Michael Peel, 47, punched the 17-year-old twice in the mouth while his son Rhys Peel, 25, gave him encouragement.
Newcastle Crown Court heard the men targeted the teen, who lived in supported accommodation and was "vulnerable" because they thought he was responsible for causing damage to a car.
Prosecutor Paul Cross told the court Peel Jnr had gone to the victim's door and asked if he could help him with a "two-man job" moving car parts.
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When the teen agreed to help he was taken to a car, which Michael Peel was driving.
The court heard all three men got into the vehicle, with the teenager in the back.
Mr Cross said: "He was driven to a small car park in South Shields where Peel Snr got him by the coat and accused him of damaging a vehicle.
"He said he didn't know what they were talking about but he punched him twice in the mouth, causing a burst top lip.
"The complainant admitted the damage because he was so frightened and didn't want to suffer further violence.
"Rhys Peel shouted further encouragement, saying the complainant had stolen from the vehicle.
"They took him back to his supported accommodation."
The victim said in an impact statement he was "frightened for his life" and nothing like that had happened to him before.
Mr Cross said the victim "believed they would come back and get him" and left him "always looking over his shoulder".
Peel Snr, of Turner Avenue, South Shields and Peel Jnr, of Copley Avenue, South Shields, both admitted assault.
Mr Recorder Ian Mullarkey told the men: "He was terrified and admitted to doing something he said he didn't do because he was so frightened you would strike him again as you had hold of him."
The judge said the dad and son "threatened to do worse" to the teen unless he confessed to what they claimed he had done and the offence involved a "significant degree of planning".
Peel Snr was sentenced to 12 months imprisonment, suspended for 18 months, with 180 hours unpaid work and rehabilitation requirements.
Peen Jnr was sentenced to 12 months imprisonment, suspended for 18 months, with 140 hours unpaid work and rehabilitation requirements.
Gavin Doig, defending Peel Snr said the violence was "spontaneous" and added: "He has expressed heartfelt remorse.
"That remorse is very much not for the position he finds himself in and the risk he has placed himself at but for the harm he caused to the victim.
"He feels particular shame for having involved his son."
Nicholas Lane, defending Peel Jnr, said the offence was almost two years ago and added: "He is remorseful that he allowed himself to be involved in this incident.
"It is not a case where he used any violence himself, he simply encouraged his father."
The court heard both men have stayed out of trouble since, have good work records and are assessed to pose a low future risk.
Both were given a five year restraining order.