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As eluded to above this was the result of the owner that used the car in question as a test bed for his twin screw supercharger in concert with loose clamp. That missing piece was long gone before the transmission was dropped to be replaced with another GT transmission I provided the PO.
Now that is a weird story, loose clamp? missing piece long gone? I am very confused where this came from. That tranny was never removed under my ownership. Please keep in mind this car has had 2 owners after me in the last 8 years, and now a new owner, so that's 3 now.
Please advise,
Dave
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Now that is a weird story, loose clamp? missing piece long gone? I am very confused where this came from. That tranny was never removed under my ownership. Please keep in mind this car has had 2 owners after me in the last 8 years, and now a new owner, so that's 3 now.
Please advise,
Dave
Let me try to clean this up.
Not everybody is as meticulous with their cars as you are DR.
Somehow, the clamp loosened ( my guess) and that was a contributing factor. The failure could have begun with one of the PO's.
So when the clamp is loose, the driveshaft and the splines move back and forth on each other. The result is always a boatload of rust inside the splines.....and a worn driveshaft that is unusable with another gear.
Perhaps this gear has been cleaned up on the inside splines, but I'm not seeing the telltale rust.
At any rate, given the cost of a 5th gear and the labor to change that gear, this gearbox is probably just good for parts, now.
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
Not everybody is as meticulous with their cars as you are DR.
Somehow, the clamp loosened ( my guess) and that was a contributing factor. The failure could have begun with one of the PO's.
OK, but you said this about ME ..
Originally Posted by Kevin in Atlanta
..the owner that used the car in question as a test bed for his twin screw supercharger in concert with loose clamp.
Could you imagine, me using a trans with a loose clamp and a missing chunk on a 450rwhp Test Mule...and implying I knew this and continued for years and then sold it this way, much less even think it could survive the implication for more than 5 feet in my testing(which is the craziest part of this). How do stories like this start, it never ceases to amaze me.
So when the clamp is loose, the driveshaft and the splines move back and forth on each other. The result is always a boatload of rust inside the splines.....and a worn driveshaft that is unusable with another gear.
Perhaps this gear has been cleaned up on the inside splines, but I'm not seeing the telltale rust.
I agree Greg, I am still wondering what the symptoms were to cause the replacement and I don't believe that broken nose was the issue. I have seen what one looks like that breaks, it is a freaking mess of stripped teeth, parts and very evident damage.
Edit: Kevin, have you opened that thing up yet? I think the real issues are going to reside inside. Now if you find evidence of extreme heat and stress cracks from hard use...I will be the 1st to raise my hand for my part in that!
I agree Greg, I am still wondering what the symptoms were to cause the replacement and I don't believe that broken nose was the issue. I have seen what one looks like that breaks, it is a freaking mess of stripped teeth, parts and very evident damage.
Cheers,
Dave
Pretty sure this is not about you or what you did 8+ years ago....
With one of your supercharger kits, I'm thinking the spline life would be measured in days, with a loose clamp.
It's really tough to tell much from the picture, but a loose clamp "erodes" the teeth of the splines and makes them very narrow. Same thing occurs on the driveshaft. That's where all the rust comes from.
And the driveshafts are "softer" and wear worse....faster.
If Kevin didn't have to replace the driveshaft, this is not from a lose clamp.
Pretty sure this is not about you or what you did 8+ years ago....
With one of your supercharger kits, I'm thinking the spline life would be measured in days, with a loose clamp.
It's really tough to tell much from the picture, but a loose clamp "erodes" the teeth of the splines and makes them very narrow. Same thing occurs on the driveshaft. That's where all the rust comes from.
And the driveshafts are "softer" and wear worse....faster.
If Kevin didn't have to replace the driveshaft, this is not from a lose clamp.
Which begs to question going forward, is the broken gear via loose coupler or not, or is the original problem for replacement still lurking inside, undiscovered.
People can say that tranny had a shorter lifespan because of my hard usage and I will agree, I have said it many times how amazed I was at how it held together under such usage. I have touted that for years as a testament to the tranny. Heck, it was tight with no issues when I passed it to Shawn, and he never mentioned any issues either.
BTW, Do we even know the original symptoms that prompted the replacement, did it get noisy, or did it just grind to a stop and no movement after that? Even after all this BS I am still curious if that gear is all that is wrong with it, and what eventually caused it to fail for my future reference. Could be another learning experience for those running more than stock power, always looking for the next weakest link.
Anyway, hope at least you are having a great night,
I never had any issues with it, nor did I go investigating down there. IIRC, it was Brian MCMullen who bought it from me and it broke sometime when he had it. He was not a rennlister and he sold it sometime in the last year.
I never had any issues with it, nor did I go investigating down there. IIRC, it was Brian MCMullen who bought it from me and it broke sometime when he had it. He was not a rennlister and he sold it sometime in the last year.
The 5th gear broke into more than one piece as witnessed by the fact that not all of it was still inside the torque tube when Brian did an inspection.
What we don't know is if the cracks developed before or during any of the PO's ownership - that is unknowable. But, we should be able to agree that cracks preceded the break.
So, get back to the purpose of this topic - can it be repaired?
The 5th gear broke into more than one piece as witnessed by the fact that not all of it was still inside the torque tube when Brian did an inspection.
What we don't know is if the cracks developed before or during any of the PO's ownership - that is unknowable. But, we should be able to agree that cracks preceded the break.
So, get back to the purpose of this topic - can it be repaired?
Greg says no, DR thinks maybe.
Mary has a bad a$$ hot glue gun.
And the instruction sheet that used to come with JB Weld claimed one could repair stripped tractor axle splines.
Literally anything can be repaired....it's just a question how much one is willing to spend to do it.
You'd have to figure out exactly what material it was made from and if the heat treating is different on the gear than on the shaft section (likely.) (It is even possible that the gear is made from completely different material than the splined section and the two pieces were friction welded together.) Then it would require the dog teeth to be removed. You would then have to have the part annealed. At that point, if you could find the proper filler rod, it theoretically could be welded. (It would be easier if the broken piece existed.) It would then have to be machined and have the splines re-broached. Then it would need to be heat treated back to the original specifications and have the dog teeth re-installed so that they don't come loose and work their way off towards the inner hub (super common when dog teeth are changed.)
I'm betting a new gear would be cheaper.....even if you had to have one made from scratch.
Is this a common way in which the manual transmission fails while being run, instead of being damaged when separated from the long drive shaft? I'm trying to understand what's weak and what's not weak in these transmissions.
Look close at the splines and surrounding area below, there are 0 witness marks of anything out of the ordinary. IF 1/3 of the clamping area was missing I don't think that would withstand a stock GT engine for very long, much less a torquey Twin Screwed GT and there would be some sort of evidence showing.
Now think about this, rotate that shaft in the pic until the clamp bolt is aligned for removal which puts the broken part on the bottom. Then imagine a couple of guys sliding the tranny back off of the shaft, and opps, someone let the back of the tranny droop a little ....and you hear a distinctive "snap"..as that lower part breaks off. When this happens you are left with exactly the damage shown in the pic.
I have been there and done it decades ago, trust me, when you get in a hurry, you only make that mistake ONCE. Luckily for me it was an already broken 79 box being replaced. I know what a broken input shaft looks like(and sounds like), and exactly how that happens. I didn't want to man up about it either, but I did. AND, I certainly didn't go around making wild a$$ accusations in a lame effort to blame it on someone else!!
So when the clamp is loose, the driveshaft and the splines move back and forth on each other. The result is always a boatload of rust inside the splines.....and a worn driveshaft that is unusable with another gear. Perhaps this gear has been cleaned up on the inside splines, but I'm not seeing the telltale rust. At any rate, given the cost of a 5th gear and the labor to change that gear, this gearbox is probably just good for parts, now.
Originally Posted by DR
Look close at the splines and surrounding area below, there are 0 witness marks of anything out of the ordinary. IF 1/3 of the clamping area was missing I don't think that would withstand a stock GT engine for very long, much less a torquey Twin Screwed GT and there would be some sort of evidence showing.
Now think about this, rotate that shaft in the pic until the clamp bolt is aligned for removal which puts the broken part on the bottom. Then imagine a couple of guys sliding the tranny back off of the shaft, and opps, someone let the back of the tranny droop a little ....and you hear a distinctive "snap"..as that lower part breaks off. When this happens you are left with exactly the damage shown in the pic.Dave
I'm asking a general question, quite apart from this particular box and damage. If the clamp is properly secured, does the transmission input shaft ever break that way in a running car? I'm just trying to understand the weak spots of these transmissions, that's all.
I'm asking a general question, quite apart from this particular box and damage. If the clamp is properly secured, does the transmission input shaft ever break that way in a running car? I'm just trying to understand the weak spots of these transmissions, that's all.
I have seen and experienced a few stripped Clutch 1 shafts in my time, those leave lots of nasty chewed up "residue" when they let go. But I have never seen an input shaft damaged from being weak or not up to the power transmitted with properly torqued clamps. Every one I have seen broken was exactly like in the pic above and IMHO happened by human hands, not from too much torque. However I am darn sure Greg has seen more damaged transaxles than I have, by far!
I never had any issues with it, nor did I go investigating down there. IIRC, it was Brian MCMullen who bought it from me and it broke sometime when he had it. He was not a rennlister and he sold it sometime in the last year.
Is this the one that ended up here in Dallas a couple years ago?
08-15-2018, 08:18 PM
