John Mihovetz [ ACCUFAB ] Modifying my crankshaft


Lorenzo

GT Owner
Mark II Lifetime
Dec 28, 2008
625
U.S.A.
Here the crank from my car being massaged by john AKA ACCUFAB as Shadowman methodically moves this project forward.
 

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Chris A.

GT #32
Mark II Lifetime
Feb 6, 2007
1,199
Ortega Mountain, CA
I'm thinking about buying one of his cranks for Shadowman to install. John explained that this is a potential weak link..... especially for Whippled cars.

Is this the OEM crank or one of the ACCUFAB units?
 

Mullet

FORD GT OWNER
Le Mans 2010 Supporter
Oct 21, 2008
2,461
Houston Texas
I'm thinking about buying one of his cranks for Shadowman to install. John explained that this is a potential weak link..... especially for Whippled cars.

Is this the OEM crank or one of the ACCUFAB units?
I have not heard of a crank failure even in a TT car.
 

KMCBOSS

RED GT owner
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Dec 3, 2006
995
Bremerton, Washington
what.......no safety glasses!!!
 

Chris A.

GT #32
Mark II Lifetime
Feb 6, 2007
1,199
Ortega Mountain, CA
I have not heard of a crank failure even in a TT car.
The potential for failure is reduced when TT's are installed
 

Mullet

FORD GT OWNER
Le Mans 2010 Supporter
Oct 21, 2008
2,461
Houston Texas
The potential for failure is reduced when TT's are installed
not sure I understand. Are you saying a Whipple car is more likely to break a crank than a TT car?
 

tmcphail

GT Owner/Vendor
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Apr 24, 2006
3,985
St Augustine, Florida
Joe's original TT motor snapped the snout off of the crank Waaayyy back when.
 

Chris A.

GT #32
Mark II Lifetime
Feb 6, 2007
1,199
Ortega Mountain, CA
My understanding is that our crank wasn’t specifically designed for our motor, meaning it was designed beforehand. The weak link lies in the tiny keyway at the end of the crank. Not a huge cause of concern for gen I Whipples or the stock SC but as the rotors grow heavier on the Gen II and III’s they put too much strain on that keyway. If that goes you strip the end of the crank and the flywheel takes off.

Also, regardless of the TT or SC our cranks are not bolted in the middle. Long-term that might reveal itself as a problem.

I’ll double check the above with Shadowman but I believe ACCUFAB can modify our cranks or we can purchase a new one from him that specifically addresses all of the concerns.
 
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Mullet

FORD GT OWNER
Le Mans 2010 Supporter
Oct 21, 2008
2,461
Houston Texas
Joe's original TT motor snapped the snout off of the crank Waaayyy back when.
know of any others?
 

tmcphail

GT Owner/Vendor
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Apr 24, 2006
3,985
St Augustine, Florida
know of any others?
Not that I am aware of.
 

SteveA

GT Owner/B.O.D
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Dec 13, 2005
3,673
Sandpoint Id
As I recall Joe's car was putting out well over 1400hp when the crank failed.
 

tmcphail

GT Owner/Vendor
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Apr 24, 2006
3,985
St Augustine, Florida
As I recall Joe's car was putting out well over 1400hp when the crank failed.
Correct on the hose. It was never driven on the street like that, just on the dyno.
 

Lorenzo

GT Owner
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Dec 28, 2008
625
U.S.A.
I was unable to connect to the Forum for some reason untill now, sorry for the late reply.

It is my understanding that some { possible } issue's with our crank shaft is due to the weight of the balancer, the length of the snout, the pressure applied by the SC, and the small size of the bolt holding the balancer and associated pullys in place.
Now i dont want to stir up a hornets nest here so dont rush out to your cars and panic over the above statment.

That crank in the picture is the OEM being modified with a larger bolt to hold the balancer in place as well as an additional keyway located 180 from the OEM for a total of two.
I'm sure the OEM Ford crank shaft and balancer are more then enough to handle the stress when presented within it's design perimators However , i am no longer within those and am no longer useing the OEM balancer.
 
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Empty Pockets

ex-GT Owner
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Oct 18, 2006
1,220
Washington State
...as well as an additional keyway located 180 from the OEM for a total of two.
"Back in the day" we always use to do the 'double key' thing on any mill with a gilmer belt driven 6-71 (or larger) blower. 'Not really sure the 2 keys would be at all necessary on the FGT's v-belt blower setup - at least in the stock configuration. BUT, as you said, you're no longer playing in that ball park.:willy
 

Accufab

Well-known member
Mar 14, 2006
142
The issue with the crank is simple. It is fine in the application it was designed for. Adding a Whipple is outside of that design parameter. Now, that does not mean to call Whipple and complain either. Its simple physics and some good old common sense. The keyway is very small, the factory bolt is torque to yield and that combination just is not made for repeated abuse.

For sure, all of the Whipple applications will have crankshaft issues at some time in the future depending on how much it is driven and how hard its driven.

For example on this particular engine, this engine had 3500 miles and I'd suspect relatively hard miles. The keyway was already damaged to the point that we removed the crank and fixed it. I have pictures to display this. I have fixed several of these over the last year. It can go so far that the end of the crank can break off and who knows where the 20 lb balancer will go. The costs to fix at that point is pretty high.

The best fix available is a billet crank. We designed one that also added material to the front of the crank, bigger threads and a larger face for the cam gears to fit against.

Best regards,

John Mihovetz
 
H

HHGT

Guest
The issue with the crank is simple. It is fine in the application it was designed for. Adding a Whipple is outside of that design parameter. Now, that does not mean to call Whipple and complain either. Its simple physics and some good old common sense. The keyway is very small, the factory bolt is torque to yield and that combination just is not made for repeated abuse.

For sure, all of the Whipple applications will have crankshaft issues at some time in the future depending on how much it is driven and how hard its driven.

For example on this particular engine, this engine had 3500 miles and I'd suspect relatively hard miles. The keyway was already damaged to the point that we removed the crank and fixed it. I have pictures to display this. I have fixed several of these over the last year. It can go so far that the end of the crank can break off and who knows where the 20 lb balancer will go. The costs to fix at that point is pretty high.

The best fix available is a billet crank. We designed one that also added material to the front of the crank, bigger threads and a larger face for the cam gears to fit against.

Best regards,

John Mihovetz
John, always great to see you post here... I have 2 questions...

1) Is there a visual way we can inspect the crank for damages? and do Gen 1 Whipples less prone than say the 4.0 Whipple

and

2) Does the same prognosis apply to the Ford Pulley Upgrade and in your opinion do the Ford engineers know that the limits of the Key/Bolt in question are for another 100 Lbs of torque but no more.
 

Waldo

GT Owner
Mark IV Lifetime
Sep 7, 2005
755
Fort Worth, TX
For sure, all of the Whipple applications will have crankshaft issues at some time in the future depending on how much it is driven and how hard its driven.
John,

For those GTs with Whipples, are there any preventative measures one can take that do not require removing the crankshaft?

Best Regards,
 

B.M.F.

GT Owner
Mark II Lifetime
Jan 29, 2009
1,260
Minnesota
John,

For those GTs with Whipples, are there any preventative measures one can take that do not require removing the crankshaft?

Best Regards,
Don't put a whipple with lots of boost on it:) Ford racing is now putting double key ways in the cobra jet motors after the issues they have with them... I would think that anything less then 20lbs of boost will be fine and anything over 20 a person at somepoint will have problems. Another thing that will help with this is installing either a innovators west alum balencer or a Ati. John uses the Ati i believe. The 07 shelbys also had a ford GT style 20lb balencer and ford replaced those in 08 with a lighter 10lb unit as it was easier on the crankshaft.
 

Fubar

Totally ****** Up
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Aug 2, 2006
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Dallas, TX
I wont add any more HP until I can replace the crank. Interesting news about the balancers... ATIs site list a different part number for the GT500 and the GTs. However, the replacement parts (Shell assembly and Hub) share the same part #. It kind of makes you think the only difference is the price they charge the two respective parties.
 

B.M.F.

GT Owner
Mark II Lifetime
Jan 29, 2009
1,260
Minnesota
I wont add any more HP until I can replace the crank. Interesting news about the balancers... ATIs site list a different part number for the GT500 and the GTs. However, the replacement parts (Shell assembly and Hub) share the same part #. It kind of makes you think the only difference is the price they charge the two respective parties.
The difference is the distance between the 6 and 10 rib. Its like .100 closer between the two pulleys on the Gt balencer versus the gt500