Auto Gear Box: Roll Back

[Ian]

With the gears in D (drive), and idling at trafiic lights facing uphill, I don't need to have my foot on the brake as the Bongo will not roll backwards. But on my previous van, it would roll very slowly backwards.

I didn't think anything of it at the time, I just thought it was something to do with the torque converter generating little power at idle. But now I'm not so sure it was normal.

Is this a known problem? Is there an anti-rollback feature on the Bongos?

[M 80NGD]

Funny you should say that Ian,mine rolls back on steep inclines unless I keep the revs on,or keep my foot on the brake!!

Is this a fault as you say or is it normal?

[mikeonb4c]

I've accepted that mine doesn't roll back on slight inclines, but will on steeper ones. I've assumed it is simply a consequence of (1) the fact the torque converter is always putting some power through from engine to transmission and (2) that it ups its efforts (within limits of engine ability to provide power) if it detects more work to be done, and decreases them if it detects less.

Having said that (which could be wrong anyway!) I feel it doesn't hold on inclines perhaps as well as when I first bought it. The difference is very slight and I can't even be sure that it is so. But one thing I do wonder is whether as the transmission fluid ages, it loses its properties a bit and one sign of this is less 'grippy' transmission and thus diminished ability to hold on inclines.

Anyone who knows feel able to comment?

[francophile1947]

Mine rolls back slightly, if the incline is steep enough - both before and after a fluid change.

[ScubaBongo]

I've also been pondering this over the last few days!

Mine holds the vehicle steady in "D" even on a relatively steep incline before some lihgts etc.

What I was wondering, is - is this bad for the autobox? Should I actually make the effort to move into "Park" or "NEutral + Handbrake"? You wouldn't ride the clutch at an incline in a manual, would you? (Well, you might in a hired/company car, but not in your slightly-elderly pride and joy!)

[helen&tony]

Hi
I think that quite a few autos do roll backwards on a steep slope. I have had a number of autos, and I like them...on slight inclines they save a lot of pedal pushing if you do it for a moment. As regards the slipping damaging the autobox, I don't know, but I'll wager it heats up the transmission a treat, which heats the radiator....and in traffic, it could cause the engine to get all hot and bothered. This I say COULD...as I don't know the rate of heat transference of the transmission to the radiator coolant, but I would not like to chance slipping the transmission in this way in a traffic queue. Personally, I keep my foot on the brake, and put the transmission in neutral if waiting for more than 30-40 seconds
Cheers
Helen

[mikeonb4c]

Hi
I think that quite a few autos do roll backwards on a steep slope. I have had a number of autos, and I like them...on slight inclines they save a lot of pedal pushing if you do it for a moment. As regards the slipping damaging the autobox, I don't know, but I'll wager it heats up the transmission a treat, which heats the radiator....and in traffic, it could cause the engine to get all hot and bothered. This I say COULD...as I don't know the rate of heat transference of the transmission to the radiator coolant, but I would not like to chance slipping the transmission in this way in a traffic queue. Personally, I keep my foot on the brake, and put the transmission in neutral if waiting for more than 30-40 seconds
Cheers
Helen

Spot on Helen - thats exactly as I would see (all of) it.

...not that I'm Mr Expert-Mechanic or anything

[BongoMTBer]

Mine creeps forward on the flat, holds on a slight incline and anything steep rolls back. Not at all like my Merc which holds on anything apart from really really steep. Holding it on the throttle for a short while on an inclime will do no damage, but prolonged periods will obviously use more fuel and warm things a little, but nowhere near as much as climbing at high power which is what the tranmission hydraulics are designed to deal with.

Scuba, don't be tempted to hold it on an incline in P without first applying a good amount of handbrake, you will be loading the lock and then the selector when it comes to dissengaging. For shorter stops, keep in D and use the footbrake IMHO. For longer stops, footbrake on, into N, handbrake on and footbrake slowly off.

[apole]

Ian,

I think all of the above are very valid points. One thing I'd add is how fast is your tickover, mine recently fell quite a bit (less than 500RPM) and that made it more inclined to roll back, but now it's been adjusted back up to 900 it's less likely to roll back.

[mikeonb4c]

Ian,

I think all of the above are very valid points. One thing I'd add is how fast is your tickover, mine recently fell quite a bit (less than 500RPM) and that made it more inclined to roll back, but now it's been adjusted back up to 900 it's less likely to roll back.

Don't know about other Diesel Weasels but this Diesel Weasels tickover is notable for how exceptionally stable it is. I've never had a diesel before and it's something that has struck me about the Bongo

[francophile1947]

Ian,

I think all of the above are very valid points. One thing I'd add is how fast is your tickover, mine recently fell quite a bit (less than 500RPM) and that made it more inclined to roll back, but now it's been adjusted back up to 900 it's less likely to roll back.

Don't know about other Diesel Weasels but this Diesel Weasels tickover is notable for how exceptionally stable it is. I've never had a diesel before and it's something that has struck me about the Bongo

Isn't Apole's a V6?

[mikeonb4c]

Ian,

I think all of the above are very valid points. One thing I'd add is how fast is your tickover, mine recently fell quite a bit (less than 500RPM) and that made it more inclined to roll back, but now it's been adjusted back up to 900 it's less likely to roll back.

Don't know about other Diesel Weasels but this Diesel Weasels tickover is notable for how exceptionally stable it is. I've never had a diesel before and it's something that has struck me about the Bongo

Isn't Apole's a V6?

Yup, sorry, that was my point. I was indulging in a bit of superiorness (Andy knows me by now)

[francophile1947]

Ah! - you were making disparaging comments about those powered by the fuel of Satan

[dandywarhol]

Sounds quite normal Ian - it'll depend a lot on idle speed, weight in vehicle and severity of the hill.

You can idle in D almost indefinately - it'll hardly affect the torque convertor temperature - it'll get hotter under normal operating conditions