Equipping a G-Body with a manual trans

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Doober

Royal Smart Person
Apr 8, 2007
1,253
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Swartz Creek, MI/Tucson, AZ
I'll probably update this more as I attempt to consolidate the info from various posts I've made. I'll start with mechanical linkage for a traditional Saginaw/T-10/Muncie. Some of this info I got from t5montecarlo's site (http://www.garage-scene.com/t5-into-ag-body/) so I give kudos to him of course :D
Until recently nobody made a reproduction G-Body clutch fork. StreetBu on MalibuRacing.com (he may be here too) first made the post about it. It appears there were two different designs, one in '78, and I believe it changed for '79-'80. You can get it from The Parts Place. They also make a reproduction shifter hump, where coupled with the reproduction plastic cover, trim ring, and shifter boot, you can finally add the original 3- or 4-speed look to a G-Body.
1978-G-Bodyclutchfork.jpg

q3.jpg


Clutch fork (Part #MT10680Z)
Be4bIkQBWkKGrHqMH-C0ErfzVgjSNBKFKcf.jpg

Be4bKdB2kKGrHqMH-CcErfFMM1t5BKFKhZu.jpg


Manual trans hump (Part #MT6672Z)
steelfloorshifthump.jpg


They also have a somewhat complete kit to convert over to a factory-style setup, but doesn't include the hump/trim/boot. It costs $289, I've seen other kits upwards of $475 :shock:
PN MT9895Z
Kit includes:
*Brake & clutch pedals
*Z-bar
*Z-Bar bracket
*Pedal pushrod
*Clutch fork boot
*Clutch fork
*Clutch fork pushrod
*Clutch fork ball
*Clutch return spring(s)
*Hardware kit (Engine ball stud, frame side ball stud, 1 spring clip, 1 felt washer, 2 nylon bushings, 1 lock washer, 1 nut)
clutchkitmt9895z.jpg

A couple pieces this kit is missing are the clutch safety switch (not required but helpful in keeping the car from starting in gear and keeping it in factory-correct working order), and I believe there is a rubber stop for the pedal to prevent excessive pedal travel. There is also a clutch rod firewall boot that is missing.

For the trim plastic, trim ring, shifter boot, clutch pedal boot, and clutch safety switch, they (sans clutch switch) can likely be sourced from a couple different places, but for ease of this post I used Dixie Monte Carlo's site.
Trim plastic, pn DM90802


Trim ring, pn DM90809


Shifter boot, pn DM90801


Clutch pedal boot, pn 90811


Clutch safety switch... couldn't find much more info on replacing one besides the GM part number, which appears to be of either 344889, 303651, or 469085. It appears one from an older model may work (found at The El Camino Store), but it doesn't have the shaft/clip like the one from a G-Body has, so you may be able to use a shoulder bolt with a nyloc nut.
Original part
1978-1981_nss.jpg

replacement_nsw.jpg


Part #06-0077


For those who already have the factory linkage, but their setup is getting slop in it, or just want an upgrade, Speed Direct has a tubular linkage setup (clutch rod, pedal to z-bar rod) with spherical ends on it that take out the slop that the original setup has.
 

Doober

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Apr 8, 2007
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Swartz Creek, MI/Tucson, AZ
Bellhousing/fork/flywheel info

Most of the G-Body bellhousings won't take a 168-tooth manual trans flywheel, so you need to use a 153-tooth. Be sure to know the year of your engine when/if you need to buy one, one-piece rms blocks started in '86, 2-piece engines are pre-'86.
Pre-'86 blocks use this flywheel


'86 and later engines use this flywheel


The curve of the fork is required because of the floorboard, and the geometry of the linkage. If you drew a line to the crank centerline from where the clutch pushrod meets the fork, you'll see it's not simply horizontal like you would see with all the straight forks, and this is why the G-Body bellhousing won't work with a standard clutch fork. You could use a straight clutch fork with a couple different bellhousings though.
'82 F-Body (casting #14037657, fork #140376472)
140376571982F-Body-fork140376472.jpg


'84-'88 Corvette (casting #14048867, fork #140662352)
1404886784-88Corvette-fork140662352.jpg


Lakewood 15015 bellhousing (PN 15015, fork PN 15500) - this will also fit a T-5 trans, as you can see the canted bolt pattern.
Lakewood15015-forkLakewood15500GM34.jpg


I believe most of the linkage compatibility comes into play with where the ballstud is on the block.
DSC01979.jpg


If the #7 tube doesn't come down almost vertically, it will be in the way of the z-bar.
DSC01631.jpg
 

Doober

Royal Smart Person
Thread starter
Apr 8, 2007
1,253
38
Swartz Creek, MI/Tucson, AZ
Saginaw/T-10/Muncie info

All 3 transmissions will bolt up to the same bellhousing, and (I'm 90% sure) have the same transmission mount location. I don't know the specifics on all the output shaft specs, but they will have either a 27-spline shaft (same as TH350), or 32-spline (same as TH400).

Trans case/input shaft i.d. (number of rings around the shaft) & ratio info:
Code:
Saginaw 4 Speed:
All cast iron, No separator plate between front case and tail housing. All shift levers (3) in the side cover.
7 bolt side cover. Lowest rotational weight.

No lines on the input shaft  1st-2.84   2nd-2.01  3rd-1.35  4th-1.00
1 line on the input shaft    1st-2.54   2nd-1.80  3rd-1.44  4th-1.00
2 lines on the input shaft   1st-3.11   2nd-2.20  3rd-1.47  4th-1.00
3 lines on the input shaft   1st-3.50   2nd-2.47  3rd-1.65  4th-1.00


Saginaw 3 Speed:
All cast iron, No separator plate between front case and tail housing. 7 bolt side cover. Lowest rotational weight.

No lines on the input shaft  1st-2.85   2nd-1.68  3rd-1.00
1 line on the input shaft    1st-2.51   2nd-1.50  3rd-1.00
2 lines on the input shaft   1st-3.11   2nd-1.84  3rd-1.00
3 lines on the input shaft   1st-3.50   2nd-1.89  3rd-1.00

Muncie 4 Speed:
All aluminum, 7 bolt side cover.
Casting numbers may end  with 336, 010, 660, or 661

No lines on the input shaft- Early Wide Ratio   1st-2.56  2nd-1.91  3rd-1.48 4th-1.00
OR M-22 with same ratios as below
1 line on the input shaft-Close Ratio           1st-2.20  2nd-1.64  3rd-128  4th-1.00
2 lines on the input shaft-Late Wide Ratio      1st-2.54  2nd-1.88  3rd-1.46 4th-1.00

Second Design Borg-Warner Super T-10:
9 Bolt side cover. May be all aluminum, all cast iron, or half and half
2 lines on the input shaft  1st-2.43   2nd-1.61  3rd-1.23 4th-1.00
3 lines on the input shaft  1st-2.64   2nd-1.75  3rd-1.33 4th-1.00
5 lines on the input shaft  1st-3.42   2nd-2.28  3rd-1.46 4th-1.00
6 lines on the input shaft  1st-2.88   2nd-1.91  3rd-1.33 4th-1.00

Hurst shifter application info for G-Bodies:
Code:
Shifter with appropriate stick:  391 8794
Shifter installation kit:        373 0017
Shifter body:                    391 5401
Stick only:                      538 8009

The '74-'81 F-Body with a T10 (w/o console) uses the exact same shifter body and stick, but uses installation kit 373 8609 (if you're swapping a BW T10 in).

The '70-'72 (no '73 listed...???) F-Body with a Muncie (w/o console) uses shifter 391 6848, same body but uses stick 538 6836 (538 8009 can likely be used since it's the same body), and installation kit 373 7897.

I figured an F-Body would be the closest to a G-Body since the overall body is a similar size.

Hurst2004-42.jpg

Hurst2004-43.jpg

Hurst2004-46.jpg

Hurst2004-47.jpg

Hurst2004-48.jpg

Hurst2004-49.jpg

Hurst2004-50.jpg
 
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Doober

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Thread starter
Apr 8, 2007
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Swartz Creek, MI/Tucson, AZ
T-56 info

This post may be a bit dated currently, I wrote it a little over 2 years ago.
Basic T-56 info
TREMEC'S OFFICIAL PAGE FOR THE T-56

A basic rundown of what's available as far as GM T-56 transmissions (thanks Chree):
  • GM LT1 T56 ('93-'97 F-Body): Works with Gen 1 SBC, you use the LT1 bellhousing and F-Body hydraulics with John Bzdel's pedal.
  • Aftermarket T56: has an adapter plate to mount the T56 to a traditional SBC bellhousing.
  • GM LS1 T56 ('98+ F-Body, GTO, etc.): can be mated to SBC with the McLeod modular bellhousing. LINK


Linkage
There are a few ways to install a T-56 into a G-Body, depending on what transmission you use and/or what linkage you use.
Starting with the linkage:
  • First, there's the factory F-Body linkage, which utilizes hydraulic master and slave cylinders. You can most likely pick these up at a local salvage yard, or purchase them new from an auto parts store (much cheaper at a salvage yard, also more chance of premature failure). There are also two types of available slave cylinders.
    One mounts on the F-Body bellhousing:
    amss0417003.jpg

    And the other actually slips over the input shaft, the cylinder itself pushes on the thowout bearing:
    amss0418003.jpg

    Weir Hot Rod Products also sells a new bellhousing to use with the F-Body (OEM) T-56, it includes a self-adjusting hydraulic throwout bearing, steel block plate (clutch cover), pressure and bleeding tubes (mounted on slave/t.o. bearing), and new bellhousing and transmission bolts. They also recommend a master cylinder from either McLeod or Wilwood for proper operation. This would be a good upgrade if you came across a screamin' deal on an OEM T-56 without a bellhousing, the kit also allows you to use a standard starter, where (I believe) the starter required the factory bellhousing is F-Body-specific.
  • Next is the factory style G-Body linkage, which you can now find numerous places, including eBay and various aftermarket suppliers (Mike's Montes, El Camino Parts, Honest Charley to name a few). Also keep in mind if you are switching from an automatic to a manual that you will need to relocate/remove the vacuum/wiring that runs through the firewall for cruise control, as it uses the same hole. Here is an exploded view of the entire pedal/linkage assembly:
    78-87%20%20clutch_1.jpg

    EXCELLENT LINKhttp://imageevent.com/publicgallery/carsandtransportation/agbodybellhousings000http://imageevent.com/publicgallery/carsandtransportation/agbodybellhousings000 regarding factory linkage and bellhousings, covers both 153 tooth and 168 tooth flywheels.

    If you use the factory linkage, some things also need to be considered. An aftermarket T-56 can be used with the factory bellhousing/linkage as it has a standard Muncie/Saginaw/Borg Warner bolt pattern, but if you choose to use a Camaro/Firebird-specific transmission an adapter plate is required. There are two that I've seen so far, one is from THE GEAR BOX (Garden City, MI). Their adapter plate allows the use of an LT-1 T-56 on either a standard (Muncie/Saginaw/B.W.) bolt pattern or the slightly rotated (17º to the right) T-5 pattern, which was in the 3rd generation F-Body. It allows the use of an LS-powered F-Body or Viper T-56 to be used.

    An extended pilot bearing is also required here.


    The other adapter plate is from FORTE'S PARTS CONNECTION (Framingham, MA) and allows the use of your factory (Muncie/Saginaw/B.W., NOT T-5) bellhousing with the T-56 from an LS-1 equipped car.

    The Gear Box's home page
    Forte's home page

Driveshaft
I haven't really found more than a couple sources for driveshaft length, so you might be best to measure it yourself to double check. I found a measurement for both a G-Body with 7.5" rearend, and an 8.5":

Crossmember
Aftermarket crossmembers are available to retrofit a T-56 into a G-Body, one of the most well known companies is Crossmembers.com. The part number for their crossmember is RCT56, and it allows you to run the exhaust on both sides of the transmission, unlike the factory crossmember which only has provision on the passenger's side. The site also states that for a '78-'83 car will need PN FE100 (driver's side extension, adds 2 mounting holes), and that '84-'88 cars don't need this extra part. I could be wrong, but I believe I've read of people just drilling through the frame where needed on the driver's side. I've also read of 'Iceman' having a T-56 crossmember (his parts can be found via the main page of this site), but from the list I've seen on the main page only showed one lightweight crossmember (he also sells the extension listed previously for the driver's side).
 
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FE3X CLONE

Comic Book Super Hero
Dec 2, 2009
2,714
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McLeod makes a modular blowproof bellhousing now to fit the T-56 behind most engines. The one I have on my 455 has the bellhousing bolt pattern that covers the BOP engines as well as the Chevy's.

I've had the Weir aluminum housing and personally, if your pushing any kind of power, I wouldn't trust it.
 
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anakputa

Master Mechanic
Nov 27, 2009
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If you headers sometime the mechanical linkage doesn't fit BTDT. I have Dynomax Headers and the Dual Exhaust kit from jegs on my 350 Chevy engine and theres no way the mechanical linkage work. I even had to cut off where the hydraulic slave cylinder is located on the F Body bellhousing. I am using a Howe Hydraulic Throwout bearing and Raybestos Clutch Master Cylinder. Jegster Double Hump crossmember. I had a 700R4 in it before but then it started slipping..looking back I shoulda re-built it..
 

Doober

Royal Smart Person
Thread starter
Apr 8, 2007
1,253
38
Swartz Creek, MI/Tucson, AZ
True, some headers won't fit. That's one of the downfalls to using mechanical linkage. I may have to go with a different set out here in AZ if they have to be emissions-legal, and if that's the case I have a lot of pondering to do.
 

Phoenyx

Royal Smart Person
Jun 27, 2007
2,393
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Alberta, Canada
Good info. I really like that someone makes a reproduction shifter hump.

I did a 4-speed swap on an 80 GP a few years ago. had a Pontiac 301/TH350 in it. Used a bell housing from a 70s TA. M-22 with a Hurst Super Street Shifter (I had a bench and it fit perfect). The original drive shaft worked fine. My pedals and clutch linkage came from a 70's Nova.

I had put dual exhaust on the car when it was an auto. Off the manifolds, both pipe down the passenger side until the cross member (kept the original one). Everything still fit fine after the 4-speed swap.

The only issue I had was that the shifter linkage was rubbing on the transmission tunnel. So I had to pound it a bit with a hammer.

I plan to do a 4-speed car next. Your info will be very helpfull.
 

joey_schel

Apprentice
Feb 11, 2009
89
0
Stratford, Ontario
Lotsa good info here guys! just a couple things i learned when doing my t-56 swap:

- LT1 t56 has a different "pull-type" clutch, this requires a special flywheel if used on an internally balanced chev.. (centerforce makes a good one)>

DSCN6961.jpg


- For an LT1 t-56 w/ stock bellhousing, the driveshaft needs to be shortened by exactly 3 inches (if original trans was a 200-r4)

- 153 tooth starter (LT1 or aftermarket) is needed for the flywheel/clutch *ss'ly

- There is kind of a "boss" where the master cylinder can be mounted, but its where the cruise control comes into the cabin, here: http://www.motortopia.com/album/view/p/ ... /po/5/pl/1

- Can't think of much else right now, here's some pics from my swap, enjoy

DSCN6962.jpg


DSCN7055.jpg


DSCN7061.jpg


DSCN7088.jpg


DSCN7090.jpg


DSCN7086.jpg


DSCN7085.jpg


DSCN7094.jpg


DSCN7096.jpg


DSCN7164.jpg


Then celebrate with a nice burnout:

DSC00692.jpg
 
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