LeMons Barber MotorSports Enduro: Breaking the brakes

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FJCamper
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LeMons Barber MotorSports Enduro: Breaking the brakes

Post by FJCamper » Wed Feb 14, 2018 12:28 am

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RETRORACING vs BARBER MOTORSPORTS PARK. BREAKING THE BRAKES


02Feb18; Fri. Barber LeMons Track Day. The Barber track, home of the Porsche Sport Driving School, is a real beauty, modern, clean, and well equipped. It is also the only world-class track (besides the Daytona-clone Talladega) within an hour's drive or less from Birmingham.


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Above: The tiered paddocks at Barber, fully air conditioned in the winter, sun and baking asphalt heated in the summer.


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Above: As usual, the Blitzwagen is equipped with a dry sump 2.2 litre Type 1 engine, 40mm intake valve DRD heads, 44mm Solex (Kadron) carbs on 34mm venturis, and a SCAT C95 cam. The big difference out this time is our transaxle. We've replaced our trusty 3.88 r&p unit with a 4.12 close ratio 3rd and 4th. Last, we've plumbed in a second oil cooler in the driver's side rear fender scoop.


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David is first to take the Blitzwagen out for a test run, followed by Jamie, then Hawk, Dr. Steve, and Justin. All like the newly-installed close-ratio transaxle. And all say this is the best the Blitzwagen has ever run. Only Dr. Steve cites possibly spongy brakes but only possibly. He likes the performance so much he doesn't want anything changed.


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Above: LeMons mandated head and neck restraints. which are commonly csalled Hans devices. But Hans is a brand name. We use an SFI 38.1 Head-And-Neck Restraint from Z-Tech Sports Series 1A.


While the front tires are off for tire swaps I note the front Wilwood B10 brake pads are at about half life.


The weather is clear, windy, and freezing cold. Our oil temp never passes 190° F. all day. We've taped off the new aux side pod oil cooler.


At tech, we are told to reweld a couple of places where the roll cage contacts the cabin floor, slot the driver's seat to relocate the driver's harness submarine belt, and add a "tow" decal or marking to the engine cage. We do all this with Dale Sale's local shop help and pass tech by 1700 hrs.


SATURDAY


03Feb18; Sat. Barber Lemons Race Day. Again, cold and clear. At least 99 cars are due to start. But before the race even begins David discovers the left rear brake hub is loose on the stub axle splines. Spline failure knocked us out of class wins twice before, once at CMP May15 and once at Barber Feb17. Both times we were running 3rd, closing on 1st in class.


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Above: David feels the left rear rotor is loosening.


The difference now is we have CB brakes with chromoly center hubs, not stock cast iron. David drives back home to Talladega to grab parts. Justin and Jamie tighten the axle nut (300+ ft lbs) with shims to take up the slack enough to allow the car to race. The green flag goes down at 0930 hrs. Dr. Steve is out first.


Steve quickly has the Blitzwagen running fast and hard. He turns an astonishing 1.59. Last year here his best time was approx 2:10.


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Above: The race is on. Here, the Blitzwagen drafts a BMW, as close as NASCAR but in a much more confined space.


Hawk goes out next, feeling as if he were just cruising fast, and cuts his last year's time by about 5 seconds. By 1200 hrs we are holding 2nd in C Class.


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Above: Between a 944 and a Bimmer,the Blitzwagen is diving for the best line in the next turn. Steve bragged about passing groups of cars.


Then Jamie logs faster laps, just cruising. David goes out and gets a very fast 1.57. Justin is also seconds quicker than last year.


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Above: Side by side with a big MOPAR in the hairpin. This type of close racing takes big chrome balls.


However, endurance racing is not all about lap times. It's about lasting. Because of the cold weather and our new secondary oil cooler, our oil temps have stayed at about 190° F. , just barely hot enough


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Above: Towards the afternoon, using the spare parts David has provided, we have to swap the chromoly hub with a rusty old spare cast iron rotor hub. The chromoly hub has begun to wear out its splines. I say again begun to wear out its splines. While we are swapping rotors, we also note the rear R4 brake pads in the ATE/VARGA calipers are badly worn and change them.


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By the end of the day, 15 minutes before the flag, David (on his second run), suddenly brings the Blitzwagen in. The old cast iron rotor hub has actually broken loose, its center hub (and splines) still on the stub axle.


We finish Saturday in 3rd in C, 44th place out of 99 cars, having run 162 laps. The first place C-class car has 28 laps on us.


SUNDAY


04Feb18; Sun. Barber LeMons Race Day. So far the race has been dry, but this morning it's misting rain. We hope the rain will slick the track enough to let our tires spin and slip a little, on the desperate guess that we have too much grip and that's causing our brake hub failures.


David has our last brake hub installed. We start the race within striking distance of a class win.


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Above: The Blitzwagen's new profile shows up here. Look at the 911 on the lower track behind us. That's actually, in full LeMons tradition, a 911 body on a custom chassis with a turbo diesel engine. It was also a class C car. It set a fast lap of 2:00 and finished with 345 laps.


Our driver's take turns running smoothly, the track wet as light rain blows through across the hours.


This race has been relatively tame, with only minor fender-benders, some lost wheels, a few blown engines, but no crashes. Our only damage is the loss of two stingers, both with insert baffles. One was knocked off in traffic, and the other failed at the bolt flange because of vibration caused by the weight of the baffle. We ended up the race with an open (and illegal) stinger.


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Above: Tightening the rear axle nut again


Finally, two and a half hours from the final checkered flag, we start to lose time, with one pit stop to retighten the left rear axle nut, and one (as the afternoon warmed) to pull out the shop towel and duct tape we'd used to block off the new aux oil cooler when Justin pitted to tell us the oil temperature had risen to 240° F. That's where it should have been running that hard, but he'd gotten used to 190°. He been going for broke, late braking, sliding the Blitzwagen, rotating it to get sideways weaving through traffic.


After a few minutes, Justin is back in again yelling something about "No brakes." David pulls the left front wheel and we see brake fluid dripping from the Wilwood Dynalite 120-6808 caliper. David clips the caliper pad retainer cotter pin, and pries out the brake pads with a big screwdriver. One has a piston welded to it. We have new pads, but no replacement caliper.


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Above: The big Wilwood "stock car" pads are for a much heavier car than the Blitzwagen and wear slowly on us. The only explanation we have is our significantly improved performance was taking its toll on the brakes.


Even losing about four hours, we finish 68th overall, 223 laps total.


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Above: The 250hp Super Bug finished close behind us at 71st overall, totaling 212 laps with a 1.52 best lap.


This race is a loss, but we consider it a milestone. The Blitzwagen has risen to the next level of performance. We're on average five seconds a lap faster, per driver, than last year at this track.


David flat tows the Blitzwagen home with him. We are all pondering the brake hub failure. We're blaming it on bad stub axle threads. A new chromoly stub axle in on the way.


***
Winner A Class: 1991 Mercedes 300E
Winner B Class: 1987 Toyota Corolla FX-16
Winner C Class: 1964 Pontiac Banshee (348 laps)

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GS guy
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Re: LeMons Barber MotorSports Enduro: Breaking the brakes

Post by GS guy » Wed Feb 14, 2018 8:17 am

Great write up as always FJ. Love to hear the trials and efforts you guys go through following your passion!
FWIW, when I had a set of 944 stub axles modified for T2 CV joints (by Precision Allow, excellent work) we discussed the amount to torque the axle nuts. In my mind, the more the better, but Todd said he had see them start to separate at the axle to CV flange connection from over-tightening. This may be an area you want to scrutinize carefully when rebuilding the hub assemblies, maybe establish a stretch dimension like rod bolts?
Also, did you notice any (extremely minor) play between the chromoly hub and stub axle during initial assembly, like the hub splines were slightly oversize? I noticed this with mine, on the 944 stubs, which I cross-checked with a set of old German drums which has a tight-sliding fit, so likely it's not the stub axles.
You guys definitely limit-test your equipment, definitely appreciate sharing your findings!

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Re: LeMons Barber MotorSports Enduro: Breaking the brakes

Post by FJCamper » Wed Feb 14, 2018 9:38 am

You have some valuable tips there. We run Type 1 CV joints on the Blitzwagen and Historic Sportscar Racing Ghia because neither car exceeds 150hp, we don;t do drag-racing starts, and we want the lightest rear-end parts we can use. We've never broken a CV in 17 consecutive seasons of racing.

Stub axle flanges separating from over torquing? That's scary.

Thanks,

FJC

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Re: LeMons Barber MotorSports Enduro: Breaking the brakes

Post by FJCamper » Wed Feb 14, 2018 10:45 pm

Anyone else had this type of hub failures? FJC

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Re: LeMons Barber MotorSports Enduro: Breaking the brakes

Post by woodsbuggy1 » Thu Feb 15, 2018 6:10 pm

Thanks again for the great write up, sorry to hear about your problems.
I have seen the cast hub/rotor assy fail many times off road. The only way I have seen that setup work is with floating calipers, otherwise the rotor always seems to break at the splines.
Maybe time to think about micro stub setup? Quite easy to fab brakes with common, non VW parts.
Kenric
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Re: LeMons Barber MotorSports Enduro: Breaking the brakes

Post by GS guy » Thu Feb 15, 2018 8:07 pm

Mendeola (aka coolrydes) now makes a good looking aluminum rear hub assy - as part of their rear brake kit. Not sure if they'd sell the hub separately? I don't like that there is 0 comparison, reliability or other testing available on their components. I've read about a couple of light duty street car reports (all positive BTW), but no serious performance testing that I've been able to find. They "look" fantastic, but on a race car, we all know looks are way down the list! Could definitely be a lighter weight option for the hub. I went as far as fitting the Wilwood Al hat, matching steel rotor and Al caliper to "add lightness" as much as possible.
What would be slick is if someone could come up with a cartridge style bearing, that could be fitted to IRS rear arm and retained with the C-clip - then install appropriate "micro-stub" style hub and inner axle that fit the bearing. :idea:

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Re: LeMons Barber MotorSports Enduro: Breaking the brakes

Post by sideshow » Thu Feb 15, 2018 8:42 pm

A. I like what you are trying, don't stop
B. Take a step back, factory drums offer no performance penalties over crap discs and DNFs

Trade visual serving for the unsexyness of and old induction heat treated cast iron splines to place
Yeah some may call it overkill, but you can't have too much overkill.

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Re: LeMons Barber MotorSports Enduro: Breaking the brakes

Post by GS guy » Fri Feb 16, 2018 9:26 am

Another option would be adopting 944 IRS bits. Get OEM quality disc brakes and even the Al arms in the package. Doesn't adopting used parts from other vintage vehicles fit into the spirit of the race series? :-) Those front brakes look like they may need more cooling! May be time for some vented discs?

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Re: LeMons Barber MotorSports Enduro: Breaking the brakes

Post by MegaRookie » Sat Feb 24, 2018 2:38 pm

To start, always nice to read your experiences on the races. :D

Regarding the problem you had/have, a long time ago i also had problems with nut of the hub which came loose. (Swing axle, only on the left side) After changing the gearbox (complete with swing axles) with another one, the problem was solved. I think the problem was radial play between the axle and hub, also the nut had a small radius on the side which should be flat.

And a friend of mine had the complete teeth loose in the hub when leaving at a traffic light. (Brand/material unknown)

I dont know if this info helps you a bit, but you never know. :D

Best regards Mark

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