Overdrive issues

[Greggers]

I recently added an overdrive to my car.

While traveling down the highway at a comfortable 70 or so and at what I recall to be about 3200 RPM, I had what I believe to be a small OD issue. I let off the accelerator a little and eased over into a different lane. For whatever reason, it seemed like the OD disengaged and then reengaged, temporarily sending the revs into the 5000 range. It happened a few more times on the trip.

The next day, I checked the oil in the tranny, and it was full.


Any suggestions on where to start to make that stop happening?

 

[RootesRich]

Have you checked the connections on the relay at the firewall? It's the easiest place to start troubleshooting OD electrical gremlins. I had a similar issue a few years ago where one of the female ends of spade terminal connections was not tight and when it came loose... no OD.

 

[Tom H]

I'd make a wager that the problem is electrical. And the problem is either the OD relay or the OD solenoid. As Rich suggested first check for loose connections. Let us know what happens next and I'll offer more suggestions.

Tom

 

[Greggers]

As a test, I turned the car on but not running and put it into 4th. Then I flicked the OD column switch into the on position. I heard the click from the relay, so that seems to work nicely. After that I went under the bonnet and wiggled all the wires at the relay. Everything there seems tight, and nothing turned off.

For good measure, I wiggled the OD switch on the column a bit. No change there until I flicked it to the off position, which, as expected, de-energized the relay.

I guess the next step is to do the same at the 3rd/4th switch on the transmission. I recall those connections being sufficiently snug when I hooked them up, but I'll definitely check to be sure. And the switch itself works properly. It turns the OD off when I put it into neutral.

Assuming the connections on the 3rd/4th switch work fine, what next?

 

[RootesRacer]

When you decel the shifter fork may move a bit and cancel the 3/4 switch on the gearbox.

If this is the case, you probably have too many shims between the switch and the shift tower.

 

[Tom H]

BIG word of caution! Just because the relay clicks does NOT mean it's OK. There is a BIG problem with these special relays with 2 contacts. One contact simply applies power to the relay itself, to latch it on. That same contact also energizes the indicator lamp, if installed, telling you, supposedly that the OD is ON. BUT if the second contact does not also close, there is no 12 V applied to the solenoid, so the OD is NOT on, even tho the relay is closed and the OD light is ON. I have disasembeld my OD relay twice to attempt to adjust the contacts so that both close when relay is energized. Both times it eventually failed, most recently while on my road trip.

To temporarily solve the problem while on the road trip, I simply bypassed the OD relay with a spare headlight switch. I disconnected the Yellow and Yellow/ Purple wires (that are in the cable coming from the tranny) from the OD relay and connected a pair of wires to those wires and ran them in thru the firewall hole and connected them to a spare headlight switch. I taped the headlight switch to the shift lever for convenience.

Wired this way, the switch controls the OD solenoid directly, but it does run its power from the 3/4 switch, so it only engages in 3/4 gear. The only difficulty is that with OD ON, once you switch out of 3 /4 it does not automatically cancel the OD power, you need to flip the switch OFF. Otherwise next time you engage 3 or 4 , it again goes into OD.

I think this is a good way to diagnose whether the OD relay or the 3/4 switch, or the solenoid is the problem.

A quick test to see if the OD relay is at fault is to test for 12 V at the term C1 the yellow purple wire, with the relay engaged. If there is no 12 V at C1, and yet the relay has clicked and stayed on then you have a bad second contact. Problem is this contact can be intermittent as you have experienced. I solved this by semi permanently wiring a small test lamp to Term C1 and put that lamp where I could see it inside the car. Now when the OD cuts out, I look at that test lamp, and see that it is not lit, confirming that the OD solenoid is not getting 12 V and that the problem is almost certainly the OD relay. If both my test lamp and the standard OD light are off, the problem is most likely the 3/4 switch needs its shims adjusted like Rootes said.

Tom

 

[Hillman]

When you decel the shifter fork may move a bit and cancel the 3/4 switch on the gearbox.

If this is the case, you probably have too many shims between the switch and the shift tower.

My early series likes to do this unless I hold the gear lever to the right. Does that suggest fewer shims or more are needed?

 

[Tom H]

This suggests that fewer shims are needed. But when you remove shims , verify that the 3/4 switch goes OFF when you are in 1 or 2 gear.

Tom

 

[Hillman]

I thought the same way. I have no shims installed, still it falls out unless gear selector is pushed right. Since 1 & 2 are to the left of 3 & 4 , and IIRC the switch is on the 1 & 2 side I thought I might have it basakwards. The diagram in the WSM is vague enough it doesn't help.

If fewer shims (than none) are the way to go, do I try to reduce the size of the switch (letting it turn in farther), use the MIG to add length to the 'switch rod' or something else?

 

[Thor 1211]

od

I agree with Tom, fewer shims, and usually only one less will do and a thin one at that if the o/d has just been working.

However, I found the best way to test out the solenoid was to put everything in " o/d on" mode and crawl under the car and remove and replace the wire to the solenoid. It does engage and disengage with an audible click, louder than the relay. no difference and then a test with a separate 12 v supply will tell you if it's engaging or not. Working backward you can go through the 3/4 switch, the relay and then the column switch.

my tempermental o/d turned out to be a problem with the adjustment arm fork inside the o/d and the end adjustment nut on the solenoid pin.

 

[Tom H]

Hillman, on a SV, the 3/4 switch is on the (US) passenger side and the backup light switch is on the drivers side of the tranny. I am puzzled how you know there are no shims, but are unsure which side the switch is on. Do you have both switches ( OD and BU) ? and both have no shims? I am not sure of the switches are the same orientation on an early series tranny with no synchro on first and with Reverse down and left.

Tom

 

[Hillman]

Tom,

I have an early trans, non-synchro 1st. I haven't been under the covers lately. I tried removing shims last summer and I'm about 90% sure the switch was on the driver's side. I don't have a backup light. I started by removing shims (and I only had one) since logic said that a worn 'shaft' was the most likely (as in 'shafts' don't get longer). In retrospect, the guy I bought it from mentioned this problem, and I had it, but IIRC, it got worse with the shim removal. Reading this thread made me say whoa (am I an idiot)? I think I might be (if the switch is really on the left).

Now that yesterday's 4 inches of snow are mostly gone, I'll visit the car tomorrow and confirm.

Thanks

Al

 

[Tom H]

Al, I just read up in my early manual, and it shows the switch on the driver's side for early trannys. I suggest you might solve the problem with a new switch. But if you install a new switch be sure to check and adjust (with shims) as necessary to be sure the switch does not allow OD in 1 or 2 gear. It seems more likely to me that the switch itself has worn rather than the shaft in the gearbox. and certainly it's a lot easier to replace the switch than mess with the tranny itself.

Note that the switch is normally Open and is closed (or ON) only when the plunger on it it is pressed, so there is no way that removing shims would make it less likely to close.

Tom

 

[Mark B]

I was having similar issues with my overdrive in a SV, and began troubleshooting using similar methods to what was described here. In the process of isolating the issue, I cleaned all the contacts on the harness, grounds and relay and secured everything because my problem was so intermittent. I ended up by-passing the relay with a switch that I wired in and just had sitting on the floor of the car by my right knee. This allowed me to use the car on the road and engage the overdrive to see if the stuttering in and out of engagement or simply dropping out of engagement suddenly, was possibly a faulty solenoid or something else that might be caused by vibration while driving. The situation eventually turned out to be the relay. When the relay was by-passed, the OD worked flawlessly. The big issue for me was when it would drop out at speed and run the RPMs up and/or chirp the tires. I could see spinning some of the shafts or trashing the engine or more, because it was always when you least expected it and generally at higher speeds.

Of note is that I have 3 of the 33199 relays and they are all in some state of old/cranky. Swapping them seemed to produce the same results and led me to think it was not the relay. These relays are getting very hard to find and very expensive.

Bottom line, is I purchased one of Tom's relay solutions that he and Rich, (and others), had hashed out in a post many moons ago. The recent Spring weather had not allowed me to install it, but about 4 days ago, I saw my opportunity. It took all of 5 minutes to install on a very common 6RA relay, thanks to the wiring diagram. It would not have been intuitive, because this electric relay stuff is just north of quantum voodoo to me. I have driven the car every day since installing this, and it has been brilliant. The renewed confidence to engage the OD, and not have this nagging worry in the back of my brain that kept me at lower speeds and somewhat tentative on the throttle, was awesome.

The 6RA was brand new and about $20, and Tom's solution cost about 3 cups of coffee. A big thanks to Tom and all others who sorted this out. Its spot on and really puts the mental and highway drivability back into the car.

This morning, I took a long spin up into the hills, and hit some steady cruising speeds on the trip that I have not seen for a while. The ride was much less frantic and the engine ran cool, and just flew down the road in a relaxing and comfortable way.

Thanks to the forum yet again for being a stellar community for these cars.

Mark B

 

[Tom H]

Glad it's all well, Mark. Congrats. As I have said many times, the biggest issue with these ODs is the electrics and the biggest electric issue is the relay. Nice job temporarily bypassing the relay with a switch, that's exactly what i did on my long trip last Sept. So maybe you understand electrics more than you realize.

And by the way, my kit can also be used to make the original special relay work better, bypassing that dual contact messiness.


Tom

 

[Deacon Blues]

Overdrive

Im new to all this. Where can one get an overdrive for a series 5? (I would do my own drive shaft)
Thanks

 

[Tom H]

Where to get an OD for an SV? Keep looking! They are quite rare. Many of us have bought a complete OD Transmission from Jeff Howarth, a UK member here who will post a couple times a year that he has one for sale, rebuilt by John Roseby. See post #5 two weeks ago here:
http://www.sunbeamalpine.org/forum/showthread.php?p=147274#post147274

Note that if you buy just the OD assembly you will not be able to add it to your existing tranny as it requires a different mainshaft in the tranny itself.

Tom

 

[Greggers]

So I have an update.

I switched to a Tom H relay kit with a brand new Bosch-type relay. Works the same. With more driving and longer trips, I discovered the problem wasn't just limited to the downshifting I mentioned in my original post. It happens when switching on the OD and when accelerating. Usually it works fine on the way to wherever I'm going, then it acts up on the way home.

I made the decision to buy a purpose-built OD pressure gauge. I was pleased to discover that my OD ran a comfortable 450psi... for the first couple of miles (Of course, that range is below the Sunbeam spec of 470-490).

With OD disengaged:
0-10 psi

With OD engaged:
0-10 minutes: 450 (OD operates fine)
10-20 minutes: 400 (OD operates fine)
20-30 minutes: 375 (OD slips some)
30-home: 325-350 (OD slips a lot)

Unless somehow the solenoid doesn't work as well when things get hot, I guess my issues are oil pressure/heat related. I've read some (a ton) of sites and it's been suggested that issues like mine are caused by:

• Low oil (I'm topped up)
• Solenoid out of adjustment

Various sites recommend:

• Adjusting solenoid
• Switching to Redline MT-90 (SAE 30 thins and so pressure goes down as it gets hot, but Redline's viscosity doesn't change significantly as temperature changes)
• Adding a washer under the pressure relief valve's spring to raise pressure (but the initial pressure doesn't need to be raised much. Pressure when hot does.)
• Replacing o-rings
• Rebuilding the whole damn thing

Anybody been down this road? Suggestions as to where I go next?

 

[Bill Blue]

Greg, haven't been down that road, but it sounds like an oil viscosity problem.

You mention SAE 30 oil. Just exactly what are you using? Straight 30? (poor choice, no temperature compensation) 30w30? (good choice, would be 30w at tempt) 10w30?(same as 30w30). I think that something like Rotella (15w40) or a 20w50 would be the best engine oil, but I don't know how it would compare to the Viscosity of the gear oil.

Bill

 

[SIVAllan]

Where to get an OD for an SV? Keep looking! They are quite rare. Many of us have bought a complete OD Transmission from Jeff Howarth, a UK member here who will post a couple times a year that he has one for sale, rebuilt by John Roseby. See post #5 two weeks ago here:
http://www.sunbeamalpine.org/forum/showthread.php?p=147274#post147274

Note that if you buy just the OD assembly you will not be able to add it to your existing tranny as it requires a different mainshaft in the tranny itself.

Tom

I've got two syncro OD setups complete and don't need any as I'm moving over to the dark side for a while.

Might have three, will have to check.

One of the OD gearboxes (the non OD part of the setup) was sent to England for a rebuild.

Also have a few on/off switches and relays and a couple of wiring harnesses and at least one OD drive shaft.

I'll make them available to any interested club members after SUNI, before going to Ebay.