Need help with my 4+3 tranny

[my_85_vette]

Hi .. i have an 85 coupe with a 4+3 tranny.

The oil pan is leaking and i need to replace the gasket. this is a pretty stupid question. how do i check the oil level?

an other question .. does anyone know what causes this?
when i hold the throttle steady in any gear .. the car seems to play on the play on the tranny gear. the car jerks forward and back and i'm not sure why it does this. Can anyone help me out here.

Thanks
Luc

[Aurora40]

I can't really answer the 2nd question, but it would help to know if your overdrive unit or your manual tranny part is leaking. The 4-speed part you check the oil level via the fill plug. It should be full to the plug. However, IIRC it doesn't have an oil pan.

The overdrive unit has an oil pan, and this is how you drain it and replace the filter. It doesn't actually have a gasket from GM, you just RTV it. Mid America sells (or used to) a filter kit that includes a gasket, which is supposed to make it a lot easier. For some reason I think it has a dipstick just like a normal automatic, but it was 4 years ago when I sold my '87... You'd check the fluid level as well as fill it via the dipstick.

Each part takes a different kind of fluid, so make sure you know which you are working on.

[JonM]

You know its full when it starts returning out of the hole you fill it. As mentioned just use RTV no gasket is recomended. Change the filter, I got this off another site, if you have a CarQuest near you...As for your other question...change the fluid and filter...the 4+3 needs and wants to be clean...you don't know when it was clean last...also you said you had a leak, make sure its full all the time...then see if it does the same thing
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For those of us with the Doug Nash 4+3 transmission in our C4's, the source for replacement filters seemed to be pretty much limited to Mid America or Eckler's and the cost has been around $20 plus the freight charges. I bought one from Mid America last month and the whole thing came to damn near $30.00.

I had read somewhere that this filter (no longer stocked as a GM or AC Delco part) was the same filter as was used on the Ford "FMX" automatic tranny used on late 60's and early 70's 351W-equipped Cougars, Torinos and other mid-size sedans.

I found an FMX filter today at my shop that was sold by Carquest so I compared it to the one I bought from Mid America.
Both filters are the same dimensions, made from the same material, have the same molded depressions and curves, ad the stainless pan is the same. MAD doesn't supply the o-ring nor does Carquest so if that needs replacing, it will have to be purchased separately.

The MAD filter does come with a cork gasket, but black RTV sealant is really the preferred material to seal the pan to the rail. The Carquest filter comes with a gasket but it's for the FMX tranny which is a larger square-shaped pan.

The Carquest filter is about $8.00 list Fram also has a filter for the FMX and it should run about the same price at AutoZone or Shucks or Kragens.

the filter will be #85926

[ATL 84]

Thats true there is no dip stick you check it the same as the 4-speed. Auto Zone and O'Reilly's both sell the filter, but for a ford tranny.