Overdrive question on my rebuilt trans.

[SCguy]

Today I decided to try and get my (J-type) newly rebuilt overdrive working in my TR6. After connecting the wires to the overdrive I took my car out for a little test drive. What seemed to happen was this... after switching the overdrive on, the car paused and then lurched as if going into overdrive, but then didn't. After this, the switch seemed to have no effect on the car (turnning it on or off). Thinking that perhapss the trans. didn't have enough oil (I remember my mechanic telling me to add oil after I first ran the overdrive) I went home and changed the oil. Then I took the car out again and again it lurched as if to go in, but nothing. The switch, again having no effect after my initial attempt. Any guesses as to what is going on? /ubbthreads/images/graemlins/confused.gif

 

[Guest]

Larry, I hate to scare you but the same exact thing happened to me when I intalled overdrive (J-type) in my car for the first time. I had Quantum build me a unit and he himself installed it on my 4-speed. I, in turn, reinstalled the whole setup. It worked once! After much wailing and gnashing of teeth (and doing everything in the world to make it work) I jerked the whole thing out, reshipped and put in a whole new (rebuilt) unit. No problems. John to this day has no idea why that unit never worked. Gremlins.

Bill

 

[vagt6]

Sorry about your OD woes. There's lots of stuff that may be checked without opening the gearbox. Wisdom tells us that a significant number of Jtype problems are related to the solenoid. Make sure it's working properly first.

Then, check your wiring. Easy to do.

If it's still not working, refer to TR6Bill's post, above. Painful, but it may be necessary to pull the thing out again if all else fails.

My bet is the solenoid, or the wiring.

Good luck, let us know.

 

[SCguy]

I'm thinking/hoping that perhaps there's still not enough oil in the trans. When I changed the oil I only put back in about a 1 and 1/2 quarts. My manual says that the trans. with overdrive takes 4.2 pints. If this is the case then I'm still 1.2 pints short? Could this cause the overdrive symtoms I described. Am I missing something?

 

[vagt6]

Low oil in the gearbox can cause a wide range of problems. Ensure that the oil level is topped up ASAP. If you're lucky, that's all it is.

Sounds likely since you state that the box was recently rebuilt.

I used to check the gearbox oil every time I put fuel in the car. Cheap insurance for a potentially costly problem (i.e., knacked gearbox due to low/no oil).

Let us know . . .

 

[Alan_Myers]

Hi,

I agree, the very first thing to check is the oil level and top up as needed.

Keep in mind that the oil serves two purposes in an OD gearbox: It provides lubrication just like a non-OD gearbox, of course, but also hydraulic action within the OD itself.

When the OD is first used after a rebuild, i.e. it's "dry", it will fill up various parts of the hydraulic system and should require topping up right away. Later, when you change the oil with the gearbox/OD in the car, it never all completely drains out. So a fill from "dry" takes more oil than a refill after draining.

Also important is the *type* of oil being used. I'm sure you got advice about that already, from your rebuilder. Just be very certain to use a *non-detergent* oil, such as a racing motor oil. Foaming action in typical detergent motor oils will cause air bubbles to get within the OD hydraulics, which could cause the OD to stop functioning.

Personally, I'd not use a synthetic motor oil in there either, even if a non-detergent type could be found (many or most synth motor oils are high detergent/high mileage).

There are some specific non-detergent synthetic gear oils available, some even with friction modifiers. But I'd even think twice about using those in any TR gearbox. Problems (mostly popping out of gear) have been directly traced to using synthetic oils in TR g'boxes.

The next most likely suspects are the solenoid, wiring harness connections and switches, or some adjustment of the OD actuating mechanism. After that, the innards of the OD are the next thing to consider. But, I'm not all that familiar with the J-type in these respects, so can't really make any suggestions.

Another thing that can be tested, after all the above have been eliminated, is the amount of hydraulic pressure being generated within the OD unit. Again, it's different (much lower psi) on the J-type than the A-type I'm familiar with, but with the right tools it's pretty easy to check.

Hope this helps!

 

[SpannerMan]

[ QUOTE ]
All the above advice sounds good. I would think you ought to be able to rule out the first level of electrical problems by a basic test of the O/D wiring and solenoid. Sit in the car with the motor off, ign on, top gear, and switch the o/d in or out and you should hear it clicking in/out. You could also leave the o/d 'in' and move the gear lever through the gears to check it clicks in and out in the appropriate gears (checking the interrupter switches in other words). If that checks out, the next level would be to have a look under the car and see if there looks to be any difference in the actuation of the solenoid between the first try and the subsequent tries (needs a helper to switch it in/out). Assuming that the solenoid appears to be actuating the lever (or however it's set up- sorry, I'm only familiar with A-type) properly you can pretty well assume t'aint the solenoid. If you listen carefully at low speed you may be able to hear the solenoid going in and out when you're driving too. As far as oil, top it up to the level of the filler plug on the left side of the case - make sure your pipe that you're filling with doesn't seal the hole or you won't know when you've reached that and end up spilling gear oil on the garage floor. My experience with gear lube is the synthetic (Redline MT90) shifts nicely but is a lot thinner and can get past seals in a hurry. Good luck. Pete


[/ QUOTE ]