924Board.org

[Minhiriath]

whats the minimum parts required to do a 5 bolt switch over from 4 bolt.

[Paul T.]

RTFAQ!

[coconutcowboy]

I will soon be getting a setup from an 84 944 if that interest you.

Sean Ross

[gohim]

In case you didn't figure out what Paul T's message was, it was "read the FAQ".

The brake conversion is a simple bolt-on job that can be easily accomplished in less than a day, as long as the correct parts are obtained, and prepared in advance (replace caliper seals, headware, and pads as necessary).

The Technical Section as an article on the conversion that is a little short. If you are serious, email me directly, and I can give you more detailed instructions.

You should budget $300-$400 for the used parts that you will need (not including wheels), $150-$250 for replacement parts, and supplies (caliper seal kits are $10 each, assembly lube, brake fluid, brake hardware, brake pads, cv joint grease, grease, and oil seals). You will also need to buy a set of five bolt wheels (a set of 15 X 6 924S phone dials cost me $250 (plus shipping), and 15 inch tires (if you are not already running 15 inchers that you can move to you new wheels).

[eturbo924]

I am going to part out my 83 944 starting next week. I need to give the potential friend who wanted to buy it until then.

Anyway I have all the parts some one would need to do the conversion. Come and take the parts off and save yourself ship charges.... anyone in the NE area I am in Mass. Cost for the parts smack dab in the middle of the quote above. Say $340. Do not have wheels for you though since I have Fuch Alloys that are going to go for much more than the cost of the brakes.

Also have a 5spd with Limited slip dif. Price will be $750.

Anyway I will put a post in the parts section next week. But if some one wants to get in an early bid give me a shout. Best is if you could come and pick the parts up.

Eric
Eric.Lynch@itt.com
Eturbo924@yahoo.co

[Minhiriath]

I don't recall seeing that info in the faq the first time I read it before the board was switched over to this new setup, but I now see that it does, and a whole lot information that could be useful.
*hits the print button*

Min

[friskynibbles]

bad bad min
when ya gonna come stare at my shifter?

[larso]

It's cool to do the 5 bolt swap to "say you've done it" but in my opinion, if you don't have very much time, and don't RACE your 924 with a 450 HP engine..the drums are just fine. I only like the Disc brakes because they are easy to maintain. As for performance, drum brakes are just as good as disc brakes. You only would notice a diffference if you were a freaking formula one driver..a brake is a brake...disc brakes also look cooler...Again, I mainly like them because they are eaier to maintain, not because they help me stop a lot better.

[924 turbo]

I hear this brought up a lot. Is the 5-bolt swap worth it or not? Every time this is asked, people say "well if you don't have (insert ridiculous horsepower number here) you don't need them".

What does braking have to do with horsepower? Unless you're using that horsepower to achieve speeds higher than are possible with a stock car, I think the argument is erroneous.

Now, I'm no engineer, so bear with me.

AFAIK, braking comes down to four things:
Braking friction, tire friction, weight, and heat dissipation.

A car with massive clamping power but the same tires would have almost no improvement in braking performance, and in fact could be more dangerous as it may be easier to lock the brakes, especially in a panic situation. It would be too easy to overcome the tire friction with the braking friction.

So clearly, a brake upgrade is essentially a waste of time for those of you who would continue to use h-rated 185's on 15x6 wheels.

If you are planning on upgrading to larger, lower profile tires with a softer compound, you can benefit greatly from the higher clamping power of the 4-wheel disc system.

No matter what tires you choose, the 4-wheel disc brake system has superior heat dissipation capabilities. If you do a lot of canyon driving (with lots of slowing down over and over again) the 4-wheel disc brake system is a virtual necessity. It may save your life. Of course, so would slowing down.

If you do any spirited driving where you will be braking over and over in a relatively short period of time, I recommend the brake upgrade.

If you have a car loaded with 400 pounds of stereo equipment, I recommend the brake upgrade.

If you do any multi-lap racing, I recommend the brake upgrade.

If you want bigger, wider wheels, I recommend the brake upgrade.

If you like the bling-bling painted caliper look, I recommend the brake upgrade (painted drums are so tacky).

I only wouldn't recommend the brake upgrade to people who can't afford it (it's almost $1000 with wheels, although it can be done for as little as $400), people who cannot complete it on their own and are unwilling to pay someone to do it, and those who think an H-rated 185/70-14 is an adequate performance tire for the 924.

Where does horsepower fit into all this? I have no idea. Maybe an engineer could fill me in on what I'm missing.

[gohim]

The biggest gripe that I had with the rear drum brakes was the fact that they are not self-adjusting.

Since the rear drums were not self-adjusting, it seems like they were always out slightly out of adjustment (except immediately after I crawled under the car to re-adjust them. As long as the rear brakes are not adjusted properly, the car did not brake as well as it could have, regardless of the tire size and type.

On a 924, regardless of how you use your car, if you have rear drum brakes, you will almost never have full braking capability.

Changing to four wheel disc brakes will make your car's brake performance much more stable and reliable.

You can buy the parts over time, overhaul them, and store them, until you have accumulated all of the parts, if the $1000 buy in fee is too steep for you all at one time.

If your 924 is your only car, this would probably be the most prudent way to complete the conversion. Build a checklist, collect the parts, overhaul, assemble, and store what you get, as you get it. This way, you will have all the parts ready to go, and you won't end up with extra downtime after starting the conversion to rebuild, the used components when you find that you need replacement seals, hardware, or parts.

When I had rear drums, tire friction was never the problem, either with my earlier 77 924 with 14 X 6 factory wheels, or my 81 924 with 15 X 6 factory wheels. The problem was always poor brake pedal consistancy, and poor clamping/brake force due to the rear drums being out of adjustment. There was always the question of how far the brake pedal would sink, before the pedal would firm up, and apply the brakes.

The conversion to four wheel disc brakes has improved overall car performance because now, when I drive into a turn, I know exactly how much brake I have available, and exactly when, and how, it will be applied when I step on the brake pedal.



[ This Message was edited by: gohim on 2002-06-18 01:05 ]

[ This Message was edited by: gohim on 2002-06-18 06:25 ]

[924RACR]

As a brake engineer:

Jon is quite right about the limits of the drum/solid rotor system. They're quite acceptable for street driving. The braking limit is determined by the tires, not the brake system, except for possible different proportioning for the rear circuit (I haven't done the calculations, and really don't care about it).

However the maintenance does suck as compared to the discs. This, pedal feel, and heat capacity are the differences between the two systems. The first two, as far as motivation for a brake upgrade, are for each and every one of us to decide on. The last is also for us to decide upon as a function of intended use.

Personally, I hate having to screw with my brakes on a regular basis, I feel that every Porsche should have a high hard brake pedal, and I race wheel-to-wheel for about 15 miles at a time. My outstanding reliable brakes are one of the many factors that enable me to do as I wish with my competitors. I feel the same for my street cars, though acheiving heat soak is far less likely - a fact I know having driven thermocoupled vehicles on the street.

The upgrade is by no means manditory. It sure is nice, though!

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[larso]

More horsepower means you drive faster, accelerate faster. I've driven a 931 with drums, and a 931 with disc brakes. hey both stop the same. People have this "false" idea the all drum brakes suck. DRIVE a 931 with drums, and DRIVE a 931 with discs. They both stop the same! A brake is a brake. TOO sensitive disc brakes, will cause you to lock up you brakes. In some cases, a less sensitive, more modulation drum would be safer than a PUMPED UP 928 brake set up. Personally, I've driven a late 90s new honda civic, that has VERY sensitive brakes...Your foot can only have so much skill and ability...too much sensitivity means that your foot must be a gift from God to handle sensitive brakes. When travelling at high speeds, pressing on a very sensitive, not much modulation, no air in the system brakes, you can KILL yourself. You lock up the tires, and spin out, and die. A less sensitive system will allow you to have more testing area in the pedal, before the brakes lock up...I enjoy a car with nice firm brakes, BUT NOT one that is VERY sensitive, that will kill me. The 924 brake system, disc or drum, is not very very sensitive...from my experience anyway (I haven't driven a NEW 924).

As for HP relating to braking, really I was just giving an example. It;'s not a direct relationship, it is a simple example, and easy way to post an easily understandable relationship on this message board.

If you have more HP, you have more acceleration, and you have more speed. This means more braking. If I have 450HP in a 2900 pound car and am traveling 0-60 in 4.9 seconds, I sure as hell want to have really good brakes, incase a bloody deer runs out in front of me! If I have 105 HP, 2900 pound car, I don't need to have as good brakes to avoid hitting the deer. See the relationship? No engineering or engineer needed.

Think about why the AC cobra was able accelerate and stop in less than 8 seconds (or whatever it was). Now think about if that car had crappy brakes....it would slam into a dear pretty hard, or SPIN OUT on the race track when it tried to brake for a turn. No HP and braking are not a direct relationship, but it's a pretty close relationship if you have some controlled variables (such as car weight).

I don't know if it's the fact that the 924 handles well, that people think they need disc brakes, or what. Just drive a car with drums, and drive a car with discs. Slam on the brakes, and try it out. THERE REALLY IS NO NEED FOR DISC BRAKES for performance reasons for street.

IF YOU NEED dis brakes for street use, you are driving way to fast and have a death wish!!!

But as mentioned, discs are much nicer looking, much easier to work on, and much easier to adjust. I love them.

[Cbass]

Now I'm not sure exactly how fade resistant the disc/drum brake setup is, but I have experience with other similar arrangements, and brake fade is not fun. Especially not if something jumps out on the road while you have little braking power.

[Minhiriath]

then there are those of us who just want the better rim selection that the 5 bolt disc setup provides. kinda hard finding nice phone dials for a 4 bolt setup.

Min

[gohim]

At one time ATS did make 4-bolt phone dials. I think the going rate was around $600 a set.

But they've been gone for years..

The 2nd reason why I wanted to convert my car from four bolts to five, was so that I use a set of 15 X 6 phone dials on my 81.

I only paid $250 with the caps and the lug nuts, because I was will to take a set with bad pair, since I was planning on powdercoating them the original silver color.
Powder Coating cost me $160 for (4) wheels, and (5) center caps (I wanted a spare). The shop also did some other work for me for free, at the same time.

The brake conversion and the wheels came out great. The only mistake I made was buying Pirelli P600s. They suck. I shoulda gone with the Dunlop D60A2 like I did on my Taurus Wagon.

[ This Message was edited by: gohim on 2002-06-21 05:38 ]