hi everybody.i have just purchased a 11 metre converted hino domino bus .problem is it has a front mounted motor.top speed is 90kph downhill with motor flat out.any ideas on best way to achieve a more sensible and economical cruising speed.would a change of crownwheel and pinion.give better results,if so what ratio .?or would a two speed diff give better results. all ideas would be appreciated.thanks.alan
-- Edited by nalasekots on Saturday 2nd of January 2016 05:37:32 PM
What you are looking for is what is called a highway diff. Sounds like your bus was built as a school bus or a city bus, desighned for around towns etc, around town top speed is not a problem. try and do a google serch for ' highway diff suit your model / make . May take a while, but they are out there. Normaly remove old diff and replace with your new diff. Try also bus wreakers etc. It is a big job and not for the faint hearted !
hi valiant81 thanks for the info ,will do as you advised.i am fairly proficient mechanically.always worked on fc,,hr,hq, holdens and land rovers when i was a young hoon. now as long as the wheels keep turning i am happy.lol
If you have a manual gearbox a two speed diff would be the go as not only would it give you an overdrive gear it would make towing in hilly conditions much more flexible and comfortable.
Firstly Welcome Alan to this wonderfull forum
Firstly how many gears do you have in the bus if it was a city bus as the diff ratio you have would suggest I am guessing either 5 or 6 in which a two speed diff would probably be a good way to go if there is such an animal made for your model if it is an 8 or 9 speed a single diff ratio would be the most reliable, by the way what year was it built.
You will need to know what breed the diff is for a start this info will / should be on an ID tag on the diff. There should be an ID tag in the cab some where also possibly in the door recesses this one should give you the information you require to identify it to a truck wrecker so they can assist you with finding the correct diff it should be a simple matter of removing the axels and driveshaft and unbolting the diff Center and swapping it over the tricky part is holding it up to remove and replace it cause they are quite heavy
Good luck in your search
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When the power of Love becomes greater than the love of power the World will see peace ! 24ft Trailblazer 5th wheeler n 05 Patrol ute and Black Series Dominator camper trailer ( for the rough stuff)
My suggestion is to get to a few truck and bus wreckers and see what they say about the diff in your bus. If it is a common type, then one out of a highway bus or truck will fit and they will tell you what is available and probably what ratios are available from them or elsewhere. Also an estimate of the cost and labor etc. Normally you would swap the whole diff center not buy just the crown wheel and pinion as then the seting up of the gears has to be done correctly by an experienced workshop.
If you have not done any heavy vehicle fitting then I would not recommend doing it yourself. Bloody heavy and hard work under there on the ground. I also would not try to find one yourself and buy it as there are several pit falls if you are not really sure what you want. If you can find out then go for it. I would say the highest ratio you can get if you have a six speed with a good low first gear.
Cheers Jaahn
-- Edited by Jaahn on Saturday 2nd of January 2016 09:47:33 PM
Many, many years ago (back in the 80's) I converted a 30 foot Leyland Cub (Ex Perth MTT) with a 6 cylinder 400 CI mid mount deisel motor & 4 speed semi auto box to a motor home it was great but had the same problem as you, the diff was low geared for city driving. Luckily, my good mate who was a truck mechanic and had some contacts with truck wreckers. After a bit of searching they came up with a Bedford 2 speed electric change diff which improved the drive line. Whilst a big job it went straight in with hardly any modification. After that, the bus was still a bit slow but didn't scream at 90k's.
Point here is seek advice from both wreckers & old school truck mechanics as they tend to think outside the square and your bus looks like the same era so you might get lucky too.
Regards Steve.
edit typo
-- Edited by madaboutled on Saturday 2nd of January 2016 10:26:35 PM
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Steve, Di & Ziggy We named our Motorhome "Roadworx" because on the road works "On The Road Again" Ford Transit with 302 Windsor V8 conversion, C4 Auto, 9 Inch Ford Diff All Lighting L.E.D., 260 Amp/h AGM, 530 Watt Solar + Kipor Backup Gen.
Look at overdrive trans depending what is available could be pricy but wreckers have options on some models even on Auto trans.... Changing whole diff could be easier with lower ratio numerically.. Another option is larger diameter wheels.. I guess you want to bring RPM down 800 or so rpm? How does it pull up hills ??
Hi,I to have a hino school bus that I'm converting to a motorhome, it's 9 mt and I would be interested in what yyou do as I find our bus noisy when cruising at top speed 90 klm, I'm going to try and find out if I can what sort of diff that I have as anything I can do to quieten the noise would be goo as we have to talk a bit louder than normal for us to talk when driving, although after reading the replies I didn't realise the work that is needed, not just changing the diff, the cost in changing will be the deciding point. cheers Danny
You MAY be able to make it cheaper by taking head unit out yourself and fitting lower numerically ratio ??
Pull axles out, one good part about floating axles. Remove driveshaft undo bolts around flange..
Purchase new gasket, fresh oil..
Ring around the transaxle repair shops and truck places.. You'll work out quick what type brand of diff ??
It doesn't have to be from Hino ?? Is it tyre noise ? Or engine etc ??
I also would not try to find one yourself and buy it as there are several pit falls if you are not really sure what you want. If you can find out then go for it. I would say the highest ratio you can get if you have a six speed with a good low first gear.
