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3.94 final drive trans build by Spiders1
Started on: 02-02-2016 10:00 PM
Replies: 11 (424 views)
Last post by: Spiders1 on 03-28-2016 09:59 PM
Spiders1
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Report this Post02-02-2016 10:00 PM Click Here to See the Profile for Spiders1Click Here to Email Spiders1Send a Private Message to Spiders1Edit/Delete MessageReply w/QuoteDirect Link to This Post
When I was looking for a FWD Getrag I found a very rare 3.94 final drive from a Quad 4 W41 optioned car with 32k on it.
It had been at the salvage yard for a decade.

I was going to open the trans and change the speedo gear anyway so decided to grab the trans and swap the gears while
it was in the shop lol

It has been pulled apart and cleaned. I have to get a few bearings before it can go together. I put the newest pics in my photobucket.
It also has pics of the pulley change and rolling onto the dyno.

http://s292.photobucket.com...library/?view=recent

------------------
86 GT 3.8 SC/ 5 speed Getrag swap in progress

05 Mustang GT Supercharged tuned down from
560 to 530 RWHP (sold)

92 Stealth twin turbo JDM engine swap
Upgrades in the works...turbos, injectors
and computer. (sold)

91 GMC Syclone 20k original miles

[This message has been edited by Spiders1 (edited 02-02-2016).]

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Raydar
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Report this Post02-05-2016 09:23 PM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
Are you going to retain the 3.94 FDR? Bolted to a 3800 SC?

I think you'll find that you will blow through first gear almost immediately. People I have known who used a regular Getrag (3.61(?) with a 3800SC complained about how short first gear was.

Regardless, it looks like you have some fun toys.
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Spiders1
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Report this Post02-06-2016 12:20 AM Click Here to See the Profile for Spiders1Click Here to Email Spiders1Send a Private Message to Spiders1Edit/Delete MessageReply w/QuoteDirect Link to This Post
Yes I'm replacing the 3.61 with the 3.94. I never rag first gear anyway so it doesn't bother me at all ^_^

------------------
86 GT 3.8 SC/ 5 speed Getrag swap in progress

05 Mustang GT Supercharged tuned down from
560 to 530 RWHP (sold)

92 Stealth twin turbo JDM engine swap
Upgrades in the works...turbos, injectors
and computer. (sold)

91 GMC Syclone 20k original miles

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lou_dias
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Report this Post02-08-2016 12:21 PM Click Here to See the Profile for lou_diasClick Here to Email lou_diasSend a Private Message to lou_diasEdit/Delete MessageReply w/QuoteDirect Link to This Post
I think some J-Body Getrags came with a lower final drive... 3.23 or something like that. Seems more sensible to me when you have that much more torque...and might even get past 60mph in 2nd gear...rather than 3rd as shifting slows you down...
One of the ways the Corvettes achieve a high 0-60 time is they do it in 1st gear. Their first could be our 2nd with enough launching torque.

The F-40 6 speed can do 62mph in 2nd gear at 6000rpm.
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Spiders1
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Report this Post02-08-2016 07:24 PM Click Here to See the Profile for Spiders1Click Here to Email Spiders1Send a Private Message to Spiders1Edit/Delete MessageReply w/QuoteDirect Link to This Post
Well I definitely do not want to slow the car down with 3.23 but that's just me. And I'm not going to be going
doing any high speed runs lol so I don't care about losing a few miles per hour on the top speed.

------------------
86 GT 3.8 SC/ 5 speed Getrag swap in progress

05 Mustang GT Supercharged tuned down from
560 to 530 RWHP (sold)

92 Stealth twin turbo JDM engine swap
Upgrades in the works...turbos, injectors
and computer. (sold)

91 GMC Syclone 20k original miles

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lou_dias
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Report this Post02-09-2016 09:47 PM Click Here to See the Profile for lou_diasClick Here to Email lou_diasSend a Private Message to lou_diasEdit/Delete MessageReply w/QuoteDirect Link to This Post
it's just metrics. Cars are rated for 0-60 and top speed. By removing a shift, your 0-60 increase by about 1/2 a second...and so does your top speed.
1/4 mile is another metric and 4th gear will only get you to 120mph with a 3.94 final drive and you'll lose speed shifting to 5th, so depending on your goals, you would probably want 4th gear where it is or closer to 140mph at 6000rpm...

[This message has been edited by lou_dias (edited 02-09-2016).]

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Spiders1
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Report this Post02-10-2016 06:35 PM Click Here to See the Profile for Spiders1Click Here to Email Spiders1Send a Private Message to Spiders1Edit/Delete MessageReply w/QuoteDirect Link to This Post
I had the machine shop resurface the flywheel even though it only has a few hundred miles on it at best.

They also balanced the flywheel and clutch plate together. They took a decent amount of material out the pressure plate
to get it balanced out. I uploaded 2 more pictures. I zoomed in on the clutch plate so you could see how out it was.

------------------
86 GT 3.8 SC/ 5 speed Getrag swap in progress

05 Mustang GT Supercharged tuned down from
560 to 530 RWHP (sold)

92 Stealth twin turbo JDM engine swap
Upgrades in the works...turbos, injectors
and computer. (sold)

91 GMC Syclone 20k original miles

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FieroReinke
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Report this Post02-11-2016 12:41 PM Click Here to See the Profile for FieroReinkeClick Here to Email FieroReinkeSend a Private Message to FieroReinkeEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have this tranny behind my 3.4 DOHC and love it. First is very short, but it will pull out of the hole like crazy. The high RPMS on the highway get annoying and my fuel mileage took a big hit, but its a toy car so who cares. Mine was an hydraulic throw out bearing and it took some interesting fittings to connect to the Fiero Slave line, but I was happy to be rid of the slave cylinder. I had to get the cable adapters from Rodney to get the cables to work properly.
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Spiders1
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Report this Post02-11-2016 03:17 PM Click Here to See the Profile for Spiders1Click Here to Email Spiders1Send a Private Message to Spiders1Edit/Delete MessageReply w/QuoteDirect Link to This Post
Exactly, it's a toy. Not a commuter car for me lol.

I bought the swap pieces from Rodney also.

Going to have a custom clutch line connector made up for me though. I don't want to adapt it too many times to make it work.

------------------
86 GT 3.8 SC/ 5 speed Getrag swap in progress

05 Mustang GT Supercharged tuned down from
560 to 530 RWHP (sold)

92 Stealth twin turbo JDM engine swap
Upgrades in the works...turbos, injectors
and computer. (sold)

91 GMC Syclone 20k original miles

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Spiders1
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Report this Post02-19-2016 10:15 PM Click Here to See the Profile for Spiders1Click Here to Email Spiders1Send a Private Message to Spiders1Edit/Delete MessageReply w/QuoteDirect Link to This Post
Added a picture of the trans going together. Very soon it will be put back together and then back to the dyno!

------------------
86 GT 3.8 SC/ 5 speed Getrag swap in progress

05 Mustang GT Supercharged tuned down from
560 to 530 RWHP (sold)

92 Stealth twin turbo JDM engine swap
Upgrades in the works...turbos, injectors
and computer. (sold)

91 GMC Syclone 20k original miles

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Spiders1
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From: Fredericksburg VA USA
Registered: Jul 2013


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Report this Post03-19-2016 09:37 PM Click Here to See the Profile for Spiders1Click Here to Email Spiders1Send a Private Message to Spiders1Edit/Delete MessageReply w/QuoteDirect Link to This Post
Trans is done and installed. Working well.

The holes for the lower cable mount were not threaded. Didn't find that out till it was already installed. I never read anything about
needing to tap and die it in any post. There is only about 2.5 maybe 2.75 inches of clearance between the tranny and frame rail of an 86. Had to cut down a tap and use a wrench, slow work but got it.

Have not gone full throttle yet. I have to tap a tranny mount bolt. Could not do it there the car had to leave the shop that day.
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Spiders1
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Report this Post03-28-2016 09:59 PM Click Here to See the Profile for Spiders1Click Here to Email Spiders1Send a Private Message to Spiders1Edit/Delete MessageReply w/QuoteDirect Link to This Post
Got everything fixed up. My tuner friend came over and hooked up to it so we could check the knock sensor that was
going crazy last time it was on the dyno. It hit 3 degrees of knock this time so it's much better than before. Hopefully
it is just picking up some b.s. noise and taking the timing.

It is pretty quick though haha 3 gear pull was very strong! Might get back on the dyno soon or may switch to E85 and see
what that does for it.
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