i have an 86 gt 4speed. mods include ported exhaust manifolds, ported air box, ram 9 11/16 clutch from fiero store. i drag race weekly. is this a common problem with
4 speeds? will the later model beretta trans hold up better... i am NOT willing to go auto trans.

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I have never blown up a late model 4spd, (85-86.5) however I have blown up 3, 84 4spds and 2 85-88 5spd Isuzu's.

The 4spds were due to cracking the case, the 5spds were due to sheering the teeth of off 2nd gear.

I have only heard of maybe 2, late model 4spd failures. I drag race and uhm drive spiritedly on the street from stop lights. Running 245/50/16's with a Centerforce Archie clutch.

If you are really going through 4spds I would look at 2 things, what are you using as trans fluid. 2, how are you driving. You may need to adjust your driving style. I am not saying slow down, but rev match the shifts better. Slip the clutch a bit more and dump it less.

Check your mounts, if you have bad mounts it can lend a serious hand to blowing up trans axles. As the mount will flex and when it goes to full flex and contacts the safety latch in the mount it will be like hitting it with a hammer.

Oh and make sure the engine strut is in good shape.

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85GT 5spd ,93 Eldorado 4.9 Dual O2 Custom Chip, Archie Clutch. Custom Exhaust. MSD Everything 245/50/16's Not Your Average 4.9 Capt Fiero Com --- My Over View Cadero Pics Yellow 88GT 5spd Stock.

i do let it slip enough not to break traction. im cuttin 2.1 60' with a 15.5-15.7 1/4mile et. i dont think my driving is the problem it feels like the 1/2 synchro is stuck...again. my first trans locked the 1/2 synchro in the hub(worked for 3 months after rebuild) then shatterd the 1/2 hub. after that was fixed it blew the diff out of the case.

anyone...anyone?

Gee... are you dumping the clutch at max revs and then power shifting each gear? Can you be more spicific about the damage, 1st gear, the clutch, bell housing, etc. WHen does it let go, between shifts?

dude...WTF...how? I BEAT on my car like it owes me money (well it kinda does, lol). I have been running a 75 shot and a 100 shot for a while and it still is holding up...so far. My 1/2 is kinda tricky but that is because I have Rodney's short throw comp shifter that is cutt down an extra inch. BUT I do have a spare sitting in my garage. All i can say is buy 2 since they are fairly cheap. You can usually buy 3 spds 3.65 4 spds for the price of one fiero getrag.

I agree I would check your mounts...the easy is to have someone rev the motor and see if it rocks with the revs. I would also run syncromesh if you can and if you are willing to spend the cash get some lucas synthetic gear oil.

[This message has been edited by goatnipples2002 (edited 10-30-2006).]

I'm on my 4th I believe tranny on my 86 4speed GT. I baby the car. The mounts are good, everything's fine. I don't do burnouts, I rarely race people.

The first failure was most likely due to misadjusted shift cables. It happened about a month after I bought the car and the guy had just replaced the cables before me. I took it into a shop and they repaired the tranny for maybe a year or so. While in the shop. they managed to spin a bearing during a test drive. Didn't take ownership of the problem. Told us the car sounded like that when we brought it in. Tigard Transmission in Tigard Oregon. Stay away from them.

Next one, I bought a junk yard tranny. That went bad about a year into it. Was repaired once, couple months later, had to take it on for warranty repairs. A few months after that, took it in again. Now it seems to be sticking. It has lasted a couple of years so far.

quote Originally posted by goatnipples2002: dude...WTF...how? I BEAT on my car like it owes me money (well it kinda does, lol). I have been running a 75 shot and a 100 shot for a while and it still is holding up...so far. My 1/2 is kinda tricky but that is because I have Rodney's short throw comp shifter that is cutt down an extra inch. BUT I do have a spare sitting in my garage. All i can say is buy 2 since they are fairly cheap. You can usually buy 3 spds 3.65 4 spds for the price of one fiero getrag. I agree I would check your mounts...the easy is to have someone rev the motor and see if it rocks with the revs. I would also run syncromesh if you can and if you are willing to spend the cash get some lucas synthetic gear oil.

My friend does that and more, but his trans has 240k MILES on it, never had a problem. Now he is putting his 3800SC motor on this same trans. (I did rebuild the trans for him using some parts from a cavi trans, the diff was slightly fatigued, with some wear on the teeth of the main gear, but other than that, the syncros were fine, so I left them alone.

I didnt change the trans for him, I just helped with the rebuilding I know better than changing transmissions on fieros.

im using synchromesh...i do race regulary i hardly ever "dump" the clutch...i let it slip to avoid wheel spin. shifter cables adjusted as it says to in my haynes manual
it fail the same way my first did... 1/2 shift got hard for a few weeks then it locked between gears.

I had an '85 with the Isuzu 5 speed that chewed up three tranny's on me before we found the heart of the problem. The clutch master cylinder needed new seals, and wasn't disengaging the clutch all the way. Before we found the problem, I'd replace the trans and within 6 months; I'd experiance the same problems you're describing. - Harder to shift between 1st and 2nd, and ultimatly the tranny would lock up between gears.

A master cylinder rebuild kit was only $25, and once it was rebuilt; I never chewed up another tranny.

Check for wear on the shifter fork (inside tranny). I had the same thing years ago. There is a coating (Teflon?) on the contact surface of the fork that wears off and throws clearances off. Or so I was told..........

Joe

ive had 3 4 speeds, only failures ive had were syncronizers, i beat on all my transmissions including my 3800 4 speed and no failures yet.

matthew

are you sure the ones you put back in there that lost the diff through the case actually had the later v6 casing?

can you post any pictures of the failures? the syncro failures do sound like the clutch isn't fully disengaging. since you drag race regularly maybe you should look into double clutching for the synchros sake. no its not just something made up in the fast and furious movies.. it does serve a purpose

yes the diff was sent through the later "reinforced" 4 speed case. i can fit my hand through where most of the gear was ejected into my clutch...ill look for pics...the case is in my garage...it looks sweet

This would be a good site to have handy --grab a couple at a time--used to blow the hell out of rear-ends in a shop rod we built (76 Vega Wagon) SBC built to the hilt, new rear end every other week. Drag racing cost a little more money & time than I orignally thought...
http://www.car-part.com/

My Ferrari kit had a 4 spd. It took lots of hard drivng for 100K from 300 hp, but no drag racing except maybe a few street races. The whole first year I drove it I didnt realize it had no oil in it...just lazy and never bothered to check. I put in new axle seals when I did realize it and filled it. Drove it for 6 or 7 years after that without even any noises. Guy that bought it put a caddy swap in it so someone else may be driving with my old 4 spd now still.

quote Originally posted by hatchetrider84: i have an 86 gt 4speed. mods include ported exhaust manifolds, ported air box, ram 9 11/16 clutch from fiero store. i drag race weekly. is this a common problem with 4 speeds? will the later model beretta trans hold up better... i am NOT willing to go auto trans.

They can and all do break. 4 spd Munices, the bulletproof (I wish) 5 spd Getrag and the Isuzu 5 speed.

Is it a *known* problem? Sure, they wear out and break. If you are beating on it, it will break sooner. How long until it breaks? Who knows.

The other than the expensive 284 Getrag, all Getrag 282s seem to be about the same in durability. They break too.

If you aren't beating on them the 4 spd Muncie and Getrags seem to hang in there for a long time (150k miles+) but they get loose and shift poorly. I have 240k on my Munice 4 spd and it's fine. A buddy has been through 3 Getrags (all very low miles) on his 3.4L DOHC. One was rebuilt (all new brass, bearings, etc.) Lasted about 20k miles but he beat on it. It completely tore up the trans.

Since you are drag racing I would expect the trans to last maybe 100k (starting from new) before it got loose and then failure is a matter of divine intervention. Either way, you should consider a new or fully rebuilt trans and not something unknown from a junkyard. There are upgrades available that will help with durability.

Statistically the difference between a *good* Getrag and *good* Muncie in durability is a wash. The Muncie 4spd *might* have an edge. You will get quotes of infinite miles behind a 1000HP big block Chevy for each trans but that's not of much value in making a decision.

[This message has been edited by TK (edited 11-01-2006).]

thanks for the imput everyone. since the diff was the weak point on the last failure so i might swap the internals from that and put it in the latest synchro failed trans...would this be ok?? or do the gears have to wear together like a cam and lifters?...it was only 3k out of a rebuild before the diff was 86'd out the case if that
makes a differance on swapping internals. i know almost nothing about swapping trans internals so id have some help from some guys at work.