Syncro Driving

Post by **Walrus** » 27 Oct 2008, 12:34

As you may be able to tell, I have no experience of driving anything off road before!

I took TVFKAB to Wales this weekend; up a nice steep slate road, no problems. Coming down though I have read that the engine braking (petrol engine, in G gear) should be enough to keep it going slowly but I had to keep my foot on the brake all the way down - is this normal?

Post by **peasant** » 27 Oct 2008, 13:41

Sooner or later (sooner in a diesel, later in a petrol) the engine will run away from you if the hill is steep enough.

The secret is to start really slow, stay off the gas and just crawl along. Every now and then you may still have to apply the brakes, once you gather too much momentum.

It is preferable to read the road and just sharply apply the brakes to kill the gathering speed where that is possible rather than stand on the brakes all the time.

It's best though, if you manage to go down without braking. Braking on a steep hill always carries the risk that you over-do it and start sliding and loose traction altogether. It is very difficult to impossible to get out of a slide on a steep hill. (other than just letting go of the brakes, hold on and hope for the best

)

Post by **KarlT** » 27 Oct 2008, 14:22

peasant wrote: Braking on a steep hill always carries the risk that you over-do it and start sliding and loose traction altogether.

Post by **Walrus** » 27 Oct 2008, 17:34

peasant wrote:(other than just letting go of the brakes, hold on and hope for the best )

That wasn't an option: slate tip on the left, 50' drop on the right and a gate followed by a hairpin bend in front! Need more practice...

Post by **HarryMann** » 27 Oct 2008, 17:37

It is very difficult to impossible to get out of a slide on a steep hill. (other than just letting go of the brakes, hold on and hope for the best )

Yes, agree with all your advice peasant. There's also cadence braking, very fast on/off/on/off, but not fiercely...

if it starts sliding there is something you can do and it usually works well and fairly instantly ina Syncro.... give it a whiff of gas and stop worrying about speed, if wheel is pointing in the right direction will straighten her up nicely, then sort it all out. After all, you shouldn't really be in a sitaution where there isn't adequate run-off at the bottom... and being straight at any speed is preferable to sliding sideways and going over.

Try it sometime when conditions are good, that's why the Syncronauts hold events like Coney Farm in the Spring, to build confidence and allow the more experienced to give tips and advice to those new to off-road... and it can be a great training ground for Green Lane driving where you don't always have as many options open!

Post by **jed the spread** » 27 Oct 2008, 19:04

I learnt and practiced quite a few basics at synropendance and became more confident because of it. Its all very well talking about them but its the actually doing it that makes the difference. Recovering from a stalled assent on a hill for example seems easy when you talk about it but it takes a few goes to get it right.

jed

Post by **Syncro G** » 28 Oct 2008, 00:21

If your going streight down a slope (ie its not a sideslope) and the surface is uneaven so lifting a wheel is possable, engageing the rear locker can make it less likely to crossaxle thus run away, also reduices stress on the driveshafts alot (as it won't loose grip, pickup speed quick and then rapidly regain grip as it de-crossaxles when the vehicle is probubly moveing faster than the wheels are going - can be harsh on a rocky surface).

Post by **HarryMann** » 28 Oct 2008, 01:23

So the vehicle is consuming more power to roll-down the hill diff-locked?

That sort of fits with the extra power required to climb with diff-locks in heavy ground, which I seem to find.

Post by **Syncro G** » 28 Oct 2008, 02:03

HarryMann wrote:So the vehicle is consuming more power to roll-down the hill diff-locked?

That sort of fits with the extra power required to climb with diff-locks in heavy ground, which I seem to find.

No its nothing to do with power (that shouldn't make any difference in a streight line). Its just if you lift a wheel on each axle (or to a degree maybe just a rear axle on a syncro as the VC will give a little), ie cross axle it, as a syncro is very prone to; you'll have no drive to the ground, thus no engine brakeing so control is lost and it'll start to tabogen till it can regain grip. With a locker engaged it doesn't matter if it lifts a wheel, the other side will still have some grip and still hold you back. I'd have thought only the rear locker should be needed/used (not really off roaded my van with both lockers functional) as your going down hill you won't require much power so extra traction gained by front axle locker isn't needed, more importantly the open front diff retains steering control so you can keep it pointing streight down the hill. As always if it really starts sliding you'll want to leave it in gear and pick the speed up to match (even if that envolves some welly, may well do if your in a low gear and it really slides!), might then want open diffs incase it yaws? but maybe thats digressing into other tecneques/issues - start a decent slow and controled, trying to maintain traction and it less likely to get trouble in first place.

A landy has better syspension travel so doesn't suffer cross axle so much but when it does the forces of the wheels re contacting can be bad if you don't match the wheel:ground speed and on a landy that means smashing halfshafts, the weekest bit on them - more an issue when climbing obveously as your useing power then so wheels spin up faster but I favour easing strain on vehicle as much as poss as I despise spending money and time on broken vehicle if its avoidable.

Post by **Russel** » 28 Oct 2008, 06:49

Be very careful locking a diff when going down a hill.The slightest side slope and you can find ureself sideway.When diffs are locked a vehicle is far more prone to wonder of on a slight surface camber.
Russel

Post by **v-lux** » 28 Oct 2008, 08:25

Walrus - how much weight were you carrying in the van on this slope?
If you had a few people and a load of caving equipment in there you might find it a bit of a different experience going down a steep slope.

Mind you weight or no weight, i always find the downhill slope the trickiest.
It is a bit of an art, getting used to how your van handles, what the best thing to do in a certain situation is etc etc. Would be well worth getting along to a syncro meeting when you can, get a bit of practice in those "difficult" situations.

When diffs are locked a vehicle is far more prone to wonder of on a slight surface camber.

I have to agree with Russel, in my experience of driving the clay mud woods around here (very slippery) i've noticed that the rear end of the van, especially as the engine is back there, is very prone to wandering off if the rear locker is engaged on a camber.
Sometimes it just wants to go whatever, but it seems to encourage it with the locker on.

Higher gear and creepy creepy seems the best option when that all starts.

Post by **Walrus** » 28 Oct 2008, 09:32

I did it twice empty, no problems, and the last time quite loaded up (3 adults, 3 generators and loads of mining equpment, tool boxes etc) - that was the hairy one. The track has a gentle bend to the left so couldn't keep in a straight line. Going back in 3 weeks so I'll try to get some video for people to advise on - its a fairly regular trip.

Post by **v-lux** » 28 Oct 2008, 16:11

(3 adults, 3 generators and loads of mining equpment, tool boxes etc)

That'll do it

Might be best to try and do it in two runs in future, its no fun trying to control a very heavy syncro on anything slippery going downhill steeply.

Post by **syncrodoug** » 28 Oct 2008, 16:58

I apologise if I missed it but what tyres are you using?

Post by **Syncro G** » 28 Oct 2008, 17:07

Russel at Syncro-Nutz wrote:Be very careful locking a diff when going down a hill.The slightest side slope and you can find ureself sideway.When diffs are locked a vehicle is far more prone to wonder of on a slight surface camber.
Russel

Is that mainly for slippy stuff like mud or everything? Round my way the lanes tend to be hard surface but uneven so it doesn't slide around as grip is usally good but can crossaxle.