Sportomatic tranny question

cnavarro · 04-29-2005, 01:43 PM

Hey guys. I've now driven my '70 sporto for about 2500 mi and have swapped out the tranny fluid for synthetic royal purple which helped smooth out the shifts greatly. The only problem I still have is that after not driving the car for a few hours (say overnight), it grinds when shifting into reverse. After a block, it doesn't make a grind whatsoever when shifting back into any gear from neutral. Any suggestions? RPM is fairly low when cold, ~750 rpm and idles smoothly. The car has only 91k original miles.

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

Grady Clay · 04-29-2005, 01:49 PM

Charles,

It sounds like the clutch isn’t releasing completely when cold. The first order of business is to check the clutch adjustment.

Best,
Grady

cnavarro · 04-29-2005, 01:54 PM

I guess I need to read the haynes manual once it dries out (got soaked front to back) to check into the clutch adjustment. Any words from the wise?

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

B D · 04-29-2005, 02:15 PM

Sounds like there maybe a small leak, the reservoir is loosing pressure overnight I bet. It's probably a very slow leak and when the car is running it overcomes the leakage. Try letting it sit overnight and pull the line going in to the reservoir and you should here a pop or air moving if not you have a leak. Also I usually throw it in second before going in to reverse and then it goes in with ease. Try letting idle for a little longer and give it a rev to build pressure. I would replace all vacuum lines with new ones.

Fishcop · Fishcop's Garage

Charles, good advice from both Grady (always reliable

) and BD. In your case I'm leaning towards BD's description of slow vacuum loss. I had this problem for some time before I rebuilt my vacuum slave and got rid of the pin-hole leaks that it had. Basically I'd give the car a little bit of revs to build vacuum before selecting reverse. See if that helps, otherwise Grady has nailed it. If you need to adjust the clutch, it is pretty much impossible without droping the engine and gearbox, you just don't have the vision or room...

cnavarro · 05-02-2005, 04:48 AM

I guess i'll borrow the lift from the shop next door and check out the clutch, since no matter how long I let it idle, warm up, or rev, it still grinds a little. Theoretically, how long should it take to build vacuum? Currently I just park so that I don't need to use reverse, and I don't have any problems in that case. I did notive that the shifts from the modulator were a little too fast, so I slowed them down a little bit and it does feel smoother on decel shifting. I did notice that the linkage that goes to the wheel under the modulator is very, very loose and only when it makes contact with the actuator, does it snug up. I read the manual a few times, but I still don't fully grasp it's purpose. Everything is just a tad more complicated than my autostick beetle ever was :-)

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

Fishcop · Fishcop's Garage

Vacuum should build rapidly.

Definitely adjust all the throttle linkages over and under the engine. I too don't fully understand the system, but I was much happier once I took any play out of the ball and socket linkages.

Spaking of linkages, one other thought is the adjustment of the gear-shift linkages. You may be lucky to find that you only need to tweek the uni-joint in the tunnel.

cnavarro · 05-05-2005, 07:10 AM

Here's an update:

I've replaced all the vacuum lines. Even after sitting for a while, when I pull off one of the lines it makes a slight pop. Was thinking of tee'ing in a vacuum gauge to actually time the bleed off if you guys think it's useful to know.

I also checked the clutch freeplay while I had the car in the air and it seems to have sufficient clearance per the instructions in the owner's manual.

That said, it still grinds when going into reverse from neutral. I did try something different this morning when backing out- I put it in reverse before starting (taking it out of gear of course first) and it didnt' make any noise. On occasion, when going from reverse to L, it makes a slight clatter, nothing on order of what it makes going into reverse.

Any suggestions?

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

B D · 05-05-2005, 08:30 AM

Sounds like you've made some progress. The vaccum leak should be non-exsistent, I have pulled the hose to the reservoir after sitting for over a week and still get a nice pop. The vaccum builds up quickly so I think that's not the issue. I think it may be the clutch adjustment that is slightly off. Try going in to other gears before engaging reverse, it's common to have to do this in even new cars.

cnavarro · 05-05-2005, 10:43 AM

So far I have tried today parking it in reverse then going back into reverse from neutral when started and every time it has done so smoothly. I left one single line (the one from the carbs to the modulator) original, since the line and tees weren't working due to the angles. I think I am going to have a local place that makes custom hydraulic lines fab me up a similar piece. If it were that the clutch was not adjusted properly, would it be that it's too tight (not disengaging?). It seems that it has more than enough clearance, although I didn't physially put a measure to it.

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

cnavarro · 06:08 AM

New question. I usually don't have the wife in the car, so I drive it pretty hard. Last friday we went out to dinner and I was driving very gently, and when shifting from D to D3 and from D3 to D4, it seems to spit the shifter out of the gear. If I rev it over 4k rpm or give it a WOT condition, it shifts smoothly and doesn't exhibit this problem.

Wayne 962 · Wayne 962's Garage

If reverse grinds, it's a sign that your clutch is not releasing all of the way. If it grinds all the time, then you're wearing your 1-5 synchros heavily when you shift, and you will have to replace them soon.

Unfortunately, your popping out of gear problem is also a sign of worn synchros, so it may have happened that they wore...

-Wayne

cnavarro · 05-09-2005, 07:52 AM

It hasn't made a peep since I replaced the vacuum lines. It doesn't literally pop out of gear by itself, just it seems like it's helping me out of that gear once I pull it out of that gear, but only when accelerating and shifting like granny. Would it not accentuate the problem and make it more pronounced when I am driving it really hard and shifting rapidly?