I have been soul searching as to why I keep failing my transmissions. The easy answer is too much power, but I am getting tired of replacing the transmission. I am far too good at getting the case apart. A skill I never wished to obtain!

We all know that history has shown that worn diff bearing can cause problems. I think that these worn bearing are the leading cause of my past two failures. In each of these failure, the output shaft has "punched" a hole in the bellhousing around the bearing. Normally, this shouldn't have load in this direction (in forward motion anyway). Obviously, something is causing a force to be directed in that direction or is putting a bending moment on the bearing.

I took apart my Euro Getrag last night and studied it and my failed transmission. My guess is that worn diff bearings are allowing the entire diff to "tilt" under load and apply uneven meshing with between the ring and pinion. This would cause the bearing there to experience loads it wasn't intended to have and lead to cracking the aluminum case around the bearing race. There isn't a lot of meat that holds it together. I want to look more closely at the fracture marks on the bell housing to see if there were signs of cracks and polishing. This would lead me to believe that it was a gradual breakdown over time and finally, a catastrophic failure. Unfortunetaly, I don't know the best way to determine if the diff bearing are "worn". There is over 4500 lb-ft of axle torque with my car. Me checking it with my hands is hardly a reliable test.

I am building this new transmission for the car with all new parts. Hopefully this one will last a bit longer due to that. Just a thought. Let me know what you think.

Aren't the main gear cluster teeth cut at an angle? If so, you will get end-loading on the two shaft end bearings.

JazzMan

The force should be toward the other end of the case. And not very much.

[This message has been edited by Matt Hawkins (edited 04-28-2009).]

I don't believe that anything that you do will allow a transmisson designed for 250 ft lbs of torque to survive the torque of a 400 HP engine. This is not the answer that you are looking for and its not one to antagonize but perhaps its time to look into using an auto. The 4T65eHD will take the power that you are putting out with ease.
However, if you are dead set in staying with the stick, the later Getrags (ala Beretta) are stronger in that area and have bigger ring and spider gears. I haven't seen too many failures with these later Getrag designs so its possible that they will stand up. Its worth a try.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Well an auto is out of the question. I know all the arguments of how and why. I just prefer the manual.

quote Originally posted by Dennis LaGrua: I don't believe that anything that you do will allow a transmisson designed for 250 ft lbs of torque to survive the torque of a 400 HP engine.

BTW, the GM service manual says it's rated for 200 ft-lb. But anyway, I agree with the basic statement.

Matt my vote is to try this with a Berretta Getrag. I believe they are not difficult to swap and should hold together better. That's what I will be doing with my Turbo 3.4 pr.

The improvements for '92/'93 were a stronger diff carrier and stronger spider gears. These are the only hard parts that changed.

The difference is year, not application.

[This message has been edited by Will (edited 04-28-2009).]

quote Originally posted by blkpearl: Matt my vote is to try this with a Berretta Getrag. I believe they are not difficult to swap and should hold together better. That's what I will be doing with my Turbo 3.4 pr.

It doesn't look like will we convince Matt to run an auto, so I would second the motion to try the Beretta box due to its heavier construction in the problematic differential side. As I said before I do not recall hearing of many failures with the Beretta Getrag design so it might be worth a shot. Bolt it up add Rodneys shift bracket, address the VSS issue and its done. I've seen the Fiero and Beretta gear sets side by side and there is a notable difference.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

I have all the diff parts from a later Getrag. I think that having brand new bearings and the proper shims will help a lot. I don't expect it to be indestructible, I just want to understand the failures and try my best to prevent the next one. I know it is coming sooner or later. I don't know if I have gotten 20k miles on a trans yet.

What about an F40 6 speed? Can get it brand new. Cryo it, put a LSD and give it hell and be the fist to search its limits. If it fails then you can still get another NEW one cheap

[This message has been edited by Alex4mula (edited 04-28-2009).]

quote Originally posted by Matt Hawkins: I have all the diff parts from a later Getrag. I think that having brand new bearings and the proper shims will help a lot. I don't expect it to be indestructible, I just want to understand the failures and try my best to prevent the next one. I know it is coming sooner or later. I don't know if I have gotten 20k miles on a trans yet.

I believe that the later Getrag case is a little beefier in the differential area as well. I'll do some futher checking as that might be critical to longevity. IMO using high quality bearings are also important. There is lots of imported Chinese junk around and they look just like Timken, Fafnir, Hoover/NSK and NTN brands but they are junk. Don't ask me how I know!!!

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

you could always do the nsx swap that west cost fier sells. the nsx trans has been proven to hold up in racing applications. it also comes with a lsd and alot bigger bearings. can find them cheap if you look around. the 5 speed will be your strongest and lowest cost since alot of guys swap them out for the 6 speed. it does cost more up front but look how many trans you have already went threw trying to get a fiero trans to hold up.

http://www.westcoastfiero.c...ssion/transaxle.html

[This message has been edited by gold87 (edited 04-29-2009).]

quote Originally posted by Dennis LaGrua: I believe that the later Getrag case is a little beefier in the differential area as well.

Having compared a Fiero style bellhousing side-by-side with a HTOB bellhousing, I'll have to disagree.

There was some additional diff bracing added to the Isuzu in '87 or so.

I agree having both in hand. There are some small changes in oiling, but nothing with the case.

yeah Matt, go with the FWD tranny and then do a "how to " on it ....for me I plan on doing the same thing when I can figure out the swap process correctly.
I can't afford the WCF NSX trans. << then again I don't want to wait forever to get it either

quote Originally posted by gold87: you could always do the nsx swap that west cost fier sells. the nsx trans has been proven to hold up in racing applications. it also comes with a lsd and alot bigger bearings. can find them cheap if you look around. the 5 speed will be your strongest and lowest cost since alot of guys swap them out for the 6 speed. it does cost more up front but look how many trans you have already went threw trying to get a fiero trans to hold up. http://www.westcoastfiero.c...ssion/transaxle.html

I still can't understand why a transmission rated for a car with 210+bs of torque will be that strong

quote Originally posted by Alex4mula: I still can't understand why a transmission rated for a car with 210+bs of torque will be that strong

Not all trannies are designed to only handle the max torque of a particular car or engine. The tranny maybe rated for far more than a given engine output combination; this is common because manufacturers don't want to design themselves into a corner when investing the millions it takes to get a new tranny designed and validated.

JazzMan

quote Originally posted by JazzMan: Not all trannies are designed to only handle the max torque of a particular car or engine. The tranny maybe rated for far more than a given engine output combination; this is common because manufacturers don't want to design themselves into a corner when investing the millions it takes to get a new tranny designed and validated. JazzMan

I'll wait then to see that hi-po car where Acura will use it. Until then and using same reasoning I will trust the higher rating of an F40

quote Originally posted by Alex4mula: I'll wait then to see that hi-po car where Acura will use it. Until then and using same reasoning I will trust the higher rating of an F40

Look at the gear ratio's of the F40 vs the NSX tranny . I am currently doing a engine swap and now stuck at my drivetrain decision . If can I muster up the extra 1g I will go with the NSX, GM front wheel drive manual tranny's have the worst gearing as far as I am concerned . There are a few places who sell the J4A4 ( 5speed ) rebuilt for racing applications, here is one http://daliracing.com/v666-5/welcome.cfm .

I am interested to see the end result of this topic

-Jared

quote Originally posted by Alex4mula: I'll wait then to see that hi-po car where Acura will use it. Until then and using same reasoning I will trust the higher rating of an F40

Perhaps the "hi-po" car that Acura was going to use that tranny in never materialized? Perhaps Acura was planning on bumping the power during the design life of the NSX. It sure wouldn't make sense to design a tranny barely strong enough for the first generation of a platform since it means you'd either have to spend millions in another tranny design for later power upgrades or forever limit the power output to that of the first year models. In any case, the only stats that matter are the published ones, has anyone published the stats for the NSX tranny?

JazzMan

NSX was designed basically as a race car. Ayrton Senna was the development test driver. The entire car is built to be beaten like a redheaded step child and not have serious problems.

quote Originally posted by Will: beaten like a redheaded step child

I thought I was the only one that used that phrase.

Joe

[This message has been edited by motoracer838 (edited 04-30-2009).]

Any kind of mis alignment will cause improper loading on the gears and shafts leading to failure. Gustting the case can only help matters and I plan to do this extensively on my new NOS getrag when I put it behind my 302 SBC. Cast aluminum has a yeild point of around 32ksi and this only gets lower as temps go up. It can get as low as 15ksi at 200F (depending on the alloy used in the casting). You would be very surprised how much load gears can take with a proper contact patch (alignment) and proper oiling.

Cyro treating will help increase the surface harness of the gears but you have to be careful not to leave residual stress on the face leading to pre-mature wear (different failure mode). Cyro plus shot peen and then a final hone or grind may help but this may alter the final tooth profile beyond design limits.

Another option would be to "super finish" the gears. This again helps thwart off failure due to contact stresses on the gear teeth themselves. By increasing the finish on gear teeth the oil film distribution is more uniform and helps distribute the load more evenly. Corvette and Viper transmissions use this process with great sucess. It is also becoming a standard in the aerospace industry for main rotor transmissions and turbine engine accessory gearboxes where size and weight restrictions limit the size of gears.

I really don't plan to do any of the above except the gusseting becuase all of these options cost money and these transmissions are rather cheap. Plus with the advent of the F40 6 spd this may also lead to a stronger internal trans. I also plan to install an oil cooler with an electric gear pump to keep the trans oil cool using redline or some other synthetic lube.

A well designed mounting system with stout brackets (not the flimsy sheet metal brackets that came stock) will also help react the loads properly into the cradle and keep things square and proper.

Yeah

http://www.dragtimes.com/Ac...NSX-Drag-Racing.html

I think the NSX trans will hold up. I know you can find the NSX trans for 1500.00 and under.

Cheep for a Performance trans with LSD

chris at west coast fiero told me he has found many for a grand and under. he only paid 800 for the one in his car

Any decrease in the movement,, increases transmission reliability,,My first cars were 49 to 51 fords, I tore transmissions out of them with regularity ,,just adding traction masters incresed reliaility ,, you have to decrease movement and slop in all components ,, the bearings in the transmission should be Top quality (not cheap),, you need a few TRANSMISSIONS ,,TO GET THE BEST PARTS from,, blue print your gear box(Yea,sure),only top quality engine & trans mounts to prevent movement ..
The hassle of quality control on old parts is not easy ,,but the time spent tightening up pays off in less frequent tranny pulls.
My race mechanic experience comes from motorcycles,, I have little actuall race car experience.. but the practice is the same ..
use only synthetic oil / lubricant ,, the available transmission seals w bearings may help to redeuce stress
your supension has to keep the power flow smooth,,any time your wheels ""hop"" you are destroying the transmission..
When not racing ,, avoid wheel spin/avoid rapid starts ,,you will spend less time under the car and more time driving
When there is room it is often advantageous to machine an area for a wider bearing ,or add another,,some times you have to remove a lip that retains a bearing so you can install wider bearing and you use a flange/holder to hold the bearing,, you must be sure the retainer for the wide bearing will not harm the tranny..

[This message has been edited by uhlanstan (edited 05-01-2009).]

ok i did some searching tonight an found 2 nsx 5 speed one on east coast($1400) and one on west coast($1500) i aere on a lso found a 6 speed for $3900 these where on a nsx forum.

there is also a link on the 91-92 trans i guess some of them had a problem with snap ring failer, this is also the site i found all of the tran in the classifieds parts section

http://www.nsxprime.com/FAQ...ing/transmission.htm

[This message has been edited by gold87 (edited 05-01-2009).]

quote Originally posted by Datsun1973: Any kind of mis alignment will cause improper loading on the gears and shafts leading to failure. Gustting the case can only help matters and I plan to do this extensively on my new NOS getrag when I put it behind my 302 SBC.

How are you planning to do this? Are you going to weld to the case?

I don't think any sort of gear treatments are the right way to go with the 282. If they were failing by blowing teeth off the gears like the Isuzu does, then cryo treatment, REM polishing, etc might help. Since they fail in the case rather than the gears, effort spent making the gears stronger is wasted until the case issue is fixed.

have you ever thought of contacting tina on the forum, her engine puts down more horsepower and torque and definatly alot more on the low end of things, she had her getrag cryo treated and im not sure how its been holding up, i havent heard anyhting from her about it for a long time.

but if her transmission problems have ceased to exist then i would suggest building one exactly as she did.

she went through countless isuzu's before switching to a getrag and from what im told she broke her first axle with the hardened getrag.

matthew

Yes you could weld to the case but that would probably cause distortion and thus cause more problems. I am going to water jet some pieces and basically make a truss system that ties everything together in a kind of exo-skeleton and directly mount it to the cradle.

Sometime within the past couple of years I have seen pictures ands read discussions of at least two getrags built with a girdle for controlling deflection and breakage of the case. Saw and read about this here on PFF. Is there anyone reading who has info on a girdle for a getrag?

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Tom
Suffolk, Va
87 GT 350 5 spd.

someone should rig up a mount of sort for the bell housing side of the trans in order to hold it in place and prevent warpage while tigging strenghening gussets or plate to the housing

Here is an off the wall idea, anyone thought about filling in the webbing with something like JB weld? (before it breaks)

Don't think that would help much. Block fill works by keeping cylinder walls from moving, which relies on the compressive strength of the fill.

The failures of a transmission case are tensile, as the case is placed in tension by the separation forces of any given mesh.
The tensile strength of any fill material is tiny compared to that of the parent metal of the case.

[This message has been edited by Will (edited 05-03-2009).]

I know I've seen at least two pics of girdles on a getrag. I think one was painted white and the other red or orange (just the girdle painted). I'm pretty sure I saved the pics and possibly the threads on my home pc. I'm out of town right now. I'll try to find them and post from my home pc next week.

I plan on to build one in the future. Anyone else have any info or feedback on a girdle for a getrag?

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Tom
Suffolk, Va
87 GT 350 5 spd.

[This message has been edited by gt7 (edited 05-03-2009).]

quote Originally posted by gt7: . Anyone else have any info or feedback on a girdle for a getrag?

I knew a Gertrude that needed a girdle but I never said it to her face

Have u considered the g6 6 speed from v8archies or a nsx trans from WCF? I was wondering about these two mated with a 3.4 dohc

quote Originally posted by HausFiero: Have u considered the g6 6 speed from v8archies or a nsx trans from WCF? I was wondering about these two mated with a 3.4 dohc

Have u considered reading the whole thread before you post to it?

My 282 is solid-mounted with axle support bearings. Lots of axles broke, but the trans hasn't.

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