Inconsistant braking

Post by **IVIUSTANG** » 23 Aug 2010, 23:30

Ever since my last brake job I have been noticing some odd symptoms with my brakes. Usually they will have unlimited stopping power and send me screaming to a stop in a hurry, other times they will make me panic that I am not slowing down very fast. All the pads and rotors are in top shape.

Sometimes during highway driving they are pretty weak(as in to the floor no ABS or screeching yet!) I have never had a problem at my elevation of 2000 feet, but when I was in Denver my brakes were a different story. They just felt weak and took a lot more foot effort to stop at TIMES. Back home they are working great once again.

Question is, does an extra 3000 feet of elevation as well as 1000 pounds of occupants render my brakes sketchy? Could there be a vacuum problem or a brake boost leak somewhere causing a variation in braking or possibly another reason?

- Jesse

Post by **phils94850** » 24 Aug 2010, 06:15

jesse... id say just alone the extra "1000" pounds is gonna make a huge difference. thats alot of extra weight !. Add that with the change in elevation im sure your brakes are gonna act different. If your back home and everything seems fine id say it was because of the above factors and nothing to worry about.

Post by **vjaneczko** » 24 Aug 2010, 08:45

Did you bleed or flush the brake fluid with the brake job? If not, how old is the brake fluid? It's been suggested that it be changed every other year.

I agree that the extra weight will require a lot of extra time/distance to stop. The altitude *may* affect the fluid if there's air in it - but that's just a guess...

Post by **IVIUSTANG** » 24 Aug 2010, 12:49

I know these cars call for Dot 4+ fluid and not Dot4, could this make a difference in the braking performance over time as it is exposed to heat if I use Dot 4?

I have bled these brakes many times because they had issues when I first did them, bought a Motive power bleeder for the job

- Jesse

Post by **IVIUSTANG** » 29 Aug 2010, 15:56

Maybe I expect to much perhaps. I am now upgrading my brakes to a big brake kit $23 brackets was to cheap to pass up at Tascaparts.

- Jesse

Post by **thecheat** » 29 Aug 2010, 19:32

Can you elaborate on this? I assume you mean taller caliper bracets and larger diameter rotors? What are the part numbers?

I hate the brakes in my 855, too. I think the previous owner's brake pads are either glazed or just lousy quality because the car just isn't in a hurry to slow down and wants to pull to the right a little bit.

Post by **IVIUSTANG** » 30 Aug 2010, 03:58

There are two part numbers of brackets, one is from a UK police spec brake package, each of these cost $55 from FCP Groton, part number 8602456. These simply were out of my moral price range for a simple bracket of this nature.

The brackets I ended up getting are supposedly from a 2000 V70R, it is an identical bracket except this one is painted rather than anodized. Part # 8251319. I ordered this part based upon speculation on VolvoSpeed as well as confirmation

> Is this upgrade what is installed on the 2003 xc70 models?

i don't know what the '03 Xc70 has for brakes so i cannot comment.

> The Carrier Bracket/ Calliper bracket, is it essentially a v70 1999-2000
> bracket as per FCP Groton?

the caliper brackets that i used is from a '00 v70r - part number 8251319. they are come PAINTED from the factory. they cost me $36 each after a hefty discount from a friendly volvo parts department manager. that was including the $10 core charge on each bracket.

the fcp groton ones(which i have installed on my '98 s70 t5, purchased from fcpgroton back in 2007) are the UK police spec caliper brackets. part number 8602456, they come in an anodized finish and look nicer than the v70r brackets... but in 6 months they will look the same while being covered in brake dust.

long story short... both part numbers will work but the v70r ones are much much cheaper, so save your money and buy the v70r brackets from the volvo dealer.

if you have the same 16" XC SE rims that i have in the picture above, you will not have to grind the caliper or install a spacer.

at http://www.XC70.com

At http://www.tascaparts.com these brackets are priced at $23 each!

The 12" rotors are all over the place, just do a car search on any automotive website for the 12" rotors. Note that this upgrade will work with most 16" rims, excluding Columbia and I believe one other. The calipers can be ground down a touch to make them fit the Columbia's.

I still consider the part #8251319 to be experimental as it was quite obscure to find information on and hardly anyone uses this bracket, I'll let you know for certain as soon as it arrives!

- Jesse

Post by **thecheat** » 30 Aug 2010, 08:10

Thanks! This sounds like the big brake upgrade for the Taurus. Lincoln caliper brackets and rotors would get you slightly bigger brakes for under $100

Post by **IVIUSTANG** » 14 Sep 2010, 23:18

Part still hasn't come here yet, international shipping. They did in fact charge a $10 core per item so it came to $33 per bracket + shipping which is still 40% cheaper than anywhere else.

- Jesse

hrahn · Post by **hrahn** » 15 Sep 2010, 01:42

The bigger rotors alone will not make much of a difference. Actually, apart from replacing the whole braking system with a multiple-caliper-system (fixed saddles) nothing will. There are many options to choose from, look at europeantuning.com and their shop for a good overview. AP even lists the kit for the 850 on their site with corresponding order numbers.
These are however quite costly and will probably be more expensive than some of our cars

Volvo themselves offered such a kit back in the days of the 850 in the BTCC, but it wasn't listed in the dealers catalogues, you had to ask for it (and better know the part numbers).
The 850 brakes are a little bit on the weak side for the more powerful versions of the car, and they tend to warp rotors when they get hot (which happens quite fast as I had to learn on some twisty mountain roads). If you use more aggressive pads with higher grip (p.ex. EBC greenstuff), you risk ruining the rotos faster when braking hard or having even less grip on cold brakes (i.e. in city traffic - having a longer brake distance due to cold brakes in front of a school is a bad thing imo).

I would suggest to go for quality brake parts, bleeding the system quite thoroughly and leave it at that. Currently running Brembo MAX with EBC Blackstuff on the front, they squeal a little for the first 4000km, but the stopping power is good. The rear is not that important (due to lower brake pressure), just don't use no-name-stuff and you'll be fine. Steel braided brake hoses don't make that much of a difference, I have Goodridge hoses all around and they didn't do a lot for the pedal feeling.

Are you sure about the DOT4+ fluid though? In my manual (T5 1994) it says something about using DOT3 or DOT4.