Author Topic: 1978 T/A auto to manual conversion w/ Day 2 mods. Marty's transformation.  (Read 3587 times)

0 Members and 1 Guest are viewing this topic.

Offline TAKID455

  • Sr. Member
  • ***
  • Posts: 1179
  • Referrals: 0
Haven’t posted a project in a bit so here an interesting one t hat will also answer many questions other many have regarding auto to manual swaps, transmission selection, exhaust modifications, carb and distributor tuning.
Had the opportunity to transform a car’s personality from nice leisure cruiser to gear banging spirited driver. This T/A has some prior internet fame going by the name ‘Marty’ primarily the abbreviated of the Martinique Blue color name.  Intent was to ‘wake up’ the car and swap the transmission from the stock TH350 to a Richmond/ Doug Nash 5 speed all while retaining a stock appearance.  The changes could also be considered ‘Day 2’ mods  such as Mecham Pontiac of DKM/ Macho T/A fame would perform on new T/A’s back in the day.
Subject:
1978 T/A
WS6, 400 L78, auto, 2.56 rear, 31k miles. Very clean and well preserved car.






For the Factory markings people



Factory service dept ‘test pipe’. This was installed to test if the catalytic converter was faulty. Some were installed to test and were ‘forgotten’ to be removed.



Even with careful scraping, colors of stripes are undistinguishable.
36 year old underside. Oil pan should be painted. This pan was removed in its prior history for reasons unknown.




With the Th350 & exhaust  removed, one can see additional factory markings


Some stuff that fell out of the car.  All but the driveshaft will be shelved safely for originality purposes and not discarded. D-shaft will be reused.



New ceramic coated 2.5” RARE manifolds

All parts required for a complete auto to manual swap for St-10 4 speed or DN 5 speed. TKO’s and T56s will have some different parts but interior parts will be the same.  Pictured is the Richmond 5speed or commonly referenced as Doug Nash 4+1.




Since we were there and it was leaking, the oil pan gasket was replaced w/ a 1 piece gasket. Pan and engine was touched up w/ GM corporate blue but saving original color markings.  Inside a 31k mile engine

Conversion begins to take place




Manifolds and clutch linkage

New look




Better breathing. 2.5” all the way.

Tips in factory position as car was received.


Console before

After

Peak a boo

Installed w/ all factory or factory repop 4 speed parts



Carb rejected for richer mixture both primaries and secondaries and distributor recurved so all 36 deg of timing advance comes in by 2800 rpm.
Overall the job was a success. Car has changed personalities for the better and is much livelier and has decent pick up.  Even with the 2.56 rear end gears thanks to the transmission’s deep 3.27 first gear. Fifth is still 1:1 so the high gear in the back is needed. Most run 2.73 or 3.08 for road courses but this application was perfectly fine with the OE set.
2nd Gen Engineering
Specializing in Suspension and Driveline Performance Engineering
Custom/ Racing/ Restorations

Offline Squirrel

  • Ohio Firebirds
  • Sr. Member
  • ***
  • Posts: 1049
  • Dan
  • Referrals: 0
amazing, very nice.
1978 Chesterfield Brown TA
1977 Camaro 4 speed with t tops
1977 Mustang Cobra II

Offline 78T/AKID

  • Member
  • **
  • Posts: 309
  • W72, 4SPD, WS6 49K
  • Referrals: 0
I cant believed you butch that nice original 78 Martinique trans am and chance the trans !!!!! :o :o :o :o   Rain man is probably on the floor crying

Offline gilbertsta

  • Sr. Member
  • ***
  • Posts: 1125
  • "Live Like You Are Dying"
  • Referrals: 0
Wow! Great job! Your description and pics made the transformation look easy, but I am sure you put some time into this job... I bet rainman wants his old car back more than ever now...


~Trans ams rule....others drool~

Offline TAKID455

  • Sr. Member
  • ***
  • Posts: 1179
  • Referrals: 0
It wasnt too bad of a swap. Some hurdles here and there but nothing major.

Rainman would have wanted this too as he had been discussing the trans swap years ago along with  the exhaust.  Current owner agreed. Car drove like mush w/ the auto and now it much more livelier.  Put about 400 miles on it since the swap was done.  Great thing about this is it can be easily converted back to 'original'. 




2nd Gen Engineering
Specializing in Suspension and Driveline Performance Engineering
Custom/ Racing/ Restorations

Offline Dogma

  • Member
  • **
  • Posts: 255
  • Referrals: 0
I love it and really looking into doing mine the same way. Do you mind me asking what you have wrapped up in that package?

Offline TAKID455

  • Sr. Member
  • ***
  • Posts: 1179
  • Referrals: 0
 Cost depends highly on trans cost a DN5 will run 900-1500+ w/ shifter used.  Be sure to get the shifter as it will set you back about 5-600 for  a new one. ST-10 4 speeds are around 600 used. I would go with all new parts unless you score some used ones for dirt. New parts dont cost that much more than what typically used ones bring. Console is anther issue as the repops are 'EH' and clean used ones are hard to come by.  This particular car has just over 2k in parts for the swap.  Labor is around 40 hrs but that included some other tasks additional of the swap.
2nd Gen Engineering
Specializing in Suspension and Driveline Performance Engineering
Custom/ Racing/ Restorations

Offline FF273

  • Jr. Member
  • *
  • Posts: 43
  • Gone in 160 seconds....
  • Referrals: 0
Tight work I wanna do the same thing.