Some of the early Muncies had weak cases. They beefed the case up a bit on the post 84 models, but if I had to give an opinion, I would say even the later muncie 4 spd is at the bottom of the food chain compared to the Getrag 5 spd. I have a muncie in my 84 and it's fine behind the 4 cyl, but I don't think I would trust it behind anything bigger. The gearing in the 410 won't allow you to take real advantage of the higher rpms available in any performance swap.
[This message has been edited by maryjane (edited 03-15-2006).]
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09:54 PM
EMX5636 Member
Posts: 577 From: Sellersville, Pennsylvania Registered: Mar 2002
I will agree with what maryjane said about the 4.10 geared 4 spds not being as good for some of the performance oriented swaps because the gearing is REALLY high. But I have to say that I think the strength is equal to the getrag. I mean obviously anything would break behind the right engine, with the right conditions, with the right driver, but my formula with an 85 gt 4-spd has held up fine to numerous launches and pretty hard (note:not speed shifting) shifting with my turbocharged 2.8L. And even though it is just a turbo 2.8, it isn't one of the normal run of the mill kits that makes 200HP at the wheels either. So, take it as you will. Everyone will have their own opinions to which trans is stronger, but many have had good luck with both, and muncies are much easier to find and less $$$.
Justin W
------------------ '88 Fiero Formula 4-spd- Edit again- bigger turbo install done, Haltech on hold, GM ECM via Darth..... here comes 300HP 2.8L
I will agree with what maryjane said about the 4.10 geared 4 spds not being as good for some of the performance oriented swaps because the gearing is REALLY high. But I have to say that I think the strength is equal to the getrag. ...... So, take it as you will. Everyone will have their own opinions to which trans is stronger, but many have had good luck with both, and muncies are much easier to find and less $$$.
Justin W
I should have prefaced my reply with the fact that the 4.10 is the only experience I personally have, but I have noticed more and more people seem to be happier with the Getrag 5spd. I truely hate 1st gear in mine. Which ratio do you have Justin?
btw, I tried to sell a spare 4.10 last year and couldn't give it away. Finally "sold" it for the price of the shipping to Fla. If mine ever craps out, there won't be another Muncie put in, and, as much work as it will be to swap in a 5 spd, it's going to happen. Gas is too high nowdays.
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10:17 PM
Gkayeasr Member
Posts: 110 From: North, Delaware, USA Registered: Feb 2005
Scott, I have a orginal Munice M21 4 speed in my 73 Corvette which is hooked up to the stock LS 454 ci engine, the M21 transmissions are referred to as the rock crusher because they were so well built. The Muncie shifters of that era were sloppy and replaced with Hurst shifters. So to answer your question I don' t think you will need to worry about the Muncie trans holding up to the torque of your engine, the LS 454 put out 398 ft. lbs of torque.
Glenn 87 Gt auto
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10:30 PM
Pyrthian Member
Posts: 29569 From: Detroit, MI Registered: Jul 2002
the 4 speeds that were on the V6's are pretty strong. and I myself love the 4.10 gears from the 4-cyl 4-speeds. the guts are interchangable. yes, they are LOW. not for freeway use. 3500 rpm to do 70. but it does put the power to the ground.
------------------ 1985 Fiero SE - Plain Red V6 Coupe 3.1 Crane272 MSD 4.10-4spd DarthChip Borla D.A.M.M. - Drunks Against Mad Mothers
Scott, I have a orginal Munice M21 4 speed in my 73 Corvette which is hooked up to the stock LS 454 ci engine, the M21 transmissions are referred to as the rock crusher because they were so well built.
Not sure where you meant to go with this--just because they're both Muncies doesn't mean that the torque rating of a mid-80s transverse gearbox is on par with a early 70s longitudinal gearbox.
As others have said Scott, the key with using the 4-speed in a high torque application is using the case from the ones attached to the 85 and early-86 2.8s. Somewhere 'round here is a thread with photos of the different transaxles... the 85 4-speed is re-inforced all over the place compared to the 84.
edit: found the thread I mentioned above. Click me.
[This message has been edited by dguy (edited 03-16-2006).]
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09:41 AM
82-T/A [At Work] Member
Posts: 24972 From: Florida USA Registered: Aug 2002
The 5-Speed Getrag is more refined than the 4-Speed Muncies. The 5-Speed getrag was used as an upgrade to the 4-Speed simply because it was more usable to the every day driver. You had better fuel economy on the highway, and was less stress on the engine. In addition, it was also a smoother shifting transmission than the 4-speed.
That said, the 4-Speed manual is a beast. It's far stronger than the 5-Speed Getrag. The 5-Speed getrag in the Fiero is the strongest of all the FWD 5-Speeds offered in GM vehicles, but... the 4-Speed is still even stronger than the strongest Getrag.
The 4-Speed is pretty much the ideal transmission for a small block chevy swap because it's the only one that can REALLY handle the torque. Lots of people want / try to use the 5-Speed getrags with their V8 swaps. It's fine if you can manage some restraint, but people with V8s are always blowing those getrags to pieces... which is ashame becuase an original Fiero Getrag is VERY hard to find now.
PERFORMANCE can mean many things. If you were doing any kind of road-course racing... the 4.10:1 4-Speed is about as close as you're going to get to a close-ratio transmission. The gearing is PERFECT for accelerating.
The 5-Speed is decent though, because you can more closely match the speed / rpms with your situation. But that 4-Speed is great for road-course kind of stuff.
Personally, I've wanted for a LONG time to build up a race-ready Fiero... totally stripped, with a roll-cage, nice tight suspension, a 4.10:1 4-Speed and a 2.8 built for high-rpm power with a set of webber carburetors. Man, I can't even imagine how cool that'd be...
If ANY of you guys have a 4.10:1 4-Speed, I'd LOVE to have it.
------------------ Todd, 2006 Pontiac Solstice 2004 Volkswagen Beetle Convertible (Wife's Car) 2002 Ford Crown Victoria LX 1987 Pontiac Fiero SE / V6 5-Speed 1987 Pontiac Fiero SE / V6 (3.2L) Auto 1984 Pontiac Fiero 2m4 SE 1981 Pontiac TransAm (Olds 455BB) 1973 Volkswagen Type-2 Transporter
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09:52 AM
m0sh_man Member
Posts: 8460 From: south charleston WV 25309 Registered: Feb 2002
The 5-Speed getrag in the Fiero is the strongest of all the FWD 5-Speeds offered in GM vehicles, but... the 4-Speed is still even stronger than the strongest Getrag.
The getrag 284 offered from 1991-1993 in the w-body car's with the 3.4L DOHC engine, is far stronger than the fiero getrag ever thought it was, and id say its on par with the muncie 4 speeds from the 85-86 fiero's and other GM car's.
the 284 getrag was the largest production 5 speed front wheel drive transmission GM made AFAIK
matthew
[This message has been edited by m0sh_man (edited 03-16-2006).]
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03:50 PM
FIERO1985 Member
Posts: 801 From: Columbus Oh, USA Registered: Nov 2000
Read My sig it takes a beating, do not go with the 84 4:10 though learned my lesson lol
Dan
------------------ 85 GT 355 SBC .220 Dome TRW Forged Pistons 215cc Dart Iron Eagle Heads 2.05/1.60 Valves Victor Jr Intake Barry Grant Mighty Demon 650cfm Solid 306 Duration 558 Lift Cam All Comp Valvetrain All MSD Igntion All transfered through a 4 speed Manual Trans Estimated BHP 530 GONNA SPRAY IT THIS SUMMER Most likely 200 shot
Is the Muncie 4 speed any good? what is it worth? can it take the horsepower the of the 5 speed getrrag?
Just posting these links from archived threads for Scott to consider, in addittion to the 1st hand knowledge you guys have offered. I seem to be in the minority here, and will bow to the other's more lengthy personal experiences. My opinion of the Muncie is upbeat after reading yall's posts.
There has been alot of talk lately about how much power the 4-speeds can handle. I've broken all 3 versions behind my 3800SC Fiero and am sharing info for those who are curious. 1st breakage: 3:32 geared in the weak case - broke the teeth clean off of 2nd gear. 2nd breakage: 4:10 geared in the weak case - case cracked (bottom left-hand side) 3rd breakage: 3:65 geared in stronger v-6 case - broken blocker ring * cast inner piece.
jncomutt and capt fiero had their share of problems as well. Looks like the beefed up case too, but hard to tell.
Now, I have to say up front, that my 4.10 has given me zero problems, but it is behind a 4 cyl, and I know from experience that anyone can blow any tranny up if they put enough HP and torque into it. Or abuse it enough. None are truely bulletproof.
(Yeah, I'm the guy that left all the oil, aluminum, gears and other assorted '61 vette tranny parts all over the road beneath the only red light in Malvern Arkansas about 3o'clock in the morning back in 1972. )
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10:29 PM
Mar 17th, 2006
3084me Member
Posts: 1035 From: Bucks County, PA Registered: Apr 2005
The above post about the M-21 vs the Fiero Mucie's strength is correct. There is no comparison (at all) in durability between the M-21 and the Transverse Muncie. I've had several old Corvettes and have rebuilt several M-21's and M-22's.
F.Y.I. Only the M-22 is historically known as the Rockcrusher not the M-20 or M-21 although many people refer to the others as Rockcrushers. ( The name is also not because of it's strength, but because of the noise it produces).
The M-21 had a different "cut" gear angle on the first three gears which made it noisy. . The Rockcrusher name appeared in a Hot Rod magazine during a review of the Corvette. M20 and M21 Muncies had "modified gear angles and made less noise. Rockcrusher is just such a tough musclecar name that everyone uses it no matter which Muncie they have.
PS. You will also see many people bragging about their "prized Rockcrusher " when it's actually a Saginaw 4-speed. Still not a bad trans though.
[This message has been edited by 3084me (edited 03-17-2006).]
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08:26 AM
topcat Member
Posts: 5486 From: Charleston SC Registered: Dec 2001
I have a SC3800 that had the muncie 4.10 hooked to it, and I hated it. The 4.10 is a great transmission if you want to get going fast, but in the SC3800 application I found that the first gear was useless because by the time I was at 5 - 10 MPH, I was up around 4500 - 5000 rpm, and looking for the next gear. 2nd gear went pretty fast too. Then trying to cruise on the freeway was painful. I like driving with the flow of traffic, and at 70 MPH, the engine RPM was up over 3500... nearing 4000 RPM. Bottom line, I hated it.
I swwapped trannys and installed the Muncie 4 speed with the 3.65 gearing. It is much more tolerable, and more drivable. Highway cruising is much more pleasant. I have had no issues with my four speed breaking on me, but I am not at the track trying to get the best quarter mile times. I hard launch once in a while, and I often break traction from first to second, but I am not in the habit of spinning tires out of first. I'm looking for some wood now to knock on since I made the statement that my tranny has not let me down yet.
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09:39 AM
OH10fiero Member
Posts: 1541 From: struther OH Registered: Jun 2002
For those who have driven a 4spd 4:10 with a 2.8 V6 (or something bigger and more powerful) All I have to say is...............................2nd gear! There will be those who will understand, and those who will question, but most of all its when you look into your rear view mirror at that moment and see the guy that was trying to race you.
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12:19 PM
Pyrthian Member
Posts: 29569 From: Detroit, MI Registered: Jul 2002
Is the Muncie 4 speed any good? what is it worth? can it take the horsepower the of the 5 speed getrrag?
There's two different versions of the Muncie 4-speed in Fieros. The one in '84 cars has a weaker case than later models. '84 is also the only year that the 4.10 gearing was available. Not recommended for high horsepower cars; it'll split the case if you beat on it. Some of the '84 Muncies had 3.33 gearing - this is rare and hard to find.
The later model Muncie 4-speeds (used with the V6 in 85 and early 86) have a beefed-up case and 3.65 gearing. These are pretty doggone tough transaxles and it'd be my choice for a high power swap. The 4.10 gearing can be swapped in, but this isn't a great idea - you'd be much happier with the 3.65 gearing in a Fiero. Best possible would be to swap the 3.33 gears from an '84 box into a V6 Muncie; that'd give you usable highway gearing and be strong enough for any reasonable swap.
And yes, the later model Muncies are tougher than the Getrag.
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08:00 PM
California Kid Member
Posts: 9541 From: Metro Detroit Area, Michigan Registered: Jul 2001
And yes, the later model Muncies are tougher than the Getrag.
No offense meant, but is that opinion, or fact ??? I've never seen any hard data that shows that one is stronger than the other, do they have different torque handling ratings from GM ?
What would be the best choice of gears for acceleration, top speed and economy? I have a 3.65 I have thought about the getrag swap until now. Is it possible to mix and match the gears from the 3.33 (econo), 4.10 (performance), 3.61 (getrag) and the 3.65 (85-86GT)? What would be the best mix?
[This message has been edited by goatnipples2002 (edited 03-18-2006).]
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01:30 AM
cooguyfish Member
Posts: 2658 From: Hamilton, OH, USA Registered: Mar 2002
What would be the best choice of gears for acceleration, top speed and economy? I have a 3.65 I have thought about the getrag swap until now. Is it possible to mix and match the gears from the 3.33 (econo), 4.10 (performance), 3.61 (getrag) and the 3.65 (85-86GT)? What would be the best mix?
Depending on what exactly you wanted, and what RPM's/tires you'd be using, in my opinion, the best gearing would be as follows;
3.65 Case 3.65 1st, 2nd, 3rd 3.32 4th
Whichever FD suits your needs best.
This combo would give you the close ratio 1-2, 2-3 doesn't matter it's the same on all. and A great economy gear for highway cruising.
depending on RPM's, tire sizing, and which FD you use
I'd say, 3.32 for a V8 (@ 6000 RPM, with stockish sized tires) you'd be going;
1st 40.4 2nd 68.6 3rd 107.8 4th 183.2
and you'd be cruising 1965 RPM @ 60
I'd mention to hear, that 4th gear would be pretty much economy only, not very good for performance. it's like 1-2-3-5 from what I hear.
with 7000 RPM (same tires)
1st 47.1 2nd 80 3rd 125.8 4th 213.7
with the 3.65 FD, and 7K, it would be a little longer per gear than the 3.32 and 6K RPM's.
There is only one person that I've heard that has tried to build that hybrid transmission.
One other Idea that I heard, that I had considered myself, is to have straight cut racing gears made. There is a company (so I've heard), that will make gears in any ratio that you'd ask for. The bad thing about straight cut gears is whine. Reverse is usually a straight cut gear, so that gives an idea of how loud the whine would be to DD. The idea someone else mentioned was to use the stock 4th gear, with straight cut 1-3 gears. So that way you could cruise in fourth and not have to listen to that whine. Plus you could make very long and close ratio 1-4 shifts. But to be able to use 4th gear as a performance gear, you'd have to use the 3.65 4th. So with a 3.65 case, you'll be spinning 2400 RPM at 60.
My theorectial gears that I would chose if possible would be as follows;
1st 56.8 2nd 89.8 3rd 129 4th 175.2
That's with a 2.5 first 1.58 2nd 1.1 3rd .81 4th
3.65 FD and 7K RPM's
You'd need an engine with some serious torque to be able to pull those gears, or you'd have to use a 4.11 FD and spin 2800 RPM on the highway.
What would be the best choice of gears for acceleration, top speed and economy? I have a 3.65 I have thought about the getrag swap until now. Is it possible to mix and match the gears from the 3.33 (econo), 4.10 (performance), 3.61 (getrag) and the 3.65 (85-86GT)? What would be the best mix?
well, accelleration has opposite gear requirements than top speed & economy. accell is low gearing - like the 4.10 & 3.65, top speed & economy is high gearing, like the 3.65 & 3.32. also, the fastest factory Fiero made was the '85 2M6 with 4 speed.
mix & matching is possible. I use the 4.10 gears, and would like the higher 1st from the 3.65 gearset.
------------------ 1985 Fiero SE - Plain Red V6 Coupe 3.1 Crane272 MSD 4.10-4spd DarthChip Borla D.A.M.M. - Drunks Against Mad Mothers
The 3.65 Muncie is very strong, and it is also the best gear ratio for grunt and go. You'll find that if there are 2 cars, one driver, same engine, but Muncie 3.65 vs. Gehtrag, the Muncie will have the edge in strength and acceleration.
Here is the problem, when I have my 3.65 on the freeway, I'm always looking for 5th and can't find it. If you are doing alot of freeway, and you are not doing alot of track work, the edge goes to the Gehtrag. On balance, the 5 speed is likely friendlier for day to day general purpose driving. My preference in town, personally, is the 4 speed. It has a nice gear ratio going between lights.
That being said, neither of the trannies are bad, they just get beat up by some pretty aggressive driving. Look up Tina, and you'll see her standard tranny problems with her pretty powerful and definitely trick ride. (I have Tina's ride in my screen savers)
Before my 3.2 swap I would race my stock 86 fastback vs my brother in laws 88 formula Of the line was about the same but by 2 he was a little ahead then by time we hiy 3 third he was pulling on me. Is this because the formula weights less?
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12:03 AM
Pyrthian Member
Posts: 29569 From: Detroit, MI Registered: Jul 2002
Before my 3.2 swap I would race my stock 86 fastback vs my brother in laws 88 formula Of the line was about the same but by 2 he was a little ahead then by time we hiy 3 third he was pulling on me. Is this because the formula weights less?
maybe. could be many things. he coulda just had a better motor. the was MUCH variance in the 2.8's. either of these 4-speeds?
maryjane- I am using the 3.65 out of an 85 GT. First gear isn't too short, and when the turbo came in, would spin till redline, but I think the gearspacing is pretty ideal for either a high torque engine or a higher revving engine.... Like many said, if I was doing 30+ miles a day highway, I'd probably stick the getrag in just for the 5th gear, but my car isn't really being built for street as much anymore, mostly auto-x and road race so I may even swap to the 4.10 ratio gears sometime in the future, but I don't hate my gears that much so I dunno.... I only road in a 4.10 v6 car once, and it definately felt like it pulled slighter faster, but like you said, first gear is very short, I think the 3.65 fd makes a huge diffence, it feels about as long as my eclipse or my old supra was...
------------------ '88 Fiero Formula 4-spd- Edit again- bigger turbo install done, Haltech on hold, GM ECM via Darth..... here comes 300HP 2.8L
Its all in your choice of driving I preffer the 4.10 for street or drag but in my final decision I decided to go auto with paddle shifter. Though for tranny strength I had my run in with my 83 z28 and the 4 trannys I went through on that car in less than 2 years. I was running 400+ with over 200hp on the bottle and the standard 700r-4 couldn't take it and I took out gears so fast till I went with a th350 and I damaged the valve body. But I will see how that engine handles in my vega with a muncie 4speed.
There is only one person that I've heard that has tried to build that hybrid transmission.
One other Idea that I heard, that I had considered myself, is to have straight cut racing gears made. There is a company (so I've heard), that will make gears in any ratio that you'd ask for. The bad thing about straight cut gears is whine. Reverse is usually a straight cut gear, so that gives an idea of how loud the whine would be to DD. The idea someone else mentioned was to use the stock 4th gear, with straight cut 1-3 gears. So that way you could cruise in fourth and not have to listen to that whine. Plus you could make very long and close ratio 1-4 shifts. But to be able to use 4th gear as a performance gear, you'd have to use the 3.65 4th. So with a 3.65 case, you'll be spinning 2400 RPM at 60.
I currently run a 3:65 case & ring gear with 4th gear from a 3:32. It's not a bad setup and isn't too unruly at highway speeds.
A straight-cut gearset for 1-3 would probably be tolerable on the street just because you're really not in the low gears too much, but machining costs would be high because 1st and 2nd gear are part of the shaft so machining would be difficult & time consuming. Also - even though straight-cut gears would put less sideload on the trans case, I believe helical gears are stronger than straight-cut (given the same dimensions/materials).
-Tim
------------------ 84 Fiero, 3800SC Series II,4spd manual 12.90 @ 108.9mph
the 4speed is not the one to use if you want good milage but its the one i'm using for my 3.4dohc turbo because its the only one i trust
I just blew up my 4 speed (85, 3.65 gears) after about 5 years of abuse - broke every tooth off the spider gears in the diff. Twas behind a turbo 3400DOHC with around 330 hp, 360 ft-lbs. I'm now switching to a 5 speed Getrag from a 94 sunbird. I guess we'll see shortly if its any better or worse. Gonna hang onto the guts of the 4 speed just in case...
Originally posted by 3400Fiero: I just blew up my 4 speed (85, 3.65 gears) after about 5 years of abuse - broke every tooth off the spider gears in the diff. Twas behind a turbo 3400DOHC with around 330 hp, 360 ft-lbs. I'm now switching to a 5 speed Getrag from a 94 sunbird. I guess we'll see shortly if its any better or worse. Gonna hang onto the guts of the 4 speed just in case...
yes, any open diff will do this eventually, if you break the tires loose alot, especially when corning. with a LSD, your trans would still be intact.
