Derrick the Volvo! Update P47

[theo2468]

haha sorry derrick, calling you a girl!

[jon-ovlov]

ha ha, he forgives you

[jon-ovlov]

Got the new (replacement) clutch shaft today, an fitted into the housing. I'll wack it on the car as soon as it stops raining!

Comparison of the wear - left is old, right is replacement



Massive thanks to TJ for getting it for me!!

[jon-ovlov]

Got the clutch shaft on, all nice and straight. Bit of a faf getting it on there though, as the one of the bellhousing to clutch shaft bolts decided to disappear into the bellhousing (it was the top most one, ffs) Anyway, managed to get it all on, so that's cool! Waiting on the prop to be finished tomorrow, and that'll go on the same day all being well. It'll cost me an arm and a leg, but I won't have to worry any more.



Also got a new actual throttle cable with proper bulkhead mounts, and the throttle is real nice and responsive now, and full travel too, which I wasn't getting with the MTB one, as it stretched quite easily.

Last job to do is this bit of rust on the bonnet which keeps popping up. It's on the other side of the bonnet too, so I'm best off just replacing the thing, as it's pretty much rusted through. Nothing structural though, and a lick of paint will hide it for a bit.

[jon-ovlov]

Finally bolted the oil cooler down now. More than likely won't be able to plumb it in before RR though, so it'll just be for show, temporarily

[jon-ovlov]

So. managed to get hold of the new prop. AWESOME! Really well built, "fully balanced" and got it on no problems.







Drove to Manchester no real problem, a bit of vibration, but I put that down to it not being damped. However, the same day, "rattle rattle rattle BANG!" oooooh no. Looking under the car, I found the shaft end of the gear box casing has shattered. Fantastic. Limped back to my mates house, and I'm now stick in Manchester trying to source a replacement box.

That night I got the car up on jack stands, and me and my mate inspected the damage, and began to remove the half shaft bolts, which were a bugger.





The damage.



So, after removing the prop, I found that there was machining coolant in the prop. That'd be why it's not balanced properly. I also think the prop was balanced without the spline end on. I'm in talks with the company that did the prop to get re-imbersed for the price of either replacing or repairing the gear box. I just can't believe I've got another problem.

I've managed to find a 340 prop to get me home and to RR, but for the price I paid for the prop, I would have expected it to be done better and checked. Lets hope I can get to RR, and more importantly, home.

[volvodspec]

good stuff!

balancing with machining fluid still in it is kinda a rookie mistake though, weird how did they make the spline couplings; adaptorflange over it and a bolt drilled trough + welded or sth by the looks of it?

if they can give you a proper shaft, well balanced and without vibration etc; any chance you might be able to ship one to holland?

[jon-ovlov]

Yeah, I know. I guess it's easy enough a mistake to make, it's just made my week a lot more stressful than it should have been.

The spline couplings are the originals removed from 2 props I had that were worn on one end, welded to the plates. Then put the splines on the shafts either end, and do up the bolts. I don't see any reason why the shaft shouldn't balance up. It's good for around 500HP (not that I'd ever go anywhere near to that power). The slider takes the strain off the UJ's.

I see no problem with them shipping one to Holland. I'll ask when I go back in.

[SteveP]

Highly unlucky dude! Keep at it, shame about the prop - hope they sort it out as it looks like a nice bit of kit

[Chris_C]

This is what I have in my mind as to prop design...

Did you notice any more loading on the synchro's when changing? What's the weight relative to a stock prop.

[macplaxton]

That's a bad failure there.

I'm wondering if it's also a design flaw and "re-invention of the wheel" is going on here. You do have to ask why Volvo chose to make the original props as they did. (carry over from DAF, but why did DAF do it that way)

(thinking aloud below and may contain flaws as it's a bit early in the day for me)

For most things I think "why" has it been designed a certain way. It could be that it's down to cheapness / previous experience / weight / noise, etc. and also look at the way others have approached the problem in hand. I don't think a solid prop (as designed here) is the answer as it fixes a weak prop, but breaks everything else. The whole driveline needs considering, as it's not a conventional layout

Some issues being:
prop always spinning at engine speed.
torque damping or lack of it in this case.
quite a long prop for a single piece one.

Why did Porkers get a torque tube? Why did Volvo use a torque tube on their red blocks? Why did Alfa do it the way they did it? (although do they have a clutch at the gearbox end???)

I'm not saying that is the solution, but there must have been a technical or other reason for them to go down the particular road they chose.

It may be the case that a solid prop might be doomed as at one end the engine can flop about its mounts, and independently at the other end, the gearbox can too.

[Chris_C]

That is a sliding spline section 2/3rds up isn't it Jon?

I've sat and talked over this lots with several engineering types over the last 12 months, the reasons we've managed to come up with for the rubber bonded stuff is lightness (it's a lot more work for the synchros to have to change the speed of the prop as well as the input shaft, when "normal" boxes only have to spin up a comparatively tiny input shaft) and cheaperness. The vulcanised rubber has no worries for me at all, bonded rubber lumps are used in squillions of applications where the shock torque experienced makes the puny amounts our valvers put out look silly.

The other thing we came up with, was exactly the same as you MP. Why did Volvo consider making a new thing when they put a Redblock in? It has to be down to the reliability vs power and this is the only reason I'm still interested in a different prop design. What I'm hoping is that the stock engine mounts had too much flex for such a system, so rather than reducing ride comfort (it was after all an old peoples car, not a sports design) by putting in stiffer engine mounts they moved to a torque tube for alignment.

Which is why I'm hoping the full set of accurately aligned poly mounts keep mine good for a long while However, it's only mine (and mates) ideas and views on the subject. If this prop when fully balanced doesn't break other things (strengthening one component always passes on it's problems, it's why I broke a prop with soft worn rubber ends, then when I had a low mileage good rubber prop it broke the bellhousing within weeks) then it's going to be hugely interesting. The main thing I had my money on were syncros going first though, not the casting!

[macplaxton]

That is a sliding spline section 2/3rds up isn't it Jon?

Looks that way to me, but I'm trying to convince myself why the prop between a fixed engine and fixed gearbox needs to lengthen and shorten.

I've sat and talked over this lots with several engineering types over the last 12 months, the reasons we've managed to come up with for the rubber bonded stuff is lightness

And probably shock damping too. Prior to around 1973 and once piece props, the DAFs used a steel tube with a coupling bell riveted on either end of it.

Which is why I'm hoping the full set of accurately aligned poly mounts keep mine good for a long while However, it's only mine (and mates) ideas and views on the subject. If this prop when fully balanced doesn't break other things (strengthening one component always passes on it's problems, it's why I broke a prop with soft worn rubber ends, then when I had a low mileage good rubber prop it broke the bellhousing within weeks) then it's going to be hugely interesting. The main thing I had my money on were sync[h]ros going first though, not the casting!

I'm thinking like this: (engine vibrates at a set of frequencies)||------prop vibrates at a set of frequencies------||(gearbox vibrates at a set of frequencies)

Engine / gearbox alignment is one thing that results in dead props.

What failures have we seen? Rubber couplings shearing, tick. Stripped splines, tick. Was there a picture of a broken tube? (Can't remember).

[Chris_C]

Thing is, with the rubber mounting on the engine and box, with enough torques they do move. Fake's on the old (albeit knackered) mounts would happily move 4" left to right at the cams relative to the shell with a calibrated shove, which given the point of rotation was probably about 1in at the crank. Chris' New Awesome Engine Mount Solution (tm etc etc) means that with the same calibrated shove it hardly moves and if you try and move anything now the suspension kicks first.

I agree with the frequency idea though, each component has a different resonance too. I found with my banana'd prop for the 12 hours it was on the car I had a small kick at 1k and subsided, larger at 2k and subsided, approaching 4k felt like something expensive was about to come loose... so never went through it.

Shock damping I'm in two minds about, in theory, isn't that what the clutch springs (in the friction plate, not the pressure plate fingers) should be doing? Then again in theory, our engines and gearboxes should never move!

I've torn rubber due to misalignment and have bought props with knackered splines. I'm pretty certain that the knackered splines are a factor of numpty prop fitting, and then putting a good prop on a knackered spline shaft will kill the good prop damn quick. Not ever seen a metal tube failure.

[jon-ovlov]

Yeah the sliding spline is to compensate for forward/aft movement. Even though I explained both engine and box are pretty much rigid, 1. you will always get some for/aft movement from the engine (all be it very minimal) and 2. he wouldn't warranty the prop without the slider, as UJ's aren't meant to take forces in that direction.

I've had stripped splines before, due to worn clutch shaft, and I remember seeing a twisted prop once too. Bookmarked it somewhere.

I had the option for damping, with a tube in tube, in-between them would be rubber the length of the tube. However this was very heavy, very expensive, and too big for the transmission tunnel.

I'm sure the reason the box failed is because the engine is able to move, however the gear box is not, at least not enough. The casting eventually fatigued and shattered. Just a matter of time.

Still in search of a gearbox. Looks like I'll be in Manchester for a while.