Tyres and drive shaft

[Hippotastic]

My driveshaft broke 4 weeks ago whilst in Scotland, and I asked the AA man to take it off and the van is running sweet now. My observations.

1. in Scotland covering 1800km with 4 wheel drive I got about 19.1mpg, in France last week with 2 wheel drive covering about 1400km I got about 28mpg.

2. my front tires are "puckering up" The tread blocks are lifting around the edges, like someone has been dragging the tires across the tarmac sideways, rather than rolling it. But it is not across the whole tread, only 25% of it or so.

3. I get bad steering wheel wobble over 60mph, and vibrations throughout the van.

4. a kind of drag I was feeling has gone since the front wheels have been disconnected from the rear.

5. my over heating issues seem to be under control since the break.

I was going to replace all four tires with 215/65R15 96T GOODYEAR GT2. Now before I spend my hard earned, what is the opinion on the state of my front tires currently? They were puckered up before the break, and they are still puckered after the break and the trip to France. I thought they might go back to being sort of flat again whilst covering so many miles in a short space of time. I think it is fair to assume my wheel wobble and vibrations are from running square tires. Could my front diff be a problem, or have I just blown the tire and they will never roll round again?

I am worried about replacing the tires with quality items, only to find the front start to pucker up again. I want to replace the tires before buying a new drive shaft and having it fitted, going back to 4 wheel drive. But not at the expense of 10mpg.

I think I must have had transmission wind up to break the shaft, but could that be bad tires causing that, or are the tires a result of the front diff not being right? Was the shaft break just old age wear and tear? Anyone got any ideas of how I might go testing bits of my transmission to identify the bits that need replacing, before I go wasting money on good tires?

If I wanted a refurbished front diff, can someone point me in the right direction, and give me a rough ball park figure for said item?

Thanks

[francophile1947]

19mpg is very low, although if you were in hilly Scotland it'll make a difference - I usually average 26ish in a 4WD, with a bit more on long journeys if I don't hammer it.
What size tyres have you got fitted at the moment? It sounds as if the front and rears are different sizes and outside the limits recommended.

[ste]

the 'puckering' or feathering is almost definatly a tracking fault. as you rightly say it caused by the tyre edges dragging rather than rolling on the tarmac. any other type of wear ie smooth wear can be a camber or suspension fault.
i would suggest getting the trackin checked and new tyres (the wear alone has probably out balanced the wheels).. avoid cheap wheel alignments tho(the one where you drive onto 2 round plates ie ats) and have a full 4 wheel align done as this should highlight any suspension issues..
remember any 4 wheel vehicle steers from the rear wheels and if the rear is out then it will effect the front and no amount of front adjusting will make any difference (think shopping trolley).

[munroman]

What size tyre do you have, if the rolling radius is different then that could certainly account for the wind up in the transmission.

The vibration is probably due to out of round tyres, if they have been dragging across the ground they will not have worn smoothly.

Also, have you had the Viscous coupling checked in case that was a cause of the transmission problems?

The fuel consumption and overheating reductions imply that energy was being wasted somewhere, so the four wheel drive front end sounds a good place to start, this difference in mpg between 2 and 4wd is normally nothing like you experienced.

[Northern Bongolow]

i am pressuming that the shaft that broke is the front prop shaft!!!
this would indicate to me that something in the rolling diameter of the wheels is wrong,if you have different size fronts to back,this could wind up the transmission,it would break at the weekest point.
even if you have the same size tyres,but the backs are new and the fronts are well worn this may give the same result.the wear on the tyres also suggests to me that this may be the case.

are there any other symptoms.noises from the transmission,that could point to any other problem.

i would get a piece of string and remove each wheel,lay it over the circumference of each wheel/tyre to double check the measurement just to rule this out.
after this if found within the tolerances on the fact sheet on here,i would start looking at the transfer case.
hope this helps.

[Hippotastic]

195/70 R15 front, newish, cheap
215/65 R15 back, old tires, cheaper

Yes the front prop shaft broke, I am running rear wheel drive. There are no symptoms now. The driving is smooth, my drop links are clattering, maybe that is masking other noises.

I have not had the Viscous coupling checked, I should have that looked at.

I had the tracking done twice once the front tires were changed. Maybe it has moved, but the wear is normal, and apart from the blocks being a little raised, they look like good tires. Until you are doing speed, and obviously something broke the shaft.

the 19mpg was a shock to me. It felt like I was towing a house, not a small caravan, and it was okay at 60 as long as the hill was not steep. Then I had to let it slow to 50 to be happy that the temp gauge was not going too high. Since the break, the temp gauge is good as gold, and the caravan feels like it is not there and keeping 60 is not a problem at all.

Maybe just changing all 4 tires at the same time will cure my ills and then I can put a replacement shaft back on and see.

[dobby]

Was it a UJ that went on the prop? Also, can a viscous coupling seize or create a greater load? One for Dandy methinks?

[munroman]

195/70 R15 front, newish, cheap
215/65 R15 back, old tires, cheaper

Yes the front prop shaft broke, I am running rear wheel drive. There are no symptoms now. The driving is smooth, my drop links are clattering, maybe that is masking other noises.

I have not had the Viscous coupling checked, I should have that looked at.

I had the tracking done twice once the front tires were changed. Maybe it has moved, but the wear is normal, and apart from the blocks being a little raised, they look like good tires. Until you are doing speed, and obviously something broke the shaft.

the 19mpg was a shock to me. It felt like I was towing a house, not a small caravan, and it was okay at 60 as long as the hill was not steep. Then I had to let it slow to 50 to be happy that the temp gauge was not going too high. Since the break, the temp gauge is good as gold, and the caravan feels like it is not there and keeping 60 is not a problem at all.

Maybe just changing all 4 tires at the same time will cure my ills and then I can put a replacement shaft back on and see.

The standard tyre sizes have about a 1% difference in circumference.

However, by having newish front tyres and old back tyres, this may increase the difference to over 2%. So every 100 meters or so one set of tyres is a full turn behind those at the other end of the Bongo.

This could well have overworked the viscous coupling, I know the VW Syncro guys are paranoid about regular tyre rotations so that the tyres are of very similar circumference.

It is quite possible that the different diameters have fried the diff and/ or viscous coupling, as the wheels would have been trying to run at different rpms, and this would have caused a lot of friction and tyre scrubbing, I am sure there was a recent case where a diff blew because of different sized tyres.

[Hippotastic]

Was it a UJ that went on the prop? Also, can a viscous coupling seize or create a greater load? One for Dandy methinks?

Luckily, yes the rear UJ went. I am glad it was not the front one, it would have dug in rather than trail along.

[Hippotastic]

This could well have overworked the viscous coupling,

What would the symptoms be for that? I take it I will not know until I put a drive shaft back on?

[keycare]

I am sure there was a recent case where a diff blew because of different sized tyres.

Yep, that was me. The diff casing split it got so hot and spilled all of the diff oil all over the place (it caught fire on the motorway). The diff was replaced for £300 plus fitting. It was the rolling radius of the tyres that did it. I am currently running the same size all around (same rolling radius as stock rear tyres) and so far had no problems.

Symptoms were:- wining from front passenger side (turned out to be diff wine and not the kids), slightly odd handling feel, increased tyre wear, followed by plumes of black smoke and flames, panicking, swearing and alot of humble pie

[francophile1947]

Sounds like VC is shot . It will cause the tyres to scrub and also create a lot of drag, which would account for the low fuel consumption and potential overheating. Interesting article here http://www.club80-90syncro.co.uk/Syncro ... plings.htm - may well be worth sticking with it as a 2WD

[Hippotastic]

Sounds like VC is shot . It will cause the tyres to scrub and also create a lot of drag, which would account for the low fuel consumption and potential overheating. Interesting article here http://www.club80-90syncro.co.uk/Syncro ... plings.htm - may well be worth sticking with it as a 2WD

To change the VC, do I need to change the front Axel? I am a bt confused as to where it sits in the drive train.

[skater]

VC in the middle of the van. Looking under from sliding door position the front
prop-shaft connects to the transfer " box" on rear of gearbox.
VC is inside and is chain driven from rear prop.
VC itself is not serviceable as far as I know.

You can find how it's laid out on Lushprojects. Sorry, don't know how to do a
handy link.
Maybe missfixit can show us.

[Hippotastic]

http://www.lushprojects.com/bongopartsm ... o=.html#18

27-580?

R50127580 27580 UNIT,VISCOS

When the shaft went, the rear UJ went, next to the transfer box, and it kind of makes sense. If it is in the transfer box, then why are the front tires still furling up? I guess that they are already shot from before, but I was kind of expecting them to flatten down and return to normal rather than staying raised.