1973 40 Series: Intro Phots and Clutch Disengagement Question (2 Viewers)

[FastFleet]

Afternoon gents,

Long time lurker first time poster. Back in Jan 2023 I bought this 1973. The PO had done a (semi botched) 1978 SBC 305 swap. I have since proceeded to replace or rebuild every component on it, to include:
-POR-15 coated frame
-Skyjacker Suspension (3 inch lift)
-Rebuilt front axle with 60 Series Birfields/knuckles/disc brakes
-Rebuilt 3 speed transmission
-New master/slave cylinder
-AA slave bracket/transmission mount
-New GM Flywheel/clutch/pressure plate
-Various new body panels
-Stainless brake lines/brake master
-Seats
-Various new engine components (carb, fuel pump, plugs ect)

The goal here (for now) is a fun vehicle I can drive to the hardware store/around town/occasionally to work if I get it that reliable. I just got the transmission back in and have the engine running/idling reliably. I am very close to that glorious first drive (I think).

The issue that I'm hoping the collective knowledge of the forum may be able to help me solve is this:

I am able to start the vehicle in neutral but can't shift into gear. I am aware of all the issues with Toyota hydraulics trying to disengage Chevy clutches (I think I've read 20 or more threads on that). I'm fairly confident I have enough slave travel as I can see a 1/8 inch gap between the clutch material and the flywheel. I have gone as far as to use a clamp to pull the clutch arm as far back as possible to guarantee that its not a lack of slave travel. I bench tested the transmission before re-install and everything seems to be working perfectly on that front. I am at a loss as to why the clutch does not seem to be disengaging when the vehicle is running.

The only possibility I can imagine is that I installed the clutch backwards. I am 90% certain I installed it correctly, as shown in the photos, but its schroedinger's cat at this point. Also, IF that were the case, I don't think the clutch would sit flush against the flywheel like it is now, as the springs would bottom out on the flywheel bolts.

Do any of you fine folks have any ideas as to what I could be looking at here? Thanks!

 

[FastFleet]

A few more photos for your viewing pleasure. The one with the flag on the wall is from today.

 

[65swb45]

What did you use for a pilot bearing/bushing? Did you clearance check it with the tip of the transmission input shaft before installing it?

Point being, if the input shaft of the trans is pinched, it will keep the transmission spinning with the engine even when the clutch disc is free.

 

[FastFleet]

What did you use for a pilot bearing/bushing? Did you clearance check it with the tip of the transmission input shaft before installing it?

Point being, if the input shaft of the trans is pinched, it will keep the transmission spinning with the engine even when the clutch disc is free.

Ah, that's something I had not heard of or considered!

I opted to not replace the pilot bearing as there was minimal play with my existing one when I tried it with the shaft out during the tranny rebuild. I did not clearance check it either. For some reason I'm thinking with these swaps, the input shafts on the Toyota transmission wind up being on the shorter side, hence the need for longer pilot bearings (I think?).

Thanks for this though, I'm guessing I will be pulling that back out.

 

[FastFleet]

Is there anything else I should consider/examine while I'm at it?

 

[Tancruiser]

What bellhousing are you using?

 

[FastFleet]

The stock one it had when I bought it. PN: 3925505.

 

[pb4ugo]

I agree with @65swb45, if the input is still spinning when the clutch is disengaged and the disc is free, then it's likely the pilot bushing. Have someone watch the disc when the clutch pedal is depressed. It appears your missing an alignment dowel on the pass side of the block. I've dealt with a miss aligned input b4, with a sbc and a poorly aligned and drilled steel scattershield and had the same symptoms. That's an old gm bellhousing and conversion. The conversion is probably a hodge podge of various parts. Since you have it down to the frame you might also consider moving things around for better fitment. Or consider a better set up. Typically you don't need to hack the firewall for a sbc. What's the frt motor mounts look like? How close are the valve covers to the firewall?

 

[FastFleet]

It does seem to be a botched conversion. The front mounts are nasty stick welded. I had the truck down to the frame, its mostly reassembled now.

Valves are ~.75" from the firewall at worst case. This would explain why it was so difficult to shove the transmission back in I guess.

Thanks so much for the feedback.

 

[65swb45]

I think @Tancruiser asked a good question too. That bellhousing requires a spacer plate between it and the transmission. There is no spacer plate in your pics.

 

[73FJ40]

Looks like another example of "red is the new black" for ground cables:

 

[pb4ugo]

Those motor mounts are worthy of the "Wall of Shame" thread.

That' could be it. The input is binding against the crank.

 

[FastFleet]

Yes Sir, looking into that spacer now.

Yes, I debated not showing you guys those mounts but you've been super helpful and I didn't make em so I'm not that ashamed. I pulled this DEEP out of a holler in eastern Kentucky.

Yes, a lot of stuff here is me making do with what I have right now. Ideally I'd do everything right the first time here, but then this build would take me 4 years and more money than I have right now. I'll have to rework a lot of things down the road, but one step at a time.

Just trying to get this thing to be able to haul my trash can up my 1000 ft driveway for starters .

 

[FastFleet]

Update: Dropped the transmission in an hour (getting good at this now) to check the input shaft spacing. I could see where it bottomed out on the crankshaft so the spacer is definitely needed. Also found that the SBC crankshaft is not machined for a pilot bushing, it just has the same ID that a bushing would. First time I've seen that on an SBC.

Parts will be here Thursday, I'll keep y'all updated.

 

[pb4ugo]

Update: Dropped the transmission in an hour (getting good at this now) to check the input shaft spacing. I could see where it bottomed out on the crankshaft so the spacer is definitely needed. Also found that the SBC crankshaft is not machined for a pilot bushing, it just has the same ID that a bushing would. First time I've seen that on an SBC.

Parts will be here Thursday, I'll keep y'all updated.

Id like to see a pic. The only 2 things I know about 305's are the #'s are in the wrong order and the heads suck when the PO's mechanic put them on the 350 in my 40.

 

[FastFleet]

Id like to see a pic. The only 2 things I know about 305's are the #'s are in the wrong order and the heads suck when the PO's mechanic put them on the 350 in my 40.

It's hard to tell, even in person, but that is all crankshaft, no bushing. I had spent the better part of a day trying to remove what I thought was a bushing using all the usual tricks. When I finally resorted to using a sawzall blade by hand, it dawned on me that maybe not all SBCs are machined for them.

Best I can tell, some Autos out of Buicks came this way. But I've yet to see another image on the Internet that matches my setup.

So I've jacked up my crankshaft there a little as you can see, but I plan to part ways with this engine pretty soon.

 

[pb4ugo]

That hole looks pretty big for the end of the input shaft. I guessing they removed the bush because they didn't use a spacer and the input needed to go in deeper, or the engine's from an auto trans and they never installed one. The input shaft needs to be supported by the pilot, without it, it could be contributing to your problem.

 

[FastFleet]

That hole looks pretty big for the end of the input shaft. I guessing they removed the bush because they didn't use a spacer and the input needed to go in deeper, or the engine's from an auto trans and they never installed one. The input shaft needs to be supported by the pilot, without it, it could be contributing to your problem.

The spacer block did the trick! This is the first time this thing has moved under it's own power...likely since the 90s when the PO attempted the swap.

Thanks for the advice, I would have been stuck for who knows how long.

 

[pb4ugo]

I'm curious, Did you add a pilot bushing?

 

[FastFleet]

I'm curious, Did you add a pilot bushing?

Sorry forgot nyo explain that more.

No, that hole looks big, but it's the same ID as the pilot bushing I had. Literally impossible to put one in. The plan is to swap out the crankshaft (or engine) pretty soon. I'm risking some wear on the input shaft perhaps though. Works fine at the moment and I didn't get any awful sounds coming from that area. Wouldn't recommend using this setup if you have the option though lol.