Thread: MYY Gearbox?

Originally Posted by the_grubb

My thought personally is that behind a well intercooled and turboed 4BD1, a wide spread of 5 gears is more than adequate. The bucket loads of torque compensates for any slight ratio advantage. I get over changing gears so quickly when driving my 110, 6 would make it even worse In a N/A may be a different story and more is always better... just comes down to time and cost like everything else... I've even bee struggling to find time to do 5 speed conversions

I've had 20 years driving this beast with MSA boxes. First the MSA-5P, then the MSA-5G.

Basically first is too low, it's a crawler for going slow. I always start in second. This makes it a four speed box rather than a 5. Yes I always have a gear that will do, but I often don't have the gear I want.
Going to a 6 speed box will give me one "crawler" and 5 useful ratios. The closer ratios around town will be a huge improvement.

A splitter on the back would give me a similar result to changing transfer ratios on the fly. Improving total gear spread, but not helping the gap between ratios and making it a bastard to drive compared to a 6 speed.

It's almost the same with my other work cars. I have 5 and 6 speed tdi 4wd wagons. The 6 is just nicer everywhere. It always has the gear you want. The 5 is closer spaced than the rover, but it's still just not quite right in many situations.

Time and cost? I want to re-do my adapters and I need to redo my gear linkages when I do a body swap. The work needs done already.

Originally Posted by the_grubb

JFYI in a 110, to keep everything in stock location that 193mm of adaptors is 175mm.

What gearbox were you originally replacing with that length?

Mine is in a 100" RRC, was LT77 and LT230 originally. Part of that 193mm is the rear housing from the original LT77.

Originally Posted by Dougal

I've had 20 years driving this beast with MSA boxes. First the MSA-5P, then the MSA-5G.

Basically first is too low, it's a crawler for going slow. I always start in second. This makes it a four speed box rather than a 5. Yes I always have a gear that will do, but I often don't have the gear I want.
Going to a 6 speed box will give me one "crawler" and 5 useful ratios. The closer ratios around town will be a huge improvement.

A splitter on the back would give me a similar result to changing transfer ratios on the fly. Improving total gear spread, but not helping the gap between ratios and making it a bastard to drive compared to a 6 speed.

It's almost the same with my other work cars. I have 5 and 6 speed tdi 4wd wagons. The 6 is just nicer everywhere. It always has the gear you want. The 5 is closer spaced than the rover, but it's still just not quite right in many situations.

Time and cost? I want to re-do my adapters and I need to redo my gear linkages when I do a body swap. The work needs done already.

Fair comments. Given you can already wheel spin (and I can't) I would of thought you would of had ample torque available.

Perhaps if you finish doing what ever it is you have been doing with your turbo that you've been working on for the last 20 years and intercool it to get what your fancy graphs are showing us is possible your thoughts might change.

I would of thought the time and cost (that already needs doing) to your turbo and intercooler would be a better return than an extra gear initially.

Just my thoughts (as always) though

Originally Posted by Dougal

I've had 20 years driving this beast with MSA boxes. First the MSA-5P, then the MSA-5G.

Basically first is too low, it's a crawler for going slow. I always start in second. This makes it a four speed box rather than a 5. Yes I always have a gear that will do, but I often don't have the gear I want.
Going to a 6 speed box will give me one "crawler" and 5 useful ratios. The closer ratios around town will be a huge improvement.

A splitter on the back would give me a similar result to changing transfer ratios on the fly. Improving total gear spread, but not helping the gap between ratios and making it a bastard to drive compared to a 6 speed.

It's almost the same with my other work cars. I have 5 and 6 speed tdi 4wd wagons. The 6 is just nicer everywhere. It always has the gear you want. The 5 is closer spaced than the rover, but it's still just not quite right in many situations.

Time and cost? I want to re-do my adapters and I need to redo my gear linkages when I do a body swap. The work needs done already.

In terms of driveablility on the road, I find the 5 (or yes 4 with one low crawler, I start in 2nd on flat ground and when not towing always) is good for my turboed and intercooled 4BD1.

The splitter allows for choice in selecting gears offroad or to simply get that bit better gear in certain situations - ie. going up a hill where 4th is too much and 3rd is too little. We are not in race cars, if one is simply driving and going up through the gears, there is no reason to use the splitter. I highly doubt in a quarter mile there will be little difference between a 5 and 6 speed.

Originally Posted by Dougal

What gearbox were you originally replacing with that length?

Mine is in a 100" RRC, was LT77 and LT230 originally. Part of that 193mm is the rear housing from the original LT77.

The original standard 5 speed as fitted to 110 4BD1 - the LT85.

To keep the engine and transfer case in stock position there is a gap of 175mm between the rear face of the MSA and the front face of the LT230.

Originally Posted by the_grubb

Fair comments. Given you can already wheel spin (and I can't) I would of thought you would of had ample torque available.

Right now I'm about 2 turns in on the fuel screw from where I was 3-4 years ago. The good part is I don't have to keep backing off the accelerator to keep it under 750C when passing.
The bad part is I'm not spinning wheels. But I'm still north of 500Nm, torque isn't the problem. Keeping the engine in a sweet spot in different driving conditions is.
I am running one of those pretty graphs. See if you can pick which one.

This won't change when I have more torque, nor would it change with less. If it feels best at 1500rpm in a given situation but my gears can only give me 1200rpm or 2000rpm then it's a compromise. A compromise that can be easily fixed with a 6 speed box.
It's not a show-stopper, but it's something I can improve on.
It isn't high load that I mostly want more gears for. It's low load cruising. But there will be acceleration benefits from a 6 speed. Our peak power and torque are only 1200rpm or so apart.

It's clear you have a vested interest in selling people 5 speed MSA boxes and all your work would be wasted if people decided they wanted 6 sp MYY boxes instead.
But 6 speed is always better. You can't subsitute gears with boost.

FWIW, some time ago I created a spreadsheet to look at my gearing options. I have a MXA-6R and an Atlas II transfer case with 1:1 hi and 5:1 lo. I made my diff ratio 4.1:1. I also wanted to see what would result if I made a splitter using the hi and lo gears from a Patrol transfer case - I decided it was not worth the effort.

The spreadsheet was modified with extra worksheets for the other boxes people here are using with the the 4BD1 to compare them.

The following pics compare the the overall reduction in each gear from some of the worksheets. All of the LT230's were 1.2xx:1 hi and all diff ratios except for mine are 3.54:1

The individual worksheets have more useful information. It is in the spreadsheets thread if anyone wants to use it.

Originally Posted by Dougal

Right now I'm about 2 turns in on the fuel screw from where I was 3-4 years ago. The good part is I don't have to keep backing off the accelerator to keep it under 750C when passing.
The bad part is I'm not spinning wheels. But I'm still north of 500Nm, torque isn't the problem. Keeping the engine in a sweet spot in different driving conditions is.
I am running one of those pretty graphs. See if you can pick which one.

This won't change when I have more torque, nor would it change with less. If it feels best at 1500rpm in a given situation but my gears can only give me 1200rpm or 2000rpm then it's a compromise. A compromise that can be easily fixed with a 6 speed box.
It's not a show-stopper, but it's something I can improve on.
It isn't high load that I mostly want more gears for. It's low load cruising. But there will be acceleration benefits from a 6 speed. Our peak power and torque are only 1200rpm or so apart.

It's clear you have a vested interest in selling people 5 speed MSA boxes and all your work would be wasted if people decided they wanted 6 sp MYY boxes instead.
But 6 speed is always better. You can't subsitute gears with boost.

He he, love the response

Hey, I hear you - if you can improve something then do it. Sorry for hijacking your thread. I was only putting my comments forwards.... you asked. If you wanted comments from an arm chair warrior to say 'oh ah, 6 speeds, dribble dribble' then sorry, if you wanted comments from someone who has seriously looked at it then....

Can you please explain more about your low load cruising? You mean cruising down the highway? or in a specific speed zone (60, 80 etc). So highest gear where it still feels 'nice' - I understand that. So if you are only 'cruising' and not whipping through gears under high load, I fail to see how a splitter then becomes a bastard to drive and keeps the RPM at the sweet spot. In fact the splitter allows for more 'sweet' spots.

Sure the compromise can be easily fixed with a 6 speed. However the compromise then turns into fitting the 6 speed in to the vehicle. When it comes to the compromise between a 6 speed and fitting it or a 5 speed with splitter and fitting it - right now I lean towards the 5 with splitter.

Whatever speed you wish to cruise at you select which ever gear is suitable in the 6 speed or 5 with splitter....

Then when you wish to accelerate away you do so from what ever gear you are in. There is going to be marginal difference in acceleration 'benefits'.


***Umm vested interest..... ask anyone who has tried to buy a conversion of me in the last probably year..... I haven't made or sold any for a year. It is not really worth my effort. In relative terms, compared to my main source of income - it cost me money to make them. Why do you think it has been hard to get a hold of me lately? I find it hard to say no to people wanting conversions even though it cost me...

I started it out of passion and was doing it for others due to passion - not for profit. If I wanted to make a buck in my spare time I would of done night shift at Coles and stacked shelves.

I haven't formally announced that I have stopped making them (as I haven't stopped), I just need enough people to line up to kind of make it at least semi worthwhile. Otherwise I will happily spend my time on other projects

My work is no way wasted. I have had fun, made some people very happy with the conversions and love my own vehicle. If I never sell an adapter again I am happy My creations will stay in my own garage ****

You can't substitute gears with boost no, you can compensate gears with smooth deliverable torque though. I think a lot of the time we get carried away and lose sight of the end goal. If it is low load cruising someone want more gears for, then I remain in saying the the splitter will do the job. Low load cruising doesn't require tearing through gears and hence making it a bastard to drive.

To answer your original question again , yes I have looked at them and my conclusion was that for the vehicle and the intended purpose of its use I figured a more time and cost effective solution (for anyone doing the conversion) was the MSA with splitter to gain more gears (as opposed to boost )

If you didn't want anyone's opinion - you shouldn't of asked. I just gave mine and happy to do so, even if it offends

I have my fuel screw right out. Big intercooler, no smoke and max temp so far is 650C. The good part is I don't have to back off ever The bad part is I am not spinning wheels Where do you think my torque and power sits compared to your pretty graphs? Perhaps if you get to that point, your thoughts may change?

My cheeky response was simply taking on a holistic approach to what ever you are trying to achieve

Originally Posted by Dougal

Has anyone seriously looked at these? I can't shake this idea.

Can't shake the idea through shear determination/stubbornness or acceptance of facts?

Ok back to your 6 speed. I look forwards to buying a conversion off you