Installing Manual Transmission Drain Plug

[MICAH1]

In the process of replacing the manual transmission oil, and thinking of drilling a drain hole in what I see to be an (according to a extra trans I have) appropriate location on the bottom pan. I plan to weld a low profile, but not flat nut on the inside of the pan over a standard size drain opening with a half inch bolt and plastic washer. Has anyone done this???

[trlmr]

Keep in mind that you will leave oil and contaminants in the case up to the level of the top of the nut you weld on the inside of the pan. Half inch might be overkill and a smaller shouldered bolt might work better or even a actual drain plug from a chevy or ford with a newer o-ring style gasket. If you are a good welder it might work better to weld the nut to the outside of the pan, but your way will work

[MICAH1]

Originally Posted by trlmr Keep in mind that you will leave oil and contaminants in the case up to the level of the top of the nut you weld on the inside of the pan.

Good point about oil and contaminants level after oil change. I considered the best position to install the drain plug, but had not thought about the residue remaining in the pan due to the level created from the weld nut on the inside of the pan. Nut will be welded on the outside. Very good point indeed.

[RallyBob]

I've added a drain plug to the lowest rear corner on manual tranny pans before. The engine tilts backwards and to the side so in order to get everything out you need to choose a corner!

[paul.catherine]

I am new to this forum - and new to Opels - just got a 73 GT! ...and I presume that the commonest way to drain the manual tranny is to open up the tranny pan? I guess I need to order a gasket first too? (or is form-a-gasket type stuff an option?)...

I also presume the plug on the tranny's left side is the fill plug, and to fill up to there??

Thanks again!

Best,
Paul S.
Flagstaff, AZ

[BQS4]

Paul;
Watch out when you remove the pan, as there's a spring and a check ball on the outer edge that needs to be replaced when re-installing the pan. Save yourself a little trouble in the long run, since you'll have the pan off, install some sort of drain plug assembly to ease this service in the future. Just an idea.

[hrcollinsjr]

Originally Posted by paul.catherine I also presume the plug on the tranny's left side is the fill plug, and to fill up to there? Paul S. Flagstaff, AZ

Paul, the engine and trans are tilted in the GT for carb/hood clearance sooo fill the tranny to within 1/2" of the fill hole you've indicated.

A lot of these questions have been answered in previous threads if you will do a little searching. Not every question has been asked and answered but most probably have. Welcome to the group.

Harold

[MICAH1]

I installed the drain plug back in May but had not attached a photo of the enhancement. Purchase a low profile 1/2 inch drain plug set, drilled the hole, and have the bolt weld to the far corner of the pan as shown in the picture.

[Dennis Texas]

Originally Posted by BQS4 Paul; Watch out when you remove the pan, as there's a spring and a check ball on the outer edge that needs to be replaced when re-installing the pan. .

definetly watch for those parts you may not even see them fall out, expecially the ball, best to get a good sized pan and put under to sort it out after draining.

[paul.catherine]

Originally Posted by Dennis Texas definetly watch for those parts you may not even see them fall out, expecially the ball, best to get a good sized pan and put under to sort it out after draining.

Thanks everyone! I do think I'll put a drain plug in.... and pre-order gaskets etc.... I guess I should look for the thread (I am sure there exists one or I will start it... LOL) ... how also to drain and refill the rear end... I did find out how to open the bottom bolt there (not sure if that will drop any parts ), but where/how to refill, another matter...

I also read somewhere that replacing various seals in the area is also not a bad "added" idea, but that looks a much ... "bigger job"....

Again, Many thanks!

[RallyBob]

Originally Posted by paul.catherine I did find out how to open the bottom bolt there (not sure if that will drop any parts ), but where/how to refill, another matter... !

If you remove the bottom bolt on the differential cover, that'll drain the gear oil out...no fear of losing any parts though!

As far as the fill plug, it's about halfway up the diff cover, on the righthand side. In this pic you can see the plug's threaded hole pretty clearly. On most cars it's an internal hex drive (allen-key), but some older cars had a 13 mm plug.

Ignore all the stuff welded onto the diff cover!

[paul.catherine]

Originally Posted by RallyBob If you remove the bottom bolt on the differential cover, that'll drain the gear oil out...no fear of losing any parts though! As far as the fill plug, it's about halfway up the diff cover, on the righthand side. In this pic you can see the plug's threaded hole pretty clearly. On most cars it's an internal hex drive (allen-key), but some older cars had a 13 mm plug. Ignore all the stuff welded onto the diff cover!

THANKS SO MUCH!

I tried to find this info in the manual that came with the car, a maroon-looking chassis service manual, and found little help in it; got 'closer' with the iopel GT Source catalogs I just printed off a CD they just sent me... and it looks like I might wanna send a check to La Crescenta CA with a whole lotta $2 orders for various tech tips!

I do want to redo all fluids and clean the undercarriage - and then see what needs seals etc etc etc... I did read a few excellent threads on being careful to not let the tranny go dry....

Cheers,
Paul

[paul.catherine]

Originally Posted by RallyBob If you remove the bottom bolt on the differential Ignore all the stuff welded onto the diff cover!

BTW - that's some interesting stuff welded on the back... now I am very curious

Cheers, P

[BQS4]

Originally Posted by paul.catherine BTW - that's some interesting stuff welded on the back... now I am very curious Cheers, P

It's Bob's handmade/engineered WATTS linkage

[paul.catherine]

ahhhh.... I see:

Watt's linkage - Wikipedia, the free encyclopedia

sweet! and love the welds!

Paul

[kwilford]

Originally Posted by paul.catherine ahhhh.... I see: sweet! and love the welds! Paul

Bob's work is best experienced first hand, but for a little fabrication porn:
Bobpics09 005 on Flickr - Photo Sharing!
And look at some of his other work in the other albums

[paul.catherine]

Originally Posted by Dennis Texas definetly watch for those parts you may not even see them fall out, expecially the ball, best to get a good sized pan and put under to sort it out after draining.

Hi all - well I got around to opening up the rear end and the tranny (4sp man) last night to drain both and regasket, clean...

And when I opened (carefully) the tranny pan I DID catch a spring, but I saw no ball drop out... Did I miss something? If stuck in the tranny, where might I look?

And morevover, where do I stuff the spring (and ball if I find it LOL) back in when I am ready to put the pan back on? Which may include putting my own drain on it to avert some of all this fun LOL...

Many thanks!
Paul
73 Yellow GT
Flagstaff AZ

[paul.catherine]

Never mind

I found the little ball still imbedded in its hole in the starboard rail (edge) of the tranny case... even found the little tab in the oil... so all is good!

...and now I also know where the ball and spring go back, after I weld on an exterior drain nut....

Thanks,
Paul
73 Yellow GT
Flagstaff AZ