duragg

Sneaking up on the best solution for "High RPM shifting dynamics". I finally have all my new parts in from Nissan and tonight did some research on my spare tranny setup. I have a shaft configured for testing various configurations. I can test keys, engange rings, synchros, and all sorts of stuff. Tonight I experimented with shims under the key springs to see about how much pressure the Engage Ring can put on the Brass Ring before the keys give way and allow the Engage Ring to slide by. 1) Stock springs with new keys and new Engage Ring about 12 pounds. 2) Add a .030" spacer under the key spring the Engage will put about 14lbs on the Brass prior to giving up the dugout. 3) Add a .060" spacer under the key spring the Engage will put about 17lbs on the Brass prior to giving up. 4) Add a .090 spacer and the force goes to infinity as the key springs are coil bound. If you can visualize the way the keys work, they put the most pressure just after contact with the ring, and before the keys have had a chance to begin to receed much, its all downhill from there. This is only about .010" of "squish" on the keys before they give it up. This is the reason Jacks wants to "tune" the Engage Ring, keys and slider to hit at just the right time. You want the Engage ring to smack its keys into the brass ring and pound it onto the gear cone initially, then with just about .010" movement compress the keys slightly JUST as the Engage Ring teeth mesh perfectly with the Brass RIng Teeth which prevent any further movement untl synchronization is complete, at which point the brass ring moves aside and lets the engage ring make the gear. ... is my theory this time...

Its nice to have the ability to bump and crank the engine with ignition off for maintenance. Putting a guard on your start switch? I also have an alternator idiot light next to alternator switch and a big oil pressure light at the top. My "Master" switch enables a bit Battery Relay and I left a provision for an external kill switch for future racing compliance.

Hopefully we can get together this week. Probably need to dump the whole gas tank... I can bring you some 100LL which is super-stable. It tunes very close to the same as Car gas (nasty evil garbage). Glad you are making progress. Tj

Hey Ghost I am back from S.D. later today and maybe can stop by. From our offline conversation let me add: I personally would dump the bowls and start over. Pull idle jet stack, pull out idle jet from holder, clean, note the stamped size and then replace LIGHTLY in the holder. Just barely insert and then carefully replace in body and as you screw it in you will feel the body gently pushing the jet into the right position. Adjust butterfly visually on all 6 to cover the prog hole closest to engine so when u shine a light from inlet side you see light from only the outboard 2 holes and the hole closest to engine is obscured by the butterfly EDGE. Doesn't hurt to talk nice to them, buy them cigarettes, wine etc...

Great pics. I need a spare shell to spend the summer on...

Don't have any fear of using 50wt either. I Like your Benz. My other toy is a 1988 560SEC. Splitting my time and resources amongst the two projects. Aircraft get stuck rings a lot (huge bores) and I have had good luck by plugging the spark hole with my thumb, and rotating the engine backwards creating a vacuum, then quickly release. Now do it forward-then release. And backwards creating that reverse suction on the rings and just keep doing this. Its easier with a propeller, but using a bar on the crank should work too. That backwards suction seems to snap the junk loose and you can feel the compression come right back up. Then proceed to try to blow it up..

Last round of parts came in to make one last push for perfect shifting in ALL gears. The goal this round is to perfectly match the synchro engage ring / brass ring contact per Jacks website. I did purchase a BNIB Nissan Engage ring, but I must say it doesn't look a whole lot different from the old ones. The grinding is more noise than damage it seems. But we'll try this ring, and some trimming of the brass ring clearances to perfect the timing. If I am STILL able to easily push past the dog teeth during the shifting then... I'm buying a toyota.

My LSD is the single most enjoyable mod I've done. Probably need to think about changing the juice and the cooler as mentioned.

What about try running straight 50wt? Like a VR1 SAE50 I secretly hate multi-grade oil and just switched to straight 50 in my Z due to high temps oil turning to water. Im not sure just how much oil could really get by VG seals? Could you pill a full quart past them? Or more likely past the rings which have a lot more surface area to offer. More importantly, need to see a picture of that 250S and its engine please...

Update. Ordered a new Nissan Engage Ring "Sleeve" from Nissan, along with a few other seals and parts for the next surgery. Like last time I will open up, and pull the front C/S bearing to access the 3/4 gear pack. Going to replace the sleeve and modify the brass ring as needed to make the timing match as Jack's discussed on his website. Replacing the front C/S bearing since I've pushed it on and off a few more times than it deserves and FRIGGAN PRAY! or drink, either way.

Mine creaks and groans especially with the new stiffer suspension and the poly bushings seem more noisy? At a recent track event I noticed the "big kids" were showing off by jacking a front corner and watching that whole side come off the ground evenly... Ya, I get it- you are manly stiff. I feel my limp noodle approach helps me adhere to the track better, like a centipede of sorts. And rust is light, just sayin.. Future mod is a spare shell to beef up and swap all my fun parts onto.

Thats real helpful. Looks like the average weekend warrior using fresh 5.1 is doing the best they can. Suppose same deal in the clutch.

Same here. What is the best bang for the buck when upgrading fluid. I like to have a gallon at a time, so with that quantity pricing is probably reasonable. Leaves enough to soak my clothes and the floor without feeling pinched.

Got my "kit" from MSA and the quality is now known... marginal. Its not really a kit, but an assembly of stuff which shortens some of the R&D time which is valuable for me. Problem is, the "shroud" they shipped is a POS. Just a flat piece of metal which looks nothing like what is advertised on their website. I've sent in a Return Request to see what happens, or what their feedback on this is. Still probably better than what I had which was a stock fan with non-functional clutch and no shroud.

S12W with vented rotors and the pads that came with them. 280zx rear calipers and a solid rotor with stock pads. Proportioning valve removed, lines running straight through. I have 2 track days (7.25 sessions @20m each) and some street driving and few complaints yet. Its a cheap setup and scratched my itch for more heat capacity and disc bling. Bias seems fine at the moment. 15x10 wheels with street tires so for now that is the limiting factor. After each session all the wheels are covered in dust so at least I know the backs are contributing. Real track tires will want real pads- and the bleeding financial spiral begins. The mechanical handbrake on ZX rears is fine for emergency or parking, but won't come close to locking the rears. Its geometry and how I integrated the ZX cable to the Z mechanism isn't ideal, but works and is safe. The big king-crab looking ZX calipers can hit the body and stock brake mounting brackets, so pay attention to clearance with an eye towards full squat.

This research is on PAUSE for a week due to a business trip. On return I have conscripted a helper and we will make another attack on 3rd gear with a slight modification to the brass ring. My favorite part so far is the new shifter seals (2 of them: Big o-ring and little Lip seal) and finally not a single drop of leakage.

I became so bored with well behaved fuel injected cars that keeping my Triples has been a real treat. They still have a certain "I don't know what" - that sound. That smell, the occasional* burps and moods. I like the idea of the GSXR ITBs, but Megasquirt would probably be my only financial choice and reading those forums, life isn't all 12.5-14.7 for them either. They struggle with Tip-in and various issues. I love winding the crap out of my L28, might need to make one of them 9000RPM motors like TonyD gets to play with next. That sounds fun.

HI. I'm back... I have more to discuss. You can tune out now. A little recap: Fault 1) 2nd gear grinding - Worn Synchro: FIXED. Fault 2) 2nd gear popping out- Worn shift fork: FIXED Fault 3) 3rd gear grinding only under spirited driving: NOT FIXED. For lack of anything better to do tonight, I want to explain my theory of the 3rd gear grind when the lever is pushed hard. There is a lot of different types of grinding and the exact circumstance is important. In this case, hard lever push causes grinding I believe due to the Engage Ring being allowed to push past the brass ring before the speed is ready from the keys losing preload too early causing a grinding. You pull the lever from neutral towards a gear, the shift rods act on the shift fork to move the Engage Ring towards the desired gear, the Engage Rings have a detent inside where the Engage Keys ride held by spring pressure. The Engage Keys are moved toward the gear cone due to this detent and they push the Brass Ring onto the gear cone causing the brass ring to turn just slightly in the key groove and align with the Engage Ring Teeth. I think we call this PreLoad and the brass ring is just riding on the gear cone, no big braking force is happening yet. The real braking to sync the speeds happens as the shift lever is moved just a bit more and the "Engage Ring Dog Teeth" contact the "Brass Ring Dog Teeth" at the 45 degree angle and the vector created by the lever push vs the spinning gear Blocks and prevents and blocks the Engage Ring from moving more towards the gear until the speed is equalized, at which point the Engage Ring can slip the Brass Ring aside and mesh with its Gear. You really need to read and try to understand what the guys at Jacks Transmission are talking about with "Synchro Blueprinting" for this to make sense. I believe in my case and many other trannies, the keys are pushed forward by the Engage Ring but when they contact the gear cone the "Engage Ring Dog Teeth" and "Brass Ring Dog Teeth" are WAY too far apart. I measured about .030" gap between the teeth which must be touching for heaving braking (synchro action) to result. But the shifter continues moving forward until the Dog Teeth mesh, however to make this movement the synchro keys have had to "give" some as the Engage Ring pushes them inward, and some of the preload is lost, causing less braking force and the engage ring just slips on by - crashing into its gear. A bunch of random theory which is really hard to verbalize, but here is what I did. I took the Brass Ring Keyways and measure them and in all brass rings I have the key slot measure about .160" So then I took a spare brass ring and machined the keyway slot .020" thinner which will allow the Engage Ring Dog Teeth to be that much closer to the Brass Ring Dog Teeth when the shifter is pushed so the keys don't have to give up their spring pre-load to make full braking happen. If this modification can be performed on my tranny soon, I should be able to Slam 3rd gear and since the dog teeth will be fully engaged they will provide full braking and total blocking of the engage ring until sync occurs and then the gear will slide in without any grinding.

Fail. 3rd gear at 7000+ shift Improved but not gone. I can still push past the keys and get a crunch. Not F-ing with this box anymore (for a while) except perhaps to play with sauces. Learned a LOT. Tj Edit: 2 hours hence, beer is setting in, cooler head prevailing. Among the things I did NOT do on this round was to "lap" the synchro rings into the gear cone. I had sound reasons, but I question them now. The good news is that after 500 or 1000 miles of driving and shifting those synchros will bed-in more with their mating surface and the braking action may improve.

I am feeling like a girly-man now! I've got the car jacked as high as it will go on the big floor jacks, no way I have the muscles to do that.

I use the floor jack, inserted from below the diffy and that works fine. Still a process. I can leave the exhaust in place with my current setup which saves a little time I suppose.

They day or reckoning is upon my great adventure. I had some oil leak from the shifter so ordered new seals and while I was at it I drilled the 2nd hole for a future short-shifter. Or... perhaps just a lightening hole if nothing else. Tranny reassembled, installed and tomorrow I will finish hooking everything else up and give it a whirl. Installing a tranny alone is a PITA. Somewhere between "Can you help me move" and "Can I borrow a thousand bucks" is "Can you help me put my tranny in?"

I just ordered the MSA kit for $250 (back ordered). Comes with relays and such. Decent price, unknown quality.

It all caused me wicked vibration due to the lower nose of the diff and higher ratio of my rear end. Still finalizing my angles to this day.

Isn't that typically a sign of vacuum pulling oil past the guide seals? Then on first throttle burns it away? Valve guide seals? or just heavier oil.