Jap wideblock vs narrowblock

[Rally_2.6LC]

Is the Jap 5sp wideblock gearbox any stronger than the Jap 5sp narrowblock gearbox?
I know starion ones are but i want to know about the normal jap 5 speeds as I have both, and multiple possible engine configurations but need more compressiona and more power so want to decide what engine i should start collecting bits for.


Cheers Matt

[Superscan811]

Matt,
the output shaft is thicker on a wideblock jap 5speed gearbox and some of the bearings are a bit stronger as well.
The starion/pajero/triton wideblock gearboxes are different again. Different ratio's/gear width/bearings etc.
If you are going N/A, use the narrow, if you are going turbo, go wide.

Narrow for N/A because there will be less mass in the flywheel/clutch setup.
Wide for turbo because more mass is good and if you need to get a stronger gearbox, the starion gearbox will bolt straight on.

Cheers.

[Rally_2.6LC]

So I should use a Magna bottom end for my rally car then.
Whats advantage/disadvantage of Magna vs Sigma? I know the sigma had a better quality crank or something, what about rods?


Cheers Matt

[cheaterparts]

Matt,
the output shaft is thicker on a wideblock jap 5speed gearbox and some of the bearings are a bit stronger as well.
The starion/pajero/triton wideblock gearboxes are different again. Different ratio's/gear width/bearings etc.
If you are going N/A, use the narrow, if you are going turbo, go wide.

Narrow for N/A because there will be less mass in the flywheel/clutch setup.
Wide for turbo because more mass is good and if you need to get a stronger gearbox, the starion gearbox will bolt straight on.

Cheers.

the wide and narrow boxes use the same gears / syncro rings and bearing except 1 the spiget bearing between the input and output shafts
the narrow box has smaller splines on both input and output shafts but are the same size from the front bearing to the speedo drive
the starion box uses the same ratios but some of the gears are wider they still use the same synros and the layshaft is on taper roller bearings
pajero/triton use a wider ratio gear set

I have fitted the large spine shafts to my narrow box the main reasons were its easier to fit 23 spline to a tilton race clutch than the smaller shaft
and to change to extention housing to the larger bush type of the wide box it has a couple of lumps that can be drilled and tapped to fit a plate over the plug behind the gear shift shaft
I've had them come out while racing - you dont loose much oil when this happens but just enough to make the exhuast smoke
and then the black flags come out and theres no fun in that

[cheaterparts]

So I should use a Magna bottom end for my rally car then.
Whats advantage/disadvantage of Magna vs Sigma? I know the sigma had a better quality crank or something, what about rods?
Cheers Matt

the crank and rods are much the same and interchangable and i dont beleve there is any difference in quality in ether

[camB]

Must just say... always look for your posts Cheater: Direct. Authoritative. Clear and easily understood.

Thank you.

[Rally_2.6LC]

Ill second that CamB

Unfortunalty Cheater i dont have much money so ill be building a motor (as current one dead) with new struts and brakes and then looking into gearboxes a little later.
Got a diff on the way (stored at Scott's) and then hydraulic handbrake.


Cheers Matt

[billhincher]

the major improvement in engine block design is the hieght of the deck on the 4G64, its about 10mm higher then the narrow block, with that length, you can use longer rods and increase the 'rod ratio' adding a lot of power
the wider bolt pattern for the transmission improves strength because a wider pattern requires less effort at that union
this is the second gen casting of the wide block R154, it fits much better and the thickness is adjusted in all the right places


the flow of the casting is much nicer, this has a much nicer finish look to it



I dig the diagonal lines in the housing, that adds wall thickness to the radius of the curve in the housing and torsional strength for the twisting motion

the demensions worked out the have the right wall thickness in the right areas to build strength without much wieght penalty

the throw out bearing was moved back 1/2 inch to get a better pivot point on the folcrum of the clutch fork


the depth was absolutly correct and it is a direct ft to the G54 engine using all the same clutch parts that came standard on the carquest with the exception of a $45.00 disc from a Supra 7me engine


I have the throw out bodies built at the casting shop now , they are lighter and much easier to build

[webby]

Magna's didn't have 4G64's until about '95, it'll be the late model 4G54 that Matt's on about

[Rally_2.6LC]

Yea Webby's right.......was on about 4G54 as thats what most of us refer to 'wideblock' or 'narrowblock' over here.
However interesting info that you put forward. Thanks.


Cheers Matt