the point would be that the bigger heavier gears of a tb/td box would take more energy to get spinning, a similar effect to if you were to double the weight of the flywheel
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I was hoping the extra angular momentum of those heavier items like flywheel, gear etc would eventually compensate for the initial energy loss by the gathered extra inertia. Sure,... the take off can be bit more expensive than the lighter gearbox, but may be the extra energy spent can be recovered while cruising, the same idea as it would happen from a slightly heavier flywheel, in theory of course. I'm sure there are other factors that goes into it that might make my argument valid or invalid.
My point being, it might be the mismatch of torque ratio conversions that cause the extra fuel consumption, rather than slightly heavier gears. RB30 gearbox is purposely designed to efficiently convert the torque of the RB30 engine to the desired ratio on each gear and TB42/TD42 boxes doing the same thing for those engines. That's why I was hoping that some fiddling with the diff ration might(or might not) be able to correct the torque conversion ratio(s) and fuel consumption to an acceptable level.
Yep, and that concerns me a fair bit, 'cos if it happens in the middle of an off road track when going on solo, it can end up bad.
Of course, going solo off road too far is a no no, but there are nuts who does that occasionally, like myself. ;)
There are some synthetic additives out there to add to gear oil to make things run smoother and get more k's out of a box.
Dunno how good they are though.
BTW, assuming you still have the old bad gearbox in the garage, it may worth getting the rebuild kit from Bearings Wholesalers and have a crack at it yourself. I don't think the kit comes with gears, but comes with all the bearings and synchros. A dial indicator may be necessary for the job, but you can buy an adequate one from ebay. You probably wanna open up the old one first and see if there are any broken gear splines, 'cos buying those gears new can be pretty pricey.
I have sworn few times in the past not to touch transmissions at all(manual or auto), but the temptation is still here. What I don't have is the time and space. :)
Yeah, I've done with a sat phone in the past. I meant the recovery of the vehicle can end up as dangerously expensive unless there are mates not too far who can help with dragging the vehicle to a main road.
My anxiety actually isn't about dying(I hope) 'cos I do carry lot of dry food & water. It is about having to let go the vehicle. :)
You get attached to the troll after few years, or at least I do. ;)
Mine is a '00 GU - part of the bunch that had the crappy 5th gear from factory. It had towed camper trailers in the previous owners usage, not sure what it did in owners before then. It lasted 260k - not bad for a second rate part. But if you have to take out the gbox one way or another, I'd always vote reco, unless you know that the replacement box is from outside of the affected year range.
Additives aren't going to help, because it's not a heat/wear thing, the splines actually tear and round over from mechanical overload/fatigue. I've got my old layshaft and gear and you can see where the shoddy gear never engaged with the end of the spline. Outside of that, the shaft and gears all look like they're brand new, because of regular oil changes.
What year was the gearbox issue fixed by Nissan - & what was the fix? A beefed up 5th gear pinion?
I believe it was a problem up till some stage on '02. From all my reading you are safe of the box is from an '03 or up. Mine was an '01.
Yep the solution is longer splines of the main shaft for 5th gear to engage on, and I believe a slightly wider 5th gear.
Further more my research has shown that the CRD has lower gear ratios for the first 3 and a taller 5th. I'm going brand new box so should all be sweet and I am getting the CRD box for a lower first gear.
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