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RB25DET GEARBOX TO SR20DET S14
Posted: Thu Nov 20, 2008 10:24 am
by MyPRodOL
Hi all
So I while ago i fitted my coilovers, finished late night, wanted to go for a quik quik drive to test...
DISASTER!
Run 1st gear, run 2nd hard, get 3rd, boost comes in hard hard, and bang crackle pop! thought it was my driveshaft, nope!!!
SR20DET gearbox can handle between 500hp to 600hp, guess, I'm in the limit

The gearbox is cooked, main shaft bent and 3rd gear disintegrated....
NOW, what do I do, as I'm still planning on upping my boost to make more power!
talked to RAW, seems like O'm going to be doing a RB25DET gearbox conversion... has anybody here read about it, done it?
going to be interesting,
2ways of doing it:
1: SR bell housing and weld to RB box and then fit.

2: get a conversion plate from Australia ( really a professional kit)
thoughts etc? anybody done this? think allot of you will need this in the future!
Allot of the Ausies run this.
Posted: Thu Nov 20, 2008 10:36 am
by Sokar
I think the conversion plate looks nicer and will probably last longer.
That welding idea is kak, how is a welder going to perfectly line up the gearbox input shaft with the flywheel and then weld it? Sounds dodge.
Posted: Thu Nov 20, 2008 10:57 am
by ljS14
How long is it going to take for the convertion plate to get here from OZ???
When this is done ,Bring on 2 bar boost
Good luck sorry to here about the box

Posted: Thu Nov 20, 2008 11:01 am
by Gary57
Adaptor plate is the way to go.
Posted: Thu Nov 20, 2008 11:05 am
by MyPRodOL
Sokar wrote:I think the conversion plate looks nicer and will probably last longer.
That welding idea is kak, how is a welder going to perfectly line up the gearbox input shaft with the flywheel and then weld it? Sounds dodge.
agree, the welding is %^$$%^,
the plate is the best, very very expensive,
they have built a very successful kit for the s15, and now they making the kit for 13 and 14, will be ready to export by end DEC to early JAN.
1300 to 1500 ausie dollers unshipped.
I'll pay that for a well developed, quality product, complete bolt on.

Posted: Thu Nov 20, 2008 11:10 am
by ljS14
Posted: Thu Nov 20, 2008 11:22 am
by Gary57
Ill make you one for half the price

. Cut with HD water jet.
Posted: Thu Nov 20, 2008 11:29 am
by Hotstuff
Try Gilo Engineering... they specialise in adaptor plates....
http://www.giloeng.com/
goodluck!
Posted: Thu Nov 20, 2008 11:38 am
by MyPRodOL
Gary57 wrote:Ill make you one for half the price

. Cut with HD water jet.
nice thing is, they test their kits thoroughly, on powerful cars, spent many hours to develop.
Maybe make a kit and starting selling it?
Posted: Thu Nov 20, 2008 12:37 pm
by RB25SX
Making the adaptor plate is not a problem, but what about the extra distance btween flywheel and pilot shaft, looks like about 50mm. Welding isnt a problem, line it up on a milling machine, clamp and weld. Aeromac engineering in strand can do it for u. Cost not more than R2000. You will have to strip the RB box to line everything up. They did my gearbox on BMW V8.

Posted: Thu Nov 20, 2008 1:20 pm
by MyPRodOL
the distance is fine, aRB box is 6.5 cm shorter then SR box, making it a perfect fit with the adaptor.
Thing is, I'm not saying they can't do it, or yours will do this, but if its not lined up to absolute perfection, you stand a chance of running bearings...
thanx for sharing though, appreciated
Posted: Thu Nov 20, 2008 1:34 pm
by RB25SX
Worth a try at 10% of the import adaptor cost. To do a CAD drawing of the 2 boxes and CNC a adaptor plate is not a problem. How do you put a pilot bearing in the back of the crank with the adaptor, if the box moves back that much? Just asking, since I have never done a conversion like that.
Posted: Thu Nov 20, 2008 2:06 pm
by MyPRodOL
not truly sure how it comes together, the company claims its 100% interchangeable and bolt on your self....
I must investigate my options, obviously go for the least dodgy option, as not to hurt the motor etc....
thanks for input.
Posted: Fri Nov 21, 2008 7:43 am
by Hennie Marais
do the adaptor thing, but make it yourself. mine to have it cut including the material cost R1650, so it's not that expensive when it's done locally.
Posted: Fri Nov 21, 2008 8:23 am
by MyPRodOL
great!!! 1650!! thats great!
would you mind posting the place that helped you or PM me?
Thanx.