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 Post subject: J type overdrive problem
PostPosted: Sat Dec 17, 2016 7:12 pm 
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Joined: Wed Dec 18, 2013 5:05 pm
Posts: 336
This is about the TR6 but as the J type overdrive is in a few of our cars it is relevant.

The overdrive became intermittent a week or so ago. A few flicks of the switch and it engaged and worked ok. A few days ago it would engage and started dropping in and out. It appeared to be more a problem in 3rd than top but hard to tell.

Yesterday it stopped engaging at all.

I changed the oil a few weeks ago to Castrol VMX80. The od worked ok for the first few drives after the oil change.

The solenoid is working, I can feel it moving with someone else operating the switch (but don't know how much it is moving until I get it out). However, the solenoid black cylinder casing is very very loose. It is held on by four little rivets and the holes in the cover have elongated a lot.

I checked the oil level this afternoon and it was a bit over full (I didn't have it level when doing the topup after the oil change and tried to judge the oil level), about 300ml drained out. It didn't make any difference the od still doesn't work.

Any ideas? Wrong oil, solenoid u/s with the loose casing, something else?


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PostPosted: Sat Dec 17, 2016 8:18 pm 
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Joined: Thu Dec 19, 2013 4:44 pm
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I had a similar problem with the A type overdrive on my 3A. We worked out that the cutout switches on the top of the gearbox had worn and weren't moving enough to enable the overdrive to work properly. I found that when trying to get the overdrive to work, if I moved the gearlever with the overdrive engaged it would work, the linkages bumping the switches and making them work. Removing a couple of shims from the switches cured the problem. Maybe this will work.
Cheers, Peter


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PostPosted: Sat Dec 17, 2016 8:51 pm 
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Joined: Thu Dec 19, 2013 3:40 pm
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John
The oil is fine. The coil section of the solenoid can be loose but this will not affect it's operation. The actual working part is a iron armature with a couple of o rings on it that slides within the brass body and acts as a sliding valve. It takes only a small current to operate and does not need a relay in the circuit. Could be wrong there on the 6. It has both a power and earth lead, unlike the A type.

First check the earth lead is good, then the remainder of the OD wiring. If that looks good then run a hot wire to the solenoid with a switch in it and try that. This will eliminate the loom and isolation switches on the gearbox. You can then move on to the hydraulics.

Caution, make sure you do not go into reverse with the OD engaged. This can all be done with the car on stands.

Electrics are the most likely area where the issue is.


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PostPosted: Sat Dec 17, 2016 10:14 pm 
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Joined: Wed Dec 18, 2013 5:05 pm
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aladdin wrote:
John
The oil is fine. The coil section of the solenoid can be loose but this will not affect it's operation. The actual working part is a iron armature with a couple of o rings on it that slides within the brass body and acts as a sliding valve. It takes only a small current to operate and does not need a relay in the circuit. Could be wrong there on the 6. It has both a power and earth lead, unlike the A type.

First check the earth lead is good, then the remainder of the OD wiring. If that looks good then run a hot wire to the solenoid with a switch in it and try that. This will eliminate the loom and isolation switches on the gearbox. You can then move on to the hydraulics.

Caution, make sure you do not go into reverse with the OD engaged. This can all be done with the car on stands.

Electrics are the most likely area where the issue is.


Thanks Brian. I don't recall doing this or experiencing any immediate symptoms after being in reverse. With the TR6 od switch being next to the indicator switch it is possible to engage reverse with the od on if you thought you had the indicators on. What would be the symptoms if this happened? I thought all drive was lost. I wouldn't have thought it would work intermittently then stop engaging completely.


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PostPosted: Sat Dec 17, 2016 10:16 pm 
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PeterS wrote:
I had a similar problem with the A type overdrive on my 3A. We worked out that the cutout switches on the top of the gearbox had worn and weren't moving enough to enable the overdrive to work properly. I found that when trying to get the overdrive to work, if I moved the gearlever with the overdrive engaged it would work, the linkages bumping the switches and making them work. Removing a couple of shims from the switches cured the problem. Maybe this will work.
Cheers, Peter

Thanks Peter. A possibility. I'll try it tomorrow.


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PostPosted: Sun Dec 18, 2016 9:35 am 
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Joined: Thu Dec 19, 2013 3:40 pm
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John
If the isolating switches are OK then you should not be able to get OD in revers. My caution was meant to refer to the use of a hot wire that bypasses the isolation switches.

Engaging OD while in revers will lock up the drive and can do some real mechanical damage. You will know it if it happens.

It only takes a short time to try the hot wire and will quickly rule in or out the electrics.


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PostPosted: Sun Dec 18, 2016 12:04 pm 
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Joined: Fri Jul 10, 2015 11:12 am
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i had similar problem and it turned out to be the actuating switch in the top of the gear stick (stag type). put in new switch and relay to reduce current through switch. it was branded Lucas and its cheap and nasty but working ok
peter


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PostPosted: Sun Dec 18, 2016 12:15 pm 
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Joined: Fri Dec 20, 2013 10:19 am
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Having spent thousands on overdrives I agree with the above but will add something. Jack the back wheels and go through the gears and overdrives. If it works up there and not on the ground it may well be the clutches in the o/d are worn. If they are worn you do tend to get a warning in that the change is slow or not engaging. When they are good it comes in quickly.
I also had an o/d rebuilt after a catastrophic failure and it returned to its old ways. Replaced the relay and it has been excellent ever since.Bit like David in Albury with an original coil, I had an original relay and solenoid. The latter I replaced as a cautionary.
O/D should not engage in reverse BUT it can happen and does happen. As Brian says, "You will know if it happens". Basically the car won't move ANYWHERE so you have to drop the tailshaft to put the car onto the tilt-tray. I had my car at a garage for a wheel alignment and somehow they backed up in o/d, not that they owned up for quite a while. Cost me $3500.


Last edited by trooo3 on Sun Dec 18, 2016 6:18 pm, edited 1 time in total.

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PostPosted: Sun Dec 18, 2016 3:55 pm 
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Joined: Wed Dec 18, 2013 5:05 pm
Posts: 336
Thank you all.
I put her back up on stands this morning and gave the od a try. With the ignition on the solenoid is clicking in and out normally with normal operation of the switch.
I started her up, into top and did manage to get the od to engage twice in numerous attempts. Then nothing after numerous more attempts.
I left the od on and went between 3rd and 4th. Nothing.
I replaced the earth wire and cleaned both terminals. Nothing.
I hot wired the solenoid straight to the battery. Nothing.
The solenoid might be dicky and not pulling in properly, which I will check when I get it out.
If the solenoid is ok it is something internal.
I removed and cleaned the od filters with the oil change but I can't see that I did something wrong there that would affect the operation.
My guess/hope is the solenoid is no good. It was working ok up until this problem. It is a bit slow to engage but not much different to the TR2 and it has been working fine for 100,000 miles.


Last edited by TR1954 on Mon Dec 19, 2016 11:22 pm, edited 1 time in total.

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PostPosted: Mon Dec 19, 2016 8:30 am 
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Joined: Fri Dec 20, 2013 10:19 am
Posts: 180
John have you simply put the car into gear, switched on ignition and overdrive and watched the plunger or more simply watch the amp gauge jump. If it doesn't move you can manually lift the plunger and it may then leap unto contact. This indicates that the solenoid is weak or that the clearance gap at rest is too great.


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