Question on my tranny

[Nelson Ramos]

1986 GN Stock..
Car has 22000 miles. Transmission shift perfect no slipping no leaks. The only problem I'm having is when I put the car from park or neutral to drive I get a hard Bang? Universal joints are new. Sometimes the car turns off? Once the car is in Drive the car idles and shifts perfect the car has recently been tuned correctly.

 

[INEEDAGN]

Does it do this into reverse also or only into drive? Hot or cold only or whenever?

Like everyone else, I'm going to recommend a pressure gauge to check pressure at idle. If it's working fine otherwise, it's unlikely to be a pressure problem but it's possible in theory that the min pressure is being held higher than it should by a sticking valve or slide etc. and still allowing somewhat normal operation otherwise.

 

[INEEDAGN]

Also, has it always done this or is this recent development? BR calibrations did not get the "feed/bleed" fwd drum and piston setup like all others did starting in 86. They are stiffer than a lot of other calibrations but still shouldn't "bang" or kill the car. Converter problem is also possible.

 

[Nelson Ramos]

Also, has it always done this or is this recent development? BR calibrations did not get the "feed/bleed" fwd drum and piston setup like all others did starting in 86. They are stiffer than a lot of other calibrations but still shouldn't "bang" or kill the car. Converter problem is also possible.

It dident do it before restoring the car. After a few years of restoration it started. I'm going to check the pressure on Tuesday thanks for your help. Merry Christmas

 

[Nelson Ramos]

Does it do this into reverse also or only into drive? Hot or cold only or whenever?

Like everyone else, I'm going to recommend a pressure gauge to check pressure at idle. If it's working fine otherwise, it's unlikely to be a pressure problem but it's possible in theory that the min pressure is being held higher than it should by a sticking valve or slide etc. and still allowing somewhat normal operation otherwise.

Hot and cold and only in drive.

 

[INEEDAGN]

If the car has been restored, has anyone been in the trans for any reason?

 

[Nelson Ramos]

If the car has been restored, has anyone been in the trans for any reason?

Well we removed the pan and replaced oil and filter. No inferna

 

[1KWIKSIX]

How about rear end gear (differential ) back lash ?
If it's too much, wouldn't excessive back lash clearance be a possible contributor to the hard "bang" going from N to D?

 

[Nelson Ramos]

How about rear end gear (differential ) back lash ?
If it's too much, wouldn't excessive back lash clearance be a possible contributor to the hard "bang" going from N to D?

It's on the lift now. With a pressure test . What should it come in as?

 

[INEEDAGN]

I'd be focused on idle pressure for this test but it wouldn't hurt to check the max pressure while you're at it. Stock br is probably 60-70 at idle I don't remember. Also by pulling on the tv cable it should return to the approx same number every time the cable is released. If it's not doing that consistently then the tv valve is probably hanging up. Stock tv valve return spring is very light and doesn't take much to hang it up and keep it from minimum. This would likely affect the light throttle shift points but it's possible in theory to hit a sweet spot where it works ok but not "correctly".

Is the idle speed too high?

 

[INEEDAGN]

Come up with anything?

 

[Nelson Ramos]

Come up with anything?

Tranny was fine it turned out to be the tuning.. idle like you said. Thank you for your help.
Nelson Ramos
Happy New Year GN family. ✌