But the current LibDem leader said that the party was now looking at it improving it's disciplinary systems.
In Scotland to back his European election candidates, Mr Cable denied that the inquiry into Lord Steel was a whitewash, and added: "He had made some comments at the child abuse inquiry that weren't clear, so there was a detailed inquiry by the Scottish party - as he's a member of the Scottish party - and there was nothing ultimately to answer."
Lord Steel, the first Presiding Officer of the Scottish Parliament, was suspended from the party after he told an independent child abuse inquiry that he had "assumed" abuse allegations against the late MP Sir Cyril Smith were true but "it had nothing to do with me". The Scottish Liberal Democrats investigation concluded that "there are no grounds for action" against Mr Steel.
Asked if he felt the internal process was sufficiently robust, Mr Cable said: "We have made a decision to improve our complaints process and that is due to come into effect, but the one we used is a proper disciplinary process and I'm satisfied it's been carried out properly."
The investigation resulted from a meeting the then-Liberal-Party-leader had with Smith in 1979 about claims he had abused boys at a Rochdale hostel in the 1960s. Police had previously investigated allegations about the abuse of teenagers at the Cambridge House hostel but no one was prosecuted.
Lord Steel said he had discussed the allegations with former Rochdale MP Smith after an article appeared in Private Eye magazine. At the child abuse inquiry, Lord Steel - who is now 81 - that "the matter had been investigated by police, no further action was taken and that was the end of the story".
However, during questioning by inquiry counsel Brian Altman QC, Lord Still suggested he had "assumed" the allegations were true.
Announcing the conclusion of the investigation into Lord Steel, leader of the Scottish Liberal Democrats, Willie Rennie MSP, said: "The Executive of the Scottish Liberal Democrats has determined, after careful consideration, that there are no grounds for action against David Steel.
"We take the issue of vigilance and safeguarding incredibly seriously, so it was important to investigate following the evidence that David Steel gave to the independent public inquiry.
"The clarifications that David Steel has provided to us state clearly that Cyril Smith did not confess to any criminality which is why he took no further action at the time."
Lord Steel added: "I believe in the highest standards of safeguarding for young and vulnerable people. As such, I voluntarily attended the IICSA hearing and offered open and honest answers, some of which have been erroneously reported and taken out of context.
"These inaccurate elements led some to question my own such commitment. Opinions and assumptions are not facts, and those expressed in some quarters have caused me great personal distress."