Speedometer O-Ring Replacements - Tips Needed

[moritz55]

Hi everyone .. I have a small leak that causes a nusance drip at my Speedo cable housing attached to my transmission. So before it gets worse and I store the car for winter - I'm planning to replace both the small internal and larger outer O-Rings. I ordered them from MSA. I have an 82-83 280zx 5sp manual transmission with my '73 speedo cable. Both O-Rings are commom from '70 thru '86 for manual transmissions, so I assume no serious issue with seating the O-rings properly.

I have read thru this link and understand what to look for in the O-ring replacement of the pinion: http://www.classiczcars.com/forums/showthread.php?t=31338&highlight=Speedometer+Cable+Leak

==> I'm searching for any helpful tips on how to change the transmission oil as I'll be jacking the car up in my garage. I'll get a small hand pump for adding it, and I know the car must be level. The drain plug is in the bottom - so I'll drain it before pulling the speedo cable off. I'll get 2 Qts of gear oil to assure I have enough, most likely Valvoline gear 75W90 oil.

Any other advice is welcome..

Many thanks in advance ...

Edited October 14, 2009 by moritz55

[DeesZ]

FWIW, assure that you get the 'fill' plug loose prior to removing the drain plug.

[moritz55]

Thanks .. and will do DeesZ !

[esprist]

Hi everyone .. I have a small leak that causes a nusance drip at my Speedo cable housing attached to my transmission. So before it gets worse and I store the car for winter - I'm planning to replace both the small internal and larger outer O-Rings. I ordered them from MSA. I have an 82-83 280zx 5sp manual transmission with my '73 speedo cable. Both O-Rings are commom from '70 thru '86 for manual transmissions, so I assume no serious issue with seating the O-rings properly.

I have read thru this link and understand what to look for in the O-ring replacement of the pinion: http://www.classiczcars.com/forums/showthread.php?t=31338&highlight=Speedometer+Cable+Leak

==> I'm searching for any helpful tips on how to change the transmission oil as I'll be jacking the car up in my garage. I'll get a small hand pump for adding it, and I know the car must be level. The drain plug is in the bottom - so I'll drain it before pulling the speedo cable off. I'll get 2 Qts of gear oil to assure I have enough, most likely Valvoline gear 75W90 oil.

Any other advice is welcome..

Many thanks in advance ...

-------------------------------------------------------------

OK. I have done this many times, so I could help you here little bit.

First, you do not have to drain the fluid as long as you back your car up on the ramp(so the car is tilted toward front). When you remove the speedo cable and the cog, it will leak little, but not much. Then, dig out the seal inside the cog, and replace the outer seal(any hardware shop or auto parts shop will have one). Done. I have a picture of the parts here.

Esprist

www.jdm-car-parts.com

[moritz55]

This is very helpful Esprist ! I had my transmission fluid changed when I 1st bought the car - only 6000 miles ago (4yrs ago). I know it's still fine... My assumption was I had to drain the gear oil. I'll go with this approach and assume what little oil leaks out from when the speedo cable and cog is removed is not enough to worry about so as to not have to add any.

Edited October 15, 2009 by moritz55

[esprist]

This is very helpful Esprist ! I had my transmission fluid changed when I 1st bought the car - only 6000 miles ago (4yrs ago). I know it's still fine... My assumption was I had to drain the gear oil. I'll go with this approach and assume what little oil leaks out from when the speedo cable and cog is removed is not enough to worry about and not ave to add much back in.

By the way, try to save the roll pin that holds the cog in place. That one is metric and very very hard to get here in U. S. I tried every hardware stores around here in L.A. No luck. So I had it shipped from Japan.(Very cheap, but the time while I was waiting just for that......)

Esprist

www.jdm-car-parts.com

Edited October 18, 2009 by esprist

[moritz55]

Well yesterday I completed the O-ring replacement and ended up draining the transmission. It went well, hardest part was getting the 3/4" Fill Plug loose and most of the time was spent jacking my car up and getting it level. I took it out - drove it hard for 20+ miles and guess what .. no leaks. Thanks for all the advice...

More Observations However?

- Since I have a 81/82 280zx 5spd, I expected to drain slightly under 2liters(or around US 2quarts). FSM spec on my 280zx transmission is 2 liters .. but I knew I'd drain something less.

==> Well I actually drained ~76-77ounces! This is 2-1/4 liters or 2-3/8 quarts. I did go and buy another quart to be safe - figured I made errors calculating what I needed to fill it back up.

==> Well, filled it up till the oil starts to drip from the fill hole and guess what - it took 61-62 ounces !! This is ~1.8 liters or ~1.9 quarts, just what I expected since I knew I'd not get it all out by draining it .... now I feel better!

Question?

- While doing the job I noticed Oil Splattered around the transmission housing of the car in the vicinity of the shifter lever(rear). I cleaned it all up and dried it out. I figured it was from ~3 weeks ago when my front end was jacked up for about 1week while I replaced all the front end bushings and added Stock Height coil springs, which raised my car 1" back to stock height. Now my car sits level since the rear is at stock height.

==> So my question is with the transmission previously being Over Filled by almost 12-13 ounces (~1/2 quart too much), would jacking the front up and letting it sit for a week cause the oil to leak out the back near the shifter?

Note: I have been driving the car with the extra 12-13 ounces in the transmission for 4years and never had leaks.

So ... Right now there are no leaks after 24hrs and I'll watch this.

Any advice and insight is welcome.

Many thanks..

Edited October 18, 2009 by moritz55

[sblake01]

So my question is with the transmission previously being Over Filled by almost 12-13 ounces (~1/2 quart too much), would jacking the front up and letting it sit for a week cause the oil to leak out the back near the shifter?

If it was angled enough for the excess oil to reach that area of the trans, it would leak.

[moritz55]

Well it's been 4 days since I replaced the O-rings on the speedo pinion and changed the oil in the transmission filling it to proper level. I had 1 drip 2 days after under the shifter selector lever. It looked like pretty black & old oil so I think it was residual from the inital leak I referenced in post #7.

I'll continue to watch this - but I think I'm in good shape.

Thanks all for the advice and insight...

Edited October 21, 2009 by moritz55