Gearbox Question

[Nick V]

Was towing my car trailer yesterday, about 800kg loaded, and noticed that after a long drag up a gradient the gearbox would not go into lock out when I hit 55 - 60 mph, which is when it normally happens! I wasn't accelerating hard and this was on the flat after the hill.

Any pointers what would cause this, or is it just because the trans fluid got hotter under stress during the climb (higher revs)? If so, what would solve the problem? (I have a trans cooler already). Perhaps a fluid change, although I did this about 18 mths ago?

Cheers, Nick

[BUSHWHACKER]

My truck does the same, when you 'feel' that it should be going into lock-up, switch off O/D then back on again within 2 seconds and the revs will drop.

The transmission thinks you're still acellerating hard when pulling a heavy load so stays in a lower gear, flicking the O/D button off then back on seems to sort it out.

Works for me anyway.

[Nick V]

Thanks for that Vince. I noticed it start working a while later but I thought it was due to the txmn fluid cooling. Thinking about it now, I did flick both the o/d button and the ECT switch off/on as a matter of course, so that probably did it with me noticing immediately.

Cheers, Nick

[Nick V]

Was in the same situation again yesterday, going up the A34 after a gradient it wouldn't lock out. A while later, and for the first time ever, I had the transmission temp light come on! I stopped for five and it went out, but after that I still couldn't get it to lock out! (Flicking o/d on and off made no difference so I suspect it didn't the previously time also).
On my return journey, (obviously the trans fluid had cooled) I took it easy on acceleration and the gearbox worked perfectly all the way from Oxford to Southampton.

Can fluid condition and/or temp affect lock out?

Cheers, Nick

[BUSHWHACKER]

If the fluid is getting hot and you're not towing anything, I would say the clutch bands are on the way out.
Try replacing the fluid first with a quality ATF that has friction enhancers added, (e.g. http://www.ebay.co.uk/itm/1208187134...84.m1439.l2649 )
otherwise start looking for a replacement transmission soon.

[Nick V]

If the fluid is getting hot and you're not towing anything, I would say the clutch bands are on the way out.
Try replacing the fluid first with a quality ATF that has friction enhancers added, (e.g. http://www.ebay.co.uk/itm/1208187134...84.m1439.l2649 )
otherwise start looking for a replacement transmission soon.

Hi Vince, this was when I was towing. The box is absolutely fine when I'm not towing, and locks up at about 55- 60 mph every time. I'll get the fluid changed as soon as.

Cheers, Nick

[BUSHWHACKER]

Hi Vince, this was when I was towing. The box is absolutely fine when I'm not towing, and locks up at about 55- 60 mph every time. I'll get the fluid changed as soon as.

Cheers, Nick

Ah OK, didn't realise you were towing this time.

Change the fluid in any case, if it gets hot enough to illuminate the overheat light, the fluid properties will have deteriorated.

The fluid in that link is more resisitant to heat.

[Nick V]

Thanks Vince, I'll have a go at the txmn fluid.

Cheers, Nick