when to rebuild a manual transmission?? signs

[olaf]

Greetings everyone.
I have a few issues with my 4 speed manual transmission for my 1970 280 SL.
It is extremely hard to get into first and second gear. even if i rev it up a little it is still hard to find the gear. I end up moving the car forward a little in 3rd to then slip it into first.
When accelerating slow it can be hard to shift, but if i really step on the throttle and rev it up it will shift easier when in motion.
also. when in 1st and second gear letting of the throttle the engine whines. must be the transmission i think. I dont know how many miles are on it but the motor was said to be rebuilt not long ago.
The whole drive train from transmission and back seems loose with alot of play to me. I would really like to remove the whole rear end and rebuild also.

Where should I start?  any input would be greatly appreciated.

[JimVillers]

Olaf .... Are you using ATF as your transmission fluid (as specified by the manual). It sounds like you have 90W gear lube in the transmission.

[ja17]

Hello Olaf,

Does the speedometer needle bounce when you accelerate and decelerate? If so the whole problem can be the a loose slotted nut on the transmission output flange.

[jeffc280sl]

The easiest thing to check is the fluid and fluid level.  Next comes the shifter bushings.  Have you looked at the shifter bushings?  If you have looked at these areas I'd start next with Joe's suggestion.  While it not exactly easy to check, the output flange nut can be checked with the transmission still on the car.  You need to drop the drive shaft.  To check just about anything else the trans has to come out.

[olaf]

Thank you gentlemen.
I am shocked and sad to tell you what i found out today.
I purchased this car a few months ago and was told and shown recites for the motor rebuild.
so like you suggested first. check the oil.
I open the bottom plug and there is not a single drop of oil in the transmission.I am starring up on bone dry gears.
Nothing. I felt so bad that all this time I had been driving with no oil in there. and god knows how long the previous owner did. I have had many Harley motorcycles before and once a mechanic forgot to refill the oil in the transmission and i remember that when it got hot it started whining just like this one too.
I am just so surprised that the whole transmission has not locked it self up.
A few weeks ago i changed the bushings so they are new and it feels tight. It was just alittle hard to get into gear. NOW I KNOW WHY

So for anyone that buys a used car.
check for the unexpected before you start driving. you will never know.

Now that i opened the bottom plug. Where do i refill with new oil. i will try to flush it a few times and see what happens.
I found an allan wrench screw on the side of the transmission and then a bolt next to it. is this the level screw and the filler??
Tried looking it up in the service manual but it shows very little on the manual. i found out that it holds 1.4 liters or automatic transmission fluid.

I am very exited to see what comes out of this experience. 

[Naj ✝︎]

The filler/level plug is on the right hand side of the box. Uses same 14mm hex key as drain plug, but has tapered threads and no sealing washer.

naj

[ja17]

Hello Olaf,
Yes, the 14mm Allen only, do not disturb the bolt and screw.  Automatic transmission fluid is what is called for as lubricant.

I always check the wheel lugs when I buy a used car !   I had a wheel fall off a car I bought one time ! 

[olaf]

I think the transmission is saved. i flushed it twice and it seems to work well now.
what a scare.
thank you all.