Trouble mating LQ4 to a 350 torque converter (yes I know about the spacer)
08-12-2016, 08:27 AM
#1
Staging Lane
Thread Starter
Trouble mating LQ4 to a 350 torque converter (yes I know about the spacer) Yesterday we got my 2004 LQ4 in my car finally, and went to hook it up to the turbo 350 bell housing. My engine came with a dished flexplate, so I used GM p/n 12563532 AFTER the flexplate to support the snout of the TC. However, when we put some bell-housing bolts in, it pulls the TC in contact with the flexplate and binds so that it doesn't spin at all. Before we put the engine in, we made sure that we had the TC all the way seated in the transmission. We have 2 different TCs and tried both of them - they both rub on the flexplate. After a couple hours of head scratching, I remembered that the crankshaft we are using didn't come from the engine originally. That crank had spun bearings, so we bought a used crank from our tuner. Now I'm thinking that it possibly is the different length crank and I either need a flat flywheel or some other solution. If anyone has experience with the spacer/dished flexplate not mating up like everyone says it should, I'd love to hear what you did. With all the research I've done I expected it to slide right up. Kind of a head-scratcher.
08-12-2016, 01:03 PM
#2
Restricted User
Is the hub on the converter actually sliding into the crank spacer, or is the heads of the bolts on the spacer hitting the converter?
I don't ever get the GM spacer. Too expensive, requires bolts as well. I always use the PRW spacer for $20 (sometimes less). Slide it onto the hub, falls right into the center of the dished flexplate once they are lined up. Hasn't failed me at 7000 RPM.
I don't ever get the GM spacer. Too expensive, requires bolts as well. I always use the PRW spacer for $20 (sometimes less). Slide it onto the hub, falls right into the center of the dished flexplate once they are lined up. Hasn't failed me at 7000 RPM.
08-12-2016, 01:08 PM
#4
Staging Lane
Thread Starter
Yeah, I think that's my problem now that I've spent all day doing research. The crank does hang out the back of the block significantly, so I'm going to track down a flat flex plate, ditch the spacer, and see if everything bolts up nicely. I'll need to be careful when slotting the TC bolt holes in the flexplate, since I won't be using the spacer to locate the snub of the TC. Other than that, I think I've got it figured out.
08-12-2016, 01:11 PM
#5
Restricted User
If you have a long crank and a flat flexplate, your converter hub should be centered inside of the flexplate opening, no spacer required, everything should be machined to the right size.
If its not, don't run it. You'll destroy your trans at high RPM if there is any wobble in the converter.
If its not, don't run it. You'll destroy your trans at high RPM if there is any wobble in the converter.
08-12-2016, 01:16 PM
#6
Staging Lane
Thread Starter
I thought I had read about the turbo 350 TC snout being slightly smaller than the gen iii/iv flexplate opening. But maybe that was just the dished flexplate. Once I get my hands on a flexplate I'll make sure everything is centered and supported.