Crankshaft snapped - bottom end or full rebuild...?

[pjac67]

Happened last night after a short run out ( was fine at Dunsfold last w/e showing 150mph + ) - still awaiting a full diagnosis but certainly need a bottom end rebuild.

Not sure why it suddenly went (c. 60k miles)....

Need to consider whether full rebuild or whether my 'special' bits at the top are worth retaining....

Just need to share the pain at the mo'.....

Paul.

[jeboa]

Strange - I have one of these in the garage at the moment. V8D engine, built in 2003 with TVR 5.0l pistons (and I assume TVR Crank) - snapped at the front journal.

Considering using the block (x-bolted) to build a top-hat liner block with 96mm pistons and a shorter stroke crank (stoked 4.6 crank with 2.000" big end journals).

Depending on how 'clean' the break is, all your gucci top-end bits should be okay. If you are lucky, you may find that you can re-use the block - as long as the crank hasn't damaged the main bearings?

[TVR Beaver]

Another! ... bad luck on that one! hope you get it fixed without too much cost!!

[PeteGriff]

I may be speaking out of turn here, but from a personal perspective, are all these crank failures we are seeing due to too much performance modification, therefore pushing the car to new limits, therefore causing a standard TVR crank to die through fatigue beyond its design limits! If you are going to modify an engine surely you must look at all the strengthening methods/mods detailed by the likes of TVR Beaver. Also you need to figure in a replacement custom crank! Just my thoughts from an engineering perspective.

Would be interesting to identify if there have been significant failures reported from the Griff community with standard engines without any modification.

[chj]

Nightmare Paul - sorry to hear that - hope you get it sorted soon.

Chris

[eff eff]

That's bad news mate,

[V8Bart]

So sorry for you fella, know EXACTLY what your going through.

What the hell is going on with cranks! very strange so many are going.

Keep your chin up, you will get back on the road before you know it.

[MPoxon]

PeteGriff said:

I may be speaking out of turn here, but from a personal perspective, are all these crank failures we are seeing due to too much performance modification, therefore pushing the car to new limits, therefore causing a standard TVR crank to die through fatigue beyond its design limits! If you are going to modify an engine surely you must look at all the strengthening methods/mods detailed by the likes of TVR Beaver. Also you need to figure in a replacement custom crank! Just my thoughts from an engineering perspective.

Would be interesting to identify if there have been significant failures reported from the Griff community with standard engines without any modification.

I am sure modification does not help with matters but the issue lies with the modifications TVR made to the Rover V8 when creating the 5.0ltr, long stroke and weak externally balanced crankshaft.

Rover V8 engine builders use generally use the short stroke recipe using a 4.6 crossbolted block, internally balanced etc which is much more reliable.

[PeteGriff]

MPoxon said:

I am sure modification does not help with matters but the issue lies with the modifications TVR made to the Rover V8 when creating the 5.0ltr, long stroke and weak externally balanced crankshaft.

Rover V8 engine builders use generally use the short stroke recipe using a 4.6 crossbolted block, internally balanced etc which is much more reliable.

Thanks Matt for the clarification. Best to stick with the 4.3 then...........

[Sardonicus]

Not enough meat where it matters

[PeteGriff]

Sardonicus said:

Not enough meat where it matters

Aaaaah, certainly not enough 'meat' where it matters Sardonicus. A nice machined from billet and toughened crank, suitably designed with sufficient material at stress points and nicely balanced is what the Griff community need? Are they available?

[pwd95]

Crikey, sorry to hear this Paul!!

Time for an upgrade then....

http://www.v8developments.co.uk/products/engines/s...

[V8Bart]

Just remember if it's taken out the block, V8 coffee table !! ;-)

@Petegriff
Come on Peter, you must know some of the F1 boys ;-) lets steer them back to V8 development! lol

Edited by V8Bart on Friday 6th September 15:49

[pjac67]

pwd95 said:

Crikey, sorry to hear this Paul!!

Time for an upgrade then....

http://www.v8developments.co.uk/products/engines/s...

Mine was a V8 Devt engine Wyn.... albeit a different 'generation' from a few years ago....

Do I need one of these crankshafts ...

http://johnealesroverv8.co.uk/15.html

[PeteGriff]

pjac67 said:

Mine was a V8 Devt engine Wyn.... albeit a different 'generation' from a few years ago....

Do I need one of these crankshafts ...

http://johnealesroverv8.co.uk/15.html

It is difficult to advise just from pictures, as those particular cranks could fail also. I can remember a few years back at one of the company's I worked for, visiting a company that were making radical hi-tek 'destressing' machines for high performance engine parts (cranks and camshafts) and aerospace parts. All manner of cast or machined components have within them inherent stresses due to either the casting, machining or welding process. If this stress is not releived it could at some critical moment cause a catastrophic failure. I saw computer simulation visuals that illustrated the stress points, therefore making it clearer where the stresses lay.

So, is now the time to ask the manufacturers and designers of the RV8 cranks of all persuasions whether they have taken into account the build up of internal stresses due to the manufacture? Regards, Pete

[pjac67]

Here's the point of snapping/crack (before the first piston (also front casing cracked:

Pulley moved (crack at bottom can be seen):

Inside piston looks OK:

[A900ss]

Paul,

Sorry to hear about this. Hope it gets sorted (as cheap as reliably possible) soon.

Karl.

[FlipFlopGriff]

Is this anything to do with the bolt holding the pulley. There was a view a few years back that this should be replaced as a service item.
FFG

[Steffan]

When any major internal component fails in an engine there is very likely to be possible swarf/damage etc all over the internals. I would totally rebuild accordingly. Best of luck: components do sometimes fail for no obvious reason.

[pjac67]

FlipFlopGriff said:

Is this anything to do with the bolt holding the pulley. There was a view a few years back that this should be replaced as a service item.
FFG

Thanks for all the replies and get well wishes...

My crank pulley bolt sheared earlier this year.... coincidence or could this relate to an underlying cause I wonder?

Paul.