I have a 73 GS, full weight, running a TA413 and the brakes are pretty marginal, especially when first driving car until it fully warms up. Brakes were fully serviced last year, front disc and rear drum and have about 1300 miles on them. I'm considering upgrading but see differing comments on what is best from a cost/benefit standpoint and also wondering if there may be fitment issues. I'm running 15×7 front and 15×10 rear. Any thoughts?
I ran a 413 and had about 14 inches. My Drum brakes were fine. Mine was installed 4* advanced @109. Wonder if front disc makes much of a difference.
Don't have a vacuum gauge...will have to get one and check. I haven't seen any complaints with vacuum with a 413...factory front discs are pretty small compared to discs today.
Here's an experiment to try. I had a big KB cam in an engine that was marginal on brakes at idle. When slowing down, I would gear down into second to cause some vacuum to build up and then it would stop great. If gearing down helps, you have a vacuum issue.