981 GT4 Gearbox and other mods review

[Motorhead]

Hi Omar,

Many thanks for sharing your experience on here, and good to hear that you’ve found your own ideal and unique solution to the limitations of the standard car … as you say, there are plenty of other options available to the 981 GT4 owner! You may have noted that Twinfan Dave has modified his 718 GT4 with a custom cat-back exhaust and single mass flywheel, along with some suspension mods. Are you planning any suspension mods on your GT4, and I presume that you stuck with the standard LSD?

I note that Shark Werks reckon that modifying 1st and 2nd isn’t viable financially, I think owing to the fact that the gears are integral with the shaft.

Enjoy your modded GT4!

Jeff

 

[Twinfan]

Interesting stuff, and thanks for posting []

Several folks seem to be modifying the engine of the 981 GT4 now which is the main area that the car is lacking. Bolting on what is essentially the X51 power kit and re-mapping it seems to really open it up. Adding the gearbox mods too must make it really nippy in gears 3/4/5.

I went the other way and skipped the 981 to go to a 718 which has the power already. I've then added a less restrictive silencer and a LWFW and those, combined with the extra power the car has as standard, overcome any potential gearbox issues and I find that the car pulls through them pretty darn nicely so I don't feel the need to change the ratios.

As they say, there are many ways to skin a cat and the end results are pretty similar. It's good to see another nicely tuned GT4 knocking about! See you at a track day somewhere?

 

[GraphiteGT3]

Hi all
I wanted to post this review on a couple of UK forums as I personally found it really hard to find any real world views online from GT4 owners who have been down this road themselves.

The mods were done to my 2016 981 GT4.
My history of Porsches has seen my own various 911s, and a GT4 previously. In fact recently I went 981 GT4 to 991.2 GT3 and back to my current GT4. While this may seem odd, I love the GT4 platform so much and it feels just a better mix of value vs useable power and handling for our UK roads. Loved the GT3 but felt I was paying for so much I couldn’t use and wanted back into a GT4. I share this history as a hopefully explanation that I am not chasing power and torque unnecessarily, just wanting to get to the right level.

I have just got my low-miler GT4 back from nine-excellence having had the following mods completed:
- Gearbox rebuild to change gears 3, 4 and 5 to closer/shorter ratios
- Kline 200cel exhaust manifold
- 997 GT3 throttle body and associated IPD/Plenum upgrade
- 9e tune to wrap it all together.

There's lots online about this package of mods (see Sharkwerks in the US etc) but little written by actual UK owners that I could find.

As many will know/have read, the long gearing on the GT4 is a bug-bear for many. Not as big an issue as many like to make out, but an issue all the same and I personally find you spend too long out of the power band to get the best out of the car on the road. This is particularly true when changing from 2nd into 3rd unless doing licence-losing speeds.

The gearbox mod is naturally designed to tackle this. I wont bore you with why 2nd isn’t changed but it’s a seemingly much more expensive job that no-one seems to offer. The theory is that you bring 3rd closer to 2nd so there is little to be lost changing from 2nd to 3rd and lots to be gained. Likewise 4th and 5th are much more accessible in every day driving.

The rest of the mods just help to get the best out of the 3.8 DFI engine and take the power up to the right-side of 420bhp.

Its early days back with the car but I am so pleased with the results. Everything I read on US sites about the Sharkwerks package is correct, the car feels noticeably faster through the gears, with much more useable torque and a more rewarding manual driving experience all round. I have always thought 400bhp is the sweet spot for road driving in a car of this weight in the UK, and the mid-range performance characteristics of the engine are now a little closer to a turbocharged unit but with all the benefits of it still being naturally aspirated. There's further you could go with an unlimited budget (lightweight flywheel, LSD etc) but I didn’t feel the need, and it can bring some additional challenges.

The unexpected part for me is the impact on the noise. Wow. The already-great sounding car now sounds a lot more exotic with the Kline (using the standard PSE), without adding any drone when driving in 6th or taking it easy. This was a massively unexpected bonus for me as i thought the manifold would really just add power but not change too much else. (I suspect the newer 718 GT4 has exactly the right level of power and torque but I deliberately went back to the 981 as the sound is a huge part of the mix for me - im still pretty childish with it.)

I Was really impressed with Ken and his team at 9e who were excellent in advising me on the route to go and through the process generally. I felt very comfortable leaving a 2500 miler that was just stepping outside of its warranty comfort-blanket with them!
Hope this helps anyone else considering a similar project.

 

[pfs]

Omar

Great to hear about your experiences. I find the gearing issue on my 981 GT4 very problematic for track days and have been wondering about the various fixes. Did you look at the option to lower the final drive ratio (as offered by RPM Technik) ? What influenced your choice (including cost) ?

The breathing improvements make good sense to bring the engine up to the 420bhp level, which is plenty.

It still seems odd to me that the mid engine platform from Porsche (which would be the top of the tree for almost all others) is hobbled to avoid making the 911 look less attractive to the "market". I have owned a series of Boxsters and Caymans and one 911 (a 997)...mid engine wins everytime for me

Paul

 

[GraphiteGT3]

Thanks all for the responses, and really interesting to hear Dave how you have approached it with the 718 GT4. Im sure that has really improved the car no-end.

On your questions Paul:

- i did consider the final drive change, as it is far cheaper, but it felt a bodge to me and you are compromising in other ways, so i was also worried impact on future owners etc

- my final choice was really driven by finding (just!) the right balance between cost and improvements. there were a couple of options of places to get it done but actually not many that would do the whole package and have experience of tying it all together. I did think about the LWFW and the LSD but i just couldnt stretch to that cost right now and i dont drive on the limit of handling enough to warrant the uprated LSD.

Driving the car last night on my favourite test road, it really wasn't much slower than the newer GT3 I used to drive on the same road, and it felt more surefooted given how well balanced the platform is. So yes definitely a 911-beating contender now...

 

[pfs]

Thanks for the thoughts Omar. Useful input...still thinking about this (cost v benefit etc). I am having the geometry done shortly at Centre Gravity which seems an easy decision, and of course I can (and do) use the other way to improve the performance....which is to improve the driver.

Paul

 

[JohnCRS]

Omar

Thanks for taking the time to post details of your car on here. One of the interesting aspects of the Cayman register is the number of members prepared to undertake the research and then invest in getting their cars to meet their own specific needs. Yours is the first I have heard of going down this route in UK, so please keep us updated with how things are going.

John

 

[MrDemon]

I looked into all this and have driven everything, 2nd gear for me is the issue at 85mph.

while the shorter 3rd and more power will get you to 3rd faster, you still have to get past 85mph to get there.

dman motorsport make a gearbox but it would be £7k all in which last year on a £60k car or a spyder I was looking at, or even a 718 Spyder, but I ruled it all out.

I kept my manual 991.2 GT3 and put a deposit on the Emira.

you cannot beat a manual GT3 but I know what you mean about the money, but down grading to another Porsche for me after the GT3 would leave in me in a land of frustration with that gear box in all the models.

I hope the Lotus will be the best of both as happy to go down in BHP for the money.

I would keep the gt3 for ever if money was no object, but sadly it is lol.

if I don’t get on with the lotus I am sure I can sell it at list next summer. But cannot see any down sides atm with the emira for a fun road car.

if that’s the case I will sell the lotus and GT3 and buy a 718 Spyder and do the gearbox right for £7k.

Till then I am boming about in a z4m40 which does 46mph in 2nd it’s so nice and so punchy

that I cannot go back to long gearing In my old gt4.

hope the mods work out for you as you can easy up the costs in mods back to GT3 money and end up in a car which is just not as good but the same price. the GT3 don’t need any mods, it’s pretty perfect out the box with one of the best production engines ever made.

you can say it’s a GT3 contender, but it’s really not. Alass most GT3 have a crap geo and owners don’t swap it out, the 992 GT3 AT LAST Porsche put a strong geo on it oem, the 991.2 geo was crap out the box Most of the 992 GT3 hype how it drives is the new geo imo not the car or the double wishbones. it’s just better out the box oem vs oem.

 

[AndrewCS]

Anyone considered ... AutoQuest | (autoquestcars.com) ... 4.62 Final Drive @ $2598 (new crown ring and pinion only)

Not sure of the RPM Technik ratio / cost ?

 

[GraphiteGT3]

Hi Andrew

i couldn’t get my head around the shaving of top speed with the final drive change although I know that’s all a bit academic other than on track.

I do know the pricing out there but rather than post it’s probably better to drop me a direct message if you need to know. thanks everyone else for the responses. Look forward to getting to know the new set up. cheers Omar

 

[AndrewCS]

Hello Omar ... thank you for posting your mods, look forward to further feedback

I do like the revised / lower gear speeds of the Autoquest FD vs those of the Sharkwerks 3-4-5 & Holinger 3-4-5-6 gear sets. Having done a lower FD mod. on a previous non Porsche road - sprint car, things are a little more `buzzing` but rewarding []

 

[AndrewCS]

Look forward to getting to know the new set up.

cheers Omar

Hi Omar,

How are you getting on please ?

 

[AndrewCS]

I will sell the GT3 and buy a 718 Spyder and do the gearbox right for £7k.

Hi David,

Any plans for the gearbox please ?

DeMan Re-Gearing Review - Rennlist - Porsche Discussion Forums

 

[GraphiteGT3]

Hi Andrew

in short I love the gearbox mod. It’s really changed the character of the car for the better. Everything it’s advertised as- keeps car in the power band longer, makes driving between 30-80 just constant fun, but also allows driving around in 3rd as a cruising urban gear a lot more useful too. Its one of the best car mods I have ever made. cheers Omar

 

[AndrewCS]

Other modifications, albeit on a 718 ... Porsche Cayman GT4 MR: A Manual GT4 RS? | Catchpole on Carfection - YouTube

 

[GraphiteGT3]

Thanks for sharing. As usual Henry is spot on, especially about the impact of the gearbox mods.

 

[MrDemon]

what that the car is now is ruined for the road lol and the mods were £55k ! just buy a GT3 for less money they work all oem and will still be faster.

 

[AndrewCS]

More ...

(1) HOW TO LOWER THE GEAR RATIOS ON A PORSCHE CAYMAN GT4 EXPLAINED... - YouTube

 

[ralphmusic]

Andrew, to embed the video and save us having to watch the ads...

1. use the Full Version Window - far right "SpecialPGDCode"

2. click on "Youtube Video" which will add "[tube][/tube]" into your post AT THE PLACE YOUR CURSOR WAS

3. on YouTube select "Share" which gives a truncated url in this case "https://youtu.be/EEKv5STwBII", Select "COPY"

4. this put the url on your clipboard and then paste this between the 'tubes' "[tube]paste here[/tube]"

and the video will appear in the post..

[tube]https://youtu.be/EEKv5STwBII[/tube]

 

[ChrisW]

Well I've gone and done it ... the RPM Technik crown wheel and pinion with lightweight flywheel and clutch assembly, installed by Strasse who look after my modified GT4 in Leeds.

The car has done almost 30,000 miles, we checked the LSD at the same time and this was still in excellent condition, but it is worth mentioning that the case hardening on the pinion that was removed does look as-if it is just starting to break-down after around 50 track days.

As part of this mid-life refresh I also had my Surface Transform carbon discs skimmed ... probably a separate topic ... but it's only now that it has been done that I can feel the improvement ...



Having driven many miles in 5th rather than 6th to test if I could live with the gearing change at motorway speeds, this is not an issue and the improvement in the in-gear ratios is a massive improvement in normal driving and on track days ...



This has caused a hiccough in some of the electronics assist ... the gear downchange rev-match no longer works (didn't need it anyway!) ... and I don't think that the torque curve / power illustration displays cleanly, but the car is already tuned to 435bhp and live re-mapped (which for obvious reasons I would not wish to touch !).

The first trackday of '23 is March 3rd ... watch this space !