Cheese Weasel

Hey all, I'm trying to do an LS + T56 swap into a 3rd-generation F-body. I have the engine bolted in to the engine compartment, but when I try to bolt the transmission to the bellhousing, the trans seems to "hang up" about 9/16" away from where the trans mounting surface would be flush with the bellhousing.

Add'l. data:

I have had this engine & transmission bolted together before, but I've had the engine rebuilt since then.

The parts being used are:

• Aluminum LS3 block;
• Stock GM crankshaft;
• Solid bronze bushing (not a roller bearing);
• Centerforce flywheel;
• Spec Stage 3 clutch disk;
• QuickTime SFI-approved bellhousing;

The two things that have changed (in the list above) are the clutch disk, & also the crankshaft when the engine was rebuilt - BUT, as noted above, it's a stock-replacement crankshaft, so it should be exactly the same as what came out.

Come to think of it, the bronze bushing is new as well, although IIRC, we test-fit it on the transmission input shaft, & it seemed to be OK...

It may also be worth noting that it appears that the splines are engaged, since when we put the T56 into 3rd gear & turn the engine over with a breaker bar, you can see the transmission output shaft rotating in sync.

My buddy that's been helping to throw it together thinks that the clutch disk may have slipped out of alignment, but I'm not convinced of that. Seems to me that if that were the case, the splines wouldn't be engaged - but hell, it wouldn't be the first time I was wrong...

We've spent a fair bit of time & effort trying to wiggle and/or rotate it into the correct alignment, but no luck.

I figured I'd post up here to see if anyone could offer any other suggestions. Thanks guys.

Toddoky

Did you use a clutch alignment tool to attach the clutch to the flywheel?

Cheese Weasel

Yes sir, sure did.

S10xGN

iTrader: (11)

9/16"... Sounds about like the engagement depth of the pilot into the bearing (or bushing in your case). It may be as simple as needing a small chamfer on that bushing, or maybe the wrong ID bushing got installed?

Cheese Weasel

Yeah, that's exactly what I was thinking... I wasn't sure if the splines would engage if the input shaft hadn't even made it into the bushing yet, but maybe I already have the answer to that question...

Yeah, that could work, although I'll have to look at the tools that I have available to me, to see how I might be able to do that... I actually have a spare bronze bushing, so I'll check the ID of that sucker tomorrow.

I'd thought that we'd slipped the bronze bushing over the end of the trans input shaft before slipping it into the back of the crank, but I'm not completely sure of that. If worse comes to worst, I guess it's not that much work to pull everything off the back of the engine & just confirm that it fits like it should...

Thanks for the replies guys, they're much appreciated.

Centerforce

We would recommend checking that you have the proper pilot, as mentioned above. The LS bearing mixup is something that happens quite often.

The second thing that could be happening is the clutch disk is slightly mis-aligned, causing the input shaft to move off center and not slip into the pilot hole. Some times this takes a few tries of repositioning the PP/disk before it slips in completely. Keep us posted with what you find!

Cheese Weasel

Hey guys, I really appreciate the replies.

About 1.5 weeks ago, my buddy came over again, & we wrestled with it some more. SAME FREAKIN' STORY! We got it to within 1/2" or so, & it just didn't want to go any closer together. We even went so far as to drop the K-member about 1/2" or so to try to get a better "angle of attack" on it!! That didn't resolve the issue, so I said *SCREW IT!* & yanked the engine back out of the car, so that we could use whatever angle we wanted to...

After both of us pushing on it, we got it to within about 7/16" or so - but I got nervous that if it needed that much effort, then something wasn't right, so I went to pull the engine & transmission apart again. Interesting data point - Having gotten the two pieces that close together, I had to use a prybar to separate them again. Hmmmmmm...

Last night, I was able to get my next-door neighbor to help me out. He's done quite a few clutch swaps, & with his help, we were able to work the engine & transmission into alignment, & actually got them bolted together! What was the secret?? Well, the first thing that he suggested was to remove the QT bellhousing from the back of the engine, & bolt it to the transmission. THEN, after measuring the length of the input shaft, & a couple other things, we just kept (slowly!) working the two units together. Once we got the top-center portion of the bellhousing within 1/2" or so, we slapped a bolt in there so that we didn't lose any of the depth that we'd gained, & just kept working the two sections together - sometimes smacking the bellhousing with a rubber mallet to "coax the process along".

Now that the two sections are together, I wouldn't be completely surprised if it took a bit of "break-in" to get everything to play nicely together. During the assembly process, it felt as though the tolerances between the transmission input shaft & the clutch disk were just a few thousandths of an inch too tight - my thought was that the clutch disk (a Spec Stage III) might have had a coating that was applied slightly too generously (but in all honesty, that's a *total* "wild-a$$-guess" on my part).

Regardless, I'm really glad to have the engine & transmission bolted together. NOW, once I get them dropped back into the car, I can install the headers, finish the exhaust & fuel system, I should be able to complete the wiring harness, order the new driveshaft, & probably a couple of other things that I'm not remembering at the moment...

<sniffs the air> Ahhhh... I love the smell of progress in the morning...