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4sp Muncie Blew Up - New Trans or Rebuild by Bfisher31286
Started on: 05-14-2014 08:03 AM
Replies: 7 (275 views)
Last post by: Bfisher31286 on 05-15-2014 08:48 AM
Bfisher31286
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Report this Post05-14-2014 08:03 AM Click Here to See the Profile for Bfisher31286Click Here to Email Bfisher31286Send a Private Message to Bfisher31286Edit/Delete MessageReply w/QuoteDirect Link to This Post
So I was nearly done tuning my 3800sc on the street when I decided to take a fun windy road and get on the gas a little. I really was not beating on it hard at all but I shifted from second to third and got back on the gas. A bang and grinding caused me to decide to shut the car off and get out for some inspection. Third gear is gone and the diff is acting like its missing teeth or something too. Im in the process of taking it out and I am looking at my options. Has anyone recently rebuilt the muncie trans? Cost? I am leaning more towards the F23 or F40 but I have read a lot of conflicting info on them. Lets say im around 300-340 HP, just guessing, never made it to the dyno. Is the F23 going to hold up for long. I prefer it because of the easier install and I don't need 6 gears. But I have read the F40 is a bit stronger. Will the F23 be enough for me or should I look into the F40?
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Bfisher31286
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Report this Post05-14-2014 08:07 AM Click Here to See the Profile for Bfisher31286Click Here to Email Bfisher31286Send a Private Message to Bfisher31286Edit/Delete MessageReply w/QuoteDirect Link to This Post

Bfisher31286

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Member since Jun 2009
Also how does the Fiero Getrag 5sp compare to something like an F23
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Gall757
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Report this Post05-14-2014 11:17 AM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
I can only guess at how much torque you are making, and I"m thinking the stock Fiero transmissions are not going to hold up. You are right...you don't need a 6 speed.
Because they are so cheap, I would look for a bunch of 4 speeds and use them up one at a time....

[This message has been edited by Gall757 (edited 05-14-2014).]

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Bfisher31286
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Report this Post05-14-2014 01:51 PM Click Here to See the Profile for Bfisher31286Click Here to Email Bfisher31286Send a Private Message to Bfisher31286Edit/Delete MessageReply w/QuoteDirect Link to This Post
So I got the transmission apart and found third gear is missing some teeth...like all of them. The slow drive home did a good job of distributing the teeth to the rest of the gears, diff, and bearings so it looks like the only parts that are still good are the case. Im guessing a rebuild will be pricey compared to finding a new trans but Im still curious about what the cost would be if I stuck with rebuilding the trans. Also, I am really curious about how this gear just had all its teeth stripped off. I searched for cracks in the case or signs of the shaft moving out of place and I cant find anything. Has anyone seen something similar happen and identified the cause? I mean besides cramming over 250 ft-lbs through a 30 year old gearbox. Maybe bearings were getting sloppy?



So anyway Im thinking maybe the F23 is in my future. What is the best place to get a decent one? Which model cars had the best gear ratios and easiest direct bolt up? Can I keep my machined Camaro flywheel with the F23 that I ran on my muncie?
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Bfisher31286
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Report this Post05-15-2014 07:47 AM Click Here to See the Profile for Bfisher31286Click Here to Email Bfisher31286Send a Private Message to Bfisher31286Edit/Delete MessageReply w/QuoteDirect Link to This Post
Also, I am running a Spec stage 4 clutch that has a solid hub (no springs). Should I look into a sprung hub clutch? Are they a little easier on the trans?
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joeschuit
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Report this Post05-15-2014 08:29 AM Click Here to See the Profile for joeschuitClick Here to Email joeschuitSend a Private Message to joeschuitEdit/Delete MessageReply w/QuoteDirect Link to This Post
I've got a full set of internals from my 4 speed if you need some extras. It does have a bad 1-2 syncro hub but the rest is fine.
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carbon
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Report this Post05-15-2014 08:34 AM Click Here to See the Profile for carbonSend a Private Message to carbonEdit/Delete MessageReply w/QuoteDirect Link to This Post
There is only one gear set for the F23 that 'directly' bolts up. It has a 3.94 final drive ratio and came only in the 2000-2002 Cavalier/Sunfire with the 2200 pushrod engine. There is no best place to get one, but you can start here.

That site will find interchange parts for you so just enter 2000 Cheverolet Cavalier and select the 2.2L engine and manual transmission. If you put 2002 in there, it will also give you the option of the Ecotec 2.2 (VIN F), which you don't want as the bell housing won't work.

If you want to go nuts, you can look for a 2010 Chevy Cobalt with the XFe package (Opt FY1), it's F23 has a 3.63 final drive, but you have to swap the bell housing half of the case. Doing this makes mounting the trans even more interesting than it already is and if you don't verify that the trans is shimmed properly inside, it may not live very long.

Cavalier/Sunfire Getrag F23:


Fiero/FWD Getrag HM282:

[This message has been edited by carbon (edited 05-15-2014).]

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Bfisher31286
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Report this Post05-15-2014 08:48 AM Click Here to See the Profile for Bfisher31286Click Here to Email Bfisher31286Send a Private Message to Bfisher31286Edit/Delete MessageReply w/QuoteDirect Link to This Post
surprised I never heard of that car-part.com site before. That site is great. Thanks.
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