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MG MGB Technical - Is my OD engaged

I've been in the process of swapping an OD tranny into my '69 B-GT. I believe the overdrive is from a '72. Just got everything in last night but decided to wait for daylight for a test drive. When I had the tranny out I changed the front seal and screen filter on the O/D unit but didn't disassemble things too far. I noticed when pushing (in neutral of course, e-brake off) the car into the garage that it didn't push very easily, it felt like there was some resistance.

The gearbox has been sitting for awhile so maybe it just needs some "waking up". But I'm also concerned that the OD might be stuck engaged. And from what I read I don't want to reverse out of the driveway if that is the case.

So my question is how do I check to see if it is engaged?

I may just have someone shove me out of the driveway and get pointed straight forward to test the system out unless there is a simple under the car test.


thanks

-Bill
Bill Mertz

the overdrive cannot be in when the car is not moving as it is powered by oil when the gearbox is turning,
da wright

Thanks for the response. I was under the impression that a malfunctioning OD could get stuck in the engaged position, as I had read in the archives of people saying not to put the vehicle in reverse if the OD is stuck engaged.

-Bill
Bill Mertz

i know it wrong but my od works in all gears,and work fine, just don't drive it hard in 1st 2nd,and it will be ok, the od unit is a small clutch that run in oil ,it's not strong enough to stand hard driving in low gears,that's why they have isolator switchs so it will work in reverse 1st 2nd,
all the best
dave
da wright

will not work in 1st 2nd reverse sorry forgot the


[ not ]
da wright

Bill - Don't worry about trying to reverse with the O/D engaged. Just let the clutch out slowly - if the car starts moving, the O/D is not engaged. If it makes a sound like a ratchet wrench being turned backward rapidly, push push the clutch and get someone to push you out of the garage. A single momentary engagement of the clutch while in reverse with the O/D engaged will not harm the O/D (I have inadvertently done that several years ago and th eO/D is still working fine. Cheers - Dave
David DuBois

Thanks guys,

I summoned up the courage to roll backwards out of the garage and give it a go. Went for a brief drive and it appears that the OD is engaging as it should in 3rd and 4th. So I guess it isn't stuck engaged after all.

-Bill
Bill Mertz

A bit late now, but you can test it by jacking both wheels off the floor (take obvious precautions), and "driving" the car in 3rd + 4th.
Holding the rpm steady (2000 will do), you will see the speedo jump up when it engages, and down when it disengages using the control switch.
Martin Layton

Yeah I thought about doing that, but I just kept thinking about my MG crashing into the back wall of my garage. Either way thanks for the heads up.

Now I'm breaking this thing in and every little squeak and rattle is making me cringe. I'm extremely nervous that this used unit will take a crap.

Yesterday I even had an unexplained squeaking noise that developed at low speed after 10 minutes of driving.

hopefully it will work out.

-Bill
Bill Mertz

This thread was discussed between 24/08/2008 and 25/08/2008

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