Spare Wheel Size

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Spare Wheel Size

Postby kevinthesyncro » 25 May 2018, 03:33

Hi everyone,

2 part question, my syncro is running 15" wheels and the new tyre size means that my spare will not fit under the cab. I also have replaced the VC with solid shaft and decoupler. I do have a spare on a rear carrier but like the idea of two spares.

So.....
1, Can I run a 14" wheel until I repair the 15" wheel.
2, Because I have a decoupler, obviously running in 2WD will the 14" wheel damage anything on the drivetrain???

Cheers Kev
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Re: Spare Wheel Size

Postby Jim San » 25 May 2018, 05:56

I don't know for sure but i'd say no.

1 odd size tyre would be a no even with a decoupler as I'm pretty sure the tyres on the same axle need to be the same .

However, I'm sure someone will be along with more accurate info.
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Re: Spare Wheel Size

Postby silverbullet » 25 May 2018, 06:55

Unequal rolling radius is bad news for a VC, because the shaft speed difference puts the unit under load all the time, so it will be permanently trying to lock and overheat.
When decoupled, the rolling radius difference will make the affected diff "roll" because thats what it is meant to do i.e. allow differential speeds of each wheel in a turn, to prevent tramlining and tyre scrub.
I would severely limit road speed for the sake of the diff internals (planet wheels, cross shaft etc) and also limit the mileage when forced to fit an odd tyre due to a puncture and on no account engage the decoupler for 4wd.
The solid shaft/de-co was only designed or intended for dry sand desert conditions where wheel slip is guaranteed and the syncro is prone to "digging itself in" afaik

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Re: Spare Wheel Size

Postby Tinium » 25 May 2018, 09:27

I've had my spare wheel carrier extended, so that I can get a 15" tyre on a mefro under the cab (I'm running the common 215/75R15 BFG AT's), so that is one more option to consider.

You lose a bit of ground clearance on the approach angle, but it's not caused me to get stuck yet (it has done some digging/sliding, but has survived so far) :)
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Re: Spare Wheel Size

Postby tforturton » 25 May 2018, 10:46

That's an interesting bit of kit. Did you make it yourself? Any chance of some more photos?
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Re: Spare Wheel Size

Postby Tinium » 25 May 2018, 12:23

It was made up by CoastVW a while back; I've not got any more photos at the moment I'm afraid, and the van is back with them awaiting it's gearbox currently being rebuilt by Aidan - when I get it back, I'll happily take some more photos (once I've gone for a long celebratory test drive!) :)
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Re: Spare Wheel Size

Postby silverbullet » 25 May 2018, 12:42

Its sort of like the (massively heavy) Tristar wheel carrier/bashplate.
Just a thought: if you trim back the inner/lower flanges on the chassis rails and seam weld them, its possible to get a 215/75/15 in and it wont foul the gearchange or the steering relay shaft.
This requires extending the clamshell hinges downward a little iirc.

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Re: Spare Wheel Size

Postby kevinthesyncro » 26 May 2018, 02:45

tforturton,

Brilliant idea, I don't know why I didn't think of that! The welding is no probs for me and my spare carrier is the heavy duty one like yours!!!!

Thanks all.
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