Y4 gearbox swap

[VTECnique]

well, my gearbox is starting to go, so im looking around for another. been looking at the Y8 box, all ratios between the 2 are the same, but the Y8 has a better final drive.

While im at it, i was also going to go for a new clutch & flywheel, since im planning on FI down the road, something like a heavyduty clutch & lightweight flywheel.

On the exedy site though, it says the Y4 is 200 x 22 x 20 spline, whereas the Y8 is 212 x 22 x 20 spline. Im not sure about this, someone please correct me if im wrong, but im pretty sure i get the clutch that matches the gearbox. Im not really that good on flywheels though, can i run a Y8 flywheel with a Y4? are they the same size? any help would be great, thanks in advance...

[VTECnique]

Anyone?

those different numbers are for the actual size of the clutch. So im guessing i can use the Y8 clutch in my Y4 because they have same number of teeth on the spline & same spline OD size...

[TODA AU]

You'll be able to do that without issue....
Just use the flywheel to suit the clutch used...

[VTECnique]

Awesome. I may just stay with a Y4 box, but thats great news i can use the bigger sized clutch...

[nd55]

> well, my gearbox is starting to go, so im looking around for another. been looking at the Y8 box, all ratios between the 2 are the same,

AFAIK there are two versions of the hydraulic D16 gearbox.

On Y8's and maybe Y5's what's known as the 'big bearing' gearbox. The axles have 40mm OD bearings.

All, other D16 boxes are the 'small bearing' boxes, with 35mm OD axle bearings.

The only way to identify them is via a casting stamp about 10mm dia, about 10cm from the oil fill hole.

A000 is a small bearing box
B000 is a big bearing box.

The B000 is desirable because the various D16 LSD's only fit the 40mm axle bearings.

The A000 has sucky gear ratios. The B000 has less sucky ratios, but still not great.

> but thats great news i can use the bigger sized clutch...

I don't think a few mm difference in clutch plate size will make any practical difference.

> get the clutch that matches the gearbox

yes.

> can i run a Y8 flywheel with a Y4? are they the same size?

No need to change flywheels for small difference in size.

A light alloy flywheel and a LSD is probably the best bang for buck upgrade.
Aussie dollar isn't too shabby ATM so look into it.

Light flywheels aren't to everyone's liking cause they need a bit more skill/practice to master smooth take offs.

Nick.

PS. standard Internet mechanic disclaimer.

[VTECnique]

cheers nd55, i was actually waiting for your input.

I see it as this, since the gearbox is out, getting replaced i may aswell get a lightweight flywheel & heavy duty clutch fitted aswell. the only reason i asked if i can use a Y8 clutch is because im buying a clutch & flywheel combo over in the states, where the size is either 212mm/220mm...

[SuiJin]

highjack. y1 gearbox interchangable with y4? or even y8?

[VTECnique]

Yes they are. all D16* gearboxes are interchangable. The D16A8 g/box however has an intermediate/middle shaft/axle though where another other d-series has only left & right axles...

[lookingforboost]

hmmm interesting do you know the difference in the ratios between the Y8 and Y4 i thought the Y8's are a closer ratio box? or are they the same?

i have a Y4 box atm but we have a Y1 and Y8 box in the shead going to look see if they are the big bearing ones now!!!

[nd55]

> cheers nd55, i was actually waiting for your input.

Sorry, moved into a new house which, er.... needs a bit of work.

> I see it as this, since the gearbox is out, getting replaced i may aswell get a lightweight flywheel & heavy duty clutch fitted aswell.

Might need to get the advice of more clued in people here.

I don't know if the Honda Flywheel is internally or externally balanced.

> i asked if i can use a Y8 clutch is because im buying a clutch & flywheel combo over in the states

IMHO, overkill in this application and there are too many suspect budget clutches around.

Stick to a name brand and avoid the hassles.

IIRC Yonas uses a stock clutch in his 12 sec K24.

Also IMHO, traction bars or engine mounts will be much more useful.
No point getting a clutch which can tolerate more power if all you do is wheel hop on launch.

If you haven't experienced wheel hop, you're not trying hard enough.

> the difference in the ratios between the Y8 and Y4 i thought the Y8's are a closer ratio box? or are they the same?

[Roughly, from memory]

Y8: 3.2 1.9 1.3 1.1 0.8
Y4: 3.2 1.7 1.2 1.0 0.7

This is an area where the B16/B18 shits all over the D16.

ITR: 3.2 2.1 1.45 1.03 0.78

> Yes they are. all D16* gearboxes are interchangable.

Cable & hydraulic is the main difference.

> The D16A8 g/box however has an intermediate/middle shaft/axle though where another other d-series has only left & right axles..

Axle diameter is different too. Closer in size to B16 axles.

> im buying a clutch & flywheel combo over in the states, where the size is either 212mm/220mm

Supercheap do a 20% off birthday sale every now and then.
Go in and buy an Exedy.
If it doesn't fit you can always exchange it.

Nick.

[VTECnique]

Y4 box
1st 3.250
2nd 1.909
3rd 1.250
4th 0.909
5th 0.702
Final 4.058 (i got this info from the pdfs on the honda website)

Y8s ratios are exactly the same. The only difference between the 2 are the Y8 has a final drive of 4.250. The best close ratio d-series gearbox is from the 92-95 Y1, but have aluminium shift forks whereas the Y8 has steel.

[lookingforboost]

dose the Y4 box have the steel forks as well? caz an worried i will smash my box once i put some more power into the motor.

i suck at gearbox stuff so its all a learning for me :P but dose that mean that the Y8 box sits on a higher RPM in the final gear than the Y4?