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Discussion Starter #1
Hello
Do you think straightening the crankshaft makes sense? :confused:

At the beginning I must say I really don't like this idea ... :eek:oohhh:

The shaft is gently bended.

It has to be grinded on the main bearing shells at 0.25mm at crankshaft bearings 0.50mm.

People that built engines for motorsports in my area say that there is no problem and can fix it, it is a forged steel shaft, and they often do such operations.

But this engine will be forged and there will be a lot of boost

I bought another shaft but they are all in a similar condition,... :sad3:

Can anyone do this and dispel my doubts

Regards
 

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BMW sells .25 mm and .5 mm undersized main bearings and the same for the connecting rod journals so they seem to think that much removal is acceptable.

That seems pretty large to me, but if you can't find one that is in spec you don't have a lot of choice.
 

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Hello
Do you think straightening the crankshaft makes sense? :confused:

At the beginning I must say I really don't like this idea ... :eek:oohhh:

The shaft is gently bended.

It has to be grinded on the main bearing shells at 0.25mm at crankshaft bearings 0.50mm.

People that built engines for motorsports in my area say that there is no problem and can fix it, it is a forged steel shaft, and they often do such operations.

But this engine will be forged and there will be a lot of boost

I bought another shaft but they are all in a similar condition,... :sad3:

Can anyone do this and dispel my doubts

Regards
I'm not sure what you mean here. Normally you would straighten a crankshaft by supporting the two ends in v-blocks and either pressing the crank the opposite way to the bend in a hydraulic press, or peening the high spots with a hammer and brass chisel :eek:oohhh:. You can't straighten a crankshaft just by offset grinding the journals if that's what you mean. Maybe you have misunderstood the shop.

I would worry about crank straightening on a high HP, high dollar engine. The crank should be in perfect condition to maximize the fatigue resistance. And I think the S62 journals are hardened by nitriding, based on them usually being in great condition after a rod bearing has wiped. Any chance of this hard surface treatment cracking during straightening?

We amateurs are kind of at the mercy of the experts at the shop for stuff like this. Ask them if they will warranty the engine against crankshaft breakage for a year.
 

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Discussion Starter #4
I'm not sure what you mean here. Normally you would straighten a crankshaft by supporting the two ends in v-blocks and either pressing the crank the opposite way to the bend in a hydraulic press, or peening the high spots with a hammer and brass chisel :eek:oohhh:. You can't straighten a crankshaft just by offset grinding the journals if that's what you mean. Maybe you have misunderstood the shop.

I would worry about crank straightening on a high HP, high dollar engine. The crank should be in perfect condition to maximize the fatigue resistance. And I think the S62 journals are hardened by nitriding, based on them usually being in great condition after a rod bearing has wiped. Any chance of this hard surface treatment cracking during straightening?

We amateurs are kind of at the mercy of the experts at the shop for stuff like this. Ask them if they will warranty the engine against crankshaft breakage for a year.

Exactly as you wrote, straightening and grinding the shaft are two completely different things.:)
The shaft has been fixed in a hydraulic press and now only hammering is left However,
for the journals they were grinded + 0.25 on the main bearings Crank bearings must unfortunately be + 0.50 mm:Thumbdown:
So you would azotize these journals.
Have any of you straighten the shaft for S62 and maybe something to write about the effects:confused:
The shaft is straight but I have a little more time to think about it before the delivery from vac comes.
If anyone from Europe has a good shaft for sale Im eager to buy it:1zhelp:
Regards
 

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If your crank has run out it is no problem to fix it for a professional.
Most of the cranks I worked with have a run out and get straightened,is a normal procedure.

There is no issues with reliablity if done correct,I run cranks fixed like that on 20psi+ boost engines without problems.

But if you need all main and rod yournals re-ground,I would start with a good crank in the first place
 

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If your crank has run out it is no problem to fix it for a professional.
Most of the cranks I worked with have a run out and get straightened,is a normal procedure.

There is no issues with reliablity if done correct,I run cranks fixed like that on 20psi+ boost engines without problems.

But if you need all main and rod yournals re-ground,I would start with a good crank in the first place

I'm curious....are these cranks out of spec as originally delivered, go out of spec over time, or are the result of a catastrophic engine failure?
 

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Discussion Starter #7
Hi
I managed to buy a good shaft from England.:)
Waiting for shipment, then I can measure it and finally I will be able to
pick the bearings...

I wonder one more thing.
Do service stations have new or remanufactured oil pumps available???:confused:
Recently, I heard that BMW wants to return the old part, pay for new and
you get regenerated one back.
Is this true? If so, is it worth it to buy this pseudo new oil pump.:Thumbdown:
Regards
 

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Hi

I wonder one more thing.
Do service stations have new or remanufactured oil pumps available???:confused:
Recently, I heard that BMW wants to return the old part, pay for new and
you get regenerated one back.
Is this true? If so, is it worth it to buy this pseudo new oil pump.:Thumbdown:
Regards
Did you have a problem with oil pressure?

If the engine failed so that a lot of debris was circulated round it, there's no filter on the pump suction, just a strainer, so it can get damaged by debris.

And I have seen a couple of reports on here from owners with surprisingly low oil pressure, but no report of the cause. Could be a worn pump, could be worn crank bearings.

They don't look to difficult to take apart. Check with a BMW shop.

8235420697_5896deda93_b.jpg
 

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Discussion Starter #10
Did you have a problem with oil pressure?

If the engine failed so that a lot of debris was circulated round it, there's no filter on the pump suction, just a strainer, so it can get damaged by debris.

And I have seen a couple of reports on here from owners with surprisingly low oil pressure, but no report of the cause. Could be a worn pump, could be worn crank bearings.

They don't look to difficult to take apart. Check with a BMW shop.

View attachment 487058
As I said I bought the engine with damaged bearings, so there are
certainly a lot of chips ...
I'm building this engine for high power and boost.
With a project like that it would be a good idea to give a new oil
pump.
BMW only remanufactures pumps and sells them as new so maybe
somewhere there is a repair kit available for the pump.
Regards
Piotr
 
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