RB30-RD28 T gearbox compatability.

[mudnut]

G'day all. The Old Trol's gearbox is starting to get noisy in 1st, 2nd and mostly in third. I have to look at my options. There are some complete GU RD28T's with blown engines for sale. I know the blocks are the same, therefore the gearbox cases are compatible, except for the gear stick, maybe.

Are they the same ratios. Have the innards of the GU been beefed up in any way? Will it be compatible with the RB30?

Cheers.

[mudnut]

Bumpity bump.

[Patrol'n]

That's something that would be worth knowing, if they're stronger they might be good behind a turbo conversion

[mudnut]

This is the second gearbox to stuff up so I am looking to upgrade if I can. I was told that there is an adaptor plate for the RB30 to the auto that the TB42 uses, but how you would fit a clutch is the problem. Also have been told the bigger box would sap too much power from the RB.

[sooty_10]

I have a gu rd28t gearbox in the back yard i could take some pics tomorrow for. You also be more than welcome to make an offer on it mate if it would suit your needs. Looking at putting it on ebay soonish. No idea what they are worth. It was working perfectly before I pulled it for my conversion.

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[mudnut]

I have a gu rd28t gearbox in the back yard i could take some pics tomorrow for. You also be more than welcome to make an offer on it mate if it would suit your needs. Looking at putting it on ebay soonish. No idea what they are worth. It was working perfectly before I pulled it for my conversion.

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Thanks. I also have a gearbox, in pieces at a mechanics place. What I do need to know is if the GU box is stronger. Cheers.

[sooty_10]

Thanks. I also have a gearbox, in pieces at a mechanics place. What I do need to know is if the GU box is stronger. Cheers.
No dramas mate. Any idea what they are worth? As for strength unfortunately I can't help you out. Would make sense to be strong enough for the extra turbo forces.

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[mudnut]

Also would like to know if the ratios are different. The first gear is way too tall for bush work in the RB.

[mudnut]

The wreckers with held a four hundred dollar bond when I didn't send my gear box back, so I guess the boxes are in that range of price or a bit more I suppose.

[Patrol'n]

Makes sense about the bigger box sapping too much power, and I know what you mean about 1st being tall for bush work...

[mudnut]

After reading up on the RB30 in the article that is posted in the helpful hints thread, it was mean't to be a glorified shopping trolley. It is a shame they had that mindset as a low first gear would have made the RB just as good as the TB.

[Patrol'n]

Yep, that is disappointing. The RB30 is a good engine and runs so smoothly, with smooth gear changes too.

It might feel a bit strange on the road with a lower first gear, but it would help for off road for sure, sometimes I still have to ride the clutch a bit on rocks in 1st low or risk stalling...

[mudnut]

The other thing is hill descent. If you aren't on the brakes the engine runs away, which is a bit dangerous.

[Patrol'n]

The other thing is hill descent. If you aren't on the brakes the engine runs away, which is a bit dangerous.

That's so true, I do find that the engine braking a tiny bit more effective once my revs hit about 3000rpm, and then there is some engine braking although nothing like a diesel engine. I also find if I turn on my air conditioning, I get a bit more engine braking effect since the engine isn't quite as willing to rev with the aircon on. I must admit that I am a little (ok VERY) cautious about muddy descents where brakes are not a great idea.

I would consider reduction gears in the transfer case except that with the limited power of the RB30, I find I need to use low range quite often in soft sand (there's a lot of sand over here in WA), and then I wouldn't go anywhere at any kind of acceptable speed. Although I have been trying to resist modding the engine, I'm still thinking turbo conversion and reduction gears, guess I gotta start saving. Probably cheaper to buy a different vehicle, but I do love my truck...

[mudnut]

The best mods I have made are taking the heater grid from under the carby, blocking the stove pipe diaphragm (in the warmer months, for long trips and water crossings) and fitting headers. The engine is still a bit asthmatic so I am toying with the idea of enlarging the neck of the filter housing. All this has made the engine rev a lot easier and has not been too expensive. I am hoping the RD gearbox has a lower first cog, so if that is available I would fit that to the gearbox while it is apart.

It seems that no one has the answers we seek...

[Patrol'n]

Yep that is what it seems. I have the basic things covered as you have, and I have been told that fuel injection improves it too, but also means peak torque is achieved higher in the rev range, which doesn't sound like a great idea... if you do enlarge the neck of the filter housing and it makes an improvement then I'd love to know what you did so I can give it a shot too.

[mudnut]

There's two ways I think it could be done. Split the neck 20mm off to the side of the Pre-heat flap and weld in a strip top and bottom, or add a hose from the plastic pipe to the side of the filter housing.

[mudnut]

Could someone with an RD28t please post up the transmission number on the ID plate?

[UWN717]

still have gearbox mate wats ur location?????

[sooty_10]

Could someone with an RD28t please post up the transmission number on the ID plate?
I'll try to remember and check the one I have in the shed.

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[sooty_10]

still have gearbox mate wats ur location?????
Is this aimed at me? If so yes I still have a rd28ti gearbox. I am located in Bendigo vic.

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[mudnut]

I have got onto 360 Gearboxes in Bayswater, and they informed me that the RD28T and RB30 boxes are the the same, except for the selector inputs.

I asked if there were any upgrades that they do and the reply was as follows.

1) they could install billet forks.
2) A retainer plate that commonly wears out is upgraded with one made of harder steel.
3) Multi-spline gears are used, (something about one spline per tooth?).

With the upgrades and change over, the price is around $3150 with a twelve month /20000 k warranty which doesn't cover broken gears.

Whew, with labour and freight, I'm looking at around four grand.

[Patrol'n]

Wow, I have to ask, how much power would you be putting through this box to justify that sort of spend? I'm guessing that isn't changing the gearing?

I've seen them recoed for about $1300 exchange online before, if your rb is pretty much stock like mine, would it need the extra beefing up?

[mudnut]

It was just a fact finding exercise. There is a small chance I maybe able to rebuild the box I have, with the upgraded components.

[Patrol'n]

Well a stronger box wouldn't be a bad thing, although my engine is in generally good condition, I am still planning /hoping to go down the path of a mild turbo setup in the future, so strengthening the gearbox would make sense to maintain reliability.

If you do the rebuild, any tips / results you can pass on would be appreciated.

[mudnut]

The bloke who has possession of the box is in the middle of retiring / clearing out his workshop and setting up at home, so it may be a few months. He test drove my Q and said it should be ok for a while, but that a bearing is definitely its way out.

[Patrol'n]

What sort of noise do you get from it? Is it the usual type of worn bearing noise? The only issue I need to sort out with my truck is a strange noise under load between about 1000 and 1400 rpm, sounds like a vibration or loud rattle of some sort? I can't work out what it is, although it's been doing it for about 2 years. I thought it might have been a loose heat shield or something, but I can't find anything loose anywhere, and everything works the way it should... I would love to figure it out and fix it, but I don't want to fall into the trap of replacing bits till I know what it is.

[mudnut]

The noise is a chunky whine in 1st, 2nd, and 3rd. I think it is there in 5th, but as the car is noisy it is hard to tell. Fourth is quiet

[Patrol'n]

Ok, well my noise is nothing like that, so at least that's one possible cause ruled out.