my transmission finally exploded

[datzenmike]

Well the heavier the vehicle the heavier the flywheel needed. The job of the flywheel is to store rotating energy to make starting from a stop easier. Too light and you have to rev higher and slip the clutch more and more.

 

Look on the engine side of yours and compare to another flywheel. The one on the right below is about 29 pounds. The one on the left is scalloped and weighs 21 pounds. Both are 225mm but the lighter one is from a 280z which has a larger rotating crank. The other is from a truck 4 cylinder.

 

 

 

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[Skulptr]

oopsie, broke a bolt, but at least i rtv'd around the entire hole. i'd pull it out but its flat with the front case. filled with rtv, hopefully it will hold, or at least slow down a leak until i source another tranny

 

 

so the pictures are out of order, i think, but it shows basically what i had to do to get the tranny out. i did pull my tranny with all 4 tires on the ground.

 

 

 

 

 

so the write up, kinda. i'm still pretty out of it. had a pretty nasty end of the weekend. and i dropped the tranny on my chest putting it back in, so most of my ribs are bruised up right now.

 

1. i took off the output shaft to the transfer case

2. dropped the front driveline, and ziptied it to the torsion bar

3. dropped the crossmember under the tranny and pulled all its mounts, and ziptied the ebrake cable back out of the way.

4. completely disconnected the front differential from its front and rear mounts, pulled the driveline connector from the front diff for a little bit more clearance, also i let my front diff drain this way while i was doing other stuff.

5. pulled shifter, clutch cylinder, starter, and trans bolts

6. pulled straight back on the tranny to detach it from the engine, and pushed it back over the frame crossmember until it wouldnt go any further

7. pulled down on the front case until it cleared the input shaft of the front diff, and she came right out.

 

you can see in one of the pictures where the shifter input hit the floor in the cab and scratched it, but i really dont care, its under the truck and no one will ever see it and it didnt do any detrimental damage. putting it in was just as easy. i stood the tranny up on the front case, lifted the output shaft up towards the cab, and supported it on the crossmember, and pushed it back until it cleared the front diff and was home free.

 

the only reason i was able to do all of this by hand is the tranny had zero oil left in it. i let it drain out. and for those that commented on the milky oil, that was the last of the oil to come out, about 90% of it was still good, but that just means the watered down crap had time to settle.

 

and for those that need to drop the front diff, the bolts and nuts are 7/8" and one bitch n a half to get off. i had to hit them with my big daddy impact to get them loose.

 

also, i came across this clutch on a JY truck, caught my attention. anything special?

 

[poor-mans-720]

thats an Exedy,... Same clutch that i have in my truck. I ordered that mine on Rockauto.

Alright clutch in my opinion. but nothing special to me... Its in pretty good shape.

Its a pain to do it on the ground. I have done it twice. Not that bad, but there is alot of stuff to take down. I might invest in an engine hoist if i ever have to do this again... It sucks major to do this type of stuff while in the truck. pull the motor, seems so much easier.

I got my flywheel in. Gave up putting everything back in... Too tired, and my back is sore from lifting that transmission... man those things are heavy...

[Skulptr]

These tranny's are really light, about 65lbs empty. The tranny in my pathfinder weighed over 300 empty

[Skulptr]

If you have a body lift, you can pull the tranny without dropping the front diff. I just realized that.

[poor-mans-720]

pfhhh... mine felt at least 75.... but mine isnt drained. Its just a PITA when i didn't have a alignment thingie... So i had to slid the tranny back and forth 20 times. and wiggle it each time.

Till i got it aligned and could tighten the pressure plate up and still have the transmission aligned... my arms were killing me after 2 hours of holding that thing up...

 

yes, with a BL and a little wiggling around and turning the trans will come out...

[Skulptr]

Well I got it all back together, sourced some gl4 thanks to HRH, and she backed our of the garage under her own power. Unfortunately I lost the pin for my shifter, so I had to stick a bolt in to hold it in, but is not thick enough to shift into any gear but reverse.

 

Plus the gears did take damage, and she makes alot of noise when the clutch isn't depressed. Oh well, I'll drive it til she blows again.

[poor-mans-720]

Did you change your pilot bushing when you were in there? Clutch isnt depressed... Hmmm... just sitting at a light, in Neutral? wonder what that could be...

[Skulptr]

Only replaced the busted bearing and t/o bearing. The 2 gears most forward on either shaft had some teeth damage, I think thats what's making all the noise

[Stoffregen Motorsports]

Only replaced the busted bearing and t/o bearing. The 2 gears most forward on either shaft had some teeth damage, I think thats what's making all the noise

 

Those two gears (if you're talking about the forward most gear on the main shaft and the counter shaft) are your drive gears. If they are bad, your trans will make noise in all gears except 4th because they transfer the power to the rest of the gears unless you're in 4th when the gear hub connects the pilot shaft with the mainshaft making it direct drive.

 

Here's an image of the basic trans layout, the front of the trans being on the left.

 

Here's a flow path of the power transfer. Let's call the red line 1st gear, and the green line 4th gear. You can see how the flow path changes when the two portions of the main shaft are connected.

[Stoffregen Motorsports]

On some Datsun transmissions the front counter gear is removable and swapping this gear, along with the pilot shaft could fix your problem. It would be just as easy to get another counter shaft cluster gear from another trans and install the whole thing with the new pilot, but then if you've got a donor trans...just run it.

 

On a side note, changing the pilot shaft (input gear) and front gear on the input shaft with another pair with different tooth count changes your gear ratios.

[Skulptr]

thats not entirely true. the drive gears are constantly in place with each other, so no matter what gear i'm in, they are always spinning, and as long as the rear wheels are turning, they will be too unless out of gear.

 

 

anyway, i found the pin for the shifter and got to drive it for the first time in a few weeks. besides the noise, which seems to diminish with speed (or maybe the engine is just drowning it out), she drives just fine, and seems to drive better, doesnt grind into any gear now, especially reverse, which ground almost every time before.

[Mr.Dean_Yates]

^^^ or buy a newish trans?

[Skulptr]

^^^ or buy a newish trans?

 

Playing this thing called the waiting game. Currently, there aren't any. And my local junkyard is, literally, the worlds largest junkyard.

[Stoffregen Motorsports]

thats not entirely true. the drive gears are constantly in place with each other, so no matter what gear i'm in, they are always spinning, and as long as the rear wheels are turning, they will be too unless out of gear.

 

Whatever...

 

You're right. They are always "in place" as you say, but when in 4th gear, they are not under load and basically freewheeling.

[datzenmike]

and seems to drive better, doesnt grind into any gear now, especially reverse, which ground almost every time before.

 

If grinding into reverse then this is clutch related. Clutch is not fully releasing or dragging.

[Skulptr]

I love the way what I know based on what I have seen and touched gets contradicted. Free wheeling or not, they make contact, and.spin 100% of the time, meaning the no longer smooth sided teeth are making noise. Sorry if that doesn't compute for you, but you can just say "whatever" and go about with what ever half assed work stoffregen motorsports does, based simply on your attitude on being called wrong on something so simple to understand.

 

And mike, please explain how something caused by the clutch went away when a bad bearing is replaced, putting the shaft back into proper alignment for the first time in who knows how long, and nothing with the clutch was modified or improved.

[Stoffregen Motorsports]

Yeah, you're right. I don't know what the hell I'm talking about. I've never seen the insides of a trans. How many transmissions have you built?

 

Lighten up, Francis.

[Stoffregen Motorsports]

OK, this is not worth engaging. I'm sorry I tried to help. I thought forums were a place for people to share information, not just show off the size of their...vocabulary.

 

I have been in the business for 25 years and I've built hundreds of motors, transmissions, differentials, and I know my way around the suspension pretty well too. I was only trying to eplain how power transfer can amplify a noise. If you need to prove me wrong, that's your problem.

 

Good luck.

[datzenmike]

And mike, please explain how something caused by the clutch went away when a bad bearing is replaced, putting the shaft back into proper alignment for the first time in who knows how long, and nothing with the clutch was modified or improved.

 

Sometimes just taking things out and putting back in 'adjusts' them. There are no synchros on the reverse gear. When you put the clutch in, the counter shaft begns to slow down from the resistance of the oil it's in By the time you move the shifter the gears are stopped. Maybe the oil was changed or topped up? Usually what keeps it spinning is a dragging clutch.

[datsunaholic]

 

 

And mike, please explain how something caused by the clutch went away when a bad bearing is replaced, putting the shaft back into proper alignment for the first time in who knows how long, and nothing with the clutch was modified or improved.

 

 

That's easy. If the bearing was bad, the shaft went out of alignment. That made the input shaft slightly off angle, which allowed the clutch disc to make contact on one edge, which made the input shaft and the internal gears spin up in neutral (due to the now dragging clutch). Replacing the bearing put all shafts back into alignment, so that the clutch was no longer off-angle and didn't drag.

 

My big old Army truck doesn't have synchros in 1st (or reverse). So idling in neutral, it's pretty hard to get it in 1st unless you let the gears (which are so large they have a lot of centrifugal force) spin down. Or, just stick it in 2nd before going to 1st (or reverse).

[Skulptr]

Ok new subject. I had a weird feeling I needed to get to the jy today. And I'm glad I did.

 

This is what I found...

 

Didn't take any pictures of the whole truck. It has a 3" body lift in it, full length runner boards with full length side marker lights, blown head gasket and snapped torsion bar, and an extremely spacious drivers side.

 

 

Which in turn made the tranny she was housing really easy to unbolt. Once it was out, I realized I forgot my hammer so I didn't get to open it before I bought it. I did rotate and push in out up down on the input shaft. There is some slack in rotation and also up down so there's no way I will throw it in until I find out what's causing the slop.

 

And I found some neat finds, and FINALLY found a rear window latch in one piece.

 

 

 

 

 

And who mentioned they need a 2 pipe intake filter housing?

 

[poor-mans-720]

Im confused what this thing is... Was... What trans did it have in it? The driveshaft form the trans to transfer case is ridiculously long... Mine is only like 6" long. What motor and trans did this one have? Would have been an awesome setup for dual cases. Plenty of room to do it. Curious as, I plan on doing dual case setup to run my 40" tires... Lol

[Skulptr]

It's an 85 king cab. That shaft is the same length as every 4x4 I've seen with a z24. My king and single both had the same length shafts.

[poor-mans-720]

weiRd... my shaft Is probably less then 6" long between the trans and transfer case... Maybe its just the angle of the pic. I am looking at it, on my gf phone. Just looks hella long compared to mine.