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Gearbox: RB25 or VL turbo box

Fast31
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rb20-calais Rising Star

rb20-calais

Posted
Posted

the standard vl 6 cylinder box the (MF5?) is the same strength as the rb20det box, so dont bother with that. The RB30ET box (MX7) is the same strength as the RB25 boxes but they are older so you might have to recondition or find a good one.

One of my mates had 492rwhp with a standard MX7 in a VL turbo that cam second at horsepower heroes at the summernats (PSI-03L) he upgraded because he wanted auto. I would go for the one in better condition and cheaper because I am sure they are very similar and will definately hold 350-400rwhp no problems.

Hope that helps,

Evan

Simonster Proficient

Simonster

Posted
Posted

Another thing you may want to consider, is that the VL can have problems with the 2nd gear synchros, as it wasn't designed to rev to speeds like the RB25 and quick 1st to 2nd gear changes may reduce it's life as well. A mate of mine went down this route as well and had these problems, but hey, it might have been a sh*t gearbox from the begining?

Definately cheaper than the RB25 box though

OVL-747 Enthusiast

OVL-747

Posted
Posted

33box is slightly better than the vlt box , pricewise isnt much between em , so it may be benifical getting a rb25 box.

differences in the tailshaft yokes etc will need to be sorted out , but isnt much of a problem

mind u , a rb20 box wont fit a rb30 , so there maybe issues fitting a 25 or 30 box to a 20

Cubes Grand Master

Cubes

Posted
Posted
Originally posted by OVL-747

mind u , a rb20 box wont fit a rb30 , so there maybe issues fitting a 25 or 30 box to a 20

The RB20DET boxes do fit the RB30 VL no problems. Yokes are different and the tail shaft needs to be modified.

When I was converting my old VL 3ltr NA to a manual I looked at this path. The RB20DET box is a lot stronger than the RB30 NA box especially when it comes to the syncro's. They do have a weakness that comes with their 10year old age which is their input shaft when you are making around 300rwhp and slap slicks on it. Apart from that they are tough boxes. I have also noticed they tend to have less issues with syncro's compared to a rb25 box.

I was quoted around 1500 to slap a RB20DET box in to the RB30 NA however I was able to slap a RB30 NA box in it my self for next to nothing so that is the path I took. Then I began having second gear syncro problems 20k after the box was in. Those boxes don't like full rev gear snaps.

I have absolutly slammed the RB20DET gearbox with 225's on it and it has held together for 2 years and 60,000km's later. Lots of second gear snaps that cause wheel spin all the way through second. For example I blew a VS 5ltr 5 Speed gearbox within 6 months of owning it. It simply didn't like hard second gear changes. So I'd say the RB20DET box is pretty damn good for what they are BUT they arn't good enough. :P Good if you are looking at 200-250rwkw on street tyres. Anymore and it won't hangin there.

Remember also these cars are 10+yrs old now so you have to expect them to blow every now and again. Rebuild the box you have and it will be rock solid. This was true also with my first car a TE 250 4 speed. I went through 3 gearboxes pretty quick. I then began rebuilding the boxes and from that day on the only thing that broke was the select forks that kept snapping in the same spot.

Skyrine-Dave Mentor

Skyrine-Dave

Posted
Posted

Yeh my RB20det 5spd has seen alot of 1st to 2nd high rev gear slams and it seems to love it :P

no noises or anything from my box so i'm touching wood that it will hold up for a little while.

it just gets a little touchy on the 3rd gear flat changes :)

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