tatra 813 new owner

[FridgeFreezer]

Looking good!

The winch guide is called a fairlead.

I finally made contact with Tatra today, their tech director is translating the answers to all my questions and will mail me next week!

 

[duncan]

Im out of paint now and still have a bunch of things left to paint. My wallet is crying!

 

[FridgeFreezer]

That's looking really smart - is the cab going yellow too?

 

[duncan]

Yeah, same yellow, and will add black details (door handles, mudguards, and the likes). Hope it will look as trick in reality as it does in my head. Just not sure on the interior and the cargo cover color yet. Thinking something off-white for the interior and a khaki cargo cover, but not sure yet. Just getting everything painted now that will be hard to work on when the truck is assembled again.

Will start rebuilding tomorow, gotta put new bolts through the wooden floor, the old ones are all rusted away so I had to grind them apart.

 

[duncan]

Right been at it a lot now. Started rebuilding the air system, but running into a few problems. All the bigger air connections are m22x1.5 thread which is not available in pushfit. Theres some itialian brand that makes fittings that size, and you end up paying about 15 euros per straight fitting and have to bolt on the T sections and so on seperately. Also goverment regulations and all make air hoses allowed for braking very expensive. I bought enough gear now to replace some major sections of the main air system (compressor to air processor to the tanks and to the brake valve. All the other air lines I will clean and mount with new seals. The smallers (8mm) air circuits will all be replaced though, thats widely available and relatively cheap to do. All in all, spend an entire day mapping out the air system, which thread and sizes to use where, only to drive by about 10 different shops giving me either very steep prices or nothing at all. Hope to do something more productive tomorow!

 

[FridgeFreezer]

Well I got a reply from Tatra, very helpful people but I think it puts the brakes on my ideas life is a bit busy to do much more running around after big toys now, and the exchange rate seems to be going in the wrong direction too.

The truck was build in April 28th, 1975 for Czech Army with serial number ****-**. We were unable to find out nor the vehicle birth sheet neither the engine serial number , only engine type which is T 930-3. In my opinion this vehicle cannot be registerd for civilian use because originally was registered for military purposes only. The vehicle was tested for combined fuel diesel-petrol (ratio 60:40)and recomended only for emergency reach a destination with reduced power. We do not recommend to use the mixed fuel permanently not to damage the engine. As the production of T 813 was stopped in 1982 there are no spare parts available for drive line reconstruction. The workshop manual is available (42 MB file), i.e. we can send it to you on CD or put it some storage on internet.

 

[tatra813]

Got a picture of my lovely air processing unit Makes me a happy kid!

View attachment 146713

Went for another round of spray paint today...

View attachment 146714 View attachment 146715

And couldnt resist adding a little finishing touch to the rear bumper

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Im out of paint now and still have a bunch of things left to paint. My wallet is crying!

What does your air processing unit do?
Are you eliminating any stock units when you replace with the new one?
Where in you system are you going to intall it.?

 

[duncan]

Well I got a reply from Tatra, very helpful people but I think it puts the brakes on my ideas life is a bit busy to do much more running around after big toys now, and the exchange rate seems to be going in the wrong direction too.

Most tatra's are military, and a lot of them got a registration afterwards anyway. Could see about getting it registered here before driving it over to England maybe?

What does your air processing unit do?
Are you eliminating any stock units when you replace with the new one?
Where in you system are you going to intall it.?

The unit has a pressure regulator, water separator with automatic blow-off, a big replaceable filter for fine dust and oil particles, and an electric air heater that kicks in somewhere around 7 celcius / 44 fahrenheit. Just need to feed it 24 volts for that, and its not required for the rest of the unit to work.

I'll use it to replace the water separator between 2nd and 3rd axle, the anti freeze bottle, the oil separator unit and pressure regulator (the two units on the back of the truck).

Currently I mounted it on the back where the old regulator was, but it interferes with the rotatable trailer hitch. I'll call the manufacturer today to see if I can mount it closer to the compressor (should be fine, its that close on regular trucks too). If thats possible it'll go on the location of the old water separator.

 

[FridgeFreezer]

Most tatra's are military, and a lot of them got a registration afterwards anyway. Could see about getting it registered here before driving it over to England maybe?

That's not the issue really, you can register anything from a go-kart to a tank in the UK no problem. The issue is it's not a multi-fuel engine which means no free fuel which means a huge pile of cash to drive it anywhere - probably £1500 to get to Russia and back, even with cheap fuel in Russia.

The other problem is our wonderful government is managing the economy so well that the £ is falling through the floor against the Euro, when I started looking 8000e was about £6500, now it's £8000 - not a great time to be buying from abroad.

I think the sensible option is to hold back for a bit, we've got 3 race cars to build for May next year and one truck to make ready. In the meantime I can save some pennies and maybe end up with enough for either a restored & fully working 813 or maybe even an 815.

 

[John C]

Well I got a reply from Tatra, very helpful people but I think it puts the brakes on my ideas life is a bit busy to do much more running around after big toys now, and the exchange rate seems to be going in the wrong direction too.

Sorry to hear that pal, the multi-fuel issue I think though you will find is the same for almost all engines, it is never intended to be used long term but just as a backup when regular fuel becomes unattainable in wartime conditions, even then it's not recommended that it be used for long periods - of course it depends what the fuel consists of as to how damaging it will be to the engine.

There is also a trade off for being multi-fuel capable; different injection hardware and engine setup is employed which has the effect of making the engine thirsty on fuel and run quite dirty, this is not deemed acceptable by modern standards and most military vehicles are now diesel fuel only.

 

[FridgeFreezer]

There's multi-fuel and multi-fuel, some are very sensitive and "emergency only" whereas others out there are running round on used engine oil and all sorts of stuff with no problem.

I can only really live with terrible MPG if the fuel is cheap.

Hey ho, I'll just have to lavish some pennies on my Land Rover instead.

 

[John C]

I think the problem arises with multi-fuel when you are using a fuel that contains a large percentage of petrol or a similar substance, this lacks the lubrication needed by the injection pump to avoid damage to it's components, the other issue maybe the heat and burn characteristics of the fuel once ignited in the cylinder. old engine oil on the other hand lubricates very well and also burns slower which makes it a safer fuel if somewhat a little dirty, the only issue with old oil is getting it clean enough to use, fine particle filters do a good job of removing the swarf and larger carbon particles but not all, for this a centrifuge is needed and often the oil needs to be processed several times before it could be considered safe to use(in my opinion) - this is the setup I've been using recently for my 813, before this though I used to run old tractors on just filtered old oil without problems - but for the Tatra I use the centrifuge, I also mix the oil with a small percentage of diesel to improve the burn, no problems running the 813 on the stuff but it is a little smokey when you boot it as you would expect.

 

[duncan]

Youre running one of the later multifuel engines on that, or the regular ones? Sounds interesting

 

[duncan]

Back to construction talk, mounted the new air processing unit on the back of the truck.



That didnt work with the rotatable trailer hitch, so I moved it halfway down the truck to where the original water separator was.



Then I went to revise the 3-circuit brake valve. It worked but the main air line feeding the brake system was kinda dirty inside, so I figured I'd better not take any chances and clean it all up now. Took it completely apart, cleaned everything, greased the seals, etcetera. It shaped up quite nice. I wont know wheter it will actually work until I get to drive the truck again though. By that time there will be this nagging feel telling me "there was something important I had to test before driving again, but I forgot what it was, so lets drive!". Might need to put a little note on the steering wheel or something.

Took it completely apart, cleaned and rebuild into this. Makes me smile when I look at it Just hope it works.

 

[duncan]

Right, got the main air system done, just have to re-fit the 3 brake reservoirs at the back, but the rest is there. New air hoses fit nicely into the insides of the chassis beams, no parts exposed except where needed.



With that one solved, I went to the store and got me 100 metres of flexible 8mm air hoses and a few boxes of push-fittings. Replaced the air supply lines going to all solenoids within an hour or so. Removing the old fittings and cleaning up the mounts taking the most time. This push-fit stuff is brilliant.
I am changing the air layout a little bit here and there, taking the shortest route from the fitting to the nearest part of the chassis. Since these plastic tubes are a little more vurnerable than the original metal parts I want them to be as protected as possible.

 

[tatra813]

Right, got the main air system done, just have to re-fit the 3 brake reservoirs at the back, but the rest is there. New air hoses fit nicely into the insides of the chassis beams, no parts exposed except where needed.

View attachment 148379

With that one solved, I went to the store and got me 100 metres of flexible 8mm air hoses and a few boxes of push-fittings. Replaced the air supply lines going to all solenoids within an hour or so. Removing the old fittings and cleaning up the mounts taking the most time. This push-fit stuff is brilliant.
I am changing the air layout a little bit here and there, taking the shortest route from the fitting to the nearest part of the chassis. Since these plastic tubes are a little more vurnerable than the original metal parts I want them to be as protected as possible.

View attachment 148380

lookin good ...nice pics

 

[duncan]

Did a lot of work, but all small stuff that doesnt make good photos. Almost done on replacing all of the air system. It's been quite a fight switching from the original 12 and 14mm gas fittings to 1/4" pneumatics. Spend a lot of time on the lathe cutting new thread on plugs and connectors, but Im nearly there now.

In the process I had to remove 3 of the pneumatic cylinders that activate my inter-axle diff locks. The amount of dirt coming out once again proves I'm doing the right thing by replacing the entire air system. It also tells me I need to open the other 4 cylinders for the axle locks, theyre probably just as dirty.

I noticed once of the differentials has water pollution in the oil. Will probably drain and replace the oil for all the diffs, and do the engine and axles while Im at it. Anyone got 120 litres gear oil to spare ?

Actually, on the oil thing, anyone ever found out what replaces the old tatra oil specs? Mainly PP80 (used in the diffs, transmission, hub reduction, etc), and OA-M6AD (used in the engine) ? I'd go with heavy gear oil and generic diesel engine oil but if anyone knows what it should be, that would be a great help!

 

[duncan]

Right, connected the last few pneumatics today and used a massive amount of zip ties. Whoever invented those should get some nobel price. Seriously.

Anyway, hooked a big air compressor to the front trailer coupling to pressurize the system and hunt for leaks. The connection to the rear trailer brake coupling popped off due to a bad fitting, which I will replace tomorow. The master brake cylinder has one bad valve so it'll have to come apart again.

A few of the other valves are leaking very slightly due to the home-made fittings. I cut the original fitting threads down to the required size to use modern day pneumatics. Saved about $300 on fittings that way, just a few leak a little. Will clean them and treat with hydraulic-seal glue, wont leak after that one, for sure

Even with the small leaks the system kept pressure for over an hour (depressurized it after that), so it seems all fine. All the new plastic hoses are neatly tucked inside the frame, or otherwise out of harms way. It meant re-routing a lot of the system and at points taking a few ft of detour, but the flexibility of this system vs bending metal pipes makes it all easily possible.

 

[tatra813]

nice!

 

[duncan]

Right, the sealing glue is all in place and the air system is now leak free except for the brake valve. Will look into that soon.

Removed the steering column, it has to come out anyway when I install the new cab, so might was well do it now. Didn't remove it when removing the old cabin because the floor was rusted away anyway

I replaced the hydraulic line for the clutch, the old one was rusty and patched in a few places. Better replace it now with some totally overkill new bits. Got a 350 bar / 5000psi hydraulic hose made to fit. That should hold for now.

Lastly I reinstalled the left side tool box with the headlamp. Gives the truck its face back a little.

I noticed theres a small unit under the dashboard that has one of its wires cut. Can anyone tell me what it does, before I reconnect it and do something stupid?