Phil
swaping my heavy sierra rear brakes to either wilwood or high spec twin pistons but which!!??
how much weight are you hoping to save by doing this?
wilwood all day for me
Hi-spec make a good caliper, but if their customer service is anything like the last time I dealt with them, then I'd avoid!
I ordered a set and the delivery date came and went... they lost the order... and then the second one!
The Sierra rear calipers aren't actually that heavy and the weight saving isn't worth the cost of Hi-Specs or Wilwoods IMHO. They do
look good though.....
Phil
^^ that was my original thought. not overly heavy but dont look quite as nice! braking capability the sierras are more than adequate.
I went for the Hi spec's on my Indy R, not cheap, but they do look nice.
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yeah they do look well! i felt a small twin piston think it was a dynapro and weighed nothing compared to the sierra caliper/carrier well thats what i thought will weigh them tomo for what i can sell them for i wont have to put much towards.
Let me know if you want wilwood as i have a special buy on them, which i can sort out for you still.
I was also fell into the bling trap 
- I now wished that I kept the old calipers. One point to watch is that the braking efficiency of the Wilwoods
calipers (and possibly others too) is not as good as the bog standard Sierra rear handbrake calipers - the handbrake is crap too, so don't leave
it on a hill without putting it in gear first!
I had to change the m/c to a smaller size to get my rear brakes back and you will find that the 'swept area' on the standard disc is not
using all of the Wilwood pads, therefore even less efficient. I might even look at getting some custom discs & bells in the future. All hail the
Bling God 
nightmare! the bling god rules us all!!
another problem i have is the front brakes locking up far too easily any ideas?
Exactly why I need to get the rear brakes working better with bigger discs. An in-line restrictor would only make the pedal scary-hard. Have you adjusted your bias bar (assuming you have one of course)
yeah anymore to the back and it gets a little twitchy! im reducing the size of the fronts anyhow as im using 13s now so il see how the wilwoods are when its all back together and go from there
quote:
Originally posted by needforspeed
another problem i have is the front brakes locking up far too easily any ideas?
theyre vented on the front 280 mm i think with wilwood calipers
Vented are no good for these cars...
You need to change to Solid Discs so you can get some heat into them.
I'll enquire about price on solid discs and adapter brackets if you like.
Will take a photo of the HiSpec's I've fitted this week tomorrow and post it here, they seem like a good caliper...
yeah that would be great thanks! funily enough ben i was thinking of changeing them to solid disks! just need to strip a caliper to see what machinings involved
Ben - Interesting that you think changing to solid discs would decrease the braking efficiency and improve the imbalance described. Surely vented
discs will just stop fading when really hot - not usually a problem on light cars such as ours. Surely solid discs would just improve low speed
braking if anything, probably making the imbalance worse?
Quite often the change from vented to solid is just a case of changing the disc and removing a caliper spacer. Incidentally I would be interested in
such a kit too, I want to move to solid discs to reduce unsprung weight.
[Edited on 15-1-11 by RazMan]
Vented discs wont get hot, so they are basically on or off. Braking on our cars relys on getting heat into the brakes to produce controlled
braking.
If you look at F1 cars, if they dont get their brakes hot they just lock up. I'm talking about when Richard Hammond drove that F1 car and he
wasnt going fast enough to heat up the brakes so he was locking them up into ever corner because they werent controllable.
You need heat ! Vented wont heat.
I have exactly the same problem on my car, vented discs are crap.
F1 cars use CRC (Carbon Reinforced Carbon) discs and pads so I don't think you can compare them with our steel discs and Mintex pads as the
friction co-efficients are totally different
Having said that I can appreciate some of what you are saying, but still think solid discs will mainly just improve low speed efficiency. For example
I notice in freezing cold weather that my vented discs are very slow to 'bite' and only start to really work when stomped on at high(ish)
speeds. When they are warm they work better, but after a few hundred metres they are cold again.
In short, solid discs will be better round town - vented are really better for track use when the pads are in the upper temperature range and start to
risk fading
[Edited on 15-1-11 by RazMan]
Unless you have a heavy ass car with a heavy ass engine you will never produce enough heat in vented discs to make them better than solid discs.
All my sprinting friends, track day goers swear by solid discs. What ever the theory applied evidence shows solid discs work better for our cars.
Simples.
That's why they are recommended by wilwood and many kit manufactures.
The Hi-Specs have a bad rep amongst the RGB racers. Main complaints have been around levels of service from the company, reliability, the apparent
lack of rigidity of the calipers (resulting in uneven pad wear) and lack of braking feel. Wilwood are de rigeur with the RGBers.
I got on fine with the Hi-Specs on my Fury Busa for a couple of seasons but the handbrake was always pretty much useless - so useless in fact that at
Cadwell I did a race with the handbrakes on without noticing until the friction eventually caused enough heat to melt the caliper pistons resulting in
a small bonfire around my left rear. It also gave a dramatically soggy pedal and brown nomex ... 
The other problem I had was when the little seals within the handbrake mechanism (it's an incredibly complex system utilising a tiny haydraulic
cylinder and piston within the caliper) failed resulting in the brakes staying on once they got got. This also gave me a couple of interesting
experiences.
I swapped to standard Sierra calipers which are heavier but work great and I even have a usable handbrake now. I've since fixed the Hi-Specs but
they remain in a box as spares and I don't plan to swap them back.
The Wilwoods are pretty light, very nicely made, you can get them and all the pads etc. from Rally Design who give excellent service. The only
drawback is that their handbrake isn't as effective as a standard Sierra caliper either. You also have a range of pad compounds to choose from
depending on your application.
Regarding solid versus vented disks the 'need to get heat into them before they work' argument only applies if you're using a very race
focussed pad. I don't believe it's an issue for most of us, certainly mine work fine from cold, the limiting factor actually being tyre
temperature. When the tyres are cold they lock up very easily (Yoko AO48s) but improve within a lap or two.
quote:
Originally posted by Ben_Copeland
If you look at F1 cars, if they dont get their brakes hot they just lock up. I'm talking about when Richard Hammond drove that F1 car and he wasnt going fast enough to heat up the brakes so he was locking them up into ever corner because they werent controllable.
Hi all
I've chosen Hispec caliper for My Birkin.
Please see at http://www.locostbuilders.co.uk/forum/14/viewthread.php?tid=148276
Thanks,
Ken