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Timekeeper explosion in P400

Kinda wonder if the dogbone just snapped at the thinnest points are these just stamped steel parts? that might be the cause, a small fracture at the weakest areas due to the stamping process. how thick are these dogbones? also could have had some burs from the stamping process which caused heat when the outward pressure is applied on the gears. the dogbones are what keeps the gears in place, rotational forces would create outward pressure and if the bores on the dogbone had any burs from stamping it would create heat along with a possible fracture at the weakest area. I see the pin has a grove cut into it from the damaged dogbone.

anything is possible.
 
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Still at 1/16" that's too thin in my book! that's in the realm of sheet metal! I would think with the outward force it would at least need to be around 1/8 to 1/4. it looks like there is room for a lot thicker material there
 
dbrannon79 said:
Still at 1/16" that's too thin in my book! that's in the realm of sheet metal! I would think with the outward force it would at least need to be around 1/8 to 1/4. it looks like there is room for a lot thicker material there
Click to expand...
Like I mentioned earlier, and you can see in the pics - the material around the dowel is thickened a little. But my builder said that he thinks the DSG gears have a thicker bracket - he did say its been a long time since he's put eyes on them though.

I agree that there's plenty of space for thicker material there. Especially the ring around the dowels.
 
If it’s a force issue that pushed the gear out through the plate- then thicker might be the answer- but metal hardness would come into play long before then.
My hardness file set went byebye year’s ago.

But remember these are copies of the DSG design. It’s been way too many years for me to even guess at how thick the dsg set is. Thats what is needed - not guessing. What thickness & hardness is the dsg set?

I dont know anyone that has a dsg set that:
1. Doesn’t have them installed
2. Would be willing to put a file test to it just for others to learn.

I suppose a person could do some comparisons to say BBC, Chrysler, etc and find out what those are. If anyone is playing in the dragstrip frequently where you can find guys doing teardowns of engines running them.

Otherwise it’s speculation.

The two spinning axle marks in the timing cover- do they match up with the axles before the plate failure or afterwards.

if the axles were spinning in the correct position (as I believe they were) then the failure happens by pressure on the axle not allowing the dogbone assembly to free float. This will cause binding as the crank or cam gear tries to push away the floating gear but cannot because the axle is pinched. So the force is going to make the gear push the axle every so small an amount snd that added drag now makes the axle start to spin. The spinning was apparent on the timing cover. Now you have the axle trying to spin at the speed the engine (or half speed of engine if binding on cam gear). The axles are supposed to be free floating and because of this will rarely spin in the plate.

If you look at the plate- you have to imagine how did it fail like this.
1. The axle was rotated to dig into the plate and cause the grove you see all the way around the axle.
2. You can see the axle was being pushed outward away from the center of the dogbone. That outward force is normal but it makes the dogbone assembly move away however it couldn’t move away as an assembly for some reason. Unless the dogbone axle holes are built too close to each other- then it had to be the axle was holding it in place.

Idk if we could search the web and find it- but there used to be a diagnostic poster that was made by Pete Jackson iirc.
It showed both the spinning axle marks and the side load wear between axle and plates as being caused by improper end clearance of the axle to block/timing cover.

Now, what if the plate was twice as thick? If the axle is still spinning all the time at the speed of the crank gear driving the dog one gear- there is no bearing there. It will still wear out like this and seize or wear through enough to cause the two dogbone gears to become too far apart.

Think through the force of the 1 gear that is carrying the load from crank to cam. The crank gear spins and pulls the dogbone gear into the cam gear. The greater the force, the tighter the gear gets pulled into the crank & cam gears. It does it to the point that the optimal gap isn’t there. When you set up a differential gear to tight - the differential howls. That is why the gear drive systems have that distinct whine to them. And the higher the rpm the more it whines because it is pulling the gears into meshing together tighter snd tighter.
It does not push the gear away or the other gear would get jammed into them and the gears would be binding against each other.
So the force of the floating gear is inward against the dogbone plate.
Not outward as we see was the case in this damaged set.
To get the outward force means the dogbone assembly was trying to be pushed outward and the assembly couldn’t move out of the way. This means it couldn’t freely move or free float.
The gear being pushed outward against the outer circle of the dogbone should not have any force on it- but obviously here there was.
 
I have a set of Leroy’s gears on my shelf I plan to install in my engine build for my hummer. It’s because of medical issues I haven’t finished it yet. Financial impacted it for a long time but I have enough to finish at least getting it together and in the rig.

My reason for gear drive is the 1.7:1 rockers means no room for timing errors. And even if running the stock 1.5:1 i prefer not retiming the db2 often, nor having the risk of valve slap which becomes common with higher mileage. Frankly I never want to be inside an engine again. I’m sick of it.

So if there is a problem with Leroy’s gears- I obviously want to know. Tad is a friend of mine & I feel bad for him in this mess. Obviously I don’t wanna experience it first hand.
I am in no way tied to Leroy. But this isn’t his design- he copied DSG and they made tons of these that had ridiculous high mileage results.
My knowledge really was from all the Pete Jackson brand ones used over the years. Same thing just competing brand, and the dsg that I had in the 6.5.

This isn’t an unknown failure. I realize a lot of guys are looking at this and going “I wonder what happened”. Guys- go to the racetrack with the pictures and show people who have experience with them. This is a known problem from the 1980s if not earlier.
 
Ok, well the 1/16” is 0.0625 and DSG is 0.065. I don’t see 25 thou being enough to stretch apart.
A hardness check would be a good comparison.
A full reverse engineering? I have the brand new set from Leroy. Can measure gears, spread, etc.

Using the hardness file on the corner of the plate as is done “breaking the edge” on block, rods, etc. won’t hurt anything. Actually is a good thing.
I’m more than happy to get a set of the files and ship them to you @Twisted Steel Performance to compare- maybe then ship them to Tad? See if something went wrong on this production run vs Leroy’s first set?

Like I mentioned- I just rather everyone know for sure if there is a problem in the part so guys can choose to roll the dice or just not install sets they (and I) have on hand.
 
Here is something to think about... I don't have a set to look at physically but maybe others can and answer this.... the plates are thin metal but how tight is the tolerance for them to slide onto the pins. as well as how tight is the tolerance for the pins and the bore on the gears. I assume the gears are designed to spin on the pins and the plates are to keep the pins in position. if a bur or something would cause the pin to drag or bind on the pins causing the pin to rotate on the plates, that would create wear and destroy the plates since they are so thin and not designed to have something rotating against them. If this is the case. how well do the gears spin on the pins that came out of this engine vs other new sets.

One way to look at this is to take the pin with the gear and use an air gun to force the gear to spin rapidly simulating it in the engine minus the outward force it has when it's together against the timing gears. see if it begins to wobble or chatter vs a smooth machined spin like a cam would spin on bearings or how needle bearings spin. the take away here is the amount of clearance along with how the pins are machined. (smooth finish or still has tiny groves present from the lathe work) heat also pays a factor here with expansion. Inspection of the pins and gears from the engine looking for signs of them binding would be the failure point. if something caused the gear to bind up on the pin this would have caused the failure. could have even been a poorly machined timing gear that was minutely larger or not machined properly on the gear teeth applying too much side load on the timekeeper gears and pin. not to mention mounting tolerance where the timing gear could have been every so slightly off center when secured onto the cam. all of this creates a failure point at the weakest link which in this case was the plates that hold the timekeeper gears in place. cam bearings also might come into play as a factor in this failure too.

what I'm leading to here is the timekeeper set might not be at fault here even though it's was what failed. other things play a role.
 
Parts just aren't what they used to be. The brand new oil cooler I ordered for the rebuild was unboxed and - found to be defective. Looks like someone messed up the pipe weld/solder, then slathered it with JB Weld and send it to paint. Thankfully the vendor, Macmotors, is replacing it.
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Just a quick update.

The engine is back up and running. Everything on the truck is getting buttoned up and finished after not being able to work on it all week due to plowing duties. After checking the timing today - the hood and brush guard should go back on later today. My guy is going to drive it for a week before he gets it re-aligned and hands me the keys.

I miss the smell of leather and diesel in my garage.
 
Well. All was set for me to pickup the truck this weekend - however we ran into a small issue. The tune provided for the P400 Pump was coded for the incorrect GPC - which was causing a glow plug code to throw the CEL. I do not tolerate CEL's or warning lights on my dash. We used all new plugs during the rebuild, but I am well aware that new parts are not good parts by default. My mechanic was like "I've never seen a 6.5 crank up so fast and without a puff of smoke in 15'F cold - I know these plugs are good." So after confirming the tune issue - we're waiting for the the PCM to come back with the right GPC.

However we took the opportunity to take the truck to a different shop and get it aligned. It was so bad out of alignment that the machine initially thought it was malfunctioning. I asked how the truck felt with the new P400 Pump and he said "it feels like a whole new truck. It's effortless accelerating. Highest temp at 70mph was 186'F" This is coming from a guy that basically works on nothing but H1's and HMMWV's so he's pretty knowledgeable when it comes to these trucks' performance.

I was trying to maintain a cool and patient attitude towards the rebuild, but I'm now getting very anxious to get it back.
 
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