308 GT4 Brake pad R&R Proceedure

Hi Robert,

I did a write up at one time desribing brake pad R&R on the GT4, but not lines. The post can be found on the Fchat archives.

http://70.85.40.84/~ferrari/discus/messages/256120/265911.html

Hope this helps. Maybe someone else can report on brake line replacement?

Dom

 

Robert -

Noticed the post, and saw that Dom used Porterfield R4S pads on his brakes. I've got those in stock. As an FCHAT "DIY Special", here's a full set of pads for $100.

http://ricambiamerica.com/product_info.php?products_id=261175

R4S-AP45 & R4S-AP31

 

I'm not that familiar with the GT4 calipers which seem to be a two piston design but here's a few of tips for this kind of work generally.

1) When you replace the pads you will have to retract the caliper pistons to make space for the new pads which will be much thicker. When you do this you will normally force brakefluid back up the system which could overflow the fluid reservoir. Normally the cure for this is to use a bleed hose & open the nipple so that excess fluid exits the caliper into a jar. However, since you are planning to replace your hoses as well I'd undo these first and remove the calipers completely before retracting the pistons - should be much easier. It will also give you a good opportunity to clean them up properly

2) Before you undo the hoses, open one bleed nipple (attach bleed hose & put other end in jar to catch fluid!) and push the brake pedal halfway to the floor and then hold it there with a piece of wood wedged against the front of the seat. This will normally put the master cyclinder piston into a position that should prevent fluid from just running out the lines from the reservoir when you undo the hoses.

3) When you try to undo the hose from the fixed pipe at the inboard end be very careful not to twist the fixed pipe - sometimes these can be very sticky/corroded & if you twist it you will flatten it & probably have to replace. Soak with penetrating oil for 24 hours before you try. Have a good look at the fixed pipes (especially at the rear where they will run near the exhaust) you may want to look at replacing those back to the junction point - they should be fairly short runs of line that any competent garage could make up for you if you remove the originals & give them to them as a pattern to follow.

4) Since you will have the pads out have a good look at the dust boot seals round the caliper pistons. When I had my 328 brakes apart a couple of weeks ago I found both the front caliper dustboots had come away from their grooves - the only way to re-install is to remove the pistons from the caliper.

5) To avoid brake sqeal on new pads check the pads for any imperfections around the metal guides and file smooth any you find. Also clean the calipers (with brake cleaner) & get all the crud off where the pads meet the calipers. Also put a light smear of anti-squeal grease wherever the piston meets the back of the pad or where the pad runs in the caliper guides. A very light smear is all that's needed. You can also chamfer off the leading and trailing edges of the pads a tiny bit to help avoid any vibration (aka squeal)

5) To bleed new fluid through, first empty all the old fluid you can from the reservoir using a turkey baster or similar - be careful cos brake fluid eats paint. Then refill and bleed making sure to top it up regularly as you go.

6) Use a power bleeder is you can get one - diy ones are pretty cheap. This is better than pumping the brake pedal because that repeatedly runs the Master cylinder seals right up and down the cylinder & if that's got a little wear in it around where the seal normally travels you can blow the seal.

If you must use the old fashion pedal pumping method to bleed the fluid through then stick a bit of wood behind the pedal so that you can't press the pedal all the way to the floor - that will prevent you from going to the full range of the master cyclinder which will make it less likely to pop a seal.

Bleed from the wheel furthest away from the Master cyclinder first - the sequence is usually RR, LR, RF & then LF. You'll need to take a lot more out the first one than the other three since this will be changing the Master cylinder fluid and the fluid in the long pipe that runs to the back of the car. Plan on using around a 1.5 litres of Brake fluid at least.

Before you bleed, pump the prake pedal 2 or 3 times to close the new pads up to the disks. Since you will have a lot of air in the system you can also do a bit of gravity bleeding first & just open up the bleed nipple on each wheel in turn & let the fluid just run down to at least mostly refill the lines and the calipers at each corner before you try & close up the pads to the disks & bleed.

Lastly be sure not to get any grease or fluid on the disks or pads. If you do get some on the disks then clean with brake cleaner.

HTH

I.

 

Hi Robert

To change pads, calipers stay on the car. There are 2 pins holding each set of pads in. On rear, you need to remove a small retaining pin that goes throughthose pins. (I forget if this its the case for front ones as well).
Once you know there is no retaining pin, use a small punch and tap the pins out. The parts manual on http://dino308gt4.com shows the parts and bits.

For the rest of the process, use Iain's advice. If you end up replacing the hoses, use crows foot socket to keep the one part from turing while using a flare nut wrench on the other section. Let me know if you want pictures taken.....

 

Changing the pads alone should take you 10 minutes each wheel, including the removal of the wheel. Really easy job.

Remove wheel
Drive out the 2 pins holding the pads
Remove the pads
May need to squish the piston back a bit with a large screw driver or similar devices
insert new pads
replace the pins
Replace wheels

Repeat, test drive, and you are done.

 

on the rear you have to retract the caliper pistons with the help of the corresponding screws.
For this you first have to remove a plastic cap nut - if still there and not lost - on the outer side of the caliper and on the inner side of the caliper you have to remove an alloy screw with an allen key.

Best Regards

Martin

 

When pushing the pistons back in their bores to make room for the new pads, the fluid is forced back into the master cylinder. This can easily overflow the reservoir and make a very corosive mess. Don't forget the turkey baster routine and keep checking the fluid level as you make room for the new pads.

hth, chris