Propshaft went "BANG" at 150+mph.......

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scoobyh123
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Propshaft went "BANG" at 150+mph.......

Post by scoobyh123 » Thu Sep 07, 2017 2:24 pm

After having some work done on my Volvo today by Dusan aka Alucard7002 - big thanks for your help too - (extension housing bush/seal) and having had some vibration problems last time after doing the prop centre bearing, we decided to run it up to a good speed while still on the axle stands.

No real vibration (apart from a small amount almost certainly due to a slight wheel balance problem) at 20, 30, 40, 50 70mph so i eased further down on the loud pedal.
SPeedo needle kept climbing and off the scale at 140mph then with about 150mph showing i eased off the loud pedal at which point there was a "BANG!" followed by a strange sound and vibration from the propshaft area just underneath the centre console. :shock:

Fearing the worst, Dusan dived underneath to see if he could see the source of the noise/vibration.
Nothing found.
We then tried it on the road to make sure it wasn't the fact the wheels didn't need a load on them to quieten noisy wheel bearings.
Nope, not that either.

Coming to the conclusion it had to be something in the area of the centre bearing, we returned, jacked it back up and Dusan dived underneath and dropped the front of the prop off the back of the gearbox. No obvious play in the gearbox (shouldn't have been after renewing the bush and seal an hour or three earlier!) so whipped the flange bolt out of the output shaft to re-clean the thread and apply Loctite to the thread, just to be on the safe side.

Then he spotted a "clean looking swept area on the underside of the trans tunnel".

Oh dear! :shock:

Oh dear, oh dear!! :shock: :shock:

Oh dear, oh dear, oh dear!!! :shock: :shock: :shock:

OH FLICK!!!! (Squint and you'll get what i was really thinking! ) :shock: :P

Straightaway i thought part of the propshaft had come adrift.

OK, it wasn't the propshaft itself but the rubber dust cover behind the prop centre bearing. It had split and remained tethered to the rest of its former self by a thin piece of rubber.

As such it was spinning around with the propshaft and above certain road speeds (25-30mph) was slapping the floor like those clacker things used to slap the spokes on your Raleigh Grifter (or Chopper) when you were a sprog.

This was causing some vibration not to mention a hell of a lot of noise! Oh yeah, and me panicking and angry! :shock: :evil:

An "enthusiastic tug" soon had the offending bit of rubber removed from its past life and normal service was resumed.
I say "normal" - it's a lot smoother, quieter and seems more "eager" too.

While Dusan was doing the extension housing i crawled under and dropped the engine oil and filter, also had an oil extractor pump running to empty the ATF from the box too.
With 3.5L of fresh ATF-U, a new oil filter and 5L of Gulf 10W40 topped up to 6L with some old stock Triple QX10W40 the engine was a lot quieter and the box much smoother with more defined but cushioned changes.

Anyway, probably the only time i'll legally see the speedo genuinely reading 150mph, even if the car wasn't traveling anywhere at the time! :lol:
Cheers,
Dave


'94 827 Sterling saloon
'88 Volvo 760 V6 Estate
All auto :D
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'95 827 Coupé LPG gone but not forgotten!

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thamestyres
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Re: Propshaft went "BANG" at 150+mph.......

Post by thamestyres » Fri Sep 08, 2017 9:00 pm

better to go bang on stands.. could have been catastrophic at a genuine 150mph on a track of course.. lol you'd have lost the race...
Rover Sterling KV6 V.reg 4 tailpipes and rs5 wheels
home of the "Mad Maestro"
1935 morris 18/6, having a near end of life rejuvenation, xj6 running gear..

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scoobyh123
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Re: Propshaft went "BANG" at 150+mph.......

Post by scoobyh123 » Fri Sep 08, 2017 9:15 pm

You're not wrong Ricky! :lol:

Luckily with it being just a dust cover and not vitally important it was a relatively easy fix. Might see if i can get another dust cover just to keep things "complete" but it's running fine without and the centre bearing is double-shielded anyway with only a dust cover on one side. :shock: :roll:

I keep getting silly ideas about depriving a Renault Alpina Turbo of its turbocharger and slapping it on the Volvo in which case a genuine 150mph might be possible. :wink: :D
Cheers,
Dave


'94 827 Sterling saloon
'88 Volvo 760 V6 Estate
All auto :D
Image
'95 827 Coupé LPG gone but not forgotten!

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thamestyres
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Re: Propshaft went "BANG" at 150+mph.......

Post by thamestyres » Sat Sep 09, 2017 7:24 pm

sounds like a plan... regards ricky
Rover Sterling KV6 V.reg 4 tailpipes and rs5 wheels
home of the "Mad Maestro"
1935 morris 18/6, having a near end of life rejuvenation, xj6 running gear..

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scoobyh123
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Re: Propshaft went "BANG" at 150+mph.......

Post by scoobyh123 » Sat Sep 09, 2017 9:46 pm

thamestyres wrote:
Sat Sep 09, 2017 7:24 pm
sounds like a plan... regards ricky
:twisted: :twisted: :twisted: :twisted: :twisted:

Definitely! :wink: :D :lol:
Cheers,
Dave


'94 827 Sterling saloon
'88 Volvo 760 V6 Estate
All auto :D
Image
'95 827 Coupé LPG gone but not forgotten!

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