| Author | Message | ||
| BretM (Bretm)
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That would make for interesting track characterisitcs to say the least. | ||
| Martin (Miami348ts)
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what do you need brakes for? at least you have some. I just pulled the rear tires of my race car project and found that I had no brakes at all....  | ||
| 1989 328 GTS (Vilamoura2002)
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Edward, right click your mouse over the picture, then "save as..."into your PC. Now you know how to do it..... | ||
| Steve (Steve)
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There are 2 valves in the my 308 GTB. They are located under the front and you need to open an access panel from under the car. One valve is on the rear brake line and it is the bias valve. The other is just like in the picture Ed sent. It does 2 things. There are 2 spool valves in this and if you loose pressure in one circuit the spool shifts and closes that caliper of so you don't loose any more brake fluid. It also triggers the BRAKE light in the dash. You need to reset this prior to bleeding the brakes. Usually this happens when you bleed the system. I believe thats how it works. Steve | ||
| Edward Gault (Irfgt)
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#16 is the switch. Sorry the picture is so big, I cannot seem to make it smaller, another computer glitch. | ||
| '75 308 GT4 (Peter)
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Which is what Ed, #16 you are refering to? My GT4 brake system schematic shows a pressure regulating valve for the rear circuit line. This schematic is different than the one posted by Ed. My '82 Mondial 8 tech manual shows a pressure regulator on the rear circuit as well. | ||
| Edward Gault (Irfgt)
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Here is a picture of the 1982 brake system. It shows a warning switch which looks like a proportioning valve but may only act as a switch.  | ||
| Erik Lombard (Elombard)
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Steve I bled the brakes on my race car last summer after changing a bunch of components and They seemed fine when I finished. A test drive revealed they were not fine. I drove a little bit and did lots of pumping and re-bled. Tons of air came out. After that they were fine. I think when you change something in the middle of the brake system like that it can take a long time for the air to work its way out. Good first step anyway. It seems like I had a car one time where the brake lines were decomposing as mentioned in an earlier post. I could see bits of rubber and gook in the brake fluid that came out. Good luck | ||
| magoo (Magoo)
|
Peter, You might be correct. When I had the fiberglass cover out of the spare compt. I could have sworn I saw it down under the firewall attached to the frame. Maybe I dreamed it. | ||
| Peter Boray (Gts308qv)
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Magoo, Let me know what you find out, and I will do same. I am under the impression that all the 308's use the same MC and Callipers. The MC changed with the transition from 246 Dino to GT4, although the callipers and rotors stayed the same right up 1985 when the 328 got far better brakes. | ||
| magoo (Magoo)
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Peter, We are talking about the older 308 GTS. I am sure I saw a proportionate block in the line on my 79 308 GTS as I described with the little tip on top of it. I think this is also what Bret was referring to. Guys correct me if I am wrong. Meanwhile I will check again. | ||
| Steve (Steve)
|
Thanks for all of the pointers. I didn't have time to check out all of the suggestions here but I'll look. By the way I had both brake valves redone by whitepost. So maybe when I bled the system I didn't get all of the air out of the fronts or the MC for the front brakes isn't working right. So I'll check out these and also pull the calipers to see if the pistons are frozen. When I got the car last year it had sat for almost a year so maybe this is the problem. Thanks for all of the help/leads here. Steve | ||
| Peter Boray (Gts308qv)
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Magoo ! My understanding is that there is no proportioning valve on 308QV's. The brakes are balanced within the callipers and Master Cylinder setup. Correct me if I am wrong, can anyone confirm?! | ||
| magoo (Magoo)
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Steve, Did you diagnose your front caliper problem yet? Just curious. | ||
| Peter Boray (Gts308qv)
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My QV brakes , rear calliper,was seized from lack of use. Your callipers are probably frozen with rust and dirt as well. Now would be the time to renew the whole lot with new seal kits. The callipers take the same as Alfa GTV 75-86 kit. The MC kits are available from Superperformance and any local brake specialist should be able to resleeve the MC in Stainless. I just did my whole brake system myself and apart from the delay in getting the sleeved MC back, the job took about a day. Now I have brakes and even a working handbrake (for a while). The procedure is adequately described in any Porsche or Alfa GTV workshop manual, which are easy to find. | ||
| magoo (Magoo)
|
Steve, If your front calipers are not applying you will see a surface rust on the rotors. The proportionate valve could be bad or one side of the master cyl. could be bypassing and not applying pressure. I am pretty certain the valve is under the drivers side low on the frame behind the firewall area. Access, I believe is through the left front wheel. To be sure follow the lines from the master cyl. back through this area. Also to be sure, jack up the front end of the car have someone apply the brakes and see if the wheels lock up. Also check the master cyl. to see if you have fluid to the front calipers. There could be a leak somewhere and no pressure to the front calipers. | ||
| BretM (Bretm)
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They should be set heavily front biased (with the valve in the system). I'm not sure where exactly the valve is though. How do you know they're not working right? Try bleeding the brakes for starters. | ||
| Steve (Steve)
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Just noticed my 77 308 front brakes are not working correctly. Seems most of my brakes are in the rear. Looking at my front rotors it seems like they are hardly working. Car has been driven a few times a week (200 miles)and don't know when this started. Any suggestions? Steve |