a huge difference in driveability, though there are some disadvantages because the car is so much more stiff and perhaps darty. But the car shifts better and is much louder and sportier sounding because of the chassis resonance. However I began to have major lash issues in the rear, clacking and banging without the added support there.

So today I installed the diff carrier bushings and rear outrigging bushing, the last parts in the "positive traction kit.". This solved a lot of my low speed lash noises. But now the car has much more NVH, I probably need to double check my install but its got a lot of drone, buzz and rattle in my drivetrain just driving around normally 35-55 mph, and I think there's probably something else needed addressing to make the car operate best. I think my clutch, which is a replacement exedy and about 70,000 miles on it, may be making a bunch of rattle, or maybe the bearing. Or maybe its the driveshaft protesting. It does not like it when I lift throttle in a lower gear.

On the positive side. I am enjoying how easy it is to drive with the new mounts. Shifting is so much better. 4th gear shift much improved weight to it. The car drives more "efficiently" since there's less wasted energy taking off from a light. And at higher speed it feels much better, its louder, more responsive, and more fun. But there were some downsides so I might like to look into alternative parts that might be less aggressive. Getting an STi transmission mount sounds like a good idea, if it really is gentler than the whiteline insert? Or maybe I should look into pressing in fresh bushings rather than use the inserts? Please let me know what you think, or if I should look into addressing other mounts.