T5650 g'box

Rog246 · #1 (**permalink**) 07-15-2009, 03:11 AM

hey everyone, some advice please
have just put some money done on my drive train and I'm not sure which way to go. I have a T5650 5sp and the drive train i bought comes with a 6sp-so what would you use ?
the 5 or the 6 ?
I should also say that I'll most likely be running the std 4.11 rear gears that come the R33 V SPEC Skyline REAR AXLE, at least to begin with.
Opinions please

sambo · #2 (**permalink**) 07-15-2009, 03:52 AM

Hi Rog. I went down this path recently with my Harrison and R33 4.11 diff. A couple of things... whether to go 5 or 6 speed, work out what your RPMs will be in 5/6th gear (depending on box, tyre size, etc) using one of the many online gear calculators. Just google it. Then consider that 6th is just a second overdrive and will you need that top speed or the comfort on the highway... probably with 4.11s yes you will want 6th. Then with gears 1 thru 4, have a look at the ratios and what speeds you're doing in each gear at the top of the torque curve, whether you want to fit a big cam that makes less power down low (go shorter gears), etc. Speak to Mal Wood b/c the T56 comes in quite a few configurations with various gear ratios. He's very experienced and will probably be able to narrow it down for you - that is if you're prepare to fork out nearly twice as much as Holden wants - you get what you pay for. Lastly I would settle on the final drive ratio now because if you change the diff later your ECU will need to be edited for the speedo to be accurate, plus those gearbox ratios (if custom) won't be as effective if/when you go to a different ratio.

There's a summary of the main considerations I took into account. Ended up with the 3.7 centre from the S15 200SX for about $400 extra and using the stock VZ Holden T56. The diff and axles from the S15 are a straight swap and easily done. PM me if you want the name of a good source in Sydney or search for my thread on the subject.

Sambo

Edit: of the 2 gearboxes you have, which one is tougher, easier to service, better condition, known history, etc?

Rog246 · #3 (**permalink**) 07-15-2009, 04:02 AM

hey Sambo, the 5sp is from a BA & unknown K's but will have to be rebuilt, the 6sp is also from a BA with 40K verified

sambo · #4 (**permalink**) 07-15-2009, 04:55 AM

Rog, sorry I just assumed it was Holden gear - still Tremec? If the 6 spd doesn't have any weaknesses I'd start by testing that out once the car is going. Sounds like your bellhousing and clutch already fit together (same donor car I asssume?), so you're miles ahead with that setup.

There's a saying around here... no photos, didn't happen! Might want to put some "proof" in your gallery mate.

stiffy · #5 (**permalink**) 07-15-2009, 06:22 PM

Rog,

I have a 6 litre Chev and a 6 speed in a Harrison. It came with 3.9 nissan rear end.

The engine was standard (they are pretty good by the way) but I didn't like the amount of gear changes I had to make. The cars dont weigh that much so they dont need alot of revs to get them moving.

I have a Cobra with a 5 speed and 3.55 gears, this has a great spread of power from 1200 RPM to 6000 RPM which is perfect for the odd sprint and will easily run at 110km/h at around 2100 RPM.

Therefore after driving the car for a while I decided to change the diff to a 3.54. It was the best thing I have done to the car ( besides the heads and cam that is

) it has become a much more diveable car, it has reduced the amount of gear changes dramatically and the car still has a heap of acceleration. Dont forget they only weigh about 1200KG'S. Alot of people that have not driven a Cobra dont quite understand the weight thing (I didn't ) they spend all their time on the web discussing this and that, researching stuff and disregarding the good stuff they are told.

IMO you should go with the 6 speed as it will give you the latest gear box and more final drive ration to utalise. See if you can drive one before you start to change things.

My 2 cents worth,,,,

STIFFY

Rog246 · #6 (**permalink**) 07-16-2009, 12:52 AM

Hey Stiff, that makes some sense........especially the try before you etc.....
So I wonder who would be silly enough to let me have a drive........??

Rebel1 · #7 (**permalink**) 07-16-2009, 01:23 AM

I totally agree with Mr. Stiffy.

Dunno about the try before you buy thing but his other advice is spot on.

ledge · #8 (**permalink**) 07-17-2009, 07:57 PM

Hi
6 speed is the only way to go.
i have 4.11 rears and 17's and for cruising up the freeway 6th is great . and the take off front a stand still is superb, Especially with a well setup rear.

regards
paul

Rog246 · #9 (**permalink**) 07-17-2009, 08:53 PM

Quote:

Originally Posted by sambo

Rog, sorry I just assumed it was Holden gear - still Tremec? If the 6 spd doesn't have any weaknesses I'd start by testing that out once the car is going. Sounds like your bellhousing and clutch already fit together (same donor car I asssume?), so you're miles ahead with that setup.

There's a saying around here... no photos, didn't happen! Might want to put some "proof" in your gallery mate.

Sambo, same donor car, and yes they're tremec's. I knicked the 5 sp on Ebay, but the 6speed comes with the engine I bought