Fiat Ducato X250 motorhome/ Alko chassis A class - overheating rear steel wheels

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Fri 4 Nov 2011 13:49
Fiat Ducato X250 motorhome/ Alko chassis A class - overheating rear steel wheels - BJET

The handbrake is set exactly in accordance with Fiat's manual and neither the disc brakes nor drum shoes are binding. With the rear jacked up and the handbrake fully "off" the wheels rotate reasonably freely , after some initial slight "stickiness". Yet after travelling 12 miles or so , the wheels in the vicinity of their retaining bolts are hot ! {about 50 deg C.) There is no perceptible end-float of either hub.

Do you think it is worthwhile to adjust the end float which I understand should be set at between 0.025 and 0.10 mm. as an experiment to see if this reduces the heating of the wheels ?

The vehicle has been mine from new in Dec 2007 and has covered about 20,000 miles

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Fri 4 Nov 2011 16:49
Fiat Ducato X250 motorhome/ Alko chassis A class - overheating rear steel wheels - gordonbennet

I doubt it's anything to do with the bearings.

Possible the calipers are sticking a bit, or indeed the rear drums brakes are suffering from lack of use...it sounds like a front disc rear drum set up, would that be correct?

I'm not sure whether you are getting hot front or rear wheels but from the sounds of it your vehicle needs a full brake strip and inspection anyway, check for free movement of all caliper pistons and slave cylinder pistons too.

Check for free movement of any caliper sliders (if the fronts are getting hot that's my bet), fully lubricate all parts with the correct brake lubricants, and reassemble.

Don't forget to give your handbrake cable and linkages a good greasing...and the brake pipes while you're at it.

Don't Alko use their own complete rear axles on some of these motorhomes, used to deliver chassis cabs there, two cabs and short chassis bolted together cabs back to back like a push me pull you...interesting delivery prospect as they had no handbrake at all, but you could leave both vehicles in gear...many straps and chocks used delivering them..;)

I

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Fri 4 Nov 2011 17:25
Fiat Ducato X250 motorhome/ Alko chassis A class - overheating rear steel wheels - BJET

The system is disc brakes all round but with " top-hat " castings on rear axle and drum brakes inside the "hats" for parking and callipers on the "brims" for the hydraulic system. ( Saab used a similar system on the front wheels of their 99 and 900 series cars. ) The braking systems have been fully stripped down and re=assembled in accordance with Fiat data and work fine, which is why I suspect the taper roller bearings. My previous Fiat motorhome had a warranty job carried out by a ( no-longer ) Fiat dealership which involved the mis-fitting of a new rear hub and bearings WITHOUT ALLOWING THE PRESCRIBED END-FLOAT. Needless to say the bearings " cooked " and failed and as they did gave rise to a loud rumbling noise. As yet I only have a slight " cooking " but I do suspect that there is insufficient " end-float " present; hence my proposed experiment. I do not possess a dial test gauge to measure the amount of ( if any !) end -float but it is easy to measure the pitch of the stub axle thread and hence calculate the proportion of a full turn of the retaining nut required to give some end-float.

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