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  #1  
Old 05-20-2007, 03:15 PM
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Dino Saga 070520 _ Cracked Wheel Fixed

Dino Saga 070520 _ Cracked Wheel Fixed

Had to find a welder. My old business contacts are dying on me. Or going out of business and just playing golf. Both machine shop and welder are now gone. Wanted to find someone qualified for aircraft welding so went to SB Airport and started asking the FBOs. Only one name popped up so took the inner spinning over to see the shop. Guys didn’t want to guarantee anything but were willing to work for cash. Liability lawyers are ruining the world. They predicted 15-20 minute job since I had cleaned things up pretty well. The equipment and the shop looked fine so I said GO. 20 minutes later we were back in business. I got to watch, with eye protection. They understood my concern and knowledge. Reasonable work but not as good as my old guy. Better than I could do. My hands are not as steady as they once were, and my eyes leave a lot to be desired for close work. Their minimum billing was $40 so two twenties later I was on my way.

I cleaned up the mounting surfaces to better than I found them. The one bolt hole that had almost been torn out had 0.030” ridges on both sides. The bolts had to be working there and probably those on either side too. Guess that led to the crack propagation. Went out to Specialty Tool and Bolt and bought a set of 6mm x 32mm allen cap screws and matching stop nuts. Cleaned up the aluminum spacer that goes between spinnings. Threw away the rubber seal that does not seal. Put everything back together exactly in the same alignment as the parts were before disassembly. Ran a bead of red High Temp Silicone around the center joint and smoothed it with a moist finger. Dawn on your finger stops silicone from sticking and you can tool joints beautifully. Smeared a thin layer of silicone over the new weld area just in case. Let the silicone cure overnight and took tire and wheel back to tire shop. $10 had the tire remounted and balanced. Brought it back and traded it for the spare that had worked just fine. Only thing I noticed with the spare was a pull when braking. Small but noticeable. Set pressure on reworked wheel to 30 psi.

While changing wheels I again took some photos. Huge difference in the rubber. The Dino has an enviable reputation for handling. More folks ought to take a shot at 16” wheels and savor the huge variety of rubber available and the amazing improvement in handling that goes with medium priced modern tires. High end tires are even better. Play with widths and profiles and pressures and compounds. Not many cars can hold the road like a properly shod Dino. About the only way to help is aerodynamically and none of the tunnels and wings do much below 100 mph. 14” wheel purists claims don’t hold water if you really love to drive, drive on public roads and want to keep your license.

The photo shoot activity that prompted this wheel final failure was on public roads. Tight corners, a little gravel on edges, two lane road with traffic and bicycles. Wanted to get the car to lean some; was hard. 2nd and 3rd gear, full throttle up around 6500 got the Gs with never a squeal from the tires. Uphill and down, just drove around the corners.

Enough for today. Got to tour a visitor around Santa Barbara. More rough duty.

John
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Last edited by dm_n_stuff; 05-21-2007 at 04:49 AM.
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  #2  
Old 05-21-2007, 09:25 AM
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Quote:
Originally Posted by John Corbani View Post
Dino Saga 070520 _ Cracked Wheel Fixed
(...snip!...)

The photo shoot activity that prompted this wheel final failure was on public roads. Tight corners, a little gravel on edges, two lane road with traffic and bicycles. Wanted to get the car to lean some; was hard. 2nd and 3rd gear, full throttle up around 6500 got the Gs with never a squeal from the tires. Uphill and down, just drove around the corners.

Enough for today. Got to tour a visitor around Santa Barbara. More rough duty.

John
.


Obviously you've got a keen eye, but how did you know the wheel was cracked?
routine examination or a road "event"?

Scott


PS - agreed, 14 inch wheels and XWX sidewall flex will make you loose your hair
  #3  
Old 05-21-2007, 12:04 PM
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Scott,
I started the story on 5/13/07. Take a look.
http://ferrarichat.com/forum/showthread.php?t=150438
John
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Old 05-21-2007, 10:57 PM
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Just got a few rough proofs from the photographer. Will give you an idea of the afternoon. We exercised the car!

John
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  #5  
Old 05-21-2007, 11:07 PM
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Be it Ferrari or otherwise, I wouldn't use a cracked wheel (repaired or otherwise) for anything other than a wall hanging.
As indicated in an old posting, here's what a cracked wheel will get you:
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  #6  
Old 05-21-2007, 11:59 PM
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Originally Posted by Horsefly View Post
Be it Ferrari or otherwise, I wouldn't use a cracked wheel (repaired or otherwise) for anything other than a wall hanging.
As indicated in an old posting, here's what a cracked wheel will get you:
OUCH!
  #7  
Old 05-22-2007, 12:25 AM
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say no to crack...
  #8  
Old 05-22-2007, 03:03 AM
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Slightly off topic.

I had a longish conversation with my mechanic at a concours on Sunday. WE talked about oversizing the tires on a Dino, and about going to tires with significantly less sidewall flex.

He pointed out that the suspension is designed for tires with flex, like the xwx. That changing to a tire with a lot less flex posed hazards for the car, in that you could in fact bend suspension pieces if you over stressed them.

Now I'm no expert, but he certainly is. If he says, "Stock size is stock size for a reason" I tend to believe him. There is an article in this month's Forza about older Ferrari's at the track, and how they bent suspension pieces while running tests on suspension/tire combinations.

So for me it's stock size, live with the flex. I'd rather be safe, than very sorry.

DM
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  #9  
Old 05-22-2007, 11:03 AM
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If he says, "Stock size is stock size for a reason" I tend to believe him.DM
Dave,
Stock size is stock size because it was the best there was in 1969. Wheels and tires changed during production. 1974 had wider wheels and flairs. Dinos were raced all the time with all kinds of rubber, all grippier than stock tires. Nothing bends unless you hit something. Shocks are adjustable and can work with anything that is the same or lighter than stock wheel/tire combo. I have driven the car for 21 years with the Gotti wheels and modern tires. Car has 191,000 miles, most on those same wheels.

The crack I found had been working for more than 21 years so progression was not catastrophic. I had redone left front 15 years ago and inspect regularly. Still fine. My confidence in the welding of these aluminum spinnings is very high. In my prior life I designed lots of aluminum and stainless weldments and supervised their construction. Have made most of the mistakes and learned a lot. Anecdotal opinions by mechanics is not reliable. Talk to some working engineers before believing the worst.

John
  #10  
Old 05-22-2007, 11:27 AM
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Well, he actually has 20 years of racing background as a mechanic and he's done some driving too.

He's trained by the factory, goes back for additional training, and is what I would call an expert on the older cars that he services regularly.

If he can put a challenge car back together after it hits a wall, he's probably a pretty good source of information, even if he doesn't have a degree in mechanical engineering.

That your car has hung together all these years is great, you take outstanding care of your vehicle. Would you really suggest that a casual owner put big, oversized, extra sticky tires on his car and thrash it about?

I would not casually hand that kind of advice out. I'd prefer to know that the guys here are running their cars safely, doing prudent maintenance, and making sure they come home alive at the end of the day. If your argument is that your car is safer with the resized tires, then you are entitled to your opinion.

And the flares cars ran on 1" wider wheels, but the tires are still 205/70-14s.
I don't know what effect putting the same size tire on a wider wheel has.

But then again, I'm not an engineer, just a well intended amateur.

DM
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  #11  
Old 05-22-2007, 11:59 AM
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Just got a few rough proofs from the photographer. Will give you an idea of the afternoon. We exercised the car!

John
.
John, that looks like a blast. Fantastic shots of your beautiful car. I especially like the motion-blurred one. Very cool. Each time I see your car, I keep saying to myself your tire/wheel combo just looks right on the Dino. The proportion of rubber to wheel to fender gap is spot on. If I can only find 16" wheels that I think goes well with the Dino. All the new wheels don't have that period feel.

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I don't know what effect putting the same size tire on a wider wheel has.

DM
Dave, putting the same size tire on a wider wheel increase the contact patch.

Manny
  #12  
Old 05-22-2007, 12:36 PM
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Originally Posted by need4speed View Post



Dave, putting the same size tire on a wider wheel increase the contact patch.

Manny
Would that also then change the height of the tire? IF it's spread wider, you would lose some of the sidewall height, right?

DM
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  #13  
Old 05-22-2007, 01:26 PM
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Would that also then change the height of the tire? IF it's spread wider, you would lose some of the sidewall height, right?

DM
That would follow.
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Old 05-22-2007, 01:50 PM
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Dave,

My suspission is that the suspension on the old cars is overbuilt and therefore you have plenty of wiggle room. Also, you only start worrying about bending things at ten tenths while you will begin noticing the difference at about five tenths. For those of us that don't push the cars to their extreme limits, the newer tire combo will give you a noticable handling improvement during a spirited drive.

A simple example is my car. I have modern tires on my Borranis. They provide significantly more stick than the original tires but as I don't drive all out, just in a 'spirited' manner, the wheels are (so far) holding up just fine.

Regards,

Art S.

PS. John, great pictures and story.
  #15  
Old 05-22-2007, 04:37 PM
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Dave,

A simple example is my car. I have modern tires on my Borranis. They provide significantly more stick than the original tires but as I don't drive all out, just in a 'spirited' manner, the wheels are (so far) holding up just fine.

Regards,

Art S.
Art.

How the hell are you? Long time no talk to. You gonna do New Hope again this year???

As to the suspension issue. It's more of a wheel size/weight, tire/dimension flex issue I think.

My car was designed for 14" wheels that weigh 13 lbs. Add the tire, maybe 23 lbs for the tire. Total unsprung weight is 36 lbs, with a nice flexy sidewall.

Now, lets go to a 16" wheel. Wheel is gonna weigh 23-24 lbs, tire stays at about 23, total unsprung weight goes to 46 lbs.

Add to that that the new tire is a 50 series, less sidewall, less flex. That flex has to go somewhere, doesn't it? Or is it simply absorbed by the suspension without additional stress? An old suspension, to boot.

BTW, when we took my car apart, it had a bent up left front suspension, so you can sure as heck bend em up. Wasn't visible, but it sure did not want to come apart, and sure as hell wasn't going back together.

I'm simply postulating here. I'm not an engineer, and I didn't sleep in a Holiday Inn last night. I know new tires are better, stickier, etc.

I guess the same argument could be made about pushing the car hard. How many of us explore the limits of the conventional tires, much less an upgraded set?

Dave M.
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Old 05-22-2007, 05:42 PM
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It sure seems to me that unless you were maybe running something like an out and out ultra-wide racing tire, that the tires would lose grip and begin to side slip long before the forces were great enough to "bend suspension pieces".

You might cause some bushings and bearings to wear more quickly with a lot of high-G cornering, and from the added weight, etc., but I seriously doubt that one could bend anything in the suspension from cornering G forces.

Dave, it's more than likely that your left front suspension was bent in the usual manner, i.e. hitting something.

Last edited by dinodan; 05-22-2007 at 05:46 PM.
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Old 05-22-2007, 06:04 PM
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Dave, it's more than likely that your left front suspension was bent in the usual manner, i.e. hitting something.
I wasn't suggesting anything else. I was simply pointing out that they do bend. And that if you take flex out of the system where you're supposed to have flex, it might go somewhere else.

DM
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  #18  
Old 05-22-2007, 07:46 PM
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Now, lets go to a 16" wheel. Wheel is gonna weigh 23-24 lbs, tire stays at about 23, total unsprung weight goes to 46 lbs.


Dave M.
Dave,

I've got a set of 17s that weigh 15lbs. 16s don't have to weigh over 20lbs.

Manny
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Old 05-22-2007, 09:02 PM
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Dave,

I've got a set of 17s that weigh 15lbs. 16s don't have to weigh over 20lbs.

Manny
You are right Manny. I did weigh both wheels with tires just for the fun of it. Both just under 40 pounds. The 3 piece wheel is lighter than the cast originals but the newer ones are lighter yet. The rubber that used to go into the sidewalls now goes into the tread. A little more steel in the belts is the only difference. My spare shows no wear at all. It has been used as intended, temporary replacement until real wheel is repaired. Weight comparison is pretty accurate.

ArtS,
The comment about noticing difference is right on. I have never gotten on a track and tried to run at 10-10. All my miles have been on public roads and maybe 8-10 is as much as I have pushed things. But the difference is stark below 5 - 10. The runs for the Photo Shoot were limited by the road's tight curves. Speeds were 40-50 where every one else thought 20 was fast. More power wouldn't have helped, particularly downhill. The Dino has a magical balance that keeps all 4 tires sharing the load under most conditions. What was good 35 years ago has just been waiting for the tires to catch up. Now it is great.

John

Last edited by John Corbani; 05-22-2007 at 09:44 PM.
  #20  
Old 05-23-2007, 12:16 AM
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Well for me I would follow the theory from the guy with 190,000 miles on his Dino over the factory trained mechanic who has only "test" miles on Dino's.

2 things with that above statement, I assume that by now John has 190,000 since it was 185k late last year. And I assume the mechanic only has test miles because he does not own one, that is a big assumption, he might own one. But no matter how big a assumption it is, 190,000 miles of experience speaks volumes.
 

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