hey, to give you some backround, i have a 400hp/tq SBC fiero which i took to the dragstrip last racing season, and happened to blow the diff OUT of the tranny... there was broken gears and oil all over the starting line at the track, lol. i launched at a very reserved 2500 rpm with mild racing slicks. anyway now that its winter i have acquired a used fiero getrag from the PFF mall. i am going to totally rebuild it (at a proffessional transission shop), while i am doing that there is a place close to me that does Cryo treatment of anything metal, they usually specialize in brake rotors and drill bits to make them stronger and last longer, however i have contacted them about doing a whole tranny, they will do it. after all that is done, i plan on getting Rodneys diff bearing savers (add-on to the cv axle and they will put less stress on your diff main bearings). i dont want to take any shortcuts with this tranny, so this is what i have planned so far, within the next couple weeks i am going to have all this done to it.

now that is what i have planned for it so far, but i do know there are a few more things that i could do, and really want to do... LSD is on the top of my list. i have enough money to really build this thing up, but not enough money to buy a 6-speed. my question is to all PFF members that have any more info on how i can either strengthen the tranny, get more traction, or any other useful websites such as a few differant options for LSD's for our trannys, etc. any help is much appreciated and a positive rating will be given to anyone with useful info. thanks in advance.

so this is the thread for any big or little hints, tips or tricks on how to build the ultimate fiero getrag.

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1986 Silver 5 speed Fiero 3.4 DOHC
Bored .30, Fully balanced and blueprinted
13* retard exhaust cam, FFP UDP, much more.
13.93@101mph as it is on the street

355/400hp sbc, 4 bolt main
spec stage 3, and many other extras.
87 GT 5-speed Getrag, power everything.

sounds you have all the correct options that you need to do . as far as the diffs i believe there are only 2 places that make it for the fiero lsd and i dont remember the other. i know it is buds outback but the guy uses a different name for the diff. . as far as the 6 speed , dont bother they arent rated to handle the power you are talking about putting out. good luck , i have a spare 5 speed im thinking about doing the same thing with .

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COMING SOON: 4.9 complete rebuild with buds outback northstar pistons , delta cams E303 cam , full ported , polished , and flow tested heads and manifolds. rockcrawl's custom chip , polished crank
86 and 87 fiero database www.geocities.com/cwandall/fiero.html

quote Originally posted by wiccantoy: sounds you have all the correct options that you need to do . as far as the diffs i believe there are only 2 places that make it for the fiero lsd and i dont remember the other. i know it is buds outback but the guy uses a different name for the diff. . as far as the 6 speed , dont bother they arent rated to handle the power you are talking about putting out. good luck , i have a spare 5 speed im thinking about doing the same thing with .

Are you implying that the F40 six speed is weaker than the getrag? I guess what you're trying to say is that the F40 still falls short of his goals? (along with the getrag)

The F40 six speed is rated @ 295ft/lbs as opposed to the getrags 250ft/lbs.

quote Originally posted by wiccantoy: sounds you have all the correct options that you need to do . as far as the diffs i believe there are only 2 places that make it for the fiero lsd and i dont remember the other. i know it is buds outback but the guy uses a different name for the diff. . as far as the 6 speed , dont bother they arent rated to handle the power you are talking about putting out. good luck , i have a spare 5 speed im thinking about doing the same thing with .

What's the problem witht the 6 spd besides the cost? You can get them new kind of cheap and that is the best way to start with cryo treatment; a new part, no previous wear or strain, Cranes Cams special metal treatment if their word can be trusted has already been track tested with a ring gear failure rate comparison under drag use resulting in endurance beyond where they had been breaking them before in a particular race car to the point where it was removed and replaced before failing sometime after the usage others were subjected to before failure.

GM states the 6spd is certified for 400Nm or 295 lb/ft I don't know if certified means that's its limit or as much as they wanted to test it for but if it comes with a higher rating stock than the Getrag did I would think its cost would be the only real issue. Since I'm working on a 6 spd swap I would like to know if anyone has any actual data suggesting strength wise I should use my 5 speed instead behind a high output engine. The Getrag has a convincing predictable outcome history in these scenarios so why not start with something with a higher rating than it has and no current failure that I know of.

https://www.fiero.nl/forum/A...060206-2-064025.html

Might want to look into this stronger diff too.

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Don't look now, but I think the idiots have taken over the asylum.

AIM: JSAL86

quote Originally posted by flames4me now that is what i have planned for it so far, but i do know there are a few more things that i could do, and really want to do... LSD is on the top of my list. i have enough money to really build this thing up, but not enough money to buy a 6-speed. my question is to all PFF members that have any more info on how i can either strengthen the tranny, get more traction, or any other useful websites such as a few differant options for LSD's for our trannys, etc. any help is much appreciated and a positive rating will be given to anyone with useful info. thanks in advance. so this is the thread for any big or little hints, tips or tricks on how to build the ultimate fiero getrag.

There are some LSD's on here.
https://www.fiero.nl/forum/Forum2/HTML/079825.html

[This message has been edited by chopfren-z (edited 01-24-2007).]

wow, thank you to everybody, so far everyone has one more positive rating. with cryo treatment they say it will gain at minimum 30% stronger parts, so i figure if the stock tranny is rated at 250ft/lbs then 30% stronger will bring it up to 325 or so ft/lbs minimum. thats not to bad of a gain for alot cheaper than a 6-speed.

toaster man, thank you, that is exactly the kind of stuff i was looking for with this thread, any and all helpful getrag information. with that stronger diff the 325 ft/lbs will probably go much higher since that was the first thing that went wrong with my last getrag from a 87 gt. my goal is to make the cv axles the weak link... v8 definatly isnt weak, spec stage 3 clutch will not slip or blow, racing slicks might slip a little, but didnt when i blew the other tranny, so that leaves either the tranny or the cv axles to go bad... and i can change axles at the track in a half hour or less. thank you again to everyone who contributed, and please keep it coming if you have any more info.

are there any external areas where something can be welded/bolted to stregthen the case?

the 4-cyl & V6 4 speed trans case is just some extra gusseting & webbing around the diff area. just a few well place peices of triangular steel welded in choice spots. or bolted.

there are plenty of pics of busted ones, so you can research the weak spot - most likely - the diff area.

Got pics of how your differential blew up?

The failure mode that's been coming up in the last couple of years is that the axial loading from the helical cut of the final drive gears pushes the right diff bearing right out of the case.

The V8 adapter plate can be re-engineered to pick up the three bolts around the axle seal on the right side of the diff. This would add strength to that area and reduce the likelihood of that failure mode.

Also, be careful about those add on axle bearings. I tried one and it chewed up and galled the sealing surface of my CV joint. They don't really reduce load on the diff bearings at all. The CV joints ride in bushings in the diff carrier. As these bushings wear, the CV can wobble a bit. This is helped by the support bearings, but they're not that good at it. As I said, the can chew up the sealing surface of the CV tripot.

Sort of inline with Will. Swap all the gears for straight cut. I am presuming you are already replacing all the bearings with the highest quality you can find. The used trans is probably a little weaker than what it was originally rated for but the cryo would help. I would think by the time you actually get the cryo and rebuild, without the straight cut gears, you would have spent the money on a new 6 speed. I realize there is still the install kit, but if you get all new straight cut gears, you are probably not far from a 6-speed, with kit and maybe cryo treating. The 6 speed will be better on the street than the straight cut 5 speed would be.

Or, quaife may still make their transmissions, you can get it as a sequential for a little more. Just have to lay out that first $18K...

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Another Fiero some day...
2005 Smart ForTwo
1991 BMW 520
1986 Austin Mini
1989 Toyota *** (You know what it is...) (now sold)
1986 Fiero GT 5-speed

here is my thread that i started right after i blew up my old tranny...

https://www.fiero.nl/forum/Forum2/HTML/075644.html

pics are farther down.

and yes that pre-cut hole is for the stock speedo sensor if you were wondering where the split happend.

since that thread i have obviously decided on another getrag for a replacement tranny, for my application it just seems to be the most logical and cost effective for the gains i will recieve. the car is maily a drag car, about 50% driven on the street, and 50% at the track. like i stated before i do have enough mony to build up a getrag, and i have definatly researched the 6-speed swap and no doubt it would be a better fit for what i am looking for with the right work done to it, however i really dont have the money to do all of that to a 6-speed. for far less money i can have an equal if not better tranny than a stock 6-speed. with a direct getrag swap i dont have to worry about getting new cables, brackets, flywheel/clutch, shifter assy, etc. all i have to worry about is building a good, strong tranny.

money is and issue, however i dont want to say any spending limits right now, because i really dont have one if the right option comes along, also i dont want to limit the conversation for future builders who happen to stumble upon this thread. and i thank everyone again for your input.

EDIT: midengineracer, do you have more information about those "straight cut" gears you were talking about? what are they, how are they differant, how much do they cost, where can you get them, etc? thanks.

[This message has been edited by flames4me (edited 01-24-2007).]

I do not know of anyone that is making them for the usual Fiero transmissions.
Regular gears in a street transmission have teeth that are on an angle like this: ////
Straight cut is just: [[[[[

With the regular gears, some of the power gets transferred to the walls of the transmission, straight cut transfers it all to rotational so there is just the load on the bearings and not some much on the walls of the transmission. I think the gears themselves are also stronger.

Basically, you would have to have them custom made and prices will vary. Quaife may be interested in making them if you contact them: www.quaifeamerica.com

Hope that helps.

Straight cut gears are noisier as well...

That is what gave the M-22 it's nickname "the rock crusher".

I never advocated a straight cut gearset. I just stated that the diff failures I've seen have been a result of side loading from the final drive helix angle. You do NOT want to drive a straight cut final drive on the street. I've heard differing opinions of straight cut shifted gears. I've never driven either.

Suffice it to say that if you had a custom gearset made, you'd be into that for the cost of a 6 speed several times over.

Some of the old gearsets from the Fiero racing effort resurfaced a year or two ago. They're straight cut. I'm not sure if the guy who found them has any left.

Basically, I think you're on the right track, except for those helper bearings. Leave those out.

i say build a cradle or some sort of diff cage and just rebuild the diff bearings every year or so. im sure that would get pretty costly after a while tho...

I was running a phantom grip LSD. I blew out the spider gear cross shaft. It broke and the piece flying around in there broke the case. Look for a stronger cross pin.

Rick

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i found this at jcwhitney, is this the same tranny as what we have? if the link doesnt come up than its product number ZX490534A

http://www.jcwhitney.com/au...10000020154210371542

1990-02 chev cavilier 4-cyl. this is much cheaper ($349) rather than the $599 for the whole diff that Engineered Performance offers.

spookything, do you mean the cross pin that they give with the LSD? or the cross pin already inside the stock diff? if i do get the stronger FWD diff, than that would also come with the stronger stock cross pin. if you mean the one that Phantom gives you than i might be able to cryo treat that as well while i am doing the whole tranny.

quote Originally posted by Will: I never advocated a straight cut gearset. I just stated that the diff failures I've seen have been a result of side loading from the final drive helix angle. You do NOT want to drive a straight cut final drive on the street. I've heard differing opinions of straight cut shifted gears. I've never driven either.

I wasn't saying you advocate straight cuts, but my suggestion is in line with your statement. Side loading causes an increase in failure rate. Straight cut gears remove most of that particular risk but at great detriment to street vehicles, mostly in noise and ease of shifting from my understanding. The suggestion was more to show that it will be expensive to build a truly strong transaxle and that in the longer run, it may be better to shell out money for a 6-speed and cryo treat that.

I have my doubts about the claims of strength increase, I have never seen a scientific evaluation of the results. I have seen enough anecdotal for the decrease in wear however and that is where my focus would be. Unfortunately, 6 years ago when I asked about prices, the three shops never returned my requests for a price and all I wanted was the brakes done...

EDIT:
I do believe it is stronger, I doubt the amount that is claimed.

[This message has been edited by midengineracer (edited 01-25-2007).]

quote Originally posted by RandomTask: Are you implying that the F40 six speed is weaker than the getrag? I guess what you're trying to say is that the F40 still falls short of his goals? (along with the getrag) The F40 six speed is rated @ 295ft/lbs as opposed to the getrags 250ft/lbs.

no what i am saying is he barely has the money to purchase the f40 trans yet alone purchase it than build it . but has a getreg already and has the money to build what he already has. so yes the f40 still is weak. and yes neither trans seems to be the one he needs for the output his engine has. calm down

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COMING SOON: 4.9 complete rebuild with buds outback northstar pistons , delta cams E303 cam , full ported , polished , and flow tested heads and manifolds. rockcrawl's custom chip , polished crank
86 and 87 fiero database www.geocities.com/cwandall/fiero.html

You might contact these people and find out the price of one of their transxles.
http://www.g-forcetransmissions.com/tran_gt-50.asp

quote Originally posted by tampalinc: You might contact these people and find out the price of one of their transxles. http://www.g-forcetransmissions.com/tran_gt-50.asp

wow, would that ever be cool, can handle up to 1100hp. i contacted them about pricing and bellhousing fitment, ill post here again when they reply... probably way over my price range, but it would be cool to get some more info on it, and let you guys know.

does anyone know if that Phantom Grip LSD in my last post will fit in the fiero getrag?

wow thats a nice trans . keep us updated when you find out more info

I do not despute that the Getrag can be built for a slight improvement in power handling capacity but 400HP? Under severe drag racing conditions I kind of doubt that no matter what you do, the Getrag just won't hold up with this kind of power . The limitation is the strength of the light duty case and the gears. On the other hand there are a number of automatic trannys that can be modified for 300-1000 HP applications. My newest project will use the 4T65E HD which is already being used successsfully on V8 applications.
Actually if you are drag racing what are you doing with a stick anyway? Bracket racing requires shift consistency that only an automatic can provide. Also consider that no human can shift as fast as an automatic can and have you evaluted that sloppy slow cable operated Fiero shifter? Save yourself some time and money and consider an automatic.
OK having said all of the above now we now turn this post back for some hard criticsm from the die hard stick guys-LOL.

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87GT 3.4 Turbo- 0-60 5.2 seconds -Best
Engine Controls, ECM goodies, Chip
re-programming & odd electronics stuff

Dont know if those other guys are OEM's or what, but go to the original source for your LSD = http://www.engineered.net/eplsd.htm . Has a nice picture and everything.

Stick = fun + finesse.
I'm about to move to Northern VA, original source of gridlock. I'm not giving up my sticks.