Stock AWD Tranny Which Gears Break?

[trick engine]

I am posting this just to find out what is the most common failure in the stock 2G Awd Tranny . For me it has been 3rd and 4th Gears teeth would shear off and then get stuck up in other gears causing other gears to get messed up. I ask this cause I am thinking about trying a Treatment for the stock gears but before I do I would like to see which gears fail the most first . It looks like the stock 3rd gear is very small conpared to 1st and 2nd gear which may be the issue in it self . Any help here would be Great . Thanks.

I was also making around 300whp when these failures acurred . I am know making over 600whp But I have not driven the car enough to break anything ....YET >>> I have my spare tranny apart and was think about trying something new .

 

[JackM]

The spider gears in the center diff are the weakest. If you have a welded or 4-spider unit in there- 3rd and 4th are next. People have tried micro polishing, cryo treatments, and smoothing out the teeth ends but nothing seems to really help very much. When you make enough power, you will break them. 300hp is not enough though. If you broke a set with that kind of power you were running bad fluid (BG or synchromesh destroy gears) or had very loose preloads IMO.

Jack

 

[MidShipCivic]

What else besides spider gears?

 

[twicks69]

The late model 2G 3-4 gearset is fairly weak, but has better synchro design--great for a street car, and lower HP cars.

You can swap to a 92 input shaft with a 92 3-4 gearset and hub/slider/synchro/key/spring assembly and they will last longer. The 92 gearset uses a little thicker gear, with a smaller synchro, but a stronger 3/4 hub/slider.

Otherwise, you can go Evo 3 stuff, or buy a dogbox, or keep on breaking and rebuilding them yourself like I have learned.

It does sound though like your bearing preloads are a little on the loose side though, causing your shafts to thrust away from themselves, causing the teeth to bind/shear/fail, resulting in the damage you are getting. If you have your transmission dissassembled (but with the gearsets still pressed on, and can check what your preloads were at, by pulling the shims, replacing them with solder, and reassembling the trans, torquing to spec, etc; and then pull it apart and mesure the solder thickness vs. the shims you had in there to find where the preloads were at by measuring the difference vs. the specs.

I would also use Redline Lightweight Shockproof (blue) in the trans.

Good luck,

 

[trick engine]

Yes I am running a welded diff at this point . But I never had any issues with breaking center diffs anyway . I would always break 3rd gear sometimes 4th on factory assembled trannys . I guess maybe it was making more then 300 WHP . They did last a good amount of time before any issues . And I did Drag race 1-2 Times a week . probally lasted 15-20K
Miles.

May have been a fluid issue but I have always run the Recomended oil for the tranny mostly Redline MTL

I also tried using Redline Heavyweight Shock Proof but it shifted real bad . Guess i will try the Lightweight Stuff.

 

[Boost92awd]

Thats all I run in my drivetrain is Royal Purple. Not sure what fluid was in there before, but after I changed it to Royal Purple the car shifts like its brand new. I'm using the stock weight Royal Purple also.

 

[DGajre777]

May have been a fluid issue but I have always run the Recomended oil for the tranny mostly Redline MTL

I also tried using Redline Heavyweight Shock Proof but it shifted real bad . Guess i will try the Lightweight Stuff.

Redline Heavyweight shock proof is for the x-case and the rear diff, NOT the transmission. I've been running Synchomesh for 2 years in my tranny and I'm switching to Redline MTL next month.

 

[trick engine]

Maybe this time I will Try the light weight shock proof.

 

[Black_Bullet]

I run the Redline ShockProof Heavy in my Tcase and Diff, and syncromesh in the tranny.

My car shifts better with syncromesh but its too thin. It breaks down to the point i feel i need to change it within 5-6k. Syncromesh is good if you change it every other oil change, anything more and its water imo.

I too am switching to the Redline Mt90 stuff next time i change my tranny fluid...

 

[snox135]

I run Redline heavyweight in my TRE and have never had any problems. I just make sure it is warmed up before any hard driving.

 

[trick engine]

I also have Tre Gearset in there now but it shifted ok but worse with the Redline Heavy .

 

[1LE]

Redline Heavyweight shock proof is for the x-case and the rear diff, NOT the transmission. I've been running Synchomesh for 2 years in my tranny and I'm switching to Redline MTL next month.

I use the Heavy Shockproof in the trans as well as the t-case and rear diff. Surprisingly, there's no issues in the Winter (as low as -15F, that's the coldest the car will start for me), but I always give my engine a little time to warm up, so the trans is bound to gain some heat during that process. The Synchromesh and MTL's are just too thin, make for very notchy shifting.

 

[Black_Bullet]

The spider gears in the center diff are the weakest. If you have a welded or 4-spider unit in there- 3rd and 4th are next. People have tried micro polishing, cryo treatments, and smoothing out the teeth ends but nothing seems to really help very much. When you make enough power, you will break them. 300hp is not enough though. If you broke a set with that kind of power you were running bad fluid (BG or synchromesh destroy gears) or had very loose preloads IMO.

Jack

The late model 2G 3-4 gearset is fairly weak, but has better synchro design--great for a street car, and lower HP cars.

You can swap to a 92 input shaft with a 92 3-4 gearset and hub/slider/synchro/key/spring assembly and they will last longer. The 92 gearset uses a little thicker gear, with a smaller synchro, but a stronger 3/4 hub/slider.

Otherwise, you can go Evo 3 stuff, or buy a dogbox, or keep on breaking and rebuilding them yourself like I have learned.

It does sound though like your bearing preloads are a little on the loose side though, causing your shafts to thrust away from themselves, causing the teeth to bind/shear/fail, resulting in the damage you are getting. The front output shaft, the intermediate shaft and the center diff, are the only ones that require Preload -- around .030", while the rest of the shafts require around .020" of endplay. If you have your transmission dissassembled (but with the gearsets still pressed on, and can check what your preloads were at, by pulling the shims, replacing them with solder, and reassembling the trans, torquing to spec, etc; and then pull it apart and mesure the solder thickness vs. the shims you had in there to find where the preloads were at by measuring the difference vs. the specs.

I would also use Redline Lightweight Shockproof (blue) in the trans.

Good luck,

I have a few questions regarding this topic. Hopefully I can just ask in here and not have to start new thread.

So to begin, I have long heard of weak dsm 4th gears.
On average, or from someone elses experience, what is the amount of HP, or better yet Torque that these stock 3rd-4th gears can handle. I dont want to start breaking them all the time and would like to know my expected limits
(Generally speaking.)

I have a pretty much stock 92awd tranny, stock diff non welded. It has the standard OEM rebuild done to it about 15k ago with double syncro 2nd gear. Due to trying to avoid needing a tow and get the car home with no clutch fluid one night from my SS line leaking, I was trying to rev match and shift without clutch and banged up 3rd gear really bad. So therefore at high rpms ( above like 6500 ) shifting into 3rd has to be done precise and not so fast or it will grind. I have gotten used to being more mindful and cautious getting into 3rd now when racing, and doesnt affect me to much anymore.

My car is down at the momment for a Act2600 and sbc kevlar setup that will be in and back on the road by the end of this week. Still running evo316g, estimateing currently around 310-320awhp on 93octane, but the car will soon be only ran on E85 with a much more aggressive tune and a 75 shot of spray.
Due to times the car has already gone, Id save a conservative guess, with the e85 tune and n20 car should be capable of high 120mph traps and low 11s... That is end goal for the car.

I know a lot of the longevity will be based on my upkeep and driving, in which I normally granny shift
(though always using the NLTS when racing. ) and I dont launch often.
Will I have to worry about sheering teeth off of gears or breaking centerdiff's at the goals I mentioned?

Also I have been running syncromesh in this tranny for the past 15k and changing it every 4k or so due to it breaking down faster. The only reason I was previously running it is because my car shifted a lot better with it.

I dont want to put syncromesh in anymore.
What would be better for me, in terms of helping the tranny last longer, the Redline MTL stuff, or Redline light weight shockproof, or Royal purple?
I still have one bottle of syncromesh left in my garage, would there be anything wronge with mixing some syncromesh with the Redline this time around to not waist the bottle?


Thanks...

 

[twicks69]

If your transmission is an early 1992 transmission, it has the strongest OEM 3rd and 4th gear and hub and slider in it. This also has the 2-hole 3/4 shift fork, and the strongest 3/4 shift rail.

If you have the double synchro 2nd also, then you are just fine.

If anything, I would install a new 3/4 hub and slider, 3rd and 4th synchro, and new springs.

If it is a late 1992 transmission, then you would need an early 1992 Intermediate shaft, 3rd gear, 4th gear, 3/4 hub and slider, keys and springs, needle bearings and 3/4 shift rail and 3/4 shift fork.

You also need to have the notched center diff case.

As for gear oil, Redline Lightweight Shockproof works great -- do not mix it with synchromesh.

 

[Black_Bullet]

If your transmission is an early 1992 transmission, it has the strongest OEM 3rd and 4th gear and hub and slider in it. This also has the 2-hole 3/4 shift fork, and the strongest 3/4 shift rail.

If you have the double synchro 2nd also, then you are just fine.

If anything, I would install a new 3/4 hub and slider, 3rd and 4th synchro, and new springs.

If it is a late 1992 transmission, then you would need an early 1992 Intermediate shaft, 3rd gear, 4th gear, 3/4 hub and slider, keys and springs, needle bearings and 3/4 shift rail and 3/4 shift fork.

You also need to have the notched center diff case.

As for gear oil, Redline Lightweight Shockproof works great -- do not mix it with synchromesh.

Thanks for the informative response Tim.

I should have a early 92 tranny being my car is a early 92 model with a 6bolt motor and eprom ecu and 4bolt rear... (Plus Lasers are the lightest, I always believed I had the best model/yr 1g dsm to have. )

But say one of the few previous owners of the car before I bought it for some reason put a different tranny on it, is there another way I can tell that I have early 92. Any specific part numbers you know of, or physcial, visual ways to tell without opening it up.
Im pretty sure the tranny identification tag number is deteriorated by so much dirt and age.

Id like this tranny to hold up for at least another year or so, but I do plan on getting this tranny rebuilt better in the future, I was also even considering using the Evo gears at one point that Jack references on his site www.jackstransmissions.com

And to get this straight, your opinion is that the Redline Shockproof light weight, is better than the Redline mt90?

 

[twicks69]

Thanks for the informative response Tim.

I should have a early 92 tranny being my car is a early 92 model with a 6bolt motor and eprom ecu and 4bolt rear... (Plus Lasers are the lightest, I always believed I had the best model/yr 1g dsm to have. )

But say one of the few previous owners of the car before I bought it for some reason put a different tranny on it, is there another way I can tell that I have early 92. Any specific part numbers you know of, or physcial, visual ways to tell without opening it up.
Im pretty sure the tranny identification tag number is deteriorated by so much dirt and age.

Id like this tranny to hold up for at least another year or so, but I do plan on getting this tranny rebuilt better in the future, I was also even considering using the Evo gears at one point that Jack references on his site www.jackstransmissions.com

And to get this straight, your opinion is that the Redline Shockproof light weight, is better than the Redline mt90?

There are two castings and a vin# sticker on the bellhousing. The sticker is usually worn off or gone, so you can decipher the stamps:

The casting you are looking for on the bellhousing is a flat spot with a stamped in serial number. An Early 1992 AWD 5-speed transmission would have: "KW5M332NPXV" Which would make it a mid-1991 to Early 1992 transmission.

The second casting is a 17-digit vin code. The 10th digit deciphers what year the transmission was built. If your 10th digit is "M", then it is a 1991 transmission, while a "N" would be a 1992 transmission. I have attached a photo below showing what it would look like -- as well, the red underline is under the 10th-digit -- in this case, it is a "M", making it a 1991 transmission.

Here is also a good link to follow if you can read the second casting stamp (really small font)

http://www.dsmtuners.com/forums/dri...-decode-transmission-find-out-when-built.html

I have attached photos of a "NPXV" 1991 transmission to show you what I am talking about.

On a final note, you will know you have a mid-1991 to early-1992 by the shift linkage arm on the transmission. The main arm will be a long, upward curving one -- see the pic below for details as well.

As for the Redline gear oil, I have used MT90 and it is nice for a street car, but it just cannot handle the shockload of AWD launches and high horsepower transmissions. I would reccomend the Lightweight Shockproof Gear oil for your application.

 

[Black_Bullet]

Awesome info Tim!!!
The tranny did read "KW5M332NPXV" so looks like its the original tranny for the car! Early 92 FTW!

I will take your advice on the Redline Lightweight for the tranny fluid.
I have to order anything Redline it appears, I get my stuff from Titan motorsports which is only 100miles from my house so I can probably have some hear pretty soon.

You must be logged in to view this image or video.

 

[twicks69]

Thanks Jay!

I hope that everything goes well for you!

Here are the part numbers for replacement synchros, gears, hub and slider, keys and springs, and shift fork:

3rd and 4th Gear Synchros: MD744782 (x2)
3rd/4th Hub and Slider: MD747646
3rd Gear: MD742728
4th Gear: MD742729
3rd/4th Hub and Slider Springs: MD742441 (x2)
3rd/4th Hub and Slider Keys: MD742777 (x3)
3rd/4th Shift Fork: MD741558


These are the main replacement parts. Anything else, just ask, and I will give you the part numbers. Otherwise, if you want my discount, I can make an order list, and ship them to you via Fed Ex.

 

[Black_Bullet]

Thanks Jay!

I hope that everything goes well for you!

Here are the part numbers for replacement synchros, gears, hub and slider, keys and springs, and shift fork:

3rd and 4th Gear Synchros: MD744782 (x2)
3rd/4th Hub and Slider: MD747646
3rd Gear: MD742728
4th Gear: MD742729
3rd/4th Hub and Slider Springs: MD742441 (x2)
3rd/4th Hub and Slider Keys: MD742777 (x3)
3rd/4th Shift Fork: MD741558


These are the main replacement parts. Anything else, just ask, and I will give you the part numbers. Otherwise, if you want my discount, I can make an order list, and ship them to you via Fed Ex.

Ok I took note of all of that stuff so that when I take the tranny to my friend Drew at Darkside performance they will know what I want in it. Due to money issues Im just not positive of when I can get this thing rebuilt. It would be nice to get the tranny fully done up while its out but doesnt seem like a possibility right now.

One last question, would I be better off just saving up getting the EvoIII gears done
and doing double syncro for the 1st and 3rd gear also, or does what I have now with the addition of the main oem replacement parts you listed above sound like it would suffice for my goals.

What power level were you at approx. when you started breaking stuff in the tranny?
Im not sure if you have a dogbox Tim, but if not how the hell are you harnessing all that 2.3 stroker power thru the tranny. Arent you close to 1000awhp by now~!!

 

[twicks69]

Ok I took note of all of that stuff so that when I take the tranny to my friend Drew at Darkside performance they will know what I want in it. Due to money issues Im just not positive of when I can get this thing rebuilt. It would be nice to get the tranny fully done up while its out but doesnt seem like a possibility right now.

One last question, would I be better off just saving up getting the EvoIII gears done
and doing double syncro for the 1st and 3rd gear also, or does what I have now with the addition of the main oem replacement parts you listed above sound like it would suffice for my goals.

What power level were you at approx. when you started breaking stuff in the tranny?
Im not sure if you have a dogbox Tim, but if not how the hell are you harnessing all that 2.3 stroker power thru the tranny. Arent you close to 1000awhp by now~!!

You are better off staying with your single synchro 1st, 3rd and 4th -- save your money as you would need to replace ~$1000+ worth of parts to run the Evo 3 1st, and dbl synchro 3rd/4th in your transmission.

The parts I reccomended will meet your goals no problem.

As for the "What power level were you at approx. when you started breaking stuff in the tranny?"...well, from ~400AWHP and on. I am on transmission #16.

I do NOT run a Dogbox. As well, I am making around 1000HP/925TQ at the crank.

I run a 2G 1st gear, 2G 2nd double synchro gear, 91-Early 92 3rd gear, 91-Early 92 4th gear, 2G 5th gear, along with a 4-spider center diff (custom chromoly hardened cross-shaft), and a LSD-inserted Front diff. Stock transfer case, stock driveshaft, stock rear end, stock rear axles, Raxles RACE front axles, and solid 2-piece press-in motor mounts (urethane -- not inserts in front and rear).

There's all the secrets....


If I break stuff, it usually is the intermediate shaft stripping off its gears, the center diff lower case gears stripping, 3rd gear stripping, or twisting the splines on the input shaft -- which happened last April when I stripped the splines off the Quartermaster twin disks at the same time. Resulting in ALL OF THE ABOVE -- on the Dyno. Yay.

Otherwise, it is burning out the 3/4 slider, or shattering the 3/4 hub.

 

[MidShipCivic]

May I see pictures of your carnage?

 

[Black_Bullet]

You are better off staying with your single synchro 1st, 3rd and 4th -- save your money as you would need to replace ~$1000+ worth of parts to run the Evo 3 1st, and dbl synchro 3rd/4th in your transmission.

The parts I reccomended will meet your goals no problem.

As for the "What power level were you at approx. when you started breaking stuff in the tranny?"...well, from ~400AWHP and on. I am on transmission #16.

I do NOT run a Dogbox. As well, I am making around 1000HP/925TQ at the crank.

I run a 2G 1st gear, 2G 2nd double synchro gear, 91-Early 92 3rd gear, 91-Early 92 4th gear, 2G 5th gear, along with a 4-spider center diff (custom chromoly hardened cross-shaft), and a LSD-inserted Front diff. Stock transfer case, stock driveshaft, stock rear end, stock rear axles, Raxles RACE front axles, and solid 2-piece press-in motor mounts (urethane -- not inserts in front and rear).

There's all the secrets....


If I break stuff, it usually is the intermediate shaft stripping off its gears, the center diff lower case gears stripping, 3rd gear stripping, or twisting the splines on the input shaft -- which happened last April when I stripped the splines off the Quartermaster twin disks at the same time. Resulting in ALL OF THE ABOVE -- on the Dyno. Yay.

Otherwise, it is burning out the 3/4 slider, or shattering the 3/4 hub.

Sixteen trannies, wow. Thats kind of depressing.You must have a healthy income and a deep passion for your car to put up with it. Around 2005 when I first got into a dsm, I had a friend who had a built 60-1 gsx and he used to warn me about dsm drivetrain issues, and that is the reason why he ended up selling it, putting it all behind him and going back to muscle cars.

Good thing you can build your stuff yourself. I really hope you do some more amazing things with your car, and hopefully be another DSM icon for others to learn from.
I like talking to people who make me feel like a newbie again because Ive already learned so much from your posts.

I hope half of your bad luck with your transmission is just the fact that you have a heavy car with tons of stroker torque and that you race it hard, that will give me some bit of relief as to not expect this kind of carnage beyond 400awhp.

Have you considered going dogbox? I know there not exactly "street friendly" and there expensive but probably cheaper than even a 1/4 of your past transmission bills

 

[twicks69]

Sixteen trannies, wow. Thats kind of depressing.You must have a healthy income and a deep passion for your car to put up with it. Around 2005 ( which I almost consider back in the day ) when I first got into a dsm, I had a friend who had a built 60-1 gsx and he used to warn me about his drivetrain issues, and that is the reason why he ended up selling it, putting it all behind him and going back to Fbodies.

Good thing you can build your stuff yourself. I really hope you do some more amazing things with your car, and hopefully be another DSM icon for others to learn from.
I like talking to people who make me feel like a newbie again because Ive already learned so much from your posts.

I hope half of your bad luck with your transmission is just the fact that you have a heavy car with tons of stroker torque and that you race it hard, that will give me some bit of relief as to not expect this kind of carnage beyond 400awhp.

Have you considered going dogbox? I know there not exactly "street friendly" and there expensive but probably cheaper than even a 1/4 of your past transmission bills

Thanks for the kind words.

As for dogboxes...they still require rebuilds with more expensive parts, and...they still break. It isn't fun to break a $7000+ gearset and have to replace it.

 

[Black_Bullet]

Thanks for the kind words.

As for dogboxes...they still require rebuilds with more expensive parts, and...they still break. It isn't fun to break a $7000+ gearset and have to replace it.

Oh, I didnt know that. I figured they were a little bit cheaper than that and I thought they were pretty hard to break.

Well you could always do a power glide and a rwd conversion, should hold up then

 

[twicks69]

Oh, I didnt know that. I figured they were a little bit cheaper than that and I thought they were pretty hard to break.

Well you could always do a power glide and a rwd conversion, should hold up then

When you start making big power and big torque, nothing becomes unbreakable.

As for RWD -- definitely not in my cards -- I like the AWD street sleeper thing too much. If I wanted RWD, I would pick a different platform.