rear hubs/discs

[Elanlover]

Brian here I am!

Yup, I've sent some basic dimensions and other rudimentary info to Brian regarding the possibility of using this Wilwood caliperand this 11" rotor combo on the rears to eliminate the crappy GM parts (even the slightly better Doorman version). The rotor's diameter is slightly bigger (11 inches versus 9.3) and the caliper is slightly bigger but I haven't yet taken measurements on that. What I have measured so far indicates that this setup will fit easily within the stock wheels. Its the spare that could be the problem.

When I get my car back I am planning to fit the spare and take some addiitonal measurements. I'm hoping that the spare will fit over this rear setup OR that this sparemight work in place of our spare.

[bobbrown]

just a quick question.

if the stub axel bolts on can another stub from say a nova corsa or even a golf fit ? as then the disc ands caliper would come with it.


you have i take it checked out the mk 2 golf gri rear set up for differences to the Elan?

The golf ones are out of the question and there are differences with Nova/Corsa/Astra ones so thats a NO then

[bobbrown]

The Willwood offering should be quite easy to make fit but this is just another single pot sliding caliper
I was thinking more along the lines of 4 pot front and 2 pot rear

more like the Hi-Spec offering or using the caliper off another car

Or even the same set up as the Elise 288mm discs all round and 2 pot calipers all round

Bob

[Elanlover]

I think the appeal to the Wilwood was that it had an integrated parking brake capability, was "possibly" small enough to fit the space saver spare and was a Wilwood brake which would match what many of us have already upgraded too in the front. Also, I don't think the rears do that much braking for us anyway (so I've read here somewhere) and a bigger brake in the rear might lead to more frequent lock-ups given the lightness of the back of the car.

[bobbrown]

The back of the car although light still has to have some braking to stop it trying to overtake the front all be it as in all front wheel drive cars smaller that the front

Up to 15bar in brake pressure the pressure is a 50/50 split and above that it is 0.2:1.0 but then you have to take the calipers and brake disc diameters into account to get the correct brake split front to back
To achieve the correct split then the proportioning valves may need looked in terms of getting the correct split

Even with 2 pots on the rear you should still be able to get the correct balance

With Race/Rally cars it is not uncommon to see a front to rear split braking system (not the diagonally split system as per the elan)with 2 master cylinders driven through an adjustable bias brake bar
The two master cylinders are usually of different sizes as a start in getting the bias but it is then ajusted to suit the track/stage conditions

[Gazza]

Do those rear wilwoods have dust seals? The fronts don't and cause alot of problems.

Gazza

[Monty]

Do those rear wilwoods have dust seals? The fronts don't and cause alot of problems.

Gazza

Hi-spec are doing a rear conversion, if we can nick there caliper think that`ll be the way to go.

http://www.hispecbrake.co.uk/Start%20SVA.htm

[bobbrown]

My latest thought is to engineer the solution around the Hi-spec caliper as used on the Elise

The are a couple of changes to be made but it would be a nice solution to all of the people who have Hi-spec on the front

And yes I know the cable attachment and the hyraulic connection are different

The disc width can be selected but was thinking 20.6mm

There is a disc available at a reasonable cost which should offset the cost of the calipers at about £80.00 the pair (wilwood)
Strange mix I know but beats the **** out of £176.19 for the Elise ones

[Monty]

Is that a 4 pot?

Think the 2 pot will be good enough, IMHO we need to stick to something close to the stock rear braking force. Other wise were going to need adjustable proportioning valves

Maybe Brain (F1 Lotus) or Alan (ESM) can work out which caliper would be ideal with changing the proportioning valves,

[bobbrown]

Its 2 pot and should work well with 4 pot fronts

They are based on the Ultralite 2 - Universal Radial Mount with the handbrake part added

Piston size 38mm (1.5") against std are single pot 35 mm(1.375")

If you have upgraded the fronts then the brake ballance is going to be wrong anyway by a larger margin than fitting these to the rear

in terms of just piston areas the figures look something like this if my maths is correct

std
1662 square mm front 256
958 square mm rear 239

4681 square mm front 285 up rated fronts Hi spec 4pots 38mm
958 square mm rear 239 Std rears

4681 square mm front 285 up rated fronts Hi spec 4pots 38mm
2268 square mm rear 280 up rated rears Hi spec 2pots 38mm

Quote
“You can take this one to the bank. Regardless of your huge rotor diameter, brake pedal ratio, magic brake pad material, or number of pistons in your calipers, your maximum deceleration is limited every time by the tire to road interface. Your brakes do not stop your car. Your tires do stop the car. So while changes to different parts of the brake system may affect certain characteristics or traits of the system behavior, using stickier tires is ultimately the only sure-fire method of decreasing stopping distances.”

A good article

http://www.stoptech.com/tech_info/wp_br ... ance.shtml

[bobbrown]

Maybe Brain (F1 Lotus) or Alan (ESM) can work out which caliper would be ideal with changing the proportioning valves,

May be they can, I do not know but the fitting of big front brakes makes the car front biased and oversizing the rears can make the car rear biased
Either case is not desirable which is why a lot of race and rally cars have adjustable brake bias such that the brakes can be adjusted to suit the track/stage conditions
Rally cars are often driven with more bias to the rear than you would on a track/race car as you want the rear more un-stable.
I supose in an ideal world all four wheels should lock up together when braking in a straight line

Bigger brakes on the front do not mean shorter stopping distances in fact the opposite more likley to be the case!!!!!!!!!!!

[Elanlover]

Bob, if you're planning on building a new hub that's not part of the rotor then that will be a boon to us all. If you can do it in a way that allows folks to (with a bit more custom work for a mounting plate) select their calipers and rotors on their own that would be fantastic. There's a lot of folks with Wilwoods and probably a lot of them would want matching rear calipers (like me). I haven't had any issues without the dust seals as yet. I think it just results in more frequent maintenance?????

You will need to pay special attention to the ability to fit the space saver spare on the rears (can't fit on the fronts with a big brake upgrade) over any new caliper you select. Otherwise there'll be no spare at all - ok with some perhaps but not everyone.

[bobbrown]

I think making any allowances fot the space saver spare is going to end up as a non starter.
As one of the members pointed out it is no use for the front after a brake upgrade there so the same will be true for the rear!

Also as was suggested just keep a standard rim as a spare (I do as they do fit in the boot)

There may be another space saver from another manufacturer that may fit VW spring to mind.

[Monty]

Its 2 pot and should work well with 4 pot fronts

They are based on the Ultralite 2 - Universal Radial Mount with the handbrake part added

Piston size 38mm (1.5") against std are single pot 35 mm(1.375")

Sounds good to me

I can see my empty wallet being more empty than Dico`s head

So your talking £80 pair of disc, any ideas on the cost of the Hi-spec calipers?

[bobbrown]

The calipers are around the £350.00 for the pair
So lets add it up but its not going to be cheap!!!

Discs £80.00 ish
Calipers £350.00 ish
Hubs £100.00 ish
Brackets £40.00
Around £600 by the time you add in the minor mods required to things like hand brake cable and bearings
Some thing close to the Hi-spec fronts I think

[Monty]

The calipers are around the £350.00 for the pair
So lets add it up but its not going to be cheap!!!

Discs £80.00 ish
Calipers £350.00 ish
Hubs £100.00 ish

Around £550.00 by the time you add in the minor mods required to things like hand brake cable
Some thing close to the Hi-spec fronts I think

ochhhh think thats to much for me to spend on rear brakes and don`t forget PNM are already doing a rear conversion around that price

The calipers are expensive, there must be a cheaper alternative

What about this one
http://www.rallydesign.co.uk/product_in ... s_id=10563

[bobbrown]

I had seen that one but we are still on a single piston sliding caliper
and you would then need a custom bracket etc to make it fit.
I think they are made by www.custom-auto-craft.com and have been seen on ebay!
Radial mounted calipers are always the better option as the disk diameter can be changed with out the need for extensive modifications its just a case of moving the caliper out to suit the new disc/bell setup

So getting this to work for 15" wheels then the move to 16" is straight forward

Do not forget this is not only to allow the upgrade of the rear brakes more in line with the front upgrade but also to allow the stock brake caliper to be used (one piece rotor and hat/bell)

[bobbrown]

attached is a drawing of the proposed Hub

Will be made in 2014 Ally with 4 M12 capscrews srewed and locked from the rear to leave 4 studs in effect
Will source nuts to suit but these are not expensive along with locking ones for security
Material cost is around £13.00 for 2014 but can be made out of 7075 but the cost goes up as the material is £4.00 more + 4 capscrews and some nuts + a keep screw as per front

Just left to sort out the machining costs

Bob

[Monty]

Well i`m happy with going to studs as i`ve already done the stud conversion but i only used 3 per hub as i`m still using my old locking bolts so i would imagine this will mean i`ll have to buy a new set off locking nuts think there not that expensive anyways.

Bob, what is it you do for a living? as you certainly know your stuff

[bobbrown]

Another caliper option

This has a 38mm piston as apposed to the standard 34mm this will increase the braking on the rear by a factor around 1.25
As you are all probably aware they will not work with standard front brakes (you will just lock up the rears as the rear unloads under braking)

The caliper is for 12 mm discs so it should not be to difficult to get them to fit our 12.65 mm discs (.65mm = 0.026”)

Handed left and right