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65 4-Speed Questions
Posted by: JohnVan ()
Date: November 04, 2018 08:27PM

I'm working on a 65 Corsa with an unknown history. For that reason I drained the transmission to look for nasty oil, grit, metal pieces etc. So far it looks good. The oil did not appear to be contaminated, and it appeared to at least be Gear Oil, althought I could not tell if it was actually GL-4. I used an inspection camera and got a fair look at the gears. Nothing unduly worn or chipped. Synchros look a bit worn but not broken.

My first question is this: there isn't a traditional "drain" plug on this transmission. I did remove the side cover and pulled the back up light switch and the lowest ball-detent access plug. There is however a welch plug at the very bottom near the shifter lever. Do you think it is necessary to drill this out to finish emptying the transmission? I went ahead an ordered a new welch plug just in case.

Second question: the transmission has a large, well marked filler opening in the side case. I understand one fills this to the opening. The Differential has a square headed plug. Is the filling senerio to first fill the transmission and then top off the differential? I can always check the level at the dipstick, but the manual does not say much other than fill it...

Thanks for your advice!

John Van Valkenburgh
Knightdale NC
'65 Corsa 140

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Re: 65 4-Speed Questions
Posted by: MattNall ()
Date: November 04, 2018 08:31PM

No drain in the later ones.

Correct on filing... they equalize super slow...

Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
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Re: 65 4-Speed Questions
Posted by: Timothy Shortle ()
Date: November 05, 2018 07:09AM

I have never and never heard of someone removing the welsh plug just to change out the gear oil.
I have heard of people using a suction pump thru the filler plug to remove a good portion of the oil.
Before drilling out the plug if I really wanted all the oil out I would remove the unit from the car and
drain it that way (side and front covers off, etc.). YMMV.

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Re: 65 4-Speed Questions
Posted by: Wagon Master ()
Date: November 05, 2018 07:43AM

BUT....While the tran. is out, if you do remove the welsh plug, the shift shaft bore is the proper size to run in a 3/8" NPT tap. Shift trans. into 2nd or 4th to get a lil extra depth clearance. Eureka! A transaxle drain for future use!
Pity there isn't enough room to do this in the car with a standard issue tap.

'29 Ford Model A Tudor
'61 700 Lakewood 110 4 speed
'69 Monza Convert. 140 Auto.
'70 Dodge Challenger R/T 440 4 speed

Been aircooled since 1973
Northwest Ohio

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Re: 65 4-Speed Questions
Posted by: Early Guy ()
Date: November 05, 2018 09:40AM

John if your referring to the welch plugs at the bottom of the trans don't remove either of them they retain the reverse detent and spring very difficult if not impossible to replace while in the car even on the bench Iv'e found the only way is with all the guts out of the trans you can insert a screwdriver in the spring and wind it down with a needle nose to relieve tension enough to install the welch plug.

Ray Johnson Villa Park IL 63 Spyder Conv. 140 EFI

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Re: 65 4-Speed Questions
Posted by: jjohnsonjo ()
Date: November 05, 2018 10:11AM

You can take a magnetic pick tool and see if there are any metal particles in what's left in the bottom. After mine sat for a long time, I sucked it out and put some cheap stuff in drove a little then sucked that out. I tried 2 different synthetics with mixed results. Then I went with Brad Penn Classic. That is the best oil I have ever had in it.


65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
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2016 KIA Sorento SXL Turbo


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Re: 65 4-Speed Questions
Posted by: Wagon Master ()
Date: November 05, 2018 10:11AM

John and all others, I'm referring to the he welsh plug at the opposite end of the shift shaft. Where the earlier versions had drain plugs installed.

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