I definitely suggest you try it again with the new tires first. See, this
is why when you ask a question, it helps to provide the background up
front. Knowing that you upgraded the front calipers, but ran the test on
old tires does make a difference.
Under hard braking, you are transferring weight to the front. The more
weight you transfer to the front, the more grip your front tires have. If
the tires are old and hard, they will reach their limit sooner, therefore
you will not get to the max weight transfer you will see with new ones.
The weight transfer has a lot to do with the brake balance. Ideally, you
do want the fronts to lock slightly before the rears, but a big imbalance
does not inspire confidence. Again, with new tires, you will get more
weight transfer, which changes the brake balance. That's why a balance bar
for a dual master setup or a proportioning valve (where legal) is a good
thing. You can adjust the car for changing conditions.
Gavin Ivory wrote:
>
> Thanks everyone for all the help. Though not yet a participant in vintage
> race, I enjoy all the mail, and soak up the advice. I should have made clear
> my car is not vintage eligible, and never will be. Hopefully it's a
> transition car, until I can find out how to make my "other life" fit with a
> growing vintage obsession.
>
> The car is a '79 TVR Taimar 5000 [302 Ford], "street legal" [well... sort
> of] . I've already spent too much on it [her words, not mine]. But the
> handling is getting there [2300lbs; 50/50]. The power is certainly there
> [close to 300hp]. Re: the lock-up problem: It is definitely the front brakes
> locking ... I did have a friend watch while I stomped the brakes on the
> front straight at Shannonville during a driving school. I was wearing at
> the time a set of very old, hard Yoko 008's. Just replaced these with new
> Kumho V700's: maybe this will help?? MC is original Girling [off the TRs, I
> think]. Front brakes: I replaced the orig. TR6 solid disc 2 pots in favor of
> 4 pot Wilwoods, Hawke blues, and 11" vented rotors. Supposed to be a
> similar volume of fluid as the original set-up. But they sure stop fast.
> Whatta difference. I didn't feel safe with the original brakes.
>
> So I'll check that the rear brake line is good all the way, then look
> further in to an different MC arrangement.
>
> Mosport in July sounds like it'll be a blast. I might get there for a few
> hours, as a spectator [there, doesn't that sound wistful]. One day...one
> day...!
>
> Gavin Ivory
> Toronto
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