Derry
GT Owner
Does anyone know what strength classification the bolts are? Are the new ones a different class from the original ones?
Derry
Derry
Different Gap size for Half-shafts
- Thread starter Gimbal
- Start date
Hi Jay, thanks for your info. I am certainly interested in your analysis. I am also hoping, once I take things apart to also understand how the whole thing works. I am assuming myself that the failures so far are due to either loosening bolts or the heads break off. I don't like the bowing washer applying high loads to one side of the bolt heads. This is why I see the stronger washer as a better (not perfect) choice at the moment. I am also assuming the supplied bolts are relatively week especially if the threads go all the way up to the head. Someone mentioned that the hub could move within the tolerance of the spline fit. This makes sense and could cause the bolts to loosen. The certified mechanic at the Ford dealer said that the U-joints take up any axial load or movement in the axial direction and therefore a large axial load to the thrust washer should not happen. Until I see a cross section layout drawing thru the tranny and axles I won't understand exactly what is going on. I did order the CD manual and hope it has some good info.
Thanks a lot, John
Thanks a lot, John
Derry
The 4 bolts, that come in the "4G7Z-7B368-BA" Kits are just Din 912, Class 12.9, M8-1.25x25.4mm bolts. They AREN'T upgraded like the washers are. You CAN'T get a 25.4mm bolt that is NOT fully threaded, it has to be CUSTOM MADE. I contacted ARP, to get some ARP2000 or some 8740 chrome moly bolts made. I just got a QUOTE back from them for about $10 a bolt, depending on how meney we order; with a "10 WEEK" deleivery!!
AMB
The 4 bolts, that come in the "4G7Z-7B368-BA" Kits are just Din 912, Class 12.9, M8-1.25x25.4mm bolts. They AREN'T upgraded like the washers are. You CAN'T get a 25.4mm bolt that is NOT fully threaded, it has to be CUSTOM MADE. I contacted ARP, to get some ARP2000 or some 8740 chrome moly bolts made. I just got a QUOTE back from them for about $10 a bolt, depending on how meney we order; with a "10 WEEK" deleivery!!
AMB
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Derry
GT Owner
Class 12.9 fasteners have a tensile of 174,000 psi. We have material we can make fasteners from up to 275,000 psi. But I guess the missing info is what the loading is. Also whether it is tensile or shear.
Derry
Derry
sample bolt
Hi AMB,
I have seen the size of the bolts to be 25mm, 30mm and now from you are saying 25.4mm long. Did you measure one? When I get the kit it will be the first thing I do. Turns out 25.4mm is exactly 1 inch, I've never seen a metric length of 25.4mm. I'd be happy to pay $10 a bolt for the right one. Not sure I like waiting 10 weeks though.
I'm still looking for a good bolt and will post if I find one. I won't settle for one that is fully threaded though. Too bad it is metric, I have a 1/4-28, 12 point, hole in head, not fully threaded, hard steel bolt on my desk. I am trying to find an equivalent m8x1.25 version at what ever the right length is. I could possible shorten a bolt if it is too long, maybe.
Hi AMB,
I have seen the size of the bolts to be 25mm, 30mm and now from you are saying 25.4mm long. Did you measure one? When I get the kit it will be the first thing I do. Turns out 25.4mm is exactly 1 inch, I've never seen a metric length of 25.4mm. I'd be happy to pay $10 a bolt for the right one. Not sure I like waiting 10 weeks though.
I'm still looking for a good bolt and will post if I find one. I won't settle for one that is fully threaded though. Too bad it is metric, I have a 1/4-28, 12 point, hole in head, not fully threaded, hard steel bolt on my desk. I am trying to find an equivalent m8x1.25 version at what ever the right length is. I could possible shorten a bolt if it is too long, maybe.
Bolt picture
Here is a photo of an example of the type of bolt I am looking for.
I had to delete my other photos of the gaps to make room for this photo. Another pain....
Here is a photo of an example of the type of bolt I am looking for.
I had to delete my other photos of the gaps to make room for this photo. Another pain....
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isaakgt
GT Owner
Gimbal, I agree with you a 100% on your idea for the right bolt. This is what I have had in mind also and maybe using a thicker hardened washer with it. I will buy a set if you can put something together. Keep us posted.:thumbsup
BlackICE
GT Owner
The washers should also have a slight countersunk radius on both sides of the holes. Idealy it should mate up with the radius under the bolt head.
isaakgt
GT Owner
Your right, ICE. The washers should be chamfered. This setup will be much stronger than stock without a doubt.:thumbsup
"Gaps" vs. "bolts"
Just for the heck of it, would those of you who've HAD 'bolt failures please take a look at the "gap" referenced in this thread on your own car(s) when you get the chance and see if your car has this "uneven" gap as well?
It'd be interesting 2C if this oddity might be a "DNA" marker for the bolt pblm. Obviously, if ALL the "busted bolt" cars have the uneven spacing characteristic, and NONE of them have the "even" spacing, something's pbly in play there...
Just for the heck of it, would those of you who've HAD 'bolt failures please take a look at the "gap" referenced in this thread on your own car(s) when you get the chance and see if your car has this "uneven" gap as well?
It'd be interesting 2C if this oddity might be a "DNA" marker for the bolt pblm. Obviously, if ALL the "busted bolt" cars have the uneven spacing characteristic, and NONE of them have the "even" spacing, something's pbly in play there...
In TSB 06-23-08 it mentions to torque the two bolts to 30NM. Turns out 30NM torque is the standard torque value for a metric grade class 8.8
This tells me the standard bolts used by Ford are standard steel not Class 10.9 or Class 12.9 which are much stronger bolts. It is possible Ford is specifying a lower torque for some reason but my guess is they are using a lower strength bolt. When I get my upgrade kit I will do a hardness test on the bolts and post the results.
This tells me the standard bolts used by Ford are standard steel not Class 10.9 or Class 12.9 which are much stronger bolts. It is possible Ford is specifying a lower torque for some reason but my guess is they are using a lower strength bolt. When I get my upgrade kit I will do a hardness test on the bolts and post the results.
SteveA
GT Owner/B.O.D
Very cool, I look forward to the post. Why don't you do the test on the bolts removed as well as the old and new washers?
Gimbal
The 05 GT Manual says to torque them to 32Nm (23 lb-ft). The 06 Manual says to torque them to 40Nm (32 lb-ft), back them off one full turn and torque them to 28Nm (21 lb-ft). ARP says to torque them to (25 lb-ft) with 30wt oil and to (20 lb-ft) with Moly.
AMB
The 05 GT Manual says to torque them to 32Nm (23 lb-ft). The 06 Manual says to torque them to 40Nm (32 lb-ft), back them off one full turn and torque them to 28Nm (21 lb-ft). ARP says to torque them to (25 lb-ft) with 30wt oil and to (20 lb-ft) with Moly.
AMB
For what it is worth the Ford dealer said that the TSB specs are probably the specs to follow instead of the manuals since there are usually different specs and call-outs. This makes sense to me since I hope the engineers creating the TSB's spend a bit more time thinking about what to do. The manuals are sure to be loaded with inconsistancies.
With new suposedly hard thrust washers and new strong bolts with properly chamfered washers (good point) I plan on torquing to a yet to be determined value. Thanks for all the info, it really helps.
With new suposedly hard thrust washers and new strong bolts with properly chamfered washers (good point) I plan on torquing to a yet to be determined value. Thanks for all the info, it really helps.
Another note on torque of the two screws. TSB 05-10-13 states torquing to 40Nm. TSB 06-23-8 states torquing to 20Nm then to 30Nm.
Seems Ford took over-torquing as an issue so lowered it in the 2nd TSB.
I am starting to believe that the backlash slop in the axle splines and hub could help snap the screw heads off or un-tighten them over time (seems a short time too).
I wonder if keeping the bolts tightend to say 5 Nm or so and loctiting and saftey wiring them to allow some movement between the thick thrust washer and hub to allow spline backlash movement? If the backlash in the spline and hub need to move then something has to give.
Still not quite sure how all the mechanics work. When I take it all apart I should have a better understanding and hopefully a couple of good ideas.
Seems Ford took over-torquing as an issue so lowered it in the 2nd TSB.
I am starting to believe that the backlash slop in the axle splines and hub could help snap the screw heads off or un-tighten them over time (seems a short time too).
I wonder if keeping the bolts tightend to say 5 Nm or so and loctiting and saftey wiring them to allow some movement between the thick thrust washer and hub to allow spline backlash movement? If the backlash in the spline and hub need to move then something has to give.
Still not quite sure how all the mechanics work. When I take it all apart I should have a better understanding and hopefully a couple of good ideas.