Slow release with brakes

[LanciaFin]

Hello,

Braking system on my Flavia was completely refurbished before registering the car on 2017. Well, almost completely, because the valve assembly was only painted and booster was put back together with original diaphragm. All other parts were dismantled, cleaned, and put together with new seals. There has been absolutely no issues until now. The issue is, that the brakes release slowly after applying brakes - the harder the braking, the more pronounced is this "binding," taking 1-2 seconds until the brakes are completely released. It is clearly induced by the hydraulic system, because there is no binding with the calipers (well, except for little chirping sound when turning to right, appeared this year as well) and in no moment is the car pulling to any direction.

The brake fluid has been replaced every two years, and there has been no loss of brake fluid or any other troubles. Well, possibly the assisting effect of brake booster has been less than before, but that is difficult to say without any comparison.

Winter hibernation is coming, so there would be time to order parts, if required. Anyone, who has had same issue and found a solution?

BR,
Miika

[grifo63]

Hi LanciaFin, no I never had this problem, it look like due to some friction, most of the breake parts are in oil so it seems unlikely they can have this abnormal behaviurs ; if you already excluded calipers another good candidate is the main booster cylinder which may be rusty inside and create frition with the piston when its has to return.

[LanciaFin]

Well, the booster shouldn't be rusty, because it was entirely zinc-plated during renovation. Maybe it could be possible for it to have some internal friction, even though brake rubber grease was applied to sliding parts. Considering that the diaphragm is an original (!) part from late 60s, maybe it has swollen as a result of incompatibility with rubber grease?

Probably there can be worse ideas than finally renewing it, so in the winter time I'll try to find a replacement from somewhere.