Shifting procedure 6-speed straightcut dogbox

[Godzilla-R]

Hi all, I have got a R33 GTR with a grex Trust Greddy straight cut dogbox in it.
I took it for a drive yesterday and the day before for the first time as I was waiting for a sunny and dry day since I got the beast. Anyway my quest is to find out the correct procedure of shifting with this kind of gearbox. I did a bit of reasearch before I took the risk to take it for a drive. I also asked a few knowledgeable people for advice on how to shiftup and shift down the gears without putting a lot of stress on the gearbox. I was told to perform the changes by slamming into the next gear as hard as possible and very fast taking into account the rev's as the change should match the rev accordingly, and obviously without the use of the clutch, I was told also that the shifting is ideal at moderately high revs or very high reve (track use). I wasn't very sure how to correctly perform the downshifts 4-3 3-2 2-1. Then I found out in some site that when you downshift it is better to use the clutch by dipping it very quickly and slam into one gear down, but on the upshifting never use the clutch. Can you guys help me out with this if you could as I'm not using my car before I make sure I'm shifting the gears in the correct manner. I don't want to take the risk of breaking the box as it is very costly so your help and advice will be much appreciated.
Thanks all..

[mcfly]

You certainly cannot wuss out when shifting a dogbox and what you were told is dead accurate. If you are going to shift you want to really throw it into gear. This will allow a positive engagement with the dogs. Not using a short shifter can also be a life saver, you want to have as much force on the selector as possible.
You can still shift with the clutch to take some stress off of the driveline while shifting but you have to be certain to shift the same as if you were racing your greatest rival.


With the Trust box be very careful putting it into reverse. The gear has been known to shave itself clean. Just make sure you are at a dead stop when getting ready to back up.


You can see here how someone wore a third of reverse off

And if you run too much power through the box you can even split a shaft as seen here with a clean break between 5/6

[Godzilla-R]

Right so I was shifting more or less in the correct way when I went for a drive. so can I downshift without the use of the cluthch as well? I mean I tried both yesterday. upshifts I never used the clutch and made sure Im bliping the throttle upwards and then slam one gear up as I take my foot of the throttle split second shift hard and fast. For downshifts I was't very sure, I did downshifts without the cluthch and also with dipping the clutch quickly, but did not notice any difference really maybe a bit smoother with the use of the clutch. As for reverse yeah I have always made sure the car comes to a complete stand still before I slam it into reverse.
Appreciate your help mate.

[mcfly]

I wouldn't suggest downshifting without a clutch.
Ideally you want to double clutch downshifts if you have the time as it will increase the life expectancy of the box. The subaru forums like nasioc and the DSM forums are great places for dogbox knowledge as there are a number of guys over there running them. A lot cheaper then our skyline boxes.

[Godzilla-R]

I wouldn't suggest downshifting without a clutch.
Ideally you want to double clutch downshifts if you have the time as it will increase the life expectancy of the box. The subaru forums like nasioc and the DSM forums are great places for dogbox knowledge as there are a number of guys over there running them. A lot cheaper then our skyline boxes.

Yeah as I carry out this research I do come across a lot of Subaru an Evo forums and chats. think it is more common for the scooby's to have this type of gearbox and cheaper too. however not as much power maybe as the GT-R's.

[Godzilla-R]

Actually I found some videos that are quite helpful on youtube. Let me see if I can post them here.

[Godzilla-R]

Shifting with a dogbox, this one is an RX7 i think

http://www.youtube.com/watch?v=asFwDpLe1xo

[Dragon Humper]

I would use the clutch as much as possible. You'll notice the guys that are flat shifting in the video's don't have a whole lot of power, they can clutchless shift all day long and not have to worry very much. Once you get over 500hp though you need to keep the clutchless shifts for when you really need to prove a point or racing. Honestly once you get good enough you won't need to do clutchless. I can shift fast enough that people think I have an automatic in my car (except 3rd) and I still have the factory box.

The hardest part is just putting around, cruising nice and easy with a dogbox is a greater challange than going balls out. A delicate touch is an art form.


Jon.

[Godzilla-R]

I would use the clutch as much as possible. You'll notice the guys that are flat shifting in the video's don't have a whole lot of power, they can clutchless shift all day long and not have to worry very much. Once you get over 500hp though you need to keep the clutchless shifts for when you really need to prove a point or racing. Honestly once you get good enough you won't need to do clutchless. I can shift fast enough that people think I have an automatic in my car (except 3rd) and I still have the factory box.

The hardest part is just putting around, cruising nice and easy with a dogbox is a greater chanlange than going balls out. A delicate touch is an art form.


Jon.

Hmm so use the clutch for both upshift and downshift although I could also do it without the use of the clutch if driven a bit harder and faster?? Basically the car was dyno'd very recently at 806ps @ 7800 rpm 1.8 bar boost (althought peak boost is 2.1 bar). so it is very powerful and just a real beast. the engine is really responsive it is electric. I'm just amazed at how quick the two GT2835-R turbos spool there is no lag, it is just instant. In my previous GT-R I had a HKS T51-R Kai BB turbo and that was so laggy. I mean the turbo would kick round about 5000rpm but in this one by the time the needle hits just past 3000rpm and it is like a rocket on wheels . This kind of engine response needs good and careful shifting in the right manner as the dogbox demands i.e fast and firm.

[mcfly]

you are going to destroy the trust box if you run that much power through it, it is just not made well enough.

[Dragon Humper]

Agreed, from what I have read you're better off with a PPG converted stock GTR tranny. Still a Dogbox but the main shaft is mucho upgraded and might handle 800hp on a regular basis. Just don't run too sticky of a tire and you might be OK for a while. Any tire with a treadwear of 400 should do it.


Jon.

[Godzilla-R]

Heard that

you are going to destroy the trust box if you run that much power through it, it is just not made well enough.

Yeah I have heard there have been some reports of breaking the selectors, guess a common problem in Trust box's. But can a stock R33 GT-R gearbox handle 800 hp? I was told by a guy today that his R32 GT-R is pushing 900 hp with a stock gearbox, is that possible? And the other question, which one of the following is the best option for a dogbox/sequential box?

Holinger
PPG
HKS sequential
KPS
OS Giken
Trust Greddy ?

[mcfly]

PPG would be my first option
OS Gliken would be the second

There have been a couple broken ppg sets but of those one was for sure an assembly error. The OSG 88 box is a pretty mean machine but has a fair few dead ones documented.

There is no way someone pushed 900 hp through a stock box, if they did it likely did not last past the dyno. The two pictures i posted above were of a trust box with a split shaft.

[Godzilla-R]

Still a Dogbox but the main shaft is mucho upgraded and might handle 800hp on a regular basis. Just don't run too sticky of a tire and you might be OK for a while. Any tire with a treadwear of 400 should do it.


Jon.

Interesting point about the tyres. As for PPG I mentioned it to a reputable tuner today and the minute I said PPG they all started laughing and said they are actually working on one at the minute and added that they are not of good quality. The PPG box they showed me was in a terrible state with the shaft broken and punched through the side of the housing case.

[Dragon Humper]

Oh my. It depends on the parent transmission. The GTR boxes (and the R33 RB25 boxes) have had alot of R&D over the years (with the aftermarket) and the cases are really beefy. The gears are only half the battle, if the case isn't up to it the case will flex, the clusters will spread apart under huge amounts of torque and bad things happen.

There is alot of operator error too. I'm sure the guy with the blown apart PPG converted box didn't tell the shop the whole truth about what he was doing when it went POP. I've blown the 3rd gear shift about 6 times now and the tranny is still kickin'. You need to realize that the shift isn't going right and pullout quick enough (sounds dirty...LOL).



Jon.