Uneven Leg size how to fix with FT?

[Scott Stevenson]

Yes. When getting closer to a failure point it seems as if the stronger leg takes over the movement. And feels as if smaller Leg gets minimal activation compared to larger quad. 

OK - this is important, IMO.

First things first - I would see if you can get in to see a massage therapist, chiro, Physical therapist (aka physiotherapist in some countries) or even better a podiatrist to see if you have a leg length discrepancy.  That could be largely at play here to some degree and a custom orthotic or even just a heel lift could help.

This is what I would do:

Don't let the above happen.  Make it your intention that all bilateral movements are completely focused on the smaller leg, with the right let there to ensure that you're balanced, symmetrical and maintaining good biomechanical form.

When the sets come get near failure, all your focus is on the smaller leg. If going to failure, when it fails i.e., you can't drive the load up / control the load with pure mind-muscle focus on the smaller legs, then the set is over.  This should go for all set types and especially Pump sets where you can really spend some time in a fatigued set learning the skill of keeping a mind-muscle connection with the smaller leg.

This isn't something that's been studied quite a bit (https://www.researchgate.net/profile/Jak...tion.pdf), but I suspect this is in part neurological issue (secondary to possibly a skeletal / biomechcanical issue), that's been perpetuated over time by your handedness and the fact that you've got a larger motor on the stronger, larger, right side, which perpetuates the use of this leg over time. 

I would also do unilateral movements (particularly MR's) as often as possible and simply match reps (as you mentioned above) with the stronger side. (E.g., don't take the right side to failure on a MR - just match reps in the failure set of the MR.)  You'll not lose any size in that side, I don't suspect, and this should bring up the fatigue resistance in the weaker side. 

Also, experienced trainees will tend to have bilateral facilitation d/t training bilaterally for the most part. [This means (max) activation is greater using both legs vs. one at a time which shows up as greater strength / load with two legs vs. summing unilateral strength.  An 8 plate leg presser for 10 reps might only use 3 plates / side (yes the carriage makes a difference of course) when using one leg at a time. You probably have in particular a unilateral deficit that's most evident in the weaker leg (2 PPS for the left vs. 3 PPS or maybe more on the right.)  

SO the above is a fancy way of saying that you can do unilateral work to exploit what seems to be an activation deficit (I'm guessing) on the smaller leg.   

-S