Help with Axle loads, CG and mastercylinder sizing

Zedn · #1 (**permalink**) 01-26-2010, 04:11 AM

Hi Guys,

I am in the process of calculating my master cylinder sizes and was wondering if anyone can help out with some estimates for static weight of front and rear axles, and approximate height of Centre of Gravity?

I am only looking for estimates as every car is different. I am running jaguar suspension front and rear with an LS3 and 6 speed.

Also can anyone give some recommendations for mastercylinder sizing with Jag brakes (un boosted) and a 6.25:1 pedal ratio with a balance bar set up (wilwood). Any one running this setup?

Thanks,
Liam.

boxhead · #2 (**permalink**) 01-26-2010, 06:57 AM

Static weight is a bit of a guess.
Mine weighed in at 520kg front (LS1, Jag control arms, steel coil over shocks, standard Commodore steel radiator)

Rear came in at 600kg with half tank fuel, AU rear IRS with standard, very heavy control arms, Single steel roll bar that weighed about 20kg on its own.
My car is a Classic Revival so not sure if the RMC chassis is heavier or if the jag stuff is heavier.

Regarding brake cylinders, I am guessing that since you have mentioned a balance bar, that you are running 2 cylinders (1 for front, 1 for rear)?

I will check my cylinders in the morning and let you know what I am running, I have standard jag front and AU Falcon (single piston) rear, I have my bar setup centred and the car pulls up square with no brake lock up in front or rear yet, but test for engineering from the looks on the testers face were impressive, I should try to get the figures from him.

Zedn · #3 (**permalink**) 01-26-2010, 02:22 PM

Thanks Boxhead.

Your front end weight is probably going to pretty close to mine give or take a bit to allow for engine location. I am just looking for somewhere to start and those values help. Since there are only a few options of master cylinder size, accuracy is probably not super critical as long as i am close.

Yes i am using 2 master cylinders with a balance bar.

Are you using the Wilwood set up? I am planning on using the wilwood reverse swing with remote mount reservours.

Liam

Aussie Mike · #4 (**permalink**) 01-26-2010, 03:31 PM

I'm running 3/4" front and 5/8" rear cylinders. Car weight is 1060KG with about 1/4 tank fuel. I would guess it's about 52% rear and 48% front.

Cheers

Zedn · #5 (**permalink**) 01-26-2010, 04:42 PM

Thanks Mike, those are my initial estimates, so its good to see i am correct.

How do you find the pedal feel with those sizes? What ratio is your pedal?

Liam

boxhead · #6 (**permalink**) 01-26-2010, 05:04 PM

I am running the same Master cylinder sizes as Mike, So probably a good starting point.
Yes I am running the Willwood setup with Willwood master cylinders.

Zedn · #7 (**permalink**) 01-26-2010, 06:31 PM

Great, thats what i will go with then.

Any recommendation for clutch master cylinder sizing?

boxhead · #8 (**permalink**) 01-26-2010, 06:37 PM

I will check at lunch time what I have, but 7/8 sounds right from memory.
I am running the standard T56 slave cylinder.

boxhead · #9 (**permalink**) 01-26-2010, 06:57 PM

Just remembered I have my invoices with me at work.
It is infact 1 inch that I have for clutch.

I bought mine through a shop on eBay, here is a there physical address.
http://www.merchantcircle.com/busine...s.207-392-4101

And here is there eBay store.
http://stores.ebay.com/Race-Basics

My reciept from 2005 totalled $205.00 including freight for the 3 master cylinders.

Looking through there store I found these.
http://cgi.ebay.com/ebaymotors/Wilwo...Q5fAccessories

http://cgi.ebay.com/ebaymotors/Wilwo...Q5fAccessories

http://cgi.ebay.com/ebaymotors/Wilwo...Q5fAccessories

These are identical to mine.

Zedn · #10 (**permalink**) 01-26-2010, 11:32 PM

Great! thanks heaps Boxhead.

boxhead · #11 (**permalink**) 01-26-2010, 11:49 PM

No worries Zedn

Zedn · #12 (**permalink**) 01-27-2010, 12:53 AM

One more thing Boxhead,

The ADR requires brake warnings for pressure loss and reservoir level. What sensors did you use for these?

Liam.

Rob. Smith · #13 (**permalink**) 01-27-2010, 01:29 AM

G'Day Liam,
Who is your engineer ? There is a bit of question about Willwood brake gear and legallity in NSW...Talk to that engineer man before you spend the bux.

boxhead · #14 (**permalink**) 01-27-2010, 02:27 AM

Yes talk to your engineer, but I am pretty sure it is only the Calipers that are in question (due to a lack of dust seal).

I did not require a "pressure loss" warning light, however I did require a fluid level sensor, I will have to search, but I bought Daewoo ones (will get the part number for you) they screwed straight onto the larger reservoirs in the willwood kits I have linked.
One thing my engineer looked for was a label that advised DOT 3 minimum brake fluid, The Daewoo caps did not have this, but my clutch reservoir (original Willwood one) did have the labeling, he was happy with this.

I just searched the forum and can not locate where I mentioned it on here.
I dont have the reciepts either, so apart from saying Daewoo I am not sure I can help much more.
I will ask the shop I bought them from if they can find a copy of my invoice (in the puter), they where from a Holden dealer as GM bought out Daewoo.

Zedn · #15 (**permalink**) 01-27-2010, 03:07 AM

Thanks Boxhead,

Thats ok, i will work out the sensors. I just wanted to make sure that it was doable. Yes, i saw the adr states that the DOT3 label is required. This is recommended in the Wilwood documentation so i guess thats additional evidence.

I am going to talk to the engineer before purchasing anything, at this stage i am planning on using the guy at Wyong (Kevin). I spoke to him back when i purchased my kit and he mentioned something about the entire brake system being from the same doner car. However, several NSW people have said that wasnt the case for them so i may have misunderstood. I need to find out exactly what the requirement is, but reading the ADR, i cant see why there would be an issue with compliance as the car still has to pass the break test.

Thanks for all the help on this guys. Its appreciated.

Liam

Aussie Mike · #16 (**permalink**) 01-27-2010, 09:22 AM

Here you go Liam,

Wilwood MC Float Switches

Cheers

Zedn · #17 (**permalink**) 01-28-2010, 01:49 AM

great, thanks Mike.

Rob. Smith · #18 (**permalink**) 02-06-2010, 04:58 AM

Quote:

Originally Posted by Zedn

Thanks Boxhead,

Thats ok, i will work out the sensors. I just wanted to make sure that it was doable. Yes, i saw the adr states that the DOT3 label is required. This is recommended in the Wilwood documentation so i guess thats additional evidence.

I am going to talk to the engineer before purchasing anything, at this stage i am planning on using the guy at Wyong (Kevin). I spoke to him back when i purchased my kit and he mentioned something about the entire brake system being from the same doner car. However, several NSW people have said that wasnt the case for them so i may have misunderstood. I need to find out exactly what the requirement is, but reading the ADR, i cant see why there would be an issue with compliance as the car still has to pass the break test. I had Mr D.R.Mackay as my engineer and his history goes back to the formation of the hotrod fraternity and their battle with the RTA. Speak to him regarding brakes and compatibility.

Thanks for all the help on this guys. Its appreciated.

Liam

If you use the entire brake system it becomes very easy for the engineer....BUT if the system is compatible with similar sized components there is no argument. ..ie- I have XJS Jag front and rear brakes operated by a ford master cylinder..because the master cylinder is the same dimensions as the jag one the system is as it was designed (just better for a cobra) ...no argument !

Outwest34au · #19 (**permalink**) 02-06-2010, 03:51 PM

Rob, what model falcon sized up right for you?
Did you use it with or without booster.

Also, we have all read the article on brake bias stating that a GK Sigma wagon disc/disc master cylinder is a good match too. Does anyone know if the sigma m/cyl is effective enough minus the booster??
I have space limitations that make the fitting of the complete sigma unit awkward unless I bore a great hole in the rear of the front inner gaurd which leaves the end of the m/cyl hovering inside the wheel arch.