I'm thinking about eliminating the stock diagonal braking setup and replumb it so the rear port of the master cylinder works the front brakes and the front port of the master cylinder works the rear brakes with a adjustable proportioning valve. My 86 Daytona has the complete 11 inch setup from a 89 Daytona Shelby and I think proportion valve is going bad, the right rear locks at will. What do you guys think?
[SIGPIC][/SIGPIC] 86 Daytona Turbo Z C/S with a full 89 Shelby swap, back on the road and soon to be painted (and lose that Oggie Fisher black) 83 Porsche 944, 5 speed, all stock. 2014 Toyota Tacoma 4x4, 5 speed, daily driver. 2017 Trek 1.2 bicycle.
that would be cool, but wont fix your problem. you need to figure out "why" your rear brake is "lockin" up in the first place.
id need a better description of the problem though, are you saying your brake locks up when applying the brake, does it stay locked up after you apply the brakes, does it stay locked up all the time, does it lock up while driving without using the brake?
I might have been over stating the lock up. If I try a rapid stop, I can feel the rear tires losing grip. I would just like to dial out some rear brake. I'm being a bit unfair to the FWD Daytona here, my 944 Porsche has 51 percent of its weight on the rear wheels and honestly, the Daytona is the better handling car of the two. I just like to get the Daytona's braking as good as the Porsche's which might not be possible with the Daytona only having 39 percent of its weight on the rear tires. But I'm definitely leaving some braking performance on the table.
[SIGPIC][/SIGPIC] 86 Daytona Turbo Z C/S with a full 89 Shelby swap, back on the road and soon to be painted (and lose that Oggie Fisher black) 83 Porsche 944, 5 speed, all stock. 2014 Toyota Tacoma 4x4, 5 speed, daily driver. 2017 Trek 1.2 bicycle.
I don't see a problem with what you are doing. I think the only way to truly dial in the braking the way you want it is with an adjustable rear prop valve.
For what it is worth I'm kind of doing the same, but I'm using individual Wilwood master cylinders for the front/back with an in cabin adjustable prop valve for the rear brakes on my Rampage. Itll be a while before its road tested though.
Sounds like a serious brake setup!Originally Posted by 83rampage
[SIGPIC][/SIGPIC] 86 Daytona Turbo Z C/S with a full 89 Shelby swap, back on the road and soon to be painted (and lose that Oggie Fisher black) 83 Porsche 944, 5 speed, all stock. 2014 Toyota Tacoma 4x4, 5 speed, daily driver. 2017 Trek 1.2 bicycle.
!!!!!!!!!wow!!!!!!!!
when i tried that, it felt like something bottomed out in the master and i had almost no brakes.
so i basically teed the master cylinder outlets together and then divided it back to the front brakes and rear brakes with a single wilwood adjustable proportioning valve on the rear lines.
i went out and hammered the car till the fronts faded a touch and the rears locked up and then backed the rears off till it wasnt sketchy.
works mint now.
Brian
Why not simply use a proportioning valve from a different car with the setup you want.
Or a new fancy one like this?
http://pages.ebay.com/link/?nav=item...549021&alt=web
Wayne H.
'91 Dodge Spirit ES 2.5L turbo 5spd
'05 PT GT 2.4T HO autostick (RIP)
'89 Plymouth Acclaim 2.5L turbo auto, "Slugmobile" yes, THE Slugmobile!
'89 Dodge Caravan SE 2.5L turbo auto, "Mean Mini" yes, Gus' Mean Mini! (Current best 11.699 @ 114.43 mph! - Oct 15th, 2022 Cecil County Dragway, MD)
MeanMini dragracing videos: https://www.youtube.com/playlist?lis...URZLB1RxGYF6vw
and other cars, trucks and motorcycles
https://www.youtube.com/user/SlugmobileMeanMini
whatever you end up doing remember you HAVE TO HAVE a pressure warning switch on the brake system if you're intending this to be a street driven car as it will fail any safety inspection without it
Good point. The combination prop valve mentioned by wheming has the warning switch incorporated in. This is the proportioning valve I plan to use (or similar).
Based on great past experience by Aries_turbo, when it comes to your braking system, proceed with caution as this is a fundamental safety system for your car and can get unexpected results for what seems a logical mod.
I really regret initially commenting at this point, simply because at the end of the day my comments have no engineering basis, and sending someone off in a certain direction can have unintended consequences.
Last edited by 83rampage; 03-09-2017 at 02:51 PM.
Thanks everyone who responded. When I first thought of this I thought it was a great idea. I've decided not to go through with this mod. There's several safety issues that was brought up to me surrounding this modification and I also received a PM on the safety benefits of diagonal braking system. So a thank you to all those who took the time to respond, Marc
[SIGPIC][/SIGPIC] 86 Daytona Turbo Z C/S with a full 89 Shelby swap, back on the road and soon to be painted (and lose that Oggie Fisher black) 83 Porsche 944, 5 speed, all stock. 2014 Toyota Tacoma 4x4, 5 speed, daily driver. 2017 Trek 1.2 bicycle.
i dont think the diagonal setup on these cars is that good anyway.
every time i popped a line, i lost pretty much all my brakes and had to use the e-brake. that little sliding valve didnt work all that well.
but be careful anyway with brake mods. test it out away from people. i tested my stuff on a dirt road near my house where no one is.
Brian
I have also had a brake line failure lead to a crash with a concrete post, because the diagonal split system isn't all it's cracked up to be.
My braking system is the 4 wheel disc master cylinder, the front port splits to both front brakes, the rear port goes to a manual proportioning valve, and splits to both rear brake. It works perfectly with my brake system (all 4 corners are front brakes with 1 pin calipers) and once it's tuned in, there's nothing to worry about.
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