Announcement

Collapse
No announcement yet.

LT-1 rotating assembly

Collapse
X
Collapse
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous Next
  • #1

    LT-1 rotating assembly

    so, after having replaced every clutch related component in my 95 TA this spring trying to fix an apparent scratching problem (posted earlier) without success, i took it to the shop this past week.
    I havent driven it all summer since the guys at the tranny shop were stumped by the problem i gave up. They suggested it might be a bad crank etc. but failed to check it out. I told the shop this before i brought it in on friday. I received a call today that the motor locked up while they were test running it.
    Bottom line, i need help finding a rotating assembly/short block or whatever would be the best bang for the buck to fix this. I would get a crate motor but the top end has less than 8k miles on it with a new cam lifters and springs(comp cams 264/269)

    Can anyone suggest a good rotating assembly forged, preferrably, that wont break the bank?
    '95 Trans Am 6spd- broke
    '77 dodge custom 150 2wd tire destroyer- 440ci w/edelbrock intake, thorley headers, 2000 stall, ported heads and surface rust
    2005 Kawasaki z1000 - getting too cold for that though
    Tags: None
  • #2
    I'm sorry I don't know which the best forged rotating assembly is but could you do me a favor and try to get some pictures of the crank, main bearings, and rod bearings if you get the chance?
    1994 Firebird Formula, M6, Fan switch, 160 thermostat, Pacesetter LT headers, Morosso CAI, TB bypass, True duals.

    Comment

    • #3
      I went back and read some of your older posts regarding this problem.

      When installing the transmission, does it slide in easily by hand or do you have to use the bolts to pull it in hard?

      The reason I ask is because it is possible the transmission and engine block are not lining up exactly. You might need to use special offset dowel pins to correct the problem and get it lined up strait.

      Many facts you have posted support this theory:
      1) the input shaft bearing on the trans was shot
      2) the old pilot bearing was rounded out inside. This could be caused by overload of the bearing, due to misallignment of the input shaft.
      3) with new bearings it now shakes and shudders forward even with the clutch disengaged. (this could be due to the stress and friction of the input shaft and the pilot bearing lined up improperly)
      4) your motor now seaized up - this could be due to rear main bearing failure caused by stress from the input shaft of the transmission not being lined up correctly, similar to the failure of the bearing on the input shaft.

      I fear that you might find the rear main has failed and spend money fixing it to end up with the same problem over again. Take a little time and look at the allignment between the block and the trans, just to be safe before you start that fresh motor.
      Tracy
      2002 C5 M6 Convertible
      1994 Z28 M6 Convertible
      Current Mods:
      SLP Ultra-Z functional ramair, SS Spoiler, STB, SFCs, Headers, Clutch, Bilstein Shocks, and TB Airfoil. 17x9 SS rims with Goodyear tires, 160F T-Stat, MSD Blaster Coil, Taylor wires, Hurst billet shifter, Borla catback with QTP e-cutout, Tuned PCM, 1LE Swaybars, 1LE driveshaft, ES bushings, White gauges, C5 front brakes, !CAGS, Bose/Soundstream audio, CST leather interior, synthetic fluids

      Comment

      • #4
        sdpc 2000 makes good motors ( its a gm motor you'll get) chad over at GOLEN ENGIN makes a pretty mean block
        1994 Z28 stage 2 intercooled procharger, P-1sc, 6lb pully,42lbfuel injectors,255intank pump,1 3/4headers,highflow cat, borla ajust. cat back,chrome moly LCA,chrome moly ajust. panhard bar, Kenny Brownweld-in subframe conectors, built trans. kevlar lined 2600 stall, kevlar clutches, hardend parts,,built rearend; moser axles, eaton posi, richmond 3.42 gears, rare ROH ZR6 17* 9.5 wheels, custom computer tune with laptop and LT1edit , 380rwhp 395rwtq , 60' 1.71, 1/8th 8.00,1/412.60@109mph

        Comment

        • #5
          Update:
          The shop called me to tell me there was a problem. I had suspected bottom end problems, and they were confirmed.
          They took the car for a short test drive. It made it about 1/2 mile and the engine died and code 42 came up (ESC), indicating timing chain failure we are assuming. Upon return to the shop, found the motor will not turn.
          So it looks like its pretty safe to say ill need a new bottom end and possibky even top end (which sucks because i just had the top end rebuilt last year).
          I have a few options. Maybe you can give me some help.
          I am looking at 25 hours labor to swap a long block, plus cost of rebuild or replacement.
          I can either try to salvage this motor and see if the valvetrain is damaged, buy a new motor ($$$$) or, i know a guy with a 47k mile lt1 from an impala SS i can get for a few hundred dollars.
          I dont have a lot of money to throw around and no other wheels seeing as how snow is about to fall and i cant ride my kawi.
          The motor now has a comp cams 07-501-8 which i like, and i really dont want to step down in performance to the ss motor.
          any ideas would be greatly appreciated. thx
          '95 Trans Am 6spd- broke
          '77 dodge custom 150 2wd tire destroyer- 440ci w/edelbrock intake, thorley headers, 2000 stall, ported heads and surface rust
          2005 Kawasaki z1000 - getting too cold for that though

          Comment

          • #6
            Did the valves make contact with the pistons? Any broken locks/retainers? Did you tie up a rod bearing? Is the block and oil pan OK?

            You should also inspect the crank and cam sprocket for any damage. IF the valves did not make any contact with the pistons, your valvetrain will be OK. But, obviously if they did, there could quite possibly be some damage to the valvetrain and/or pistons.

            IF the rotating assembly survived, the cylinder bores are OK, and it is just in need of a bearing and ring job then you aren't looking at anywhere near 20+ hours of time. If a rod broke or something else broke on the rotating assembly then you can just try to find the replacement culprit part and re-ring it and do a complete bearing job. Remember a complete bearing job includes polishing the crankshaft journals. This would be the "economical" route.

            If you have some extra dough and the crank and rods are OK, you could buy an inexpensive set of 4.0299 hypereutectic pistons, have a reputable machine shop bore your cylinders 0.030" over making them 4.030" and giving you a displacement of 355ci using the stock crank.

            Call www.strokerkits.com and discuss with them your issues. They have very good deals on LT1 parts and shortblocks.

            Comment

            • #7
              Originally posted by ColdBird
              Update:
              , i know a guy with a 47k mile lt1 from an impala SS i can get for a few hundred dollars.
              That would be the 260 HP version with iron heads, not the aluminum head f-body and Corvette version. You could swap heads though, using the Impala headgasket for an ever so slight bump in compression.

              Comment

              • #8
                well, i have not had the motor pulled yet so the extent of the damage is not known for sure. thanks for your advice and ill keep you updated
                '95 Trans Am 6spd- broke
                '77 dodge custom 150 2wd tire destroyer- 440ci w/edelbrock intake, thorley headers, 2000 stall, ported heads and surface rust
                2005 Kawasaki z1000 - getting too cold for that though

                Comment

                Previous Next
                Working...
                X