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Sun Jun 12, 2016 4:13 pm

Any one tried copying any of the thrust bearing ideas used in VW Type 1 engines converted to aviation use?

Sun Jun 12, 2016 7:47 pm

Personally, i"d be wary of hanging a prop directly on a VW crank. The precession torque force of that spinning prop must really stress the crankshaft. Can't be good for the bearing next to it either. [Compare the size of the crank bearings to something like a Continental O-200.]

If you hung the prop on the pulley end of the crank, the thrust force would have to travel the whole length of the crank. If you hung it on the other end, you'd need a killer gland nut. Neither option seems reasonable.

If I were to do it, I'd opt for a secondary shaft for the prop (belt drive??), or find some sort of planetary gear reduction unit with killer prop support bearings that bolted to where the tranny normally goes.

Sun Jun 12, 2016 8:06 pm

telford dorr wrote: Personally, i"d be wary of hanging a prop directly on a VW crank. The precession torque force of that spinning prop must really stress the crankshaft. Can't be good for the bearing next to it either. [Compare the size of the crank bearings to something like a Continental O-200.]

If you hung the prop on the pulley end of the crank, the thrust force would have to travel the whole length of the crank. If you hung it on the other end, you'd need a killer gland nut. Neither option seems reasonable.

If I were to do it, I'd opt for a secondary shaft for the prop (belt drive??), or find some sort of planetary gear reduction unit with killer prop support bearings that bolted to where the tranny normally goes.

I am not intending to hang a prop on anything. I am just wondering if anyone has tried any of the aviation thrust bearing setups in a VW Transporter Type 1 engine. If one could eliminate thrust bearing problems on a T-1 it should greatly increase engine life.

Mon Jun 13, 2016 2:16 am

I'm not sure any of us besides Colin have a Type 1 engine with a high number of miles and no other issues outside of the thrust bearing.

In the mean time, do you have a link, or more info, so we might learn a bit about the different bearing setups?

Robbie

Mon Jun 13, 2016 5:49 am

I haven't yet found a drawing or even a photo for the bearings, just a mention that the Great Plains thrust bearing have 4-5 times to area of the stock VW bearing.

Mon Jun 13, 2016 6:35 am

I think the greater issue here is how hard the type 1 engine must work to push a bus around. Aviation components are triply redundant, yes, but the spinning air plane propeller is no work whatsoever compared to pushing a bus around in traffic. The magnesium case gets hot (especially in a bus) and spreads out over time due to the boxer configuration of the crank. When it spreads even a little the thrust bearing starts moving in the saddle and starts to oval it and the clutch action loading and unloading the engine erodes the shelf the thrust bearing sits on. So the problem is not the thrust bearings at all. The weakness is in the case, especially ones that have been align-bored several times and have been heat cycled a million times. The best solution is to run an aluminum case (type 4s have none of those problems) or get a new magnesium case that has never been heat cycled.

Mon Jun 13, 2016 6:39 am

in 400,000 miles on a T1 bus I never had any issues with thrust bearings. The bearing is held with crush. If the saddles get pounded out then something will give. If someone rides the clutch the end play will get excessive and the crank will slam around. Someone is overthinking the thrust bearing surface.

Mon Jun 13, 2016 6:44 am

tootype2crazy wrote: I think the greater issue here is how hard the type 1 engine must work to push a bus around. Aviation components are triply redundant, yes, but the spinning air plane propeller is no work whatsoever compared to pushing a bus around in traffic. The magnesium case gets hot (especially in a bus) and spreads out over time due to the boxer configuration of the crank. When it spreads even a little the thrust bearing starts moving in the saddle and starts to oval it and the clutch action loading and unloading the engine erodes the shelf the thrust bearing sits on. So the problem is not the thrust bearings at all. The weakness is in the case, especially ones that have been align-bored several times and have been heat cycled a million times. The best solution is to run an aluminum case (type 4s have none of those problems) or get a new magnesium case that has never been heat cycled.

A crank driven prop on an airplane is going to put a continuous large thrust load on the crank, way higher than an engine in vehicle use is going to see. VW greatly improved the thrust bearings on the 2.1L WBXer engines in the late Vanagon. These bearings are multiple piece bearing so they will never exhibits the problem so typical with the Type 1 bearing which is the bearing shell moving back and forth in the case.

Mon Jun 13, 2016 6:54 am

SGKent wrote: in 400,000 miles on a T1 bus I never had any issues with thrust bearings. The bearing is held with crush. If the saddles get pounded out then something will give. If someone rides the clutch the end play will get excessive and the crank will slam around. Someone is overthinking the thrust bearing surface.

Wow, a denial that VW even have a problem with their thrust bearings. If the problem doesn't exist why are there so many ideas on how to prevent it from happening, like not depressing the clutch when starting or just plain avoiding the normal use of the clutch like you advocate. I want a vehicle that I can just hop in and drive normally, I don't want to avoid downshifting because someone wants to use the wrong oil in the transmission and is now afraid they will damage their sychros if they OMG DOWNSHIFT, I don't want to drive slow because someone thinks they need 20W50 molasses in their crankcase, and I don't want to use some kind of special driving technique to prevent a poorly designed thrust bearing from failing. Sorry, but I expect more from my rides.

Mon Jun 13, 2016 7:00 am

Wildthings wrote: tootype2crazy wrote: I think the greater issue here is how hard the type 1 engine must work to push a bus around. Aviation components are triply redundant, yes, but the spinning air plane propeller is no work whatsoever compared to pushing a bus around in traffic. The magnesium case gets hot (especially in a bus) and spreads out over time due to the boxer configuration of the crank. When it spreads even a little the thrust bearing starts moving in the saddle and starts to oval it and the clutch action loading and unloading the engine erodes the shelf the thrust bearing sits on. So the problem is not the thrust bearings at all. The weakness is in the case, especially ones that have been align-bored several times and have been heat cycled a million times. The best solution is to run an aluminum case (type 4s have none of those problems) or get a new magnesium case that has never been heat cycled.

A crank driven prop on an airplane is going to put a continuous large thrust load on the crank, way higher than an engine in vehicle use is going to see. VW greatly improved the thrust bearings on the 2.1L WBXer engines in the late Vanagon. These bearings are multiple piece bearing so they will never exhibits the problem so typical with the Type 1 bearing which is the bearing shell moving back and forth in the case.

The air plane is a continuous load much like an industrial engine and it receives copious cooling. The bus is in a big metal box cruising around on hot city streets and stopping and going continuously. There is a big difference in the work the engine is doing between the two.

Magnesium over time and with enough heat becomes brittle. The WBX case does have a different thrust bearing but the case is aluminum. The problem is not the bearings, it's old shitty cases that should not be reused.

Millions of buses were driven like regular cars back in the day, people downshifting, starting with the clutch depressed, etc. They did fine because the parts were NEW. Old parts made of magnesium should be thrown away and replaced.

Mon Jun 13, 2016 7:04 am

Wildthings wrote: SGKent wrote: in 400,000 miles on a T1 bus I never had any issues with thrust bearings. The bearing is held with crush. If the saddles get pounded out then something will give. If someone rides the clutch the end play will get excessive and the crank will slam around. Someone is overthinking the thrust bearing surface.

Wow, a denial that VW even have a problem with their thrust bearings. If the problem doesn't exist why are there so many ideas on how to prevent it from happening, like not depressing the clutch when starting or just plain avoiding the normal use of the clutch like you advocate. I want a vehicle that I can just hop in and drive normally, I don't want to avoid downshifting because someone wants to use the wrong oil in the transmission and is now afraid they will damage their sychros if they OMG DOWNSHIFT, I don't want to drive slow because someone thinks they need 20W50 molasses in their crankcase, and I don't want to use some kind of special driving technique to prevent a poorly designed thrust bearing from failing. Sorry, but I expect more from my rides.

no - trying to avoid overthinking everything, or misleading others on certain risks.

Quote: I don't want to avoid downshifting because someone wants to use the wrong oil in the transmission

You need a reality check if you are suggesting five or six shops that rebuild transmissions for a living lied when they made recommendations based on 1st hand personal horror stories of having to rebuild a brand new trans because the owner used the wrong gear oil which destroyed the moly coated synchro rings.

Quote: 20W50 molasses

I don't know what to say other than I am not going down your path to making buses run. You live in Oregon as I recall and it doesn't get as hot in Oregon as it does in California's Central Valley or So Cal Deserts. Oregon is wet and cool except for the eastern half. Around Bend for example it is drier but it is almost 4,000' or high desert. Engines don't overheat as easily at 4,000' because the air is thinner hence less compression hence less heat. You can get by with thinner oil there. You cannot get away with thinner oil at sea level when it is hot and you are pulling a grade. The Oregon coast is cold and damp. Much like our northern coast. I doubt if 20-50, and 40 wt are needed there but it sure is in the CA central valley and so cal.

I think the things that work for you do indeed work for you. But that does not mean they work for everyone else. As an example only - I would never be satisfied with this engine in my bus but it may work perfect for you. Maybe your thrust bearings are wearing out because the engine is worn out after so many miles. Cases don't last forever.

Mon Jun 13, 2016 8:16 am

SGKent wrote: I think the things that work for you do indeed work for you. But that does not mean they work for everyone else. As an example only - I would never be satisfied with this engine in my bus but it may work perfect for you. Maybe your thrust bearings are wearing out because the engine is worn out after so many miles. Cases don't last forever.

That engine made it 14 years without ever being pulled a single time and got over 250K miles between rebuilds including any head work, and had just gotten back from a 25K mile trip. It didn't get babied like you seem to think these engines need to be, but was often run dead to the floor for hours on end. Almost the whole way across Montana one time against a 40 mph head wind. I have never had a thrust bearing go out on an engine I have owned since new or since a recent rebuild, but thrust failure is common enough and it seems like a good thing to prevent, not to just deny the existence of. Thrust bearing failure and other problems related to the pot metal Type 1 case are one reason I strongly prefer the much sturdier Type 4 engine, I hate the apologist attitude that goes with owning a Type 1 engine, this includes statements like "Cases don't last forever". Sorry but I own my cars to drive them, not to just spend all my time doing touch of work on the engine paint so that they look good in the garage.

Shops can make all the recommendations about the necessity of running GL-5 oil they want to fix a problem that doesn't even exist in typical street use, but when they come back here and start saying you need to avoid downshifting to make their transmissions last their credibility goes right out the window.

For what its worth I have driven all around the west, including the American Southwest during the summer months and deep into Central American and have never once felt the need to run a 20w50 oil. The only place I see for that oil is an engine that is primarily being run at low speeds or for worn out tubs.