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trapper

a question for experienced MMLC Drops drivers

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I bought a Leyland DAF MMLC a few weeks ago and it is not a pleasant beast to drive! It constantly judders and vibrates, this gets worse under hard acceleration and when applying power up hills. It also seems to be worse when lightly loaded, it settles down a bit when carrying a heavy load. Is this normal?

If it were any other vehicle I'd be changing the UJ's in case they were seized or if I was travelling over 45MPH I might think the wheels were well out of balance but the previous owner seems to think this is situation normal for the Drops. It's now making my back ache from tensing up against the bouncing. 

Please tell me this is not normal.

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Something amiss there. Does it the whole thing judder (drive shafts as you say - although I do recall a defect with the gearbox mountings coming loose and also cracking in cross members) or is it just through the steering?

Definitely not normal.

 

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Check that the inter axle diff is not locked or seized up and that the front axle is not engaged

Always engage the inter axle diff lock if going off road, if one rear axle spins the diff will seize in a very short space of time.

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only one i owned was a dream to drive one thing that springs to mind is if if its ever been towed  has prop shaft  been split and not been put back together with spicer joints aligned correctlly

 

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Nick,

I think you are being a bit of a mamby pamby, she is on steel suspension has wopping great tyres and the roads in Surrey are shite...mine bounces like a yoyo without any load on the back, and once you start bouncing your foot bounces on the accelerator and you get even more bounce as you open and close the throttle unintentionally...

when driving on A roads try to keep your foot steady, not easy, and no matter how small a bump she will bounce over it and that goes through all the body.  when loaded the springs are working a bit better and the bounce is much less noticeable..just to be sure she is nice and smooth on the motorway for instance, foot flat max speed 45-46 mph...

Edited by paulob1

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Interestingly we did tens of thousands of miles in Surrey and beyond during the trials and I am not sure I agree with the propensity to bounce! Maybe having come from the likes of Mk1 Militants they seemed to positively glide along.

You did say in your post vibration though, and so, notwithstanding the state of the roads, I would be taking a very close look at all the mechanicals.

 

 

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It doesn't seem to be bothered by road conditions ie pot holes and cats eyes don't even notice if you drive over them so I don't think it's suspension. The cab bounces off road but I say vibration as it seems a bit high frequency for bouncing but too low frequency for engine. It isn't felt through the steering and as Paulob1 says once the cab starts bouncing it is definitely an effort to stop your foot bouncing on the accelerator. If I take my foot off the accelerator and put my foot on the brake and slow down then it does kill it for a while which is why I say 'vibration' but it does set up a harmonic which ends up as 'bouncing' but it is constant on the motorway at 45mph. When pulling away hard or accelerating up a hill then it is more noticeable which is why I thought 'drive train' Are they prone to axle tramp? I would be surprised if they were as they are so heavily built but it is also that sort of feeling sometime?

I was looking for other drivers experiences to know whether I should spend a lot of time and effort pulling it apart or if this was the norm. If it is the norm then I'm very disappointed with the beast but I was hoping that there might be a 'known' problem that I could go straight to without all the fault diagnosis. Being human I'll always look for advice and a short cut first :) 

She is very low mileage and has been restored and well looked after by her previous owner so I'd be surprised if it was any major service item that was awry but it is driving me nuts. I guess I'll have to start stripping the drive train and do it the old fashioned way.

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21 hours ago, trapper said:

She is very low mileage and has been restored and well looked after by her previous owner so I'd be surprised if it was any major service item that was awry but it is driving me nuts. I guess I'll have to start stripping the drive train and do it the old fashioned way.

Assuming that you had a test drive before buying the lorry, has the ride become worse or are you just noticing the problem because you are driving it further.

Nothing to lose in asking the seller what he thought about the ride when he owned it and what might have happened to cause the judder/vibration if it is not normal.

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