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Yes, get it running.

I ordered the new 35/72 bearings, they will be here next week

I reached out Friday to see if there is a set of QV gears available I can (mostly) barter for. A couple back and forth clarifying emails Friday, hopefully an answer today.

I'm trying to decide if I need to send out the old adapter to be annealed of I can just heat it up here....I really want to just torch it and get to work but I don't want the splines all oxidized.....Pause.....Decision made, I ordered a some stainless steel foil for $8 so I can mostly protect it while I torch it, it will be here tomorrow.

I am go modify the drop gear case so the the adapter I'm making will fit though, that means opening it up a lot but will make assembly easier and more importantly disassembly WAY easier. The down side is that removes the sealing surface so I need to do something about that on both the drop gear case and the trans end cover.

I handed to the head gasket design off to my son, he needs a poke I think to get the models finished then he can place an order.

Right now though, some mud work in the family room, yuck

Yesterday I removed the gear from the adapter. The ring nut I made was damaged so all the special wrench did was bend




since I'm not planning to use the gear area on the adapter I cut the gear and nut off.



The SS foil I ordered was actually shim stock (Doh!) but it worked. I got the adapter mostly covered and ...out of acetylene. Today I picked up more in between paint coats so now the family room is painted and adapter is soft with minimal oxidation and ready to start remachining.

Long time reader, first time poster.

Is there any concern that the glitter from the drop gears in the trans may still be hiding in the trans? Any easy way to almost baste it with it in some reallllly light oil (Like grinder spindle oil?) and give it a few turns, spray it down again, a few more turns, etc?

Welcome and cleaning the trans is a very good suggestion that was not on my to-do list and probably should be.

While nowhere near the level of fabrication I have seen here (I'm not worthy! I'm not worthy!), i feel like with this repair I did OK with what I had. Why spend $30 on a new parking brake rod and tear the whole front of the mower part to get to it, when you already have a .30-06 shell casing, a dremel, a couple of clamps, and some JB weld and can fix it in-place?

(sorry for the attachments - I could not get the img to pick up from Imgur)

Shift above peak horsepower RPM so that the power the engine is making just before the shift in the old gear is the same power its making just after the shift in the new gear.

To get what you want out of this plot, the horizontal axis needs to be road speed, not RPM.

Yes, I changed it to mph which is easier to read but never posted. Here is a 90500 redline, notice the steps at the shift points. The traction limit is around 2000-2500 I'm pretty sure so 1st gear is worthless and can be ignored.


Shifting at 11k loos better but just ain't going to happen


Then for comparison here is a stockish 308 engine shifting at 8k when it would clearly be faster to shift around 7500

I went out to the shop to get started on the lower drop gear and realized my plan was just impossible to execute. I had it in my head I could cut the adapted to a 35mm OD but 42 is about it so its never going to fit through a 35mmID bearing.

I did slice it in 1/2 to make the machining easier so at least there was some progress.



New plan. I'm using angular conntact bearing to handle the thrust loads, that means I can make the drop gear, is shaft and inside bearing an assembly so it is removed as an assembly leaving a 72mm hole behind itto put the trans adapter on/off through.

Just as a refresher since its been about a year, this is the general idea, trans adapter on the right, drop gear assembly on the left.the left end of the shaft is shown smallish but it will get enlarged as much as practical then a bearing adapter fitted over it to make it with with the same 35mm ID bearing the inboard side is getting.

With that example gear/speed/torque plot shifting at 9500...

One of the reasons why it doesn't cross over so well is because you're still building power ALLLLL the way up. You've pushed the powerband up, and up, and up. Likely at the cost of molehill worth of midrange torque in exchange for a mountain of extra power at the top end.

Suppose just for a thought experiment that you could rev it to 15k and you had weightless unobtainium rods that would take the force, pistons that didn't care if their mean piston speed was 40m/s (Nearly double the mean piston speed of late 80's F1), and a F1 style valvetrain that didn't care, a water pump that didn't cavitate and a cooling system capable of keeping it cool enough to prevent detonation....

IF you could rev it that high, then shifting at 12k or 13k or wherever the actual crossover point might make some sense, IF you had an F1 car's worth of downforce and traction.

But I think a better comparison is your current plot, with the vast majority of shifting at the 7500-8000-8500 rpm range for spirited driving, compared against a hypothetical "mild cam" design that made more torque down low and shifted at 7500 rpm.

There is no way even shifting at 7500 vs a mild cam V12 at 7500 would cost you much area under the curve. Anything else up top is just extra icing on the cake.

The other question I've been asking myself is will it spin up so fast in first and second that traction is going to be non-existent? Is there an easy way to detect gear by ratio of RPM to Speedo, and pull some timing to rein it back some at the top of first, and then pull a bit of timing at the top of second? Artificially create the "falling off the cam" torque loss at the very top to make the shift smoother and improve drivability. Turn unusable power that just breaks traction even on the stickiest of tires into something a bit more manageable and slow the RPM climb just a bit at the top so you don't smack into the fuel cut redline abruptly before you know it.

If you cut a bit of power up top in first and second gear, and limit it to 700 horsepower, thats still damn near 100hp more than the late 80's Ferrari F1 V12's. Even 9500RPM on your V12 exceeds the mean piston speeds of those F1 engines.

I've spent most of the day looking at parts and not liking ideas. The 35mm bearings came today and just now I ordered a 40mm ID bearing because my ne plan is a 1 piece (2 if you count the outer bearing adapter) shaft that just slips on to the end of the trans shaft instead of the 2 piece that bolted on and was making my life hard because I couldn't convince myself there was enough metal there to left me cut splines/dogs of adequate strength. Now its a non-issue as is the need to find QV drop gears. I will need to modify the drop gear case to fit the larger bearing which is a bother but doesn't look horrible.

I[m a little torn what to make the shaft from, 4340 or 9310. I'm leaning toward 4340 and heat treating to RC50-52.