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MG MGB GT V8 Factory Originals Technical - Master Brake Cylinder Modification
|I used Dodge Caravan calipers with Chevrolet disc on the front and a 9" Ford positraction rear end with a 350 Chev V8 for my MGB V8 conversion. I used the original MGB (1980) master brake cylinder (new). I now have a very soft brake pedal. I am wondering if anyone has a suggestion. Is there another master brake cylinder that has a larger capacity that can be easily substituted? Do I need to place a adjustable proportioning valve in the rear brake system?|
|I have a similar problem and started a thread asking for advice on using a residual pressure valve which has now been archieved, but I would like to hear from anyone who has used these valves. The general impression is that a B braking system is very difficult to bleed without resorting to a number of tricks, printed elsewhere, so I intend to try these to make sure all the air is out of the system. |
| Hey S Fisher,I would love to see your mgb in pics please post some, you and I are a rare breed to use a small block chevy,My brake system in the front of mine is stock mgb stock master cyl I used a Dana 44 rear stock drums my pedal is ok but I would like to do somthing in the front like you did how involved is the change over.Check pics of my car at link below.|
I know this has probably already occurred to you so I don't want to sound like a 'know it all'. Check the piston size of the Dodge calipers. I suspect that the area of the pistons is much greater than the original. The original master cylinder is quite small and unable to cope with big calipers without them getting 'spongy'. Options would be to go for a dual master cylinder (RV8?) or a large master cylider from a US car. Roger Parker is the guru on this and helped me a great deal as I was purchasing Peugeot discs and Princess calipers.
Regarding the proportioning valve, I may be able to dig up a website that actually shows you how to make your own from a mini part with minor machining and probably cost less than 20 dollars.
|something like this?http://www.mgbv8.co.uk/brakelimitingvalve.htm|
|That's the one.|
I looked at your web page. Very powerfull car. I am surprised it has good braking power. I did the following conversion. Installed Porsche 944 vented rotors and hubs on the front with Wilwood Dynalite 4-pots calipers. Still running with the original master cyl. braking is great and no fading at all.
For more info e-mail me.
|Werner Van Clapdurp|
|Werner and Stainzy,|
Werner, I assume you have a RB B and using combined master cyl and servo. My B is CB and has seperate servo with 4 Pot Wilwoods but with a spongy pedal. It may be that the RB master cyl is uprated and can cope with the bigger brakes.
Stainzy, have you still got advice from Roger re master cylinder or should I contact Roger direct( Roger is so helpful but I feel awkward keep contacting him for free advice).
Werner : I also understand that you use wide boots on your car without bodyshell modifications: Again is this because the RB ride height. My B is also lowered from standard and 195x60 on 5.5 fills rear wheelarch. As I need new boots, probably Goodyear Eagle, I have thought about wider wheels so any thoughts on squeezing them in would be appreciated.
Also, would a proportioning valve help with a spongy pedal, I thought they were used to prevent rear brakes locking, if rear brakes locking then a smaller cyl on rear is usual remedy.
Advice I had from Roger is that the early B master was 19mm and that the post 78 was 20.6mm which by rights would give more fluid for the same pedal travel. Willwood calipers are a very good setup so if bled properly they should work ok. My 4 pot princess calipers have 38mm pistons as a comparison but have not had the car finished yet to try out. Sorry I can't be of more help. Regards
|Hey Werner,Thanks for the compliments,I will end up doing what you did to increase the braking in the front,My rear drums are the giant stock ones that came on the four wheel drive rear I think thats what keeps the car in check..|
Here is an address from Mike Hartwig. He did the Porsche conversion and kept the stock MG bolt pattern.
He has also a "B" V8
He will be glad to help you out on this subject.
|werner van clapdurp|
This thread was discussed between 03/10/2000 and 07/10/2000
This thread is from the archive. The Live MG MGB GT V8 Factory Originals Technical BBS is active now.