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Scammell Explorer (Dora)


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Tonight in the wind and the dark i have managed to sort out the gravity feed to the rear bearing:cheesy: I'ts not been tested yet but it can't not work.. First i drilled a hole in the side of the worm case and tapped it out to 1/2" BSP then i screwed a piece of BSP pipe into the hole. The end of this pipe has been fashoned into a sort of trough with the end blanked off. It protrudes into the worm chamber about 1" just behind the worm. An elbow, pipe and then another elbow take the flow of oil under the influence of good old reliable gravity (no pumps required here thank you) into the rear housing where the pump used to live and hence to the rear bearing...a hole was drilled and tapped in the rear housing to take the elbow. The next mission is to jack it up and run it in various gears and speed to see how much flow we get through the pipe (I do need to do the 37 point shuffle to get it out of its parking spot first though:undecided:)

 

Oh, I took some piccies too.... Look more oil in in the rear case and thats after 15 miles with no oil pump.....and being stood for three weeks.

2011-11-01 21.00.35.jpg

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2011-11-01 21.02.33.jpg

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Been busy today in this splendid weather:cool: Blanked off the unused ports on the axle and jacked it up for a test.

 

in the lower gears there is no flow of oil through my scoop system however there is a fair bit of oil held in the rear bearing and after several minutes a very small amount of oil seeped through the bearing into the rear housing. engine speed was a constant 1000rpm for the test in all gears. The oil was stone cold. 4th gear still no oil through the pipe but definitely oil through the bearing. In fact you get a very fine mist being thrown from the bearing so oil is getting through from the worm side (if you could imagine the rooster tail of oil thrown of the crown wheel straight at the rear bearing)

 

We then selected 5th gear and all everything came good. Plenty of oil through the scoop and pipe system and definitely worth the effort of drilling the axle case. I have good piece of mind the the back bearing is receiving plenty of lube. and the flow should increase with speed and with the oil warming up.Something went wrong...

 

 

the best bit about this video is, I had the wife in the cab ready to hit the clutch just in case it fell of the jacks...As you can see she was like a coiled spring.......

Edited by rbrtcrowther
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  • 3 months later...

Right then Fellow Scammell owners.......My gearbox is silent in operation in through all the gears until the top gear is selected...then the whining starts..and it's loud and as we accelerate through 23 mph its bloody unbearable then it gently subsides back down to a gentle scream... So, any thoughts? Is it something that can easily be repaired..Why is it just one gear? Am i likely to strip it all down find a load of horrors that can't be fixed easily and wish I'd left it? or spend weeks lovingly rebuilding it to find it still makes a row in top......Your thoughts please....:-D

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Rob, the Scammell 6 speed is a law to itself, it is almost too clever for its own good. When I bought my Explorer it had 6k miles on the clock but it was difficult to engage 3rd from 4th. When I stripped it down the needle bearings had vanished from one journal and the large mainshaft gear was floating about so much it had almost machined its way through the casing and destroyed the shaft. Noise? quiet as a mouse in all gears. The replacement unused REME re-build was just like yours, howled like a banshee in top.

 

A friend of mine is an LGV fitter with a large outfit that owned a Highwayman which howled in 6th. They tried everything, had the 'box out 5 times, new gears, new bearings, different gears and still never fully resolved the problem.

 

Bear in mind they are straight cut gears which are prone to whine and 6th is a serious overdrive, 0.62:1. The actual specs for the 'box call for very tight tolerances, typically the diameter of a needle bearing journal is given as 1.7313/1.7308" i.e. half a thou. although whether this was achieved in production is debateable.

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Good answer Mike, that just about sums it up! When I rebuilt mine with the new parts I got from you, I checked every one of the 140 new needle bearings to get matched sets, there was a surprising amount of variation in size.

 

Given the tight tolerances required it would only take a few oversize ones scattered about the journals to cause noise problems!

 

All that careful work and four years later my box just is starting to make the top gear whine, although it takes a well trained ear to hear it, must be just about run in then!

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Right then Fellow Scammell owners.......My gearbox is silent in operation in through all the gears until the top gear is selected...then the whining starts..and it's loud and as we accelerate through 23 mph its bloody unbearable then it gently subsides back down to a gentle scream... So, any thoughts? Is it something that can easily be repaired..Why is it just one gear? Am i likely to strip it all down find a load of horrors that can't be fixed easily and wish I'd left it? or spend weeks lovingly rebuilding it to find it still makes a row in top......Your thoughts please....:-D

 

mine would sream in top but when i changed the clutch it stop. i found the rivets had worn on the clutch:D

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On 13/04/2008 Gritineye wrote:

 

'Luckily, a couple of yrs ago I had bought the complete brand new internals from a Constructor box that had laid under a bench for around 12 yrs'

 

Sorry Bernard, you are outside of your 5 year warrantee....:cool2:

 

 

Just looked up the small print on that Mike, it says 'Warranteed for 5 yrs or 500 yards whichever comes first'!

 

I didn't think underwriters would know Scammell gearboxes that well...

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We recently finished a total rebuild of our box, just hope after all the effort it works well now, gonna be a while before it gets the acid test tho. For anyone who hasn't seen it you can see the ups and downs of our rebuild at:http://hmvf.co.uk/forumvb/showthread.php?3975-Scammell-Pioneer-Restoration

 

Richard

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I'm pretty sure the clutch was ok when i had it out. Its the original unsprung center plate and in good nick too... It must have run for years with nothing holding the rear output flange on so who knows what funny wear patterns have occured....

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