Like you said bro, 3.0L disc are thicker and firmer. Feels better during high speed braking . More confidence mah.
New year resolution for the feilo .
- Get better braking systems
- Firmer and lower stances (but not rock hard !)
- Replace all the bushings such as : Sway bars, lower controls arms, tie rods, etc for a more firmer but comfortable ride .
Rotary ? I used to wet my bed dreaming about rotaries, hahaha.. Just joking. Can't afford an FC. Used to own an RX-2 & SA. Both have mild ported rotaries with original carbies! Rubber burners on demand! Those days , we were only using thirteens but my SA had 225/60 X 13s !
Tires were not cheap back then. Cost me rm250-00 per tire! BUt the thrill of smokin a BMW 3 series and pissing off the driver was priceless!
Reason for selling; High petrol cost ! Used to live around Kelana Jaya Area. Not enough petrol for return trip from KL during Saturday Nite outing on a RM20-00 leaded petrol ! And that was 10 years ago! Moreover not many mechs have proper knowledge to repair the 12As or 13Bs locally.
Ok, coming back to the feilo thread. How come my brakes felt spongy during sudden but slow braking? Is it due to air bubble trap in the sytem or my servo pump is about to kaput. Taughts?
TIA
SB3.
It could be that the master pump is failing. To check if it is failing. With the engine on put the car in "D" with A/C off and hold the brake pedal down with firm pressure. Once you hold it there. STOP. Keep the pedal there with the same pressure. If the pedal starts to creep down to the floor, the seal in the master pump is worn and the pump needs changing as soon as possible. Rebuilding the master pump is not advised. New Nissan pump about RM700 taiwan about RM200. A friend said not to use taiwan cause he had a bad experience with it but it was in a volvo.
If the pump is ok. Then you need to change brake fluid and bleed it properly.
Another reason also could be just that you are using standard brake hoses. Standard brake hoses are made of rubber and they expand when you apply pressure which gives the spongy feeling. With the teflon brakes hoses, the plastic teflon hoses do not expand at all so there is no brake pressure loss due to hose expansion. The steel braid is just there to protect the inner teflon hose.
Servo pump failing? You mean to say servo vacuum booster right. If that is failing, it will the the opposite as it will get harder to press the pedal as there is a vacuum leak in the servo thus there will be less assistance from the servo. Just like when the engine is off and there is no vacuum the pedal becomes hard to press. So no I don't think its the brake booster failing.
Most of my experience with spongy brakes. First I check if master pump is ok, then I would change brake fluid and bleed properly as air in the system will cause the system to be "soft" as air is compressible but liquid isn't. Then I would get a set of teflon steel braided hoses.
I would also make sure that the rear brake pads are adjusted properly. For that, most people cheat and adjust the parking brake cable. But to do it properly you need to open up the rear caliper and turn the piston out as the rear caliper pot/piston has a special design. You need to turn it out enough so that the wheel can still spin freely but not stick. As a guide the hand brake should have only about 6-7clicks, anything more its too loose. Anything less its too tight.
Then its just pad thickness and disc thickness. If its worn you brake travel will be more.
Just for your info my A32 3.0L brake system consist of:
Standard calipers, new TRW discs for 3.0L, new Bendix GTC pads (front) rear 50% left. Teflon brake hoses. New brake fluid.
Most of the time sudden spongy feel is caused by air in the system and or failing master pump.
1. check master pump
2. change fluid and bleed properly
3. check pads, discs and parking brake are all with in spec.
4. change to teflon hoses.
As you described your problem as sudden spongy feeling when slow braking e.g. when crawling in traffic jam or talking on HP and driving (hahaha) or moving up to a juction. then i would check the list above.
If its general sponginess even when hard braking, its caused by
1. Air in the system
2. Expanding of standard brake hoses
3. Brake pad material is soft which will compress slightly when under clamping pressure
4. flexing of the floating caliper (also caused by worn floating caliper pins)
5. Poor material and design of caliper which cause caliper to flex.
But No:3-5 will not be your problem as my brakes works well and is really nice and firm.
80-90% of the time its either master pump failing, air in the system or worn out discs and pads.
New cars from the factory with factory stuff don't usually have spongy brakes. Well they do lah when you compare it with teflon hose setup. But when you compare apples to apples its usually pending master pump failure and air in system. As I said most of the people out there don't know how to bleed brakes properly and the stupid vacuum bleeder only does 80% of the job as my car with new pads, discs, parking brake adjusted, teflon braided hoses still felt spongy in the first 10% of brake travel with the stupid vacuum system (but no choice lah 1 man only). So try those things out first then come back with more feedback on how its going for us to help you out.