After checking the spokes, review the rear rotor.
A warped rear rotor could cause unusual braking.
A warped rotor sometimes does not give any response to light braking causing the operator to increase pressure. Basically the operator is left with an all or none situation.
A rotor can become warped by failing to remove a rotor lock or banging the rotor against a wall or floor when a wheel is dropped for service.

 

Check your swing arm bearings, pivot bolt and wheel bearings. Also checkfront wheel bearings and the tightness on your neck bearings. I've seen some nasty neck bearings and races when people neither grease or adjust the them for years. Wheel bearings should be checked, greased or replaced if necessary when new tires are mounted.


Don't forget to report back.

 

Also you need to flush the brake lines and put in new brake fluid....

if it was never done you may need new brake lines also..

 

REALLY???? 96K posts and all you have to offer is flush the brake lines to a rear wheel wobble issue????

OP, start simple, start cheap. Pay attention to your riding style, but from what I understand you have a good bit under your belt. So, mechanical failure is what you're probably looking for. You should be able to ascertain if your brakes are working correctly; spokes, bearings, rotor alignment, etc. is what you're left with.

Please post your results as we all like to see if something we mentioned helped. Best of luck to you.

 

wow- that is roughly 31 posts per day every day for 8.5 years straight. impressive...

 

Jeez man, there have been many suggestions thus far given to the OP, why keep repeating them. He gave the OP one more thing to check on a bike he bought used just to make sure that everything is in working order. Probably one thing that many wouldn't even think about doing.

 

I never rode a Heritage, but when I went to my Ultra, from a Vulcan 750, I would lock up my rear brakes on panic stops. The first few times I kept them locked and had a full *** rear wheel slide to about 70°. Not fun, but definite adrenaline rush.
You have to apply the rear brake slowly. If they start locking, but you aren't sliding, let up just enough to unlock. If you go into a slide, keep them locked, and steer out of skid. Don't release brakes in middle of skid, or you will Highside.
Those bad stops inspired me to take the Advanced Riders course. They talk about not releasing brakes after locking, but didn't teach about releasing if not skidding. It was still a worthwhile course.
Harris Neil covers this in his Motor Lessons. I don't know if he still does this but he used to send than to you for free, if you email him.
Harris Neil
Denver, Colorado
MotorLessons@Hotmail.com

 

Hey guys.. Problem solved.. I changed out the break fluid.. Was dark brown and changed out the tires..to Michelin Commander 11 . WOW a far better ride and no fishtailing! Thank you for all your help!!!