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Posted

Depends if you want the extra gear for acceleration or lower revs for cruzing in top. The extra gear in these boxes is for better pick up I reckon, 3/4/5th are really close, but 6th is not higher that 5th in most boxes. My tezza still does like 3500rpm at 100kmh (1gfe)

  • Like 1
Posted

i was looking at lower revs for cruizing. soo that link said that i could really use rx8 boxes, s15 ones...but then that 1 guy swap to the 5 speed s13 boxes in thair s15's... so i could get a 5speed s13 box and put a 1gfe hell housing on it and it will work? if that works? or am i just confused?

Posted

Even though top gear between 5 and 6 speed boxes are close, you'll be able to alter diff ratio to get better cruising RPM since you have an extra gear down low for pick up

Posted

The way I read it is the 6 speeds are all much of a muchness with ratios. (unless you get a TRD gearset)

However when comparing a W to an R....

1st in a R160 is 3.7 while 1st in a W55 is 3.6

5th in an R160 is the same as 4th in a W55 at 1:1

6th in an R160 is the same as 5th in a W55 at 0.85

All figures are "ish"

So you wouldn't gain fuck all in off the line or in cruising revs

However you have closer ratios between low and 1:1 where you do all of your fanging normally (top gear is for economy)

So you would keep within a higher powerband between gear changes.

IMO final conclusion is with an R you may get to 100km/h faster but for the extra expense and (apparantly) lesser strength then I would wonder if its actually worth it....

Posted

They swap earlier gearboxes into S15's because they're shit, well they make alot of noise. I had an S15 almost 10 years ago and the gearbox was noisey was expensive to replace (wasn't economic to repair) one I replaced it with was just as bad.

You can't swap bellhousings on the Nissans.

Posted

ok then so j160 are weaker and make lots of noise?

w55 is just.....strong..

and there no real gain except for closer gear raitos

Posted
ok then so j160 are weaker and make lots of noise?

w55 is just.....strong..

and there no real gain except for closer gear raitos

Nail on the head... Well that would be my conclusion if faced with the question myself..
Posted
ok then so j160 are weaker and make lots of noise?

w55 is just.....strong..

and there no real gain except for closer gear raitos

Nail on the head... Well that would be my conclusion if faced with the question myself..

Yep.

  • 2 months later...
Posted

Is there any substance to internet claims of 6 speed weakness, for Altezza boxes at least?

Everyone says it, but how many people have broken one, or seen a broken one?

Not talking about uncles mates brothers daughter with a 600hp S15 either.

A few things I'd like to clear up / myths to dispel:

-J160 is the 6 speed Altezza gearbox, R154 is the near indestructable Ma70 / JZA80 5 speed supra gearbox. As best I know there is no R160 box as per thread title.

-J160 is made by the same people as the W5* box, (Aisn) and people who've stripped them down have commented that the gearsets are comparable size to W5*.

-The weakness of the 6 speed box isnt the gear sets (which are comparable size to W5*) but that when a large amount of torque is applied to the helical gears it pushes against a thrust washer which makes a circlip pop off, then all hell breaks loose. People have welded the circlip in place or cut the groove deepter to strengthen the gearbox, however it seems to take a crapload of shock loading the gearbox to make this happen, your gearbox wont explode on a trundle down to the dairy.

(think clutch dumps with sticky tires and solid centre clutches in a heavyish car)

There is a Nismo gearset available for the S15 gearbox, this has the helical gears cut on a shallower angle, which reduces the torque loading against the thrust washer/circlip... But also makes the gearbox even noisier than when it started.

-J160 gearboxes are indeed prone to being noisy apparently, although often people have attributed this to the factory dual mass flywheel.

Luck of the draw though it seems, mine is fine with a solid flywheel / my diff makes 10x more noise.

-The gearsets of the various AZ6 gearboxes may be interchangable (altezza, silvia, rx8, mx5, s2000) however it's generally accepted that the Altezza has the best ratios of the lot, and the casings and speedo drive configurations etc are all different between the gearbox casings, to suit each car. For example, the S2000 doesnt have a splined output shaft, it has a flange that the driveshaft bolts to.

-The bellhousings are cast into the front part of the gearbox, from memory I think I saw someone put an RX8 bellhousing onto the front of an Altezza gearbox, but it required pretty much a full gearbox strip down and reassembly. Dont count on easy bellhousing swaps, as per W5* gearboxes if planning on using an odd engine with it.

-Silvias blow up a lot of their 6 speed gear boxes, however apart from circlip issue is this partially a cultural/behavioural?

Are silvias more prone to everyone fitting springless button clutches and shock loading the bejeezus out of their gearbox?

probably, but speculation.

Odds are highly in your favour that you'll be fine using an Altezza gearbox for:

1. NA motors with lots of revs

2. Turbo engines with less than 300hp or so

3. Cars lighter than an Altezza

4. A road car

5. A track car

6. Normal clutches

As per any gearbox, you'll run more of a risk if you plan on any of the following:

1. 3-400hp+ engines with lots of torque

2. Solid centre clutches

3. clutch dumps / shock loading the gearbox a lot

4. Using in a big heavy car.

5. Using in a drift car

If you're planning anything from my 'dont do' list, then you may be surprised to know that people have blown up an immeasurable amount of W5* boxes this way also.

Spend the money on an R154 if you want something bullet proof...

If you're going to have 2-300hp in a ~1000kg car, 6 speed is fine, as is a W series.

Altezza boxes sell for around the $6-700 mark it seems, comparable or cheaper to W5* prices...

So what's the pluses and minuses of each?

W55:

-well documented strength

-all 20+ years old

-most have high kms / unknown history

-starting to get expensive

-interchangable bellhousings

-4th gear 1:1, 5 speed

-if using for high hp will likely want old worn synchros etc replaced

Altezza J160:

-reported strength issues based on Silvia problems

-less than 12-13 years old

-cant change bellhousings

-reasonably cheap

-only good for 3S or 1G builds

-If using for high hp will want circlip issue addressed

-5th gear 1:1, 6 speed box

-1st gear is pretty useless with a high final drive ratio

Personally I think that having 6 gears is as much gimmick factor as anything...

But the fact that you're getting a 15 years newer box with comparable construction and strength for the same price or cheaper, it's hard to say no to the six speed if it suits your application.

Even more so when you can use a W5* driveshaft and mechanical speedo drive to suit your application...

Even more so when no one wants them because of internet rumours of weakness.

  • Like 1
Posted

Yep, while driving the tezza the other day, I thunked to myself "this box would be awesome behind a highly strung 4age". If I ever build a mild 4age turbo, i'd prolly go the J160, and see what happens.

Posted

Nice post Roman, but you missed out the fact that the ratios are awesome in them too.

Agreed!

From memory if you have an 8000rpm limiter, you dont dip down below 6000rpm between 2nd, 3rd, and 4th gears.

Great for peaky engines where you need to keep it on the boil.

Posted

jase at Cartune in hams has put an r154 into his turbo beams altezza after smashing numerous 6 speeds.

I don't think he had close to 600hp either.

I'll ask next time I'm there.

-Nathan

Posted

i had originally planned to run a w box in the Mazda. But the price they demand for an old box i couldn't justify.. I hope the late model 350 z box works out...

Posted

yeah you can get some cheap if you wait i paid $450 for mine on trademe i think no one else bidded because there was no pics haha

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