oldskool
Well-Known Member
No thats not what im saying, but taking advice from someone who doesn't fully understand what there doing them selves is not good, like i said there are people on here who do no there stuff.
Q for you Oldskool.....
how long will a differential running different outputs on each shaft last before it gets damaged?
I know of several engineering solutions where a differential is used to allow differing shaft speeds, and have been used for years. I agree that in an automotive application it is not ideal; but where are the qualified answers - ie "it will damage the diff after 2000 hours use" or similar? how many left turns or right turns or roundabouts can you do before you damage the diff?
how long will a differential running different outputs on each shaft last before it gets damaged?
I know of several engineering solutions where a differential is used to allow differing shaft speeds, and have been used for years. I agree that in an automotive application it is not ideal; but where are the qualified answers - ie "it will damage the diff after 2000 hours use" or similar? how many left turns or right turns or roundabouts can you do before you damage the diff?
oldskool
Well-Known Member
Do you know how to measure tyre read width?So what your saying is that you should replace the tyre's on the driven axle/axles at the same time. Because in that case everyone who has a 4X4 needs replace all 4 tyres every time and make sure the spare is the exactly the same tread depth is the same in-case of a puncher. Also he asking about a certain size he is using which is around 7mm different tread depth on a new set, so I don't think it will matter that much hey!!
Ive just taken my standard 235's off my disco and fitted (dont laugh) 255/50x19's thats a 20mm difference in tread width, but when i measured the width of the 255 they are nearly 40mm wider than the 235's. So when you sit down and work out tyre rolling radiouses on paper it may appear ok, but in reality if you measure them they can be quite different, due to the different tyre style and make.
very true - i had a problem with a rover220T wanting to dive into the hedge whever I accelerated - eventually discoved the the NS front tyre, although "the same size" as on the off-side, was from a different manufacturer and was 30mm different in diameter.
oldskool
Well-Known Member
Ive seen some as well but they dont tend to be abused like a vehicle diff, but what i do know from experience is if you fit different sized tyres (rolling radious) on a driven axle it will damage the diff
how long will that take?
thats like saying "driving your car/landy will damage the engine" - course it will, dont stop everyone doing it tho.
thats like saying "driving your car/landy will damage the engine" - course it will, dont stop everyone doing it tho.
Its too vague to say it will damage the diff.
I've done it, and it didn't damage the diff.
It depends on the % difference in rolling radius and the journey length. For small variations (eg tyre wear) the planet gear won't turn that fast so its bearing will be adequately cooled and lubricated; so it will wear at a normal rate. If the difference it larger (eg wrong tyre size by 10-20mm or so), then short journeys will not damage it but longer or high speed ones risk increase wear.
oldskool
Well-Known Member
No it wont if its driven properly and maintained properly, same as a diff if its treated propperly it will last.how long will that take?
thats like saying "driving your car/landy will damage the engine" - course it will, dont stop everyone doing it tho.
My disco (only had it a couple of month but love it already) has done 224000 miles, its got the original turbo the engines never been apart its had one replacment clutch but is starting to get a bit heavy again but not slipping, its had a hard working life towing to its limit and beond (ive seen it tow start fully loaded cement mixer lorries) its been to most if not all the ski resorts in europe, it still starts on the button and returns between 28 and 35 mpg depending what im doing with it towing ect. Thats because its been maintained properly and not abused.
Putting different size tyres on the same axle is abusing the diff not using it
oldskool
Well-Known Member
Using different size tyres on back and front axles .... is it detramental ??
Read the original post paul the above question was asked and i said yes it would be.
he also said he would be driving back to the UK from bulgaria i dont think thats a short journey do you.
yu are missing my point entirely...
yu are saying it WILL damage the diff - but yu dont qualify that statement.
The OP has "in emergency" got diff size tyres - Is he going to break the "diff" in 2 miles, 200 miles, 200K miles? without that knowledge, he is ****ing in the wind. We all agree it aint ideal, but can yu continue to use the motor for a week till he gets noo tyres or " a couple of months" till he gets back to the UK, or mustnt he drive the thing home from the place he got the "wrong" tyres from?
yu are saying it WILL damage the diff - but yu dont qualify that statement
.The OP has "in emergency" got diff size tyres - Is he going to break the "diff" in 2 miles, 200 miles, 200K miles? without that knowledge, he is ****ing in the wind. We all agree it aint ideal, but can yu continue to use the motor for a week till he gets noo tyres or " a couple of months" till he gets back to the UK, or mustnt he drive the thing home from the place he got the "wrong" tyres from?
He won't do Bulgaria-UK in one continuous non-stop journey, I imagine he'll stop every now and again. With several frequent stops the diff shouldn't fail. Of course, I can't say the diff won't fail. Diffs have failed with same size tyres on, after all!
I guess its really up to the OP to canvass a broad range of replies and make the judgement, then update us to say if he got back okay or not. That would neatly box off this internet debate!
Mseries3
Well-Known Member
Clearly have no experiance of a 19J!
If you are REALLY worrried about damage to the transfer box, Take the front prop off and drive it in Diff Lock. Neither is ideal, and you are not likely to cause damage in either situations with the minimal difference in tyre sizes but with the front prop off you are not going to be working the center diff over time.
oldskool
Well-Known Member
I can't say ive ever seen a vehicle diff with bearing's on the planet gears but i could be wrong what diffs have you had apart that do?
oldskool
Well-Known Member
Firstly exuse my ingnerence but whats a 19J, and im not worried the question was asked and i said it would damage the diff i probably should have said it will put extra load on centre diff possibly causing it to fail premetuly ( i cant spell for **** tonight) while others said it wont cause a problem. Its not me driving from bulgaria.Clearly have no experiance of a 19J!
If you are REALLY worrried about damage to the transfer box, Take the front prop off and drive it in Diff Lock. Neither is ideal, and you are not likely to cause damage in either situations with the minimal difference in tyre sizes but with the front prop off you are not going to be working the center diff over time.
Mseries3
Well-Known Member
A 19J is a 2.5TD Engine that Land Rover put in Defenders... It has a habit of cracking pistions, Blocks and Heads. Even if you service and look after them (It was a joke about you saying a engine won't go wrong if you service them
)And my idea was not in responce to you put the orginal poster if he was worried about the center diff going bang
oldskool
Well-Known Member
In the general sence of the word they dont have bearings they rely on oil alone and if they (plannet gears) are spun to fast over a prolonged period they will fail, i prooved this when i was a young hooligan 3.2ltr capri most junctions just had to wheel spin just had to it was the law when i was 18ish until i blew 2 of the planet gears out of the rear diff cover, foooking made a right mess ep oil every where :doh:
Graham Carter
Active Member
I wouldn't advise it if you plan on doing any long distances or high speeds. Once in Botswana, when I had a puncture, I ran with one Michelin and three Bridgestones, all 205/R16. Driving on soft sand, I still managed to wind up the transmission!
I think your risk is the centre differential giving up, and it could go in a big way. In normal operation, the planetary gears in a diff only move at relatively slow speeds. If you have different size wheels, you will find that the planetary gears will be turning much faster than normal and also taking more load. Definitely do NOT engage diff lock - you may find your gearbox literally explodes!
I wouldn't risk it for say £300 of tyres. While it is quite likely you would get away with it, if it does go pear shaped, the cost would be far higher tahen that.
kingsonlim
New Member
IF you REALLY HAVE TO run tyres of different makes and sizes, run it on only 1 axle with one of the prop shaft taken off, as has been mentioned by some one previously. You will need to lock the center diff tho.
