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Jumping out of 4th


Danwedges
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So my car jumps out of 4th gear every now and then and was wondering if anyone had any ideas what may cause this? It only ever happens in 4th and not every time but I'm planning on pulling the transmission tunnel soon anyways to see if I can get my overdrive to work and also check my reverselight switch so I will be having a look to see if there is anything obvious that's causing it to jump out but any suggestions of what to check would be much appreciated  thanks

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What car do you have ??

How do you select your O/D engagement ??

It is unlikely you will see anything affecting the 4th gear problem without examining the g/box internally; by the sounds of it and I am no g/box expert but it could be a weak selector.

Have attached a photo showing the O/D and reverse switch location; since the photo the transmission has been rewired with an O/D loom and a reversing light loom.

If you have a gear stick O/D switch, look at the photo to see how the wires in the shaft should NOT be wired - the protective sheath must go in to the shaft hollow.

Regards.

Richard.

DSC00220_LI.jpg

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Does your O/D relay and or solenoid click when you engage with the ignition on but engine not running ?? If so it's mechanical, if not then electrical.

Quite often the wiring in the g/stick column can become damaged and the following photos show how age and heat transfer from the transmission can break the wires down, so this is certainly an area of wiring that needs checking as well as the actual connections to the switch - a simple continuity check will confirm the wiring status. 

I ended up replacing all the transmission wiring, no other alternative.

Regards.

Richard.

 

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Naa I get no click what so ever so my plan is to do the same and replace any wiring that has seen better days and hopefully the solenoid and other stuff is all okay the previous owner said it was working but then stopped but he rarely used the car I'm hoping it's just a faulty connection somewhere

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Simplest idea for 4th would be unnel off and look at the pivot bolt that connects the lever with the remote rod 

If  the gate selection is a bit  |--》   rather than  |--| then its The  wrong way round it can foul the remote casting in 3rd And 4th , also check theres no sloppy lost movement in the two sets of bushes in the remote rods.

The worst conditions are

Failed detent spring on the selector shaft

mainshaft has lost its rear circlip

The mainshaft spigot bearing has worn /failed

Springs in3rd 4th  sliding sleeve are broken

Hopefully its the pivot bolt

Pete

 

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  • 2 weeks later...

Okay so I've had the tunnel out and sorted a few poor connections and broken wires and squared up the fork for the gearstixk and it doesn't seem to be jumping out of 4th anymore but I haven't driven it much due to bad weather and now my overdrive clicks when ignition on but not running but doesn't engage when driving what are my next steps? I've read about low oil causing this so I'm thinking change gearbox oil so any reccomendations for gearbox oil and diff oil as I might as Well change all oils at the same time I have 20w50 for the engine which I'm assuming will be correct for the engine and many ep90? For gearbox and diff? 

Any other suggestions would be appreciated too

Thanks,

Dan 

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There are two sources of clicks on a D Type OD - one is the relay on the bulkhead and the other from the solenoid - they are pretty much simultaneous, but if you have a click and no engagement have you checked the solenoid is operating as well as the relay? Remove the plate on the driver's side of the OD (3 small bolts), place the gear lever between 3rd and 4th (or in either of those gears) and operate the switch with ignition switched on. You should see the plunger move back into the solenoid as the relay clicks. If it doesn't, it's a multimeter check for power to the solenoid - if there's none, then it's an electrical chase to see where the wiring or relay is at fault. If there's power, then you may be looking at a replacement solenoid.

Oil level is an easy check with the tunnel out (on flat, level ground) - take out the filler plug and if none comes out it needs topping up. Use EP90 GL4 spec - avoid EP90 GL5.

Good luck!

Gully

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Spec for the gearbox diff and trunions is EP90  GL4 spec.and when you have done the checks Gully suggests

While the cover is off look at the lever, it has a 3mm hole when the solenoid pulls in the hole lines up with a similar hole in the case stick a 3mm drill through to test the alignment

Pete

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Thanks I'll pull the tunnel back off at the weekend and check for the solenoid actuating I know there's defiantly voltage coming out of the relay but I didn't check the solenoid at all I think I heard it click and was too eager to get it back on the road to see if it was working haha never mind I'd like to change all the fluids so it will need to come off again anyways, I'll see if I can book a ramp and get it in the air for easier access when draining everything I'll report back once I've done.

Thanks,

Dan 

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Next time test it before you fight the tunnel back on, this can be very noisy ,  saves a fight 

You can get to the filler plug from underneath  but while the tunnels off make an access trap next to the clutch pedal to get at the filler

Let us know where you get to with a top ip or oil change 

The solenoid has two coils a high current   10a  one pulls in then a switch in the end of the sol. Holds in at 0.5a

This switch can age and fail,  do also make sure the 3rd 4th inhibitor switch is operating, not needing any adjustment

Pete

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  • 1 month later...

Okay so I've finally gotten round to having a look at this overdrive fain and can confirm that both relay and solenoid click but the solenoid only moves about a milimeter so I was wondering if this is correct or should it move more than this?

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it has to move the lever till the two 3mm holes  one in case and one in lever , line up,   it dosnt move much but 1mm sounds insufficient.

solenoids can suffer corrosion inside ,  the sol armature must pull the lever back a to align the holes and at the same time the end of the armature makes contact witha push switch at the gaitor end of the solenoid body ths cuts the pull in coil amps from 10a  down to a holding coil of 0.5 amps 

if the sol doenst travel enough the pump wont pressurise the cone clutch pistons and the switch wont cut the coil currents you get no OD and a right hot solenoid 

you could be in for a replacement

now see what paul gulliver and i did to make removal exciting, its in  courier last year. ??

and its on here somewhere ...off to search 

Pete

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if you have a meter in the feed wire the pull in current is only on a few seconds till  the tail switch cuts it off

So initial pull expect around 10amps, amd switches down to 0.5amps when engaged 

As said if it doesnt drop the switch is failed or the core  has not traveled to its end stop

The holes line up and switch operation  are sort of synchronised to work together

Pete

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I've aligned it up perfectly when engaged and topped oil up, it's not getting hot and appears to have full travel on the solenoid but still not working I'm wondering should the brass arm be sprung at all? Mine just stays where it is when disengaged and I can move it with my finger I'm thinking this could be an internal problem

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My understanding is the gearleaver is not saying in 4th. A couple of the causes can be the springs that hold the gearleaver in position and the springs that hold the synco in position are weak or broken. The Springs that hold the gearleaver in position are located in the remote gearleaver setup and can be replaced without stripping down the gearbox. If you believe the overdrive switch is causing problems then as a temp measure remove it and see if 4th gear stays in.

Dave    

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Sorry I should have probably started a new thread for this  but 4th jumps out every now and then but my overdrive just doesn't engage so I was trying to find a solution to that but I will defiantly check the springs for 4th are they in the actual remote control assemble or in  the top of the gearbox?

The brass arm in my overdrive unit which the solenoid pulls on is not sprung and I was wondering if it should be as I'm trying to work out what could be the cause of my overdrive not working

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