Brakes - drums -> discs

[halifax]

Hi Guys,

I'm not a mechanic and I don't even play one on TV. But the key to the lock on the castle gate in FV is money. We need to keep the cost down everywhere possible. Any proposed change has to have a significant cost effectiveness or be a significant safety improvement. There are lots of better devices and systems out there, but for our class, affordability is one of the major factors that keeps the class having some of the best turnouts of any race group. I always try to sell FV to anyone who shows a flicker of interest in SCCA racing. The two inevitable questions, the two most concise questions, are always ... what does it cost for a competitive car and what does it cost to run a season?

To bring my FV up to optimum performance beyond my continuous effort to improve my driving skills, I need to have exhaust system and head work done - Dave says my torque curve is FUBAR. Big bucks to rectify. We all just went through manifold upgrades. Not sure why. My regular engine overhaul is pending. I was in the wrong place at the wrong time last June at Lime Rock. And my FV could really use a new, much lighter body. Heck, I lost 10 pounds over the off-season explicitly to improve my car's performance.

Now I admit ... I'm not a mechanic ... my mechanical skills are marginal. This increases my costs. But it's inescapable ... low cost is good for the class. Simple is good for the class.

We also need to keep guys like Dick Stewart and Jon Van de Car around to support teams like mine but that's a discussion for a different thread.

I'll follow the crew wherever it goes, but I don't want to have to run fewer races to 'keep up with the Joneses" in a marginal-value engineering race like the manifold adventure. Make sure that it's right for us in keeping costs down or improving safety. No arms races...

Respectfully submitted,
Harry
FV No. 8 / '82 Lynx/B
NW CT

[tiagosantos]

Wrong path. You are pushing $800+ (without a beam) to put on an out of production beam with weak axles and terrible geometry. The VW BJ beam parts for spindle to spindle is under $500 and that INCLUDES a beam with needle bearings. Neither will ever happen due to the lack of consensus. Stay with drums.

Jim, I just had a look at the SR FST section and the ball joint beam with disc spindles is listed at $1100.. Where is the >$500 beam? Is that rotor to rotor, calipers and all?

[SR Racing]

That price (on the SR web store) is for a turn-key front spindle to spindle HD spring pack, calipers, sway bar and ride height adjusters. Shock arms cut off with caps and new shock mounts welded on. I quoted here a parts only price, since most vee guys do their own beam work.

For example a BJ Beam with needle bearings is $220. Spindles are $70. A rebuild consists of replacing ball joints at $12 each.) (No backing plates)

Every single component is cheaper than a corresponding FV component.

Yes, wide 5 rotors for disc BJ beams are available off the shelf. (I have them.) (and they are cheaper than drums or FST rotors.

However it requires a one time investment of parts and labor. ($ Less than a single set of FV tires and the beam components last for years, not sessions.

To clarify re: the spindles, The VW BJ disc brake spindle is 30% wider in diameter and 30% shorter in length. It is not cantilevered like an FV axle. You will not bend or break one. Camber is a 2.5 minute adjustment. (If you are slow.)

Again, it's a moot point. Discs are not in FV's future IMO.

I know you guys hate this, but if you want to consider any "modernization" of the FV, put together a 3-5 year plan. (Or just go FST.) You can take some other non tested path and play for 5 years to perfect it. (losing lots of drivers in the process.) FST is here now and it works. A better handling, faster, safer less expensive car.

One of our early FST guys, had a Citation that he ran as FV and FST, He converted back and forth between race weekends in ~4 HOURS!

The conversion costs have been covered here many times and all info can be found here: http://www.formula-first.org/

With a 3 or 5 year plan, (not a stepped conversion) you can plan your costs and be ready for the full conversion. SRenault went to SRF in a similar way (with close to a $8000 conversion cost!) and the class faired well.

Don't make a Frankenstein.

Convert (and call it anything you want. FV or FST) Or, leave it alone.

[jferreira]

John (or anyone else)

Educate me - why do the spindles need to be stronger with disc brakes vs drums?
Also, if I buy the rotors do you think you could build a bracket and caliper setup that would work? I'm thinking about switching to discs for one of the NHMS regionals. After I run them they are available for any of you to try. I will be the guinea pig.
My thought is that allowing discs wouldn't increase the cost of entry in FV. Discs, as has been discussed, are heavier and would make the car slower so a driver should choose drums. If discs are allowed I would be selling 5 - 6 drums, a few sets of used carbotech shoes, and two sets of brand new carbotech shoes. Shoot if discs are legalized I will give my drums away to a new competitor.
Again, the only way I think this works - same spindles, beam, and wheels and a specified rotor material.
Thanks,
Craig

Two parts to this:
First, with shoes, your surface are of contact of lining to drum is spread out over a larger area than a disc/calliper assembley. With a disc -piston assembly, your torque arm force is applied at "one point" on the disc, and that point becomes the "leverage arm" of force.

2nd part, most relevant. With a hat assembly, you can offset the disc, so you are NOT limited to disc size. People are assuming that the disc would be the same diameter as a brake drum. Heck no, you design the disc to be large enough to provide: mechanical advantage, vs generated heat, vs smallest piston, vs least amount of rotating weight, vs smooth and consistent brake application. In our SuperKarts, the disc's are almost as large as the tires!

Now, what about floating hubs? That you machine the carrier for the wheel, to be seperate from the carrier of the disc. In this way, I can adjust my front end tracking by being able to slide the wheels in or out .... getting kinda complicated?
I viewed the video on what is available, even the "not so good" stuff. Never use callipers that have a piston and anvil assembly where there are slider pins. If you use a single piston unit, make sure the anvil side bolts directly to the piston side. Most units can be shiimmed.

Can I make you a bracket to test? That is a lot of work because it also includes the bearing pockets and a LARGE carrier for our 5-wide bolt pattern. The design of this would most likley make the rotor and wheel carrier a 2 piece design.
I can and will bring an assembly, probably a Wildwood to the track this weekend.
I think that you are oppening up an area that could get very costly. A lot of testing would have to be done, in order to come up with a VERY LIMITED set of rules and options.
I say stay with drums.

john

[Matt Clark]

*muffled voice from back of the room*

".... convert to FST specs"

[RickyBobby]

What brake setup do they run in Canada, UK, rest of the world? Seems what they use works real well. Think it might work for us?

[craigs]

John F - thanks for the explanation and emails.

It appears that the one technical road block could be that the forces created by the shoes on the discs could be too much for our current spindle setup because it would be located at one point rather than spread over a wide surface area. All "coulds", not actually happened that we know of?

The other issues of cost or "just convert to FST" I do not believe apply. As has been discussed the disc setup proposed is heavier and therefore would make the car slower. Discs as specified are not a performance advantage but rather a convenience that some drivers would be willing to pay for but most would not - either in dollars or speed. I appreciate the FST drivers pushing FST, but even I do not see that happening right now.

All I want is the the same beam, same wheels, same spindles, Willwood Dynalite calipers, and a specified rotor material. This would provide a much larger availability of brake pads/shoes, reduce the amount of prep work necessary to get on track, and allow easier troubleshooting.

Also, we hate to admit it, but FV has an image problem too. What's more appealing disc brakes or drums to a 16 year old kid? The first drum equipped car I ever had was my FV. IF we had new young drivers coming into FV the only time they have ever seen drums were on their grandparent's cars. Discs vs. drums - which one do you guys think a driver less than 30 year old has seen before and which one will he laugh off as "old school"?

[awhitston]

Maybe I'm missing something. The stopping power of the drum brakes is not an issue, and most likely leads to lower lap times in our cars than disc brakes would be due to the weight penalty of the disc system. Is the main reason this is being discussed is because we don't want to spend 10 minutes on a double weekend to adjust the shoes? It seems like a pretty minor issue considering all the other prep work that goes into getting any race car competition ready.

As far as making a vee more appealing to 16 yr olds, I dont think drum brakes have much to do with that conversation. I find FF, FE, FC, FA cars all more appealing and braking systems have nothing to do with why I'm driving a vee. The conversation for a 16 yr old deciding which class to run usually begins and ends with "Dad, can you write out $30K worth of checks so I can run FF this year?" (In my case, the answer was no.)

[tiagosantos]

Like some of us have been saying, I feel it's important that the drum brakes remain the clear obvious choice for winning the runoffs. If you don't mind the characteristics of drum brakes, and the price of shoes - fine, keep them and you lose nothing. Those that hate them will happily get rid of them and pay the slight lap time price or whatever for the privilege.

As for making the class attractive to 16 year olds.. That boat has sailed a long time ago haha..

[fvracer27]

Maybe I'm missing something. The stopping power of the drum brakes is not an issue, and most likely leads to lower lap times in our cars than disc brakes would be due to the weight penalty of the disc system. Is the main reason this is being discussed is because we don't want to spend 10 minutes on a double weekend to adjust the shoes? It seems like a pretty minor issue considering all the other prep work that goes into getting any race car competition ready.

As far as making a vee more appealing to 16 yr olds, I dont think drum brakes have much to do with that conversation. I find FF, FE, FC, FA cars all more appealing and braking systems have nothing to do with why I'm driving a vee. The conversation for a 16 yr old deciding which class to run usually begins and ends with "Dad, can you write out $30K worth of checks so I can run FF this year?" (In my case, the answer was no.)

Exactly

[hardingfv32-1]

Maybe I'm missing something.... Is the main reason this is being discussed is because we don't want to spend 10 minutes on a double weekend to adjust the shoes?

Yes, you are missing something.... The reason that this is being discussed is the questionable availability and high cost of top grade brake shoes. 2-3 brake shoe replacement cycles is the same cost as of a disc conversion. Disc pads are very cheap and could last many seasons. At the rear you eliminate the problem of cracked and stripped rear drums.

Brian

[BLS]

Brian, do you, or anyone else, know for sure the available rotors will stand up to the current g forces? Most of these seem designed for street cars. Might be OK, probably is OK.

[smsazzy]

Last I checked, the drums were designed for street cars too.

[BLS]

True, and they do have issues...

[fvracer27]

Last I checked, the drums were designed for street cars too.

And we know what happens to chinesse drums when we run them on our cars.

The eaiest thing I believe would be just to allow Ball Joint beam to be run and take a weight penalty if any. If you want to run it you will have to realize it's not just a bolt but not difficult. You would also be required to run VW 4 lug wheels which are easier to come by than ours. As Jim stated before why throw hundred or thousands to develope a kit on a link pin beam we can't get.

[RickyBobby]

What a great way to transition to what "the rest of the world" is using, and with great success.