Looking for people who have blown up their transmission

[_Waffles_]

I am hoping this thread does not get thrown away as it can potentially help more than just me.

I am trying to get information from people who have blown up their transmission, especially from too much hp/torque and launches.

---- What broke?

I have been hearing, or rather reading, more and more about how the DSM and 2g transmissions are like glass once roughly 300ftlb's are applied. I am planning on just getting a very stable platform before any heavy mods and need to know what to preemptively replace before it breaks.

So, what have you had/seen break in the transmission - make sure to state FWD/AWD and year of transmission.

Thank you,
Waffles

 

[miloolim]

Spider gears in the center diff can blow... The viscous coupler can wear out... AWD Thats what ive had problems with in the 1g manual tran's.

 

[bastarddsm]

No it takes 500ftlbs to break them quickly if they are in good shape.

If you have a stock wore out CD you will break spider gears, and then the shrapnel junks the rest of the trans.

Next up is stripping 3rd gear, and then 4th if you make a lot of power, and do a lot of dyno passes.

If you make lots and lots of power you will break the tcase, and then the CD.

 

[slow4g6392tsi]

I broke a shift fork and tore some synchros on a 1G I used to own but I was young and didn't know how to drive it hard correctly. I then had English Racing rebuild the trans with double synchros, etc and never had any problems again. Even through tons of hard launches and banging through the gears with an ACT 2600 clutch it lasted the next couple years until I sold the car.

My 98 GSX shifts awesome and I have not had any problems with the transmission yet. 2G transmissions are supposed to be slightly better than 1G. BTW 2G transmissions are WAY stronger than WRX transmissions from what I have seen. It's all about learning to drive your car hard correctly and having a good, properly adjusted clutch.

 

[dacowgod]

I broke 3 different Stage 4 Shep transmissions.. car made about 550-600 AWTQ ... and I stripped 4th gear twice and 3rd gear once... The gears would strip every 1000ish miles... not during a shift...but after the gear was engaged and boost would come on..... so I changed transmissions more than I changed the oil .. ;-) ..

I had REM treated gears in 2 of them... didn't seem to make any difference in longevity on my car... . My car is a big fat heavy pig...so that didn't help ....

I also destroyed a stage 2.5 TRE in about 2500 miles... one good launch and the center diff gave up.. that was early on 457 AWHP 370ish AWTQ at that point..

Light cars will break drivetrain less... prolonged pulls creates a lot of heat which kills gears fast.. so they tend to last more in track cars than they do in street cars..

I bought a Shep Dogbox my last go around and was scared to piss to round the dogs on a gear street driving...2nd gear alone is $800 w/o any labor.... and it was noisy and somewhat of a bi*** to drive around on the street .....

My latest creation sports an automatic...no idea how long it will last..but its gotta do better than the syncro boxes were for me.

 

[_Waffles_]

So far it looks like beyond replacing worn parts I find the the tranny is to replace:

1) Spider gears in the diff
2) 3rd gear
3) 4th gear
4) sync's

I am guessing a lot of people do strips here. I stated before that I plan on the build to be for street and occasional track days, but never a drag strip "track." I was referring to track days as in going to tracks like Seattle International Raceway, Portland International Raceway, The Ridge Raceway, and Laguna Seca.

I apologize for any confusion on that.

Any other parts that are noticeably 'weak' when power is applied?

 

[sincitydru]

93 7bolt AWD stock @78000 original miles changed tranny fluid. Put synchromesh Shortly after first owning the car.(Noob) (Tranny had a little bit of a notch going into 2nd gear) after a couple hundred miles got really bad and locked up and blew a hole through the case then spilled silver colored tranny fluid all over the street. put in a used tranny with probably more miles than my original tranny with Redline MT-90. Barely notchy sometimes.

 

[dacowgod]

There is not really any alternatives to the weak 3rd/4th gears in the transmissions... I believe Jacks Transmissions might have something custom going on there for those gears..but theres not a whole lot of info on them... Its my opinion the earlier 91-92 1g "HD" gearset is probably a little stronger than the EVO 3/4 Gearset... but likely not enough to matter ..

A 4 spider diff will take the abuse..or a Wavetrac if you want to spend the coin...

Heavy duty Shift rails and shift forks are good to have and come in just about any upgraded transmission out there....they bend relatively easily if you have a dragging clutch or miss a gear..

All of this information is easily found looking through these forums... I understand you're trying to come up with a good list...but your last post to me comes off as you didn't try to do any research whatsoever... .. Basically once you start making power on these cars the transmissions cannot take the abuse...keep hp and torque in the 400's and drive with a little sense and they are usually okay with that for a long time...

And as I said..weight is a MAJOR killer....lighten up the car and save a ton of money...or be stubborn like I was/am and waste a TON of money...

A good clutch is also a very good investment...a dragging clutch will kill syncros and make you miss more shifts than you'll care to admit..

 

[_Waffles_]

All of this information is easily found looking through these forums... I understand you're trying to come up with a good list...but your last post to me comes off as you didn't try to do any research whatsoever... ..

It also seems like any question on research in the forum also gets thrown into the "you did not do any research" bin and the only threads that stay alive is "Ohh God... Help me I did something wrong" threads.

Yes, I am sure I missed a few threads and did not look into every one that says "transmission" in the title. I looked at the most obvious, and the next runners up with no luck. after roughly 5 hours of looking through both the forum and google/bing, I was unknowledgable about pre-emptive replacements within the transmission. Thus I posted a thread.

So how much research is required before getting some personal opinions/feedback?

 

[1Gina2G]

I've always wanted to know what was in general considered to be the most reliable of the dsm transmissions, seems like all of em are fairly weak from what people say in general. My local transmission shop mentioned how he thought the AWD transmission was a 'nightmare' and 'unreliable' which is why he thinks they're not that common on cars at all. NOT suggesting this is true, but it sure did make me wonder about keeping my trans.

Doing minimal research on this, I actually saw some threads, on using an AWD trans as a MORE reliable FWD trans. This caught my intrest, as I just had the center diff welded durring the rebuild in hopes of gaining more strength. Actually probably made it weaker though, sounds dumb I know but I thought of all people the guys rebuilding dsm transmissions would give me good advice.

Would it be safe to 'assume' that a FWD AUTO trans, would 'in general' be more reliable, possibley less prone to breaking? Hoping to hear from someone that actually has a clue about these transmissions in general.

On a sidenote, it's like theres 10 guys ready to put together an engine, for every guy that can rebuild a transmission, what's up with that? There's 1 transmission shop in my town, and I honestly don't trust the guy, .

 

[ed1380]

The 3-4 hub on 2g's has been known to explode past the 400ft/lb mark

 

[WES_393]

1Gina2g- There's nothing wrong with welding the center diff. Well, as long as your okay with making a 12-point turn just to leave the gas station. And there's some additional driveline wear associated with it. But the last thing you did was weaken the trans.

 

[bastarddsm]

These transmissions are not unreliable at all. They kick ass imho. #### a T5 that was designed for a V8 won't take half the abuse some of us put through these things.

The problem is they are old, and lots of ####tards have had their grubby little paws in them, running things like synchromesh, non releasing clutches, and never changing the oil.

Transmission shops that are scared of em, must not be a very good transmission shop.

Here's the list of things to do to improve durability:
1. Upper torrington bearing mod. Your replacing a flat steel washer with a "real" thrust bearing. The stock washer cannot cope with the stresses we put on on and eventually disintegrates, and creates a bunch of clearance in the CD gears, then they break.
2. Also replace the lower CD thrust washer, as they are usually about to explode as well.
3. 4 spider diff, with a TRE or TMZ cross shaft. Also have it modded for double thrust washers.
4. Set the pre-loads on the tight side so that the gear lash is minimal. This minimizes tip-loading, which kills gears.
5. Shot peening and gear detailing. This improves the gears metallurgy, and helps them live longer under great stress.
6. Use a new 3rd,4th, intermediate shaft, and CD housing if yours has high miles on it, and you plan on 500ft/lbs or more.
7. Avoid evoIII gears, use late90/early 91, or late91/early92 gears.

Now for normal rebuild stuff.
1. Check all sliders for rounded teeth. They need to be sharp and not worn. You should generally count on replacing the 1st/2nd hub/slider. That's about $125. I have had good luck with using a dremel to sharpen worn ones, and get a little more life out of them. Keep in mind I don't expect them to last forever, but it does stretch the life out.
2. Check for the thrust surfaces on the sliders to not be worn. This usually occurs in high mile trans's with shit oil. Usually the slider is shot before this happens. A worn one can cause the trans to jump out of gear. It can also gall on the gear and junk that too.
3. Check the synchro's. They should have plenty of clearance between the teeth and the gear. The FSM shows how to check this. I like to run double synchro second gear, and the old fiber lined style synchro's for the rest. They seem to shift better, but not last as long as a brass one.
4. Check all bearings for pitting in the rollers and races. Replace as necessary.
5. Do the double roll pin mod to the 3rd gear fork. Basically you drill another hole in the rail right on top of the fork.


I think that's about it.

 

[1Gina2G]

1Gina2g- There's nothing wrong with welding the center diff. Well, as long as your okay with making a 12-point turn just to leave the gas station. And there's some additional driveline wear associated with it. But the last thing you did was weaken the trans.

Yeah I wish he had mentioned that even though it was mentioned that it was for a DD. He gave me $100 off to put in the center diff, so it sounded like a win-win deal at the time.

Since the shop actually closed down now, I can't ask the guy, but something I noticed on here, is the spyder 4 upgrade a diferential or an actual gear. On my receit it says welded center diff, with diff hat. Spyder 4 gear upgrade. Can you have both a welded diff, AND they spyder 4 upgrade?

it sounds messed up but I didnt realize this untill someone was comparing a spyder 4 diff to a welded diff, did I get jipped? WTF

 

[_Waffles_]

Bastard -- can early 90's gears be used in a 2g tranny?

 

[My1GLaser]

I broke my front diff bearing outer race which kicked the diff gear into the case and busted the trans case. check bearing preloads!

I shredded the input shaft where it engages the intermediate shaft on a Dogboxracing synchro trans with Evo 3/4 gearset.

I broke the intermediate shaft in half between 1st and 2nd gear when trying to grab 1st around a turn in an autoX when I probably shouldn't have.

All this happened in 16 months after swapping to an HX35 running 26+ psi. It sure was fun though lots of street driving, 3rd gear pulls and 1/4 mile passes. I think I've broken another one in that history of carnage, but I can't remember off the top of my head. All had welded ctr diffs. The first two were street discs and the last one was a Clutchnet sprung 6 puck.

I have a Shep stage 3 with 4 spider diff now. Haven't tracked it yet though...

 

[donniekak]

1Gina2g- There's nothing wrong with welding the center diff. Well, as long as your okay with making a 12-point turn just to leave the gas station. And there's some additional driveline wear associated with it. But the last thing you did was weaken the trans.

I've got a welded center diff, and I never have to do more than a 3pt turn anywhere, ever. I do not however ever worry when I launch my car that it's going to break.

 

[livedsm4g63]

Made my 11.49 pass on a stock trans

I ran about 6 times that day. All passes where in the mid 11's. I'm surprised I didn't break anything inside the trans. Now my organic disk on the other hand.. Well that started to slip.

 

[WES_393]

I've got a welded center diff, and I never have to do more than a 3pt turn anywhere, ever. I do not however ever worry when I launch my car that it's going to break.

Yeah, 12-point was a bit of an exaggeration. But the binding does get a little old.

But agree the trade off is well worth it. I have nothing but a Jacks 1.2 build with welded center diff. I've driven over 100 miles to the track, pulled off a good dozen or so hard launches, and then another 100 miles home. Never once had an issue.

 

[paul s]

I went through 3 trannys, the last 2 were stage 3-4 from TRE. I have noticed that since the 2.3L went in and 42psi the tranny did not like that much. I broke 4th gear while doing a log at 35psi or so. Just last fall I had the car tuned almost perfect and while doing a log at over 40psi the car stripped 3rd. I had no less then 150 logs on each tranny and numerous drag days and some dyno time. I can't ask for anything more at this level. The car is trapping 135mph at 3260 lb so something has to give. I will be giving Jacks a try in the spring with his hd gears. Its flowing around 77lb and 60-100mph is 2.2sec in 3rd.