OKA #251 Rebuild

G'day All,
Having recently purchased OKA LT #251, I am now in the stage of determining which way to go with a rebuild.
She certainly needs some love and attention, so I am intending to remove the bus body and cab over the next couple of weekends, to give me much better access to the chassis etc.
My primary concern at the moment is to get it up to an A1 mechanical condition, the cosmetics can come later.

I am thinking a Cummins 6BT and Allison mated to an NP205 Transfer Case is the direction I'll head in. I've had a brief chat with Kelvin from Marquand engineering regarding supplying the 6BT and Allison, not a cheap exercise, but I want this thing to be ultra reliable. I'll also probably upgrade the Dana 60 and 70 axles to 35 spline and HD knuckle as Dana 80's will be out of the budget for now.

For those that have fitted the 6BT and Allison to an LT and a married NP205, how difficult a project is this to undertake myself? I'm not a mechanic but can usually cover the basics no problem. Any advice regarding cross members or mounts that would have to be fabricated and any other gotcha's I should be aware of?



Cheers,
Steve

After having a chat with Paul from East Coast Oka's, I am now leaning towards keeping the spicer 5 speed, at least for now as it will substantially reduce my conversion cost and simplify the job for a DIY install.
He is certainly a wealth of info on all things Oka and gave me some things to think about.
Does anyone know of a good NP205 Transfer Case for sale?

@Dane, hopefully I can glean a bit of info from you as your builds progress? I am hoping to begin removing the bus body this weekend, I've had a few prior commitments that are holding me up for now.

Yes the Allison is more expensive and bit more work involved but it will make for a much nicer vehicle to travel in.
When I first bought ours I hated the spicer with a passion and seriously thought about getting rid of the Oka all together, it didn't help that our previous 4wd vehicle had had an auto. After a bit of digging and researching I found an adapter kit to put the GM 4L80E auto behind the Perky which really transformed the Oka, it went surprisingly well as it allowed the Perky to get on boost and hold it up through the gears. Even Paul was surprised how well it went.
Roll on a few more years and Paul had done a few Cummins conversions and so I went down that route too but kept the 4L80E which was a big mistake, putting a heavy duty car transmission in a 6t truck and then adding a 6bt with gobs of torque quickly broke the auto so then fitted a 6 speed Allison, a great transmission well suited to the job.

Third time lucky trying to reply to your post.....

You certainly have taken steps in the right direction on sorting out what you are going to do with your build. A new engine is a great idea unless you can find a known good engine on the second hand market. But these are rare, I was very lucky with mine but still need to do a full seal and gasket change and change every ancillary on the engine to get the reliability I want.

Happy to help where I can mate. If you get stuck please give me a call.

Cheers, Dane

Yes the Allison is more expensive and bit more work involved but it will make for a much nicer vehicle to travel in.

I think as a DIY job for now, I’ll go with the manual option but maybe down the track will convert to the Allison. I am liking the idea of a full mechanical drive train with no electronics at all, as I’ll be shipping this vehicle to Africa in a few years time for an extended trip. The easier it is to fix the better for me.

Dane wrote:
Happy to help where I can mate. If you get stuck please give me a call.

Cheers, Dane

Thanks Dane, will certainly be in touch.
Paul rang me back this afternoon and said Ian is happy to fully dress the motor with all ancillary’s, crossover pipe etc, so I’ll go down that route to make things as easy as possible

He also said I’m welcome to come to Melbourne and he’ll take me for a drive in his and let me have a good look around it, to see exactly what is required for the conversion, I think I’ll take him up on his offer!

I just need to sell my Patrol now, and gather the necessary funds to get the ball rolling. I’ll be contacting an engineer tomorrow and get things started in that regard as well.

You've no real worries with the Allison as with no power connected ie: in limp mode it still has 3rd and reverse so can still be driven albeit a bit slower than normal.

A drive with Paul in his truck was exactly what swayed my decision on which way to go mate. Once moving, gear changes aren't a thing. The 6bt is a torque monster and makes it effortless to drive. I do agree with Peter that behind the 4 pot the spicer is a bit of a dog, couple that with boogered up shifter linkages etc and it becomes a woeful thing to drive. Having had the opportunity to go for a run a couple of 6 cyl oka's with the spicer it is a different beast completely.

Horses for courses in my opinion and my horse is running on the spicer track. Hats off to anyone with the Allison it's just not for me though.

Peter really did pioneer auto Conversions and is a wealth of info (quality real life info) and perhaps my lack of understanding in how they operate is what drives my wariness.

On another note, did you get your truck to fit under your carport mate ?

Cheers, Dane

Yep, the manual is the way I’m going to go at least for now.

No chance of getting it under the carport. Once I remove the cab and bus body I’ll sit them on dollys so I can wheel them up into my back shed.
My main priority for now is the mechanical side of things and sorting out any corrosion issues. I’ll worry about the cosmetic stuff later.

I bought the Gantry Crane the same as yours, the issue I have is my drive has a slight slope, but I should be able to use a couple of packers under one side of the crane. I’ve got another building project at home I need to finish off, and then hoping I have time to remove the bus body this weekend.

Just thought to let you know that ford np205's are not suitable for the OKA. You are chasing down a right hand drop case from a dodge/chev/International truck.

Cheers, Dane

Dane wrote: Just thought to let you know that ford np205's are not suitable for the OKA. You are chasing down a right hand drop case from a dodge/chev/International truck.
Cheers, Dane

Thanks Dane, yes I was aware of that, I'll probably go with a refurbed unit from Paul Knott if I can't find another one.

Cheers,
Steve

Finally began to remove the bus seats today, and wondering who came up with the idea to bolt them down using nutserts! Every 2nd one spun the nutsert while trying to undo the bolt. Prick of a job when doing it by yourself and trying to use vice grips from the bottom to hold the nutsert.

Anyway got there in the end.





Will begin undoing the bus body bolts tomorrow.
Have also started discussion with a local engineer on steps I’ll need to take. I’d like to have 3 or 4 seats in the back for family etc, but need to work out where and how to do this. I’m still unsure if I’ll keep the bus body or build a new one from FRP panel.

Finally got around to removing the bus body today. Everything went fairly smoothly.

I’ve uploaded a video to YouTube showing the progress. Apologies for the audio sync going out in a couple of sections. I’ll get better at this YouTube thing as the build progresses.

She looks good, tidy inside anyways!

Good work mate !! Cheers for the mention, keep me in mind if you decide to go down the composite panel pathway I might have a home for that bus body.

Looks like you had to use the same height setting I did to lift your module that crane will be invaluable for everything you do in that truck. Mine is used daily.

Keep up the good work and welcome to the world of YouTube for your build, it takes a bit of effort but something you can look back on into the future.

Cheers, Dane

Dane wrote: Good work mate !! Cheers for the mention, keep me in mind if you decide to go down the composite panel pathway I might have a home for that bus body.
Cheers, Dane

Thanks Dane,
It will be awhile before I decide on what to do regarding the bus body, at the moment I’m leaning towards building a composite poptop.

I’ll have a chat with OKA-ATV and get some costings and advice on a few things first.

The chassis looks in really good condition so far. I noticed all of the fuel lines are soft hose and the routing of them has several rub points where they bend over the chassis that will be prone to failure. I’m not sure if they are standard OKA fitment? I was expecting to see hard lines, so I’ll redo all of these and make sure they are routed much better than they are now.

Hoping to make a decision on the engine etc this week.

Cheers
Steve

Great video have fun

I’ve uploaded another short video to YouTube


I’ll get the hang of this vlogging thing eventually. I’ve also bought a reconditioned NP205 transfer case and a new clutch, adapter plate, brake and clutch master cylinders from East Coast OKA spares, along with a few other bits and pieces.

I’m heading over to Melbourne on Friday for a visit with Paul and Ian to get a better idea of the whole conversion process. I’ll be going with a new DCEC 6BT with a VE rotary pump from Ian. Paul has been very helpful and it’s obvious from our calls that he knows everything required regarding OKA’s. Looking forward to the visit!

I’ve got a pretty full schedule over the next 2 weekends, so progress on the OKA will be slow. After I get the cab off, I’ll drop the engine/gearbox etc and begin cleaning up the chassis. Not sure if I’ll just wire wheel it or get it taken to a local sandblaster.

All of the hydraulic hoses, radiator hoses, fuel lines etc will be replaced. Every hose feels crunchy, and the radiator only had tap water in it. I’ll do up the fuel lines in SS316 Tube and a mix of soft lines. Not sure on the brake lines yet, 316 is a bit hard to flare without an expensive flaring tool.

Anyway, progress, albeit slow, is being made.

Good stuff mate ! I'll watch your video once my kids give me a bit of peace later this evening. Great idea to go visit Paul and Ian. I just reciever all my conversion bits from them today (yet to go pick my adaptor plates up from my father in law's ute) but it is an A1 setup from what I've looked at today. You will be blown away by how well Paul's truck gets along and how neat and tidy the install is.

Both my chassis will be wire wheeled and painted rather than blasted, just a personal preference.

Great idea to change all rubber hoses while you are doing your build. I'm using zinc plated steel for all my hard lines that need changing, again very much a personal preference there. Stainless would be lovely but as you say very hard to flare.

Keep up the good work mate and say G'day to the boys in Melbourne for me.

Cheers, Dane

Dane wrote: Good stuff mate !

Both my chassis will be wire wheeled and painted rather than blasted, just a personal preference.

Great idea to change all rubber hoses while you are doing your build. I'm using zinc plated steel for all my hard lines that need changing, again very much a personal preference there. Stainless would be lovely but as you say very hard to flare.

Keep up the good work mate and say G'day to the boys in Melbourne for me.

Cheers, Dane

I’m using stainless for the fuel lines as I have stock of 3/8” seamless tube at work along with a variety of compression fittings. We do plenty of tube bending, so it’s a no brainer for me as the fuel lines won’t need flaring.

Brake lines will likely be zinc plated as well, unless I drop the coin on an Eastwood flaring tool.

Yep, I think I’ll be giving the wire wheel a workout also!
I’ll say g’day to the lads for you, no worries.

Cheers,
Steve