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Posted (edited)

Hi

after restoring and finally getting registered and on the road I have found the old girl is bouncing on the front end and front tyres are getting warm only in top gear from about 20 mph 

ive looked in the maintenance manual and it just says inflate to correct pressure there is no pressure written on the tyres they are 14x20 22ply I’m currently running at 60psi

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Edited by Tim hudson
Put what pressure I was running at
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Posted (edited)

Those tyres will run warm to the touch because of the heavy construction, 22 ply rating. 60 psi sounds about right try 65 psi and see if it makes a difference. Warm ambient temperatures at the moment make a difference. Great looking truck. What pressures are you running the rears at? They should be lower. Check the pressures when hot to see what they are going up to. Tyre pressure should be marked on the casing along with operating load. Front shock absorbers could be the problem.

Edited by john1950
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Dear Tim,

I concur with John.  I would not expect 1400 X 20 tyres to get warm very quickly  with a Hippo going at less than 30 MPH and running empty.

Is it a harsh ride with you feeling every defect in the road surface or is it a slower frequency bounce?  I suspect the former.

The tyre pressure in the book will allow for indefinite operation fully laden and in high summer conditions..  If running permanently empty, 60 or 65 sounds  sensible.  You might try significantly lower but if you go too far the steering will start to get heavy.  Out of interest, the tyres on a ballast Antar are 1400 X 24 in twin formation and even though the vehicle weighs 36 tons with ballast, tyre pressure is only 47 PSI.

When I was driving 8 Ton Bedford TMs fitted with 1500 X 20 tyres fully laden I would go out with tyres pumped up to about 100 PSI but coming back empty going over very rough roads it made a huge difference to let the tyres down to 50 or maybe even 40 PSI.  People following me noticed that I made no effort to avoid pot holes as I did not need to.

John

 

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Many thanks chaps I’m going to have a proper go through at the weekend starting with the rears I think I’ll drop to 50 and see what she goes like then increase by 5 psi to see what happens till she feels better it is a slower frequency bouncing almost like the tyre is out of shape (it isn’t) I will post and let you know 

Thanks again 

Tim

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AEC Militant is roughly the same size as a Hippo, and has the same 1400 tyres.  Handbook for the Militant shows two sets of pressures for normal road use.

For the short wheel base gun tractor:  47 psi Front, 67 Rear

For the long wheelbase cargo:  50 Front and 95 Rear.

I find with my Timber Tractor, that when she is first run out at the beginning of the year, after being parked up all winter, the ride is very hard and bouncy.  But after a good soaking of the leaf springs in WD 40 or similiar, plus couple of hundred miles or so of driving to shows etc in the spring, she calms down and becomes a bit more respectable.

Took the Tanker out for its first test run recently and that was quite a hard ride.  I'm expecting that to improve the more use it gets. So your Hippo may be the same, suspension has got to get broken in so to speak.

As for tyres getting warm, it doesn't really happen.  1400 tyre is a big lump of rubber to get any heat into as it dissipates out too quickly. 

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Tyres especially large tyres build up heat internally, because of the way they are made. there is a natural heat build up in the tyre wall because of movement of the cords and carcase materials within the rubber compound as the tyre rotates and flexes. That is why older tyres with more layers of cords run hotter than more modern constructed tyres. Cross ply, bias belted and radial construction are made for different but overlapping purposes. Steer tyres heat up for several reasons, running at the wrong pressure, overloaded, exceeding the tonne mile per hour rating of the tyre, or running out of track. Older crossply tyes that have been standing in one spot for a some time settle to that shape and need to warm up to become round again usually giving a rough ride for a few miles. Old mechanics storing vehicles for the winter always put them up on blocks. 

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Hi Tim

John is wright i own a Leyland Hippo the pressure is not excessive i suspect you are getting bounce out of the tyre i run on the same tyre if they site for a couple of days when you first start off you will get a bounce from the front steering once you have done a mile or two and the tyre will warm and go to its normal shape

and Hippos do not have shock absorber's

Thanks 

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Hi thought I’d give you an update.....after doing about 100 miles on a round trip and having 2 punctures in the same tire on the front and repairing them on the side of the road (as I have no spare wheel carrier yet) acquired 2 second hand 18 plies for the front running @ 60psi. Now she’s handling 100% better. The previous tyres I had acquired were spares from a coles crane and I think one of them had been left flat on the crane for some time (years) which had effected the tyre and maybe put a soft or hard part in it causing the tube to rub through 

thanks for the reply’s and I’m keeping an eye out for a carrier if any one knows of one 

Tim 

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Great to see the pictures, tyres are an on going problem especially on tube type. That Leyland 0.600 is a good engine, It is easy to check and keep right the fuel pump timming using the built in TDC, INJ, plunger on the bell housing. Always remembering to retract it after use. It pays to keep an eye on the cylinder head nuts for torque and a manual check on the smaller outer ones as they do break the studs.  

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4 hours ago, john1950 said:

Great to see the pictures, tyres are an on going problem especially on tube type. That Leyland 0.600 is a good engine,  

Should be an L6 or has it been changed?

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