Big front brake conversion!

Drums, discs and conversions - they're all here.

Big front brake conversion!

Postby CTR » Mon Aug 02, 2010 10:10 am

In the for sale section I have read about the big front brake set up. Could someone give me a general outline of what's involved? I see no reason to reinvent the wheel if there is a SOP way to get there. Thanks Steve (CTR)
CTR
948cc
 
Posts: 74
Joined: Wed Apr 14, 2010 8:38 am
Location: Hampton, VA.

Re: Big front brake conversion!

Postby CTR » Mon Aug 02, 2010 10:45 am

Once again it seems I leaped before I looked. Lower down there is a thread about fitting Spitfire rotors and MGB calipers. It seems there can be some steering arm issues with this kit. I wonder what is avalible in four pot alloy caliper? Steve (CTR)
CTR
948cc
 
Posts: 74
Joined: Wed Apr 14, 2010 8:38 am
Location: Hampton, VA.

Re: Big front brake conversion!

Postby CTR » Tue Aug 03, 2010 9:50 am

I don't have the MGB or Spit parts to look at. I'm thinking the Sprite disc is about 8.4 dia. which fits inside a 13 inch wheel. It would seem Spits are 13 inch cars also and it's disc wouldn't be much larger dia. Looking at a set of fronts off a Sprite I can see where the steering arm would get involved if the disc were much larger in dia. The way I see it there are a couple of things one would want to do to improve front brakes. A larger dia disc giving greater leverage. Larger pad giving greater surface area and more small pistons or a larger piston.

When I was running 7x13s on my mini I was able to fit 10 7/8 inch disc and four pot calipers. It required a 1 inch master and gave unbelieveable stopping power. I don't see why I can't bore a 7/8 master as they would to sleeve but leave the sleeve out and rob a Tilton 1 inch master of it's guts and have a std looking master. I guess I should order some Wilwood four pot calipers and a MGB disc and see what can be done. I may have to fab up some steering arms out of bar stock. If someone else has done this I'd be interested in seeing some pics. Steve (CTR)
CTR
948cc
 
Posts: 74
Joined: Wed Apr 14, 2010 8:38 am
Location: Hampton, VA.

Re: Big front brake conversion!

Postby HAN5L778 » Wed Aug 04, 2010 12:23 am

I believe the Spitfire rotors are vented. The MGB calipers are 2.25" bore to the Spridget 2" bore. Yes, you will have more stopping power, but I could'nt lock up the front brakes ever with the original setup, good pads, and 175/70 tires.
Unless you plan to do a lot of autocrosses or track days, the bigger brake setup just is overkill. Plus it isn't cheap to buy the adaptors and have some machining work done to get everything to clear. Just my opinion.
Rick
'69 Sprite-project with lots of trick parts.
'63 MGB waiting for restoration
User avatar
HAN5L778
1098cc
 
Posts: 320
Joined: Tue Jun 15, 2004 12:24 am
Location: Ann Arbor, MI

Re: Big front brake conversion!

Postby Charlie Tolman » Wed Aug 04, 2010 12:29 am

What is the planned usage of the car; street, occasional autocross, or road racing ?? For the first two, the 1098 and 1275 disc brakes with a medium-hard set of pads will work fine. Remember, the size and grip of the tires are the limiting factor on most brake configurations.

I would not feel comfortable with a modified master cylinder or brake calipers on my car. My opinion.

Don't fall into the trap that has been popular with the "tuner" crowd, where they fit very large brake discs along with 6- to 8-piston calipers. A TV program featured this a year or two ago, and with before and after dyno runs on their front wheel drive car, they discovered a loss of 8 to 9 horsepower at the wheels, with a total near 80 to 90 hp. Rotating mass that is accelerating, absorbs horsepower.

Charlie Tolman
SCCA H/P 40 (Retired)
Charlie Tolman
Judson Supercharged
 
Posts: 1199
Joined: Wed Mar 01, 2006 10:36 am
Location: Minnesota

Re: Big front brake conversion!

Postby CTR » Thu Aug 05, 2010 10:10 am

Thanks for the replys. It's no fun to think you have come up with a great idea only to find it's been around for years. I didn't think this one up but I was thinking along the same lines. I did my first brake kit in high school shop in the mid to late 60s. I have one off kits on street, autocross and vintage race cars. When I contacted Wilwood to make me 100 calipers for a drum to disc kit for minis they said no. It seems they would be appearing to agree with my system if they did that. The little paper that comes with their calipers says something like "This part is not deemed to be suitable for anything, responsiblity to determine suitablity lies with final user.

Having done this before I would want to end up with the largest dia. disc (non vented) and the lightest four piston caliper. I believe more brakes is always better need them or not. I'm toying with the idea of a RX7 rear end with disc. It would be nice to improve the fronts at the same time. While I have not decided yet I have been looking at a low mileage SVT Ztech Ford engine at the local yard. I guess use would be listed as Rocket Ship. Steve (CTR)
CTR
948cc
 
Posts: 74
Joined: Wed Apr 14, 2010 8:38 am
Location: Hampton, VA.

Re: Big front brake conversion!

Postby Mark T Boldry » Sat Feb 04, 2012 5:37 pm

I'm with Charlie on this one..

Think unsprung weight.... (look it up if you are not aware of it's effects on a car's handling....).

All my Spridgets have had very adequate brakes using the standard set-up. Just make sure you use good quality pads and shoes (shoes less important). I DON'T use a brake servo either.

Mintex 1144 for road use and Mintex 1155 on the race car.

Mark.
Mark T Boldry
948cc
 
Posts: 81
Joined: Thu Dec 22, 2011 4:01 pm


Return to Brakes

Who is online

Users browsing this forum: No registered users and 1 guest

cron