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3.4 DOHC Tranny pick by 86GTFastback
Started on: 05-28-2009 04:54 PM
Replies: 20
Last post by: L67 on 08-02-2010 01:37 AM
86GTFastback
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Report this Post05-28-2009 04:54 PM Click Here to See the Profile for 86GTFastbackSend a Private Message to 86GTFastbackDirect Link to This Post
First off, yes I realize there are a TON of DOHC related posts. I have been searching for days for various questions. Right now I have a 4-speed in a 86GT. In the next few months I will be swapping in a DOHC, it was a close decision vs a sc3800. I was wondering if it would be worth finding a getrag, and such, does anyone have actual expirence in driving both?

Or just give me your impressions of ether. I am very curious about rpms to mph and wether going down the highway in 4th at (guessing) 3600rpm would kill mpg or be really hard on the engine.

Thanks,
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DCRFiero1
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Report this Post05-28-2009 08:12 PM Click Here to See the Profile for DCRFiero1Click Here to Email DCRFiero1Send a Private Message to DCRFiero1Direct Link to This Post
I would say you would be better off going with a Getrag 5-speed. For a few reasons:

1. More gears to take advantage of the high reving engine
2. Getrags are better than the other 5 speeds
3. With the 5 speed you will have better gas mileage at crusing speeds
4. The 4 speed may be a little more stressful on the engine


I dont own a 3.4 DOHC Fiero, I wanted one so I did a little research awhile ago. I ended up going with a 3800SC. Hope this helps you (Not a lot of new info) Look around at some of the build threads with 3.4 DOHC, some should explain their trans choice. Hopefully someone with a DOHC Fiero will chime in to help you more.

Zach
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olaf_fiero27
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Report this Post05-28-2009 11:55 PM Click Here to See the Profile for olaf_fiero27Click Here to Email olaf_fiero27Send a Private Message to olaf_fiero27Direct Link to This Post
Hey dude, I've got an 86 GT with a DOHC in it behind a muncie 4spd ( the econo one out of an 84 with 4:10's) Let me tell you it goes like a bat out of hell but first gear is useless and on the highway it's not that bad cruises at about 2800 rpm at 100 km/h. Although for what its worth I have a few ecotec parts cav's and sunfires at my shop and Im definetley going to swap in a 5 spd getrag, for the added reliability, strength, and overall a better trans.
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Mike Murphy
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Report this Post05-29-2009 12:10 AM Click Here to See the Profile for Mike MurphyClick Here to Email Mike MurphySend a Private Message to Mike MurphyDirect Link to This Post
I put a new DOHC 3.4 crate engine in my 88 with a freshly rebuilt Getrag. Nice range of gearing and dependable. The 89-90 prototype had this setup so go figure. GM refused to put the 2.8 with anything but the Muncie 4 speed and later the Getrag for dependibility purposes. The more gears the better the driving and economy experience.
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Dennis LaGrua
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Report this Post05-29-2009 08:48 AM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaDirect Link to This Post
While it came with an auto or a stick, the transmission preference for most owners of 3.4L DOHC Fieros appears to be the Getrag. I have yet to see one 3.4L DOHC swap with an automatic. To make power with this engine you need to generate RPM's and the choice of trans is probably due to the unique torque curve that this engine has.

------------------
" 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 "

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Jarhead 2m4
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Report this Post05-29-2009 09:59 AM Click Here to See the Profile for Jarhead 2m4Click Here to visit Jarhead 2m4's HomePageClick Here to Email Jarhead 2m4Send a Private Message to Jarhead 2m4Direct Link to This Post
My DOHC feels right at home mated to the Getrag. I just need to figure out why it isn't running like it should.
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86GTFastback
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Report this Post05-29-2009 12:48 PM Click Here to See the Profile for 86GTFastbackSend a Private Message to 86GTFastbackDirect Link to This Post
I was again going through some older threads, it has been stated that 4 speed would be a lot quicker, but a 5 speed would go faster. Since I get uneasy cresting 100 on a country road (took a Fiero ariborne well past there, don't ask), I'm mainly looking at quarter mile/light to light. It should go pretty fast even with a 4 speed, but could anyone confirm that the 4 speed would be quicker?

Driving impressions are still very welcome. I'm getting pretty excited, even though my swap is a little ways away.
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FieroReinke
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Report this Post05-29-2009 01:28 PM Click Here to See the Profile for FieroReinkeClick Here to Email FieroReinkeSend a Private Message to FieroReinkeDirect Link to This Post
I suggest you buy one of the 3.94 getrags on ebay and find someone with a trashed fiero getrag and swap bellhousings. Best of both worlds.
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mid engine monsters
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Report this Post05-29-2009 01:42 PM Click Here to See the Profile for mid engine monstersClick Here to Email mid engine monstersSend a Private Message to mid engine monstersDirect Link to This Post
are you talking about the new aftermarket copies on ebay for 150.00 ,anybody got any info on those ,any secret info or opinion
 
quote
Originally posted by FieroReinke:

I suggest you buy one of the 3.94 getrags on ebay and find someone with a trashed fiero getrag and swap bellhousings. Best of both worlds.


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86GTFastback
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Report this Post05-30-2009 10:52 AM Click Here to See the Profile for 86GTFastbackSend a Private Message to 86GTFastbackDirect Link to This Post
~Bump~

Still looking to see if anyone has driven both, and information about the ebay getrag.

[This message has been edited by 86GTFastback (edited 05-30-2009).]

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86GTFastback
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Report this Post06-01-2009 02:17 PM Click Here to See the Profile for 86GTFastbackSend a Private Message to 86GTFastbackDirect Link to This Post
~Bump~

Nobody else, really? Not even a, "use search"?

[This message has been edited by 86GTFastback (edited 06-01-2009).]

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86GTFastback
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Report this Post06-01-2009 03:22 PM Click Here to See the Profile for 86GTFastbackSend a Private Message to 86GTFastbackDirect Link to This Post
Anybody have a stock 3.4l 4-speed quarter mile time?
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ltlfrari
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Report this Post06-01-2009 03:58 PM Click Here to See the Profile for ltlfrariClick Here to visit ltlfrari's HomePageClick Here to Email ltlfrariSend a Private Message to ltlfrariDirect Link to This Post
Mine was mated to a suzzy 5 sp and the only real complaint I had was that the jump from 1st to second was just way too much. The engine would scream in 1st but by the time I got it into second the revs had dropped way off (my box was very slow to shif 1st to second, dunno if that is common) so it went screeeeeeeeeeem, bluuuuuuuugh then it picked up fine. It would pull away in pretty much any gear the motor had that much power. On the freeway I was cruising at 65/70 with 2500 rpm on the tach and it would still pull away when I hit the gas.
Now I've got a 2.8 mated to a 4 speed stick and it 'feels' like the gear ratios of the 4 speed would be a better match to the dohc but I can't say for sure.
As for strength, well I never dropped the clutch on mine and treated it with respect and it was fine. That's not to say I did not enjoy some 'spirited' driving, I just didn't abuse it.

Just my $0.02 worth.

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Dave

www.ltlfrari.com

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Puckhead
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Report this Post10-11-2009 12:26 PM Click Here to See the Profile for PuckheadSend a Private Message to PuckheadDirect Link to This Post
What about a G6 6 speed.......Has anyone tried mating this motor to this tranny yet???? Really curious on this one......

-T
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HausFiero
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Report this Post08-01-2010 11:58 PM Click Here to See the Profile for HausFieroSend a Private Message to HausFieroDirect Link to This Post
 
quote
Originally posted by Puckhead:

What about a G6 6 speed.......Has anyone tried mating this motor to this tranny yet???? Really curious on this one......

-T


Bump!!!
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L67
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Report this Post08-02-2010 12:03 AM Click Here to See the Profile for L67Click Here to Email L67Send a Private Message to L67Direct Link to This Post
From someone who's installed a DOHC and a 3800, don't install the DOHC.
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HausFiero
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Report this Post08-02-2010 12:13 AM Click Here to See the Profile for HausFieroSend a Private Message to HausFieroDirect Link to This Post
 
quote
Originally posted by L67:

From someone who's installed a DOHC and a 3800, don't install the DOHC.


That wasn't rly the question lol, but I'm more accustomed to lower tq, higher rev'ing cars tho anyway. This engine sounds most like me personally... But that's beside the point
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Erik
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Report this Post08-02-2010 12:23 AM Click Here to See the Profile for ErikClick Here to Email ErikSend a Private Message to ErikDirect Link to This Post
As a 88 DOHC GT owner for 5 yrs daily driven drive it like I stole it, I would continue to use the 84 4 speed 4.10...if given the choice between it and a Getrag. Nothing so far that I've encountered can beat me out of the hole and its just such fun to drive with the high revs . It is the closest thing to driving a Ferrari, Fiero wise due to the high revs the 4.10 allows the engine to get into where it is one with the world

[This message has been edited by Erik (edited 08-02-2010).]

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mattwa
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Report this Post08-02-2010 12:31 AM Click Here to See the Profile for mattwaClick Here to Email mattwaSend a Private Message to mattwaDirect Link to This Post
The choice really depends on what type of driving style your looking for. I have a quote from "fieroseverywhere" on all three stock manuals used in a fiero about his experience with each, on the same car.

 
quote
Originally posted by fieroseverywhere:
With everything I've heard on this forum I used to think the getrag was the best fiero Trans. Once I got one my opinion changed pretty fast. Now I just look at it as the best compromise between gas mileage and performance.

I've tested the Isuzu, Muncie, and getrag all in the same car. I used the same engine, clutch, flywheel, shift arm (Rodney comp1), and slave on all three (3.65 slave). Isuzu got the best cruising mileage but seemed slowest off the line. 1st especially was completely useless. It did seem to shift the smoothest.

Getrag got a little bit worse mileage but felt better off the line then the Isuzu. The shifts are shorter then both the others by design. 1st is not as bad as the Isuzu but its still useless.

The Muncie though blew both of those away. Mileage is not great but what it lacks there it more than makes up for in how it feels. 1st is tall and gives the motor a chance to find its power. I love the fact that I can punch it in any gear and it just scoots. Down shift to pass? I think not!

It’s really all about what you’re looking for. For performance driving I'll take the Muncie any day. For cruising, I'll baby the Isuzu so it doesn't break. Refinement goes to the getrag.


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HausFiero
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Report this Post08-02-2010 12:52 AM Click Here to See the Profile for HausFieroSend a Private Message to HausFieroDirect Link to This Post
TY for that quote mattwa.. Tho iv heard concerns about the 4 spd being hard on the engine

that quote gave good info, but my bump about the 6 spd with the dohc still hasn't been answered :/

iv also wondered about the 4t60 with the paddle shifter kit for it
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L67
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Report this Post08-02-2010 01:37 AM Click Here to See the Profile for L67Click Here to Email L67Send a Private Message to L67Direct Link to This Post
"Refinement goes to the getrag."

He's on crack cocaine, and the rest of what he said is voided.
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