just bought and stripped a track car in japan.... dr30 everything pretty much modified but to the era it was from.

The gear box looks half Fj (the bellhousing) and half early RB/CA (shifter tower)
it also has a serial number stamped on the top of teh bellhousing

Whats the score here ?

What has me wondering is the car had a mechanical 2 way diff from a hr31 a greddy td07 25g snail and a os gikken tripple plate clutch, unsprung..... how is it the box has survived

Sounds like you have a CA or RB gearbox with an FJ20 bellhousing on it,which would either require machining to fit the larger input shaft bearing or use the FJ's smaller one. I know as I've recently learned this :P
The diff may be a stock unit,as the DR30's also used a mechanical LSD diff. Perhaps the box is still ok because the owner treated it with some care.

You can use the FJ bellhousing, actually the main gearbox case, but its not necessary. A RB20DET box will bolt up with just a few changes to some of the bolt holes where it attaches to the engine. Some of the FJ cases require internal machining if you use them, best not to

Yes, the RB box does have the six bolt shift tower.

260,I don't see why it'd be 'best not to use' the FJ bellhousing? All they require is the input shaft bearing hole to be machined a touch bigger,and a selector shaft hole enlarged,or alternativly the smaller FJ20 bearing can be fitted to th RB shaft.
And I hear you have got you new turbo and manafold finsihed? where's the dyno sheets/drive impression?

I think its called luck that that gearbox has survived!! Either way it sounds like a very tough car!!

'day Anthony, of course you are not wrong but the 'machining' required for the RB housing is much simpler and cheaper to do, and, can be done without pulling any gearboxes apart, and, you will have an intact FJ box left to sell I said 'machining' because the RB case could be modded at home if you have a suitable drill press.

Dyno charts are a long story, the new motor was tuned in a rush to be ready to go to the Nationals, the boost controller wasn't working properly and so on. What I do know is that the power was still climbing quite steeply right up to the 6k limit, IIRC GT28RS's usually start to level out a bit by then. Its still got to have the boost limit set higher than the present one bar, plus the rev limit bumped up to 7k.

At one bar and 6k, what hp do you think it should have?

rear end and diff are hr31 def the same as my hr31 and unlike my dr30's .... that aside


I have another dr30 front cut arrive both my road car and this cut dont have a serial number stamped on their belhousing like the modified one

somebodys mentioned the possibilty that its a , "option box"

anyone know what this is?

I would not place to much emphasis on it having a number stamped on it. Both my FJ boxes had numbers, which didn't seem to mean anything that I could see.

260: Yeah,I guess it is easier to modify the RB bellhousing to fit onto the FJ.I want to get my box inspected,so pulling the front off it didn't bother me. Having said that,I DID decide to elongate the holes in the RB housing after all! :P There's a fair bit of meat that has to come out of the top 2 holes,and also the hole for the locating dowel,unless you pull it out of the FJ's block I spose. Obviously I'm only guessing at your power levels....but I'll have a stab and say 260-270HP,at that boost and revs?

DR Mayhem: When you say "rear end and diff" I assume that you have an HR31 rear cradle??? IF so,the HICAS 4 wheel steer rams must've been removed,and the cradle locked up?
As for the actual diff,I wasn't aware there was any difference between the long nose R200's?

Actually guys its the front countershaft bearing that changed . The reason why from an engineering point of view the modified FJ bell housing is the propper way to go is the top dowel . It is not in the same place on RB's and FJ's so the weld and redrill operations are more expensive to the RB bellhousing . Its not that dear to bore the FJ20 bellhousing but you will need the RB type front bearing cover wich doubles as the clutch bearing spigot . You get the bits with the RB20 box . Doing it this way ENSURES both bellhousing dowels fit and line up , if one is missing the 1st motion shaft can worm in and out on the crank spogot bush and make the box jump out of gear .
That larger front bearing is there for a reason , as torque goes up the front gear pair cops the most load as they are used all the time except in direct or 4th gear .
Just to dispell some myths , the only major differences between the FJ and RB20 boxes is that front bearing and the 3-4 syncro hub which is larger (and heavier) on the RB box . The shafts and gears are similar if not identical so strength is on par . I cannot understand why people tie themselves up in knots trying to fit a non std box when a few mods to the std one gets equal (and simpler) gains . For the drag fraternity that larger 3-4 syncro hub is not necessary , every anihilated FJT box I've seen had smashed 2nd or 3rd gear pairs not stripped syncro hubs .
Cheers .

Agreed about the front countershaft bearing DiscoP, which is an important upgrade over the FJ box. I've seen Zed boxes which have the smaller FJ type bearing fail in this area, typically if left the bearing rotates in the case and can even chew right through the front cover.

But its easy peasy to redrill the 20DET case, just use the steel sandwich plate which goes between the box and engine as a guide, which is what I did after looking at both options. But the clincher for me was the superior shift arrangement of the 20DET box. Which IIRC also has a stronger mainshaft, plus other detail improvements including more durable syncros as you mentioned.

Having used both boxes on the track there is no contest, the modded 20DET box is by far the best option.

Which reminds me, anyone in Brisbane want to buy a FJ box, just had a full new set of Japanese bearings, won't use those ? Chinese bearings.

hey guys i know its an old thread but i'm in the process of converting to a rb20 box and i also believe the better shifter mechanism of the rb box makes it a worth while upgrade.

Whats with all this machining... and drill presses? All I used was a hand held drill, 5 mins and the complete RB box is on the FJ. The bigger problem is that the RB gearbox mount is about 2 cm further rearward, so you need to make up another gearbox crossmember