Mave
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| posted on 4/1/09 at 08:12 PM |
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Need help deciding; uprights and brakes
I'm hoping you guys can help me make up my mind on the following; I'm rebuilding/modifying my Indy, and want to upgrade the brakes. Not
necessarily because I need them, but I just fancy some nice 4-pots.
Ok, here's the details; my car is an MK Indy, with Zetec engine, 17 inch wheels, weighing in at 650 kg (don't know if that weight is very
accurate though). Currently I have Sierra uprights with 260 mm ventilated discs and standard Sierra calipers in the front (on Scorpio caliper cariers,
to accomodate the 260 discs). At the rear I have a Cossie setup, which means 273 mm solid discs. Yes, my rear discs are bigger than the fronts. This
has been solved by adding a Mini brakebalance valve-thingy to the circuit. Braking is actually pretty nice right now.
But, I'm suffering from "upgraderitis", and am wrestling with the following options;
1. buy new Sierra uprights and a complete Wilwood Midilite set with 285 mm ventilated discs
2. buy Rally Designs "Raceleda" Cortina copy, and go for Wilwood Powerlite brakes with 265 mm solid discs.
Pricewise (also important) the difference is negligable.
What should I do, and why?
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sucksqueezebangblow
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| posted on 4/1/09 at 08:50 PM |
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Go for the lightest option to reduce unsprung weight (and improve handling). Probably the Raceleda (I've gone for that option on my build)
Better to Burnout than to Fade Away JET METAL ~ AndySparrow © 
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procomp
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| posted on 5/1/09 at 08:05 AM |
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Hi
You can not just swap the Sierra upright for a cortina one.
You would have to change wishbones and alter all the suspension brackets on the chassis other wise you'll end up with geometry that would be
terrible. Plus the alloy replica cortina uprights are all in the process of breaking. There's at least 12 raceleda uprights broke so far (
excluding the so called prototypes also ) so thats at least 15 of them so far. There is the other version from MNR but check out the safe working load
after they where tested.
Brakes you certainly do not need any bigger. Just replace with size for size or equivelent from Willwood. BUT to get the best from the brakes
you'll need to install a decent bias setup. Don'T know if MK supplied pedal parts are transferable from a single to a twin with bias setup
or whether its a complete change of pedal box etc. I would imagine a replacment with better pedal ratios would be in order.
Cheers Matt
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Mave
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| posted on 5/1/09 at 10:13 AM |
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Hi Matt,
I know; I'm planning on a totally new front suspension design already, even when keeping Sierra uprights (the Indy's geometry as it is
could do with some improvement too). I have already changed the rear suspension, so the rear roll centre is higher than the front (as standard
it's the other way around). For the front I was planning on slightly more caster to aid self-centering, and a higher top balljoint (upright
side), so to make the RC slightly higher as well (oh, and a pushrod system to give a slight rising rate on the shocks). The geometry of the Cortina
upright will raise RC even more (but I'll change the balljoints in order to get it slightly down again). My only concern is the increased
scrub-radius of the Cortina uprights compared to the Sierra. But I must say the steering was pretty light on the Indy (despite heavy Zetec engine and
17" 205 tires), so a bit more steering effort would not bother me.
As for durability; yes, that's certainly worrying. But to be honest; I really hate the looks of the Sierra uprights (they seem so out of place
on such a light car), and original steel Cortina uprights are very, VERY rare here in Holland (last time I searched, I found a set at 125
euro's/pounds, rusty as hell). As I understand the Rally Design cast uprights come with a test certificate (read it on the interweb somewhere,
don't remember where though). That seems to support the 700 kg weight limit.
As for brakes; I already have a bias bar set-up (which on it's own couldn't cope with the unbalance between front and rear; hence the
extra Mini-balance-adjuster). So I'm thinking; bigger front discs could bring the balance back, while equally sized discs will still result in
the unbalance, thereby requiring the extra balance-adjuster.
The wisest thing for the braking would probably be; go for the 265 mm solid fronts, downgrade the rears to standard Sierra discs. But that would also
require new discs, calipers and pads......
And those small discs look silly in my huge 17" wheels.......( know, I should also downgrade to 15", but that (again) would cost an arm
and a leg......)
Cheers,
Marcel
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procomp
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| posted on 5/1/09 at 10:26 AM |
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Hi Ahhh if starting from scratch effectively thats a bit different.
If your balance is out now then going bigger could result in the change required but also look at the size of the cylinders and pistons sizes also.
The 700 loading is not exactly up to the safe limit that an upright could see hence all the alloy versions breaking due to bad desighn and also the
problems related to the age later on. For light weight uprights look at the triumph setups as used on caterham. These are as light as you will get
from STD parts and will be able to take the loadings. All the parts are available NEW. Or alternatively fabricate a set with dimensions required to
suit your new desighn.
Cheers Matt
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Mave
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| posted on 5/1/09 at 08:56 PM |
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Hmm, did a search on "raceleda failure" and came across this piccy. The car did go off the track hard, and came across some concrete
curbs, so it is not a failure during normal conditions. But still.... Not too sure if I would feel comfy in my relatively heavy Seven with these. But
they looks so nice....maybe I should just buy a set and place them in the living room.....
[img]http://www.clubstylus.be/forum/download/file.php?id=125&mode=view[/img]
OR CLICKY
[Edited on 5/1/09 by Mave]
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procomp
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| posted on 6/1/09 at 08:52 AM |
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Hi
Yep plenty of talk around a few forums about breakages where no initial contact was made. One of the Kit racing cars had one break without warning and
had hit nothing befor hand. That was then classified as a prototype.
There was a thread on the WSCC forum regarding the MNR And Raceleda versions and an other version in billet from the guys who did the original desighn
work for race leda but the thread has disappeared for some reason.
Cheers Matt
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coozer
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| posted on 6/1/09 at 03:56 PM |
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I'm in this dilemma as well. I want to unbolt my Sierra uprights and bolt some thing lighter and better looking in. Lightness is the main
factor.
It seems there were kits available before but not any more. Is the Sierra geometory really that bad?
Can anyone point me in the right direction?
Matt, are the Triumph items a retro fit??
Steve
1972 V8 Jago
1980 Z750
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Mave
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| posted on 6/1/09 at 07:29 PM |
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It won't be a straight swap I'm afraid. Besides the five stud hub on the wilwood hub, the top and bottom balljoints are also further
apart. So they will influence the suspension design as well. The rollcentre will go up quite a bit.
As far as I can tell, the Sierra geometry is not actually as bad as people tend to think. Might even be better in some ways than the Cortina (can of
worms). But it is just so ugly, and heavy....
The Triumph/Caterham units are also not a straight swap. But probably the best option in terms of weight and geometry. Roll centre will get slightly
higher (not a bad thing), scrub radius significantly smaller than Cortina (lighter steering), even slightly smaller than Sierra.
They're not really cheap though; complete with hubs they're about 450 pounds.....
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MikeRJ
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| posted on 6/1/09 at 11:02 PM |
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The Wilwood uprights in your other post is going to be a better bet than a fragile alloy one to be honest.
If you have a big wallet you can buy the Triumph uprights from
Caterham, or you
may be able to find a cheap Spitfire dissolving into the ground somewhere local!
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procomp
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| posted on 7/1/09 at 08:33 AM |
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Hi
No the Triumph setup will not be a straight swap. It would require different mounting points and to get the best out of the triumph it needs the
upright modifying also. Like the caterham you can use a rose ball as the lower joint and either a simalar joint to the transit on top or go for rose
joint conversion. Also you would need to uprate the stub axle to the larger one from the GT6 which is the STD upgrade on the Caterhams also. Alloy
hubs are available for the uprights.
All the bits are available BRAND NEW and not from Caterham but is not the cheapest option compared to other more modern heavier setups etc. With bolt
on steering arms theres the opportunity to play with steering geometry also if wanting to fabricate new arms. Brake options in all sorts of sizes due
to the upright being used on many race car setups over the years but more likely to be from AP rather than the cheaper Willwood type.
All in all the sierra is very ugly bit of kit but dose give far superior geometry compared to the cortina setup particularly if you take the time to
mod it further than just bolting the STD item straight on. And surprisingly the sierra depite all the bull thats out there is not as heavy as the
cortina if you know which variant to chose. The side of it is that the cortina can be fetteled down in weight and alloy hubs are available off the
shelf also. Further modifying of the cortina also reduces quite a bit of the geometry problems also. So to sum it all up there is no one easy solution
using STD components as it's compromises all the way even when modifying them. But you can by various methods get pretty good results from the
Triumph sierra and cortina. But the best option really is to fabricate some new items to give the desired results that you are looking for and this
option will most likely also be the lightest as well. Cost will depend on whether you have the time etc to do them or if having to pay for desighn and
fabrication it could end up being expensive. But these options are all going to be a darn sight safer than the alloy alternatives that are on offer at
the moment. The only alloy upright currently on offer that has passed tests with good results is the Westfield version. And if you take a look at that
to see how far you have to go with an alloy version of the cortina you will see where the others are lacking. Trouble is for some strange reason the
Westfield version is the same weight as the STD Ford item and a darn sight more bulkier in comparison. So no advantage in that other than Westfield
did not have to try and source the Ford items any more. They did for a brief period do a fabricated item but not that many appear to have been
made.
Cheers Matt
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Mave
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| posted on 8/1/09 at 02:55 PM |
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Thanks for the write-up Matt. Sums it up nicely I think.
I've been working on a redesign using Triumph uprights, and it's actually looking very promising (better than either Sierra or Cortina). I
don't think it will be too complicated to have the bottom part machined to take a balljoint, but do you know what else should be changed to get
the Caterham specs? You're mentioning a different stub-axle; is that necessary? Of course it needs different hubs to suit the Ford PCD. They
can be had from Caterham (90 pounds each) or Compbrake (57 pounds each). Rally Design does Wilwood sets for the Triumph uprights as well.
I know that a few years ago Caterham changed the design of their hubs. I believe they were made "longer" (increasing the scrub radius). Do
you know the exact change and reason?
Remember, I'm still trying to do this in a relatively locost way, so rather than just buying everything new from Caterham, I'd rather try
to source some secondhand Triumph parts, and aim for the same result for much less.
Cheers,
Marcel
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