'71 pulls on acceleration

[semicrazy46]

Hi, i have a question I have yet to answer myself.
i have a 71 f100 4x2 . it started doing something wierd about 2 weeks ago.
what it does, when you come to a stop , set for a few seconds(stop light ) when you release the brakes and accelerate, it starts to pull to the left. at about 45 mph it will jerk back straight.
what i thought at first was left shoes sticking. so i went through the brake system, new everything except drums, they're fine.it still does it. just not as bad.
now i have noticed it does when you accelerate whether you use the brakes or not. i cant find anything on the suspension that looks like it is moving. it has all new bushing in the front. so i dont think that is the problem.the only thing on the brakes i hve not cleaned or replaced is the porportioning valve.
any idea?

[fordman]

king pins? check the rag joint between the column and steering box.

[ezernut9mm]

brake hoses new? radius arm bushings?

[willowbilly3]

I would be looking at the rear leaf springs. It sounds like a broken center bolt, maybe a bad bushing or something along those lines.

[semicrazy46]

i replaced all the bushings inthe front end last spring, the king pins are in good shape,replaced all the brake hoses, wheel cylinders etc. it really felt like a brake sticking. replaced the steering rag about 3 weeks ago.
the rear springs i looked at today while replaceing the rear brake hose, and they dont show any movement that i can find, but a broken spring pin might be it.i had not thought of that yet. i have been rebuilding this truck for the last 2 years. the only thing underneath i have left are the front springs , shocks etc. it sags on the left,but the rear sets good.

[fomocoguy]

You say it pulls to the left; have you put on weight over the holidays???

[kentdaryl]

I had a front brake hose go bad on me, it actually leaked between the inner hose and outer shielding. I couldn't tell any different when I stopped, but the fluid acted like a tourniqet, pinching the hose. After driving a few miles the pressure in the hose would bleed off enough to allow the caliper to relax.
PS - The hose looked just fine from the outside.

[semicrazy46]

that is what i thought at first. i have replaced all the brake hoses except the right front. i just replaced all the wheel cyclinders , shoes, all hoses except right front. this last week. didnt replace the drums , but they are in good shape and dont think that would cause it.
oh and to answer the other dudes question about gaining weight. MOre than likely, but i doubt it has much to do with this either or the truck saging on the left side. LOL