Halfshaft Bolt Answers (all threads merged)

[AZGT]

Change to Studs?

opps - double post

 

[AZGT]

Change to Studs?

Just an idea, so wonder if any of you engineering guys could answer this.

What if we changed from bolts to studs (maybe wth some locktite) with castle nuts and cotter keys or studs with lock nuts?

Any thoughts?

 

[nota4re]

As soon as the first fastener "unscrews" itself and "falls out", all of the torque is transmitted to the remaining fastener, resulting in a sheared fastener. The car stops at this point.

Impossible. If the first bolt backs all the way out there is still ZERO torque on the remaining bolt and it cannot be sheared off. We're talking about the mating of two splined shafts with the only function of the fasterners being to keep the splines engaged.

A higher quality bolt - and especially a bolt that is not threaded all the way to the head is what should be used in this application. This will address any problems of the bolt head being weakened from excessive installation torque. (A weakened bolt which is then subjected to the heat/cool cycles as well as the minute dynamics of the interaction of the spline "slop" *could* be a cause for failure. A more properly suited fastener - namely one from ARP will address the "bolt" strength risk.

The second potential issue - and the most widely speculated failure cause, is that BOTH bolts are loosening (perhaps related to initial improper seating with the underlying washer) and when they back all of the way out they permit the splines to disengage. AT THIS POINT, the bolts can/will be sheared off. BOTH bolts must walk all of the way out. So, an obvious solution to this is to prevent the bolts from walking out. This can be addressed with the use of the proper fastener, proper underlying surface, proper installation torque, proper use of a threadlocker, and finally saftey wiring just to provide added insurance.

So, an appropriate solution kit is comprised of;

(4) M8 x 1.25 Pitch Properly hardened bolts - prefer sourcing from ARP
(2) Hardened underlying washer
(1) Threadlocking compound (Loctite)
(1) Safety wire length

That, my friend is the RIGHT tree to be barking up. As soon as we have a definitive answer back fro ARP, we can move forward to have a proper repair kit available - of course completely in parallel to what Ford/Ricardo may be conjuring up (if any).

 

[Midnite Blu]

Wired Bolts ?

Impossible. If the first bolts backs all the way out there is still ZERO torque on the remaining bolt and it cannot be sheared off. We're talking about the mating of two splined shafts with the only function of the fasterners being to keep the splines engaged.

A higher quality bolt - and especially a bolt that is not threaded all the way to the head is what should be used in this application. This will address any problems of the bolt head being weakened from excessive installation torque. (A weakened bolt which is then subjected to the heat/cool cycles as well as the minute dynamics of the interaction of the spline "slop" *could* be a cause for failure. A more properly suited fastener - namely one from ARP will address the "bolt" strength risk.

The second potential issue - and the most widely speculated failure cause, is that BOTH bolts are loosening (perhaps related to initial improper seating with the underlying washer) and when they back all of the way out they permit the splines to disengage. AT THIS POINT, the bolts can/will be sheared off. BOTH bolts must walk all of the way out. So, an obvious solution to this is to prevent the bolts from walking out. This can be addressed with the use of the proper fastener, proper underlying surface, proper installation torque, proper use of a threadlocker, and finally saftey wiring just to provide added insurance.

So, an appropriate solution kit is comprised of;

(4) M8 x 1.25 Pitch Properly hardened bolts - prefer sourcing from ARP
(2) Hardened underlying washer
(1) Threadlocking compound (Loctite)
(1) Safety wire length

That, my friend is the RIGHT tree to be barking up. As soon as we have a definitive answer back fro ARP, we can move forward to have a proper repair kit available - of course completely in parallel to what Ford/Ricardo may be conjuring up (if any).

Ken, I'll take two kits when available. We'll do an install and breath easer....Thanks George

 

[SteveA]

I spoke with a tech from Ford who worked on the GT project and was very aware of all the halfshaft problems. I asked him to post some of what he told me on this forum but believed it would not be a good career move. I hate posting the o'le "I know a guy who knows a guy who said" BS but it looks like this isn't going away and needs to be reported.
He stated Ford is working very hard on the problem, has tried over 4 different solutions (bolts, washers, safety wire, locktite) and still is not sure they have the answer. He also stated this is the reason some have waited so long for the replacement bolts to arrive. At times they have been right in the middle of another update/solution (bolt, washer, wire combo) and couldn't ship.
This conversation took place in Dec.
Steve

 

[Empty Pockets]

I spoke with a tech from Ford who worked on the GT project and was very aware of all the halfshaft problems. I asked him to post some of what he told me on this forum but believed it would not be a good career move. I hate posting the o'le "I know a guy who knows a guy who said" BS but it looks like this isn't going away and needs to be reported.
He stated Ford is working very hard on the problem, has tried over 4 different solutions (bolts, washers, safety wire, locktite) and still is not sure they have the answer. He also stated this is the reason some have waited so long for the replacement bolts to arrive. At times they have been right in the middle of another update/solution (bolt, washer, wire combo) and couldn't ship.
This conversation took place in Dec.
Steve

'BEST NEWS (ONLY NEWS!) WE'VE HEARD "FROM FORD" SINCE THIS ALL STARTED!:banana :banana :banana

Did he say if Ford has even a partial idea at this point WHY the failure happens? ( I realize "yes" implies they should also have a partial answer... which they don't ...but, I'm still asking the question.)

 

[analogdesigner]

Wrong tree...

Impossible. If the first bolt backs all the way out there is still ZERO torque on the remaining bolt and it cannot be sheared off. We're talking about the mating of two splined shafts with the only function of the fasterners being to keep the splines engaged.

A higher quality bolt - and especially a bolt that is not threaded all the way to the head is what should be used in this application. This will address any problems of the bolt head being weakened from excessive installation torque. (A weakened bolt which is then subjected to the heat/cool cycles as well as the minute dynamics of the interaction of the spline "slop" *could* be a cause for failure. A more properly suited fastener - namely one from ARP will address the "bolt" strength risk.

The second potential issue - and the most widely speculated failure cause, is that BOTH bolts are loosening (perhaps related to initial improper seating with the underlying washer) and when they back all of the way out they permit the splines to disengage. AT THIS POINT, the bolts can/will be sheared off. BOTH bolts must walk all of the way out. So, an obvious solution to this is to prevent the bolts from walking out. This can be addressed with the use of the proper fastener, proper underlying surface, proper installation torque, proper use of a threadlocker, and finally saftey wiring just to provide added insurance.

So, an appropriate solution kit is comprised of;

(4) M8 x 1.25 Pitch Properly hardened bolts - prefer sourcing from ARP
(2) Hardened underlying washer
(1) Threadlocking compound (Loctite)
(1) Safety wire length

That, my friend is the RIGHT tree to be barking up. As soon as we have a definitive answer back fro ARP, we can move forward to have a proper repair kit available - of course completely in parallel to what Ford/Ricardo may be conjuring up (if any).

I hate to sound like a know-it-all, however using different (ARP or whoever) fasteners with safety wire and Loctite is not going to correct the problem! It will just postpone it...

From another post: Ford is working very hard on the problem, has tried over 4 different solutions (bolts, washers, safety wire, locktite) and still is not sure they have the answer.

If this is true, Even Ford does not understand the problem! You guys as well as Ford are wasting your time playing around Loctite, safety wire and different fasteners.

Sorry for the bad news. The good news is a fix is on it's way. I am not trying to hurt anyone's feelings here, however I just hate to see everyone wasting their time on delusional solutions. An ARP fastener with higher fatigue resistance may buy you a little bit longer run time. Ricardo made a serious design error on this one.

If I wasn't so busy my main job I could have designed a part within a few weeks. In the meantime, I have quarantined my car, meaning no more driving until some new parts are designed and installed.

Jay

 

[Empty Pockets]

I am going to tear my car apart soon to confirm my theory. If I feel that I am right, then I will redesign and machine a new part to replace what I think are the faulty part(s).

Jay:
Given that there are "umptillion" exotics out there ALL of mid-engine design w/transaxles - about which we've not heard a WORD regarding the same failures as the Ricardo 'box in the GT - what is it about the Ricardo 'box that's SOOOOOOO much different when it comes to coupling "A" to "B" in the 1/2 shaft area??????
The answer to THAT may reveal a path to the solution.

Larry

 

[nota4re]

I hate to sound like a know-it-all

Well, that's kind of hard to avoid when you jump on the thread and claim, among other things that we are discussing

delusional solutions

.

That coupled with the fact that you've done nothing to discuss what ideas, if any, you have regarding the root casues of the failure - but proudly proclaim that you will have a fix soon. Marry that with the fact that you've done nothing for me to convey that your really understand the problem - especially professing that you will have an immediate bolt shear problem when/if one bolts backs out. This is physically highly unlikely, even with the assumption that the backlash of the spline engagement is a potential root force continuously acting on the fasteners. The engaged splines would prohibit a twisting force from being exerted on the remaining bolt as long as it remains somewhat tight.

Finally, you yourself quote

Even Ford does not understand the problem!

. Wow, Ford and Ricardo resources with years of drivetrain experience and no doubt boatloads of engineering experience from which to draw from - yet our saviour is GTSAVER??

The good news is a fix is on it's way.

Yeah, that sounds a wee bit like a know it all. And, by the way, ol' wise one, how are you going to test/validate your solution? The current test case is approximately 4,000 cars with an accumulated mileage of maybe 6 million miles (1500 miles each car) with still a very low failure rate. If your test is less that 6 million miles, still not sure we can validate the superiority of a GTSAVER design.

Jay, I know this post may be a little provocative - but you are making some very strong assertions and I just want to provide a sounding board for your wholesale discounting of any solution but your secret one.

I do hope you and your family members the very best outcomes in dealing with any health crisis that are occuring in your life. It does help to keep all of this in perspective. After all, we're talking about a pesky problem for which there will be one or more solutions available soon. I don't think any of us are relying on the GT to get back and forth from work or family.... the really important stuff.

 

[Shadowman]

Well, that's kind of hard to avoid when you jump on the thread and claim, among other things that we are discussing .

That coupled with the fact that you've done nothing to discuss what ideas, if any, you have regarding the root casues of the failure - but proudly proclaim that you will have a fix soon. Marry that with the fact that you've done nothing for me to convey that your really understand the problem - especially professing that you will have an immediate bolt shear problem when/if one bolts backs out. This is physically highly unlikely, even with the assumption that the backlash of the spline engagement is a potential root force continuously acting on the fasteners. The engaged splines would prohibit a twisting force from being exerted on the remaining bolt as long as it remains somewhat tight.

Finally, you yourself quote . Wow, Ford and Ricardo resources with years of drivetrain experience and no doubt boatloads of engineering experience from which to draw from - yet our saviour is GTSAVER?? Yeah, that sounds a wee bit like a know it all. And, by the way, ol' wise one, how are you going to test/validate your solution? The current test case is approximately 4,000 cars with an accumulated mileage of maybe 6 million miles (1500 miles each car) with still a very low failure rate. If your test is less that 6 million miles, still not sure we can validate the superiority of a GTSAVER design.

Jay, I know this post may be a little provocative - but you are making some very strong assertions and I just want to provide a sounding board for your wholesale discounting of any solution but your secret one.

I do hope you and your family members the very best outcomes in dealing with any health crisis that are occuring in your life. It does help to keep all of this in perspective. After all, we're talking about a pesky problem for which there will be one or more solutions available soon. I don't think any of us are relying on the GT to get back and forth from work or family.... the really important stuff.

WOW

I think that it is time for all to take a "Chill Pill"

I have always felt that both Cooltech and GTSaver bring great things to this forum; and still do however at ther moment it appears that a common issue is being looked at from different ends of the spectrum. IMO neither are the end all of solutions at this time but rather each are complimentary to one another as the ultimate goal is to have closure to this thread and the issue within to go away.

I for one, appreciate and respect what both of you are doing and bring to this party

Takes care

Shadowman

 

[fjpikul]

Remember, we try not to slam our paying vendors here. Analog has designed some wonderful stuff for our cars. Thank you, Miss Manners

 

[analogdesigner]

More explanations on fastener failure theories

Well, that's kind of hard to avoid when you jump on the thread and claim, among other things that we are discussing .

That coupled with the fact that you've done nothing to discuss what ideas, if any, you have regarding the root casues of the failure - but proudly proclaim that you will have a fix soon. Marry that with the fact that you've done nothing for me to convey that your really understand the problem - especially professing that you will have an immediate bolt shear problem when/if one bolts backs out. This is physically highly unlikely, even with the assumption that the backlash of the spline engagement is a potential root force continuously acting on the fasteners. The engaged splines would prohibit a twisting force from being exerted on the remaining bolt as long as it remains somewhat tight.

Finally, you yourself quote . Wow, Ford and Ricardo resources with years of drivetrain experience and no doubt boatloads of engineering experience from which to draw from - yet our saviour is GTSAVER?? Yeah, that sounds a wee bit like a know it all. And, by the way, ol' wise one, how are you going to test/validate your solution? The current test case is approximately 4,000 cars with an accumulated mileage of maybe 6 million miles (1500 miles each car) with still a very low failure rate. If your test is less that 6 million miles, still not sure we can validate the superiority of a GTSAVER design.

Jay, I know this post may be a little provocative - but you are making some very strong assertions and I just want to provide a sounding board for your wholesale discounting of any solution but your secret one.

I do hope you and your family members the very best outcomes in dealing with any health crisis that are occuring in your life. It does help to keep all of this in perspective. After all, we're talking about a pesky problem for which there will be one or more solutions available soon. I don't think any of us are relying on the GT to get back and forth from work or family.... the really important stuff.

nota4re, your comments are well taken. Due to liability concerns, I must be a bit careful concerning specifics of the design until it has been analyzed by professional engineers, computer simulation and then real world testing. My concern is that all it would take is one person to file a lawsuit if they improperly implemented some "half-baked" design suggestion which resulted in serious consequences. These types of lawsuits can ruin a person's life.

This is a partial explanation of the fastener failure theories:

Every time that you accelerate hard and/or downshift hard, will result in "rotational cycling" of the spline engagement region of the output shaft flange. Due to machining tolerances, this amount of rotation will vary from car to car. This is why some cars will never experience this fastener failure problem. How much rotation is acceptable is not clear. Now, there is another complex force vector that gets exerted onto the output shaft flange. Simply, it's like lifting the output shaft flange up and down. There again, machining tolerances and the amount of force exerted will dictate how much force gets transferred to the fasteners. If the fasteners are positioned vertically at that moment in time, then the change in loading could possible exceed the fastener's yield strength. Since they are located off center, these fasteners really get beat to hell. The hardened washer doesn't work because every time the flange "moves around" (due to a sloppy spline fit), the yield strength of the fasten can be exceeded more easily than with the "soft washers". This has been confirmed by a metallurgist that examined a failed fastener. One of my associates, designs and machines splined joints for helicopters and he also agrees that this design has too many potential problems. One fastener in the middle of the washer would help this design. The spline engagement should be longer (to minimize radial play), along with a better fit (higher tolerances, to minimize both radial and rotational play).

Remember Ford and Ricardo must balance tradeoffs between cost and reliability. Any fool can throw money at a problem.

If someone has a serious contact at Ford, I would prefer to give Ford the design, which will be a new part. Mechanically it is not a perfect solution, however, it should solve this problem while remaining safely within proper mechanical guidelines. Also, Ford can deal with any liability issues.

Thanks for you comments :thumbsup ,

Jay

 

[B O N Y]

nota4re, your comments are well taken. Due to liability concerns, I must be a bit careful concerning specifics of the design until it has been analyzed by professional engineers, computer simulation and then real world testing. My concern is that all it would take is one person to file a lawsuit if they improperly implemented some "half-baked" design suggestion which resulted in serious consequences. These types of lawsuits can ruin a person's life.

This is a partial explanation of the fastener failure theories:

Every time that you accelerate hard and/or downshift hard, will result in "rotational cycling" of the spline engagement region of the output shaft flange. Due to machining tolerances, this amount of rotation will vary from car to car. This is why some cars will never experience this fastener failure problem. How much rotation is acceptable is not clear. Now, there is another complex force vector that gets exerted onto the output shaft flange. Simply, it's like lifting the output shaft flange up and down. There again, machining tolerances and the amount of force exerted will dictate how much force gets transferred to the fasteners. If the fasteners are positioned vertically at that moment in time, then the change in loading could possible exceed the fastener's yield strength. Since they are located off center, these fasteners really get beat to hell. The hardened washer doesn't work because every time the flange "moves around" (due to a sloppy spline fit), the yield strength of the fasten can be exceeded more easily than with the "soft washers". This has been confirmed by a metallurgist that examined a failed fastener. One of my associates, designs and machines splined joints for helicopters and he also agrees that this design has too many potential problems. One fastener in the middle of the washer would help this design. The spline engagement should be longer (to minimize radial play), along with a better fit (higher tolerances, to minimize both radial and rotational play).

Remember Ford and Ricardo must balance tradeoffs between cost and reliability. Any fool can throw money at a problem.

If someone has a serious contact at Ford, I would prefer to give Ford the design, which will be a new part. Mechanically it is not a perfect solution, however, it should solve this problem while remaining safely within proper mechanical guidelines. Also, Ford can deal with any liability issues.

Thanks for you comments :thumbsup ,

Jay

Jay, I am interested to learn what you think the solution is. However, you are asking us to stand by, stay tuned, and wait which is difficult. It would have been better frankly, if you did your research, handled the legal issues, and then advised us of your solution.

I have modified an earlier post that appeared here, because I did not want to be inflammatory, or insult a valued member like Jay..

 

[B O N Y]

Remember, we try not to slam our paying vendors here. Analog has designed some wonderful stuff for our cars. Thank you, Miss Manners

I have deleted my original post that was here before, the original is below. I have consulted with a most respected member of this forum. I think I understand where Jay is coming from, I understand his concern of liability. I know that we as owners are frustrated because Ford/Riccardo is leaving us high and dry. We know the SVT team is aware of the problem, we do NOT know if upper level management understand the problem. And.....frankly, none of us know really what percentage of cars are effected. I have become vocal when I found out that MY car was effected. Am I fanning the flames?

 

[Speed Thrills]

I am watching, don't think it has gotten to the slamming stage, there have been no personal attacks, or any insults, however, Jay needs to peel the onion and tell us what he thinks the answer is... so far he is teasing us...., asking us to standby might not be the best way to win support of his ideas.

I can't believe Ford would not, after all these reports ect, be pro-active and at least officially admit to the problem and reassure owners at the very least. When you have such a problem on a car that is " the pace car of the company" you'd think it would be handled better.

 

[BlackICE]

I am not an ME, but have a little common sense and some knowledge of physics and material science. Jay's description of the problem sounds right on target. Also Jay's reluctance to release details due to liability concerns is prudent.

If I were Jay, I wouldn't sell any of these parts due to the potential liability issues.

To cover Jay's butt, the cost per part would be so expensive that very few if anyone would buy them. Again Jay selling/giving the design to Ford would be the best thing to do. Likely to happen, less than 1% chance! Big companies don't like to admit it can be done better outside.

I want to thank Jay for looking into this problem, because it is not a money maker and most likely being done pro bono.

BlackICE

 

[HHGT]

Jay, I am having a difficult time understanding how the moments of inertia at the fastners in its current design can be reduced by having a single and centric fastner/washer. May be I am not understanding this correctly, perhaps you or Kendall can post a quick sketch of this probable faulty design. In fact, I suspect that even the wire tie approach will not hold up if this theory is true. The wire tensile strength is miniscule compared to the forces generated.

It seems that the only real solution to this is a whole new shaft with a tighter tolerance on the splines along with a single centric fastner/washer may be the only real long term fix.

Getting this machined and heat treated to Ford/Ricardo specifications would require assistance and disclosure from both, but nevertheless, would not be a very expensive part to make. I am guessing $500 (retail) per shaft assembly???

Finally, has anyone researched other Ricardo applications utilizing the Washer/2 Bolt design on other vehicles and any previous or current problems?

 

[BlackICE]

See post number 153 for a look at a Lambo transaxle attachment, posted by abolfaz, the father of the halfshaft bolt problems.

BlackICE

http://www.fordgtforum.com/forums/showthread.php?t=638&page=16

 

[HHGT]

See post number 153 for a look at a Lambo transaxle attachment, posted by abolfaz, the father of the halfshaft bolt problems.

BlackICE

http://www.fordgtforum.com/forums/showthread.php?t=638&page=16

Thanks BlackICE.

Is the half shaft supplied by Ricardo or by Ford?

 

[B O N Y]

Thanks BlackICE.

Is the half shaft supplied by Ricardo or by Ford?

The entire assembly is put together and sourced by Riccardo. They torqued the bolts and sent the unit over to Ford.