Lyndwood

I want to run my trans through the gears to verify my valve body mods before taking it on the road so my question is whats the best way to run the car on jack stands. here's what I was going to do.
jack the rear of the car up and support the frame off the ground. remove the rear wheels ,then put supports (small jack stands or 4x4's) under each rear trailing arm keeping the half shafts some what level. then fire the car and run it through the gears.
Just wondering what you guys do? I certainly don't want to run through the gears with the trailing arms hanging low and the half shafts possibly binding due to extreme angles.

doorgunner

1. You may want to leave the rear wheels on so the A/T can have some torque to cause it to shift.....put large wedges at the front wheels for safety to keep the car from accidentally moving off the stands(It's up to you).

Also.....the car probably/maybe will shift through all the gears, but not at the correct rpm because the A/T isn't moving a 3,000 lb. car down the street.

Try shifting the car manually through the forward gears....it may take a while to work all the air bubbles out of the valve body.


And......always depress the brake pedal VERY gently to stop the fast-moving wheels or half shafts from rotating in order to prevent damage to the calipers from a sudden brake lock-up while the car is on stands.

Wait for expert members to add more advice.

Lyndwood

good advise on the wheels, I modified the valve body with a shift kit so i want to make sure all is ok before actually taking it out on the road. trans worked fine before, guess I'm questioning my work...I'd rather find a "shift" problem now while its in the garage rather then out on the road. I should be able to manually shift the car with the kit I have installed (transgo shift kit), never did one so I want to make sure I did it right.

derekderek

lower the car as much as possible on the trailing arms. the straighter the half shafts the happier they are. you also want the car up high enough that if a jack stand pops out, the wheel cant hit the ground and send the car off on it's merry way while in your garage... I changed my mind. just drive it up and down the street in your neighborhood-assuming brakes work...

CanadaGrant

If you just leave your trailing arms hanging there is a very good chance you are going to get binding of the universal joints on the half shafts. It will shake and produce noise and is hard on the rear universal parts. I've done it before and never will again...

revitup

You know that little voice in your head that tells you when something seems a bit dangerous and probably is not smart thing to do? It should be telling you something about that plan and you should probably be listening to it. I would be.

fede

I see that you have a '74... Did you install a Transgo 1&2 on a TH400 by any chance?

A88FXRS

my 02 cents is that I will never try that again aftert seeing another club members car shake rattle and tried to roll thru the wall.

theandies

Just drive it. It's better than causing an accident in your garage and damaging your car or worse getting hurt. You should know pretty soon if there is a problem and you can turn around and get home.
I'm a safety nut so I always think about the worst case and act accordingly. There are just too many worst cases in what you are proposing for me.

Torqued Off

I think running the car on jack stands is dangerous. It is an accident waiting to happen.

Lyndwood

yes, I did the transgo (SK400 1&2) shift kit and modified the valve body for crisper shifts.

fede

I have the same kit pending to be installed after changing the bands.

Do you mind sharing your setup in terms of the feed holes sizes and springs on the accumulator valve?

Lyndwood

Geez.... your really asking me to remember what i did???? aside from the kit instructions I think I removed the spring, opened some holes and plugged another? thats why I want to run it before i take it out I did it over a year and a half ago. If I messed up something I can just jack up the car ,drop the pan and put another valve body in (stock).

Aerovette

It's either going to work or not work. What do you gain by running it off the ground?

doorgunner

In case you DO run the car on jackstands…..If you feel the SLIGHTEST VIBRATION in the drivetrain...………….

Stop the test immediately before it/the car vibrates off the jackstands (which is why members advised that blocks be placed undr the frame to prevent the wheels from getting traction if something goes wrong).

Lyndwood

I decided to just try it on the ground, I live at the end of a dead end street so I have no traffic. the thought was if the trans did not seem to shift correctly or at all I could leave the car up in the air let it cool down and drop the pan to see whats wrong. also because the trans was drained dry during the modification so other than the converter oil and the 4.5 quarts I put in the pan for initial start up i still have to burp the system and make sure its full, in the past with other cars (non IRS) i'd jack them up on the rear axle tubes and run through the gears to circulate the fluid.