Welcome to the forum.
It sounds to me like you need some professional help. Retraining an OTTB is no easy feat, and takes a very firm, clear rider to do so correctly.
I'd start in a round pen, or small area- though, to minimise chances of her trying to take advantage of you or run away. How are her ground manners? I find that going from the ground up is the best way to retrain. Make sure that she leads without being pushy, backs on cue, yields to pressure at the poll, the bridge of her nose, shoulder, and hindquarters, and understands the word 'Woah.' Take some time to hand walk her with the saddle and bridle on, so that she understands that she doesn't always have to run when she's tacked.
I'd also try trotting her in-hand, with a friend near just in case. Ask her for a nice, easy trot that you can easily lead her at. If she goes faster than you want, immediately stop and say 'woah.' Walk her in a circle, then try the trot again. Continue until she's content to trot at your pace for as long as you want. At this point you could also try lunging her while saddled. Teach her to 'walk, trot, canter' and 'change' in both directions. I did this for the better half of two months with our OTTB, Noah- although he was fresh off of the track at this time.
Once her ground manners are good, you could try mounting her and asking her for a walk both verbally and with a small nudge. If she immediately starts off at a trot, sit deep in the saddle, keep contact with her mouth- and make her 'woah.' Do not allow her to continue to move forewards until she is merely at a lively walk.
I spent a whole month only walking. Racehorses take a while to unwind after being on the track and their muscles need to be 'retaught' how to walk and trot. Begin your work on yeilding to the bit and flexation at this time. Ask her to turn her nose towards your boot while at a standstill, or tuck her head for you. Once she really understands that she's supposed to give to pressure rather than lean against it, and is willing to listen to you- you can start trotting. This it the time to really work on balancing her. If she had problems with wanting to run away with you still, do what you did when you were learning to walk. Stop, then start again. Let her know that if she isn't going to listen to you, she isn't allowed to go anywhere at all.
I didn't even try to canter Noah until late in his sixth month with me. I wanted him to be listening to me and me alone, responding correctly to all of my commands, and really be at ease under the saddle before I allowed him to run. Even then, I only allowed him to run for short amounts of time at a slow, even lope. He was not in any way allowed to move faster than I asked.
I really advise in getting a trainer to help you. I've started two OTTBs, and watched three started. I have two trainers overseeing what I do- and always have them to help me when I get stuck. Noah is the first OTTB that I started completely by myself, and even then I always made sure to have someone supervising me, even if they werent doing anything but watching.
As for her bridle, what was she in when she was racing? What do you have her in now? I began Noah in a jointed eggbutt snaffle. It wasn't rough on his mouth, but I still had control. He was graduated to a jointed rubber snaffle three months ago, and has been off of the track for ten months.
It really just depends on a) your experience b) your horse's mouth and c) your situation. Again, I'd consult a trainer about this.
ETS: if she's jumpy, you might just want to let her wind down for a while. How long has she been off of the track? I gave Noah a month of just pasture grazing when he came to us, then began ground work. I didn't begin riding until the beginning of his third month with me. Do ground work with her, and a lot of desentisizing. Look up the Seven Games of Horsemanship and do those with her. I really think you'll benifit.
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