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overdrive gear oil??


Justin

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Posted

the overdrive on my 1500 works perfectly until the car is fully warmed up then 3rd & 4th stick in overdrive mode and no response from the switch. I've cleaned the filters but read somewhere that certain types of gear oil can have undesirable effects on overdrives. any ideas?

cheers
justin

Posted

The correct oil is EP90 GL4.

I'm taking it that the overdrive only stays on when you are in 3rd and 4th and drops out again once you get into a lower gear but if it continues to stick be careful not to reverse the car when the overdrive is stuck on as this will damage the overdrive.

Check the wiring out, most overdrive faults are due to electrical wiring problems, especially with the wire that goes up the shaft to the gear knob as this is prone to chaffing and shorting out. I know you say that it only sticks when hot but this could just be conicidence. If it's only sticking in 3rd and 4th then I'd say and electrical fault is the most likely cause and any internal fault would continue to stick in the other gears.

Posted

Difficult to see how an electrical fault can make it stick on.    It needs oil pressure to do so, and that is provided by the internal pump, which runs all the time, directed by the servo to engage the cone clutch.  I supect that the oil pressure is being maintained by the solenoid valve sticking, the cone clutch sticking or a clogged control orifice.   Check the filter  for 'black hairy stuff' that is parts of a worn out clutch.

John

Posted

thanks for the reply cook1e.
the switch is fine and as soon as the car cools down the overdrive works perfectly, which makes me think its something to do with the oil as it warms up.
going out to get some ep 90 gl4 as i think the last oil was gl5.
fingers crossed :)

Posted

sorry john i missed your reply. i'm thinking along the same lines as you but i've had the filters out and they were ok apart from a wee bit sludge so i'm hoping a change of oil may rectify things.
cheers
justin

Posted

Richard_B wrote:
Should be 75/85W GL4. EP90 is for topping up only.

Available from Triumph blah, blah blah....


Interesting .... I've had opposite problem.

Fine when its cold but once warmed up it starts to drop OUT of overdrive once speed falls below about 40mph.

Completely drained it tonight and filled with EP90 GL4 - and it was worse.  It had previously been filled with Halfords 80/90

I think I'm gonna try 75/85 tomorrow night and before topping up I'll whip the solenoid out (WHY HAS NOBODY THOUGHT ABOUT SELLING A SPANNER THAT WILL FIT THAT THING?) and check the O-rings.

Anyone got any other ideas for this one?

Posted

Triumph, Volvo and MG got the same overdrive.
Triumph it's EP90, Volvo is 30W and MG is ATF (automatic transmission fluid).
I had EP90 Synthetic in my J type, it was sticking in 3th and 4th gear and it was leaking also.
I switch to 30W and it doesn't stick anymore and it stopped leaking.

Found also that article : http://www.quantumechanics.com/categories.php?op=newindex&catid=11

Laurent GT6+ 69

Posted

Ok so I seem to have a fully working overdrive - well have done about 150 trouble free miles yesterday and today.

I did 3 things.
1.  replaced O-rings on solenoid valve with slightly meatier ones
2.  secured the solenoid body to the valve better (one of the little roll pins was missing and the body was moving slightly - could b a factor.
3.  filled up with EP75/80 - looks much thinner than the EP90 but I'll go with it for a while.

One of these things has done the job.

Alternatively, it might just be that I gave the valve in the solenoid a good clean.

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