Depth of threads for ratchet nut?

alexiskai

alexiskai

Well-known member
Does anyone know offhand how deep the threaded bore is on the crankshaft for the ratchet nut?

My ratchet nut is really beat up and I've removed it – I plan to replace it with a hex bolt & Grade 8 washer that will make it easier for me to turn the engine precisely during maintenance. I know the threads are 5/8"-18, I know the ratchet nut has 7/8" of threads on it, and I can tell the bore is at least 1.5" deep, but with the engine in the car I can't see how deep the threading goes. I want to order a bolt that engages as much of the threading as possible without being so long that I can't tighten the pulley down. Do the threads go the whole 1.5" bore?

Thanks in advance
 
You might go ahead and get a long (say 2") el cheapo Grade 5 cap screw at your local hardware store, thread it in and measure how much is left when it bottoms out. Figure the length of the Grade 8 from that before you order. Empirical engineeering.



JayJay
 
Based on the two crankshafts I have laying around the hole is not tapped all the way to the bottom. I was able to thread a ratchet nut all the way in so based on these two cranks you would be good at 1". Feeling into the hole with an awl I can feel the first thread at about 1 1/4" but can't tell you where the deepest full thread is. If you need to know exactly for your crank I agree with JayJay's suggestion.
 
JayJay said:
You might go ahead and get a long (say 2") el cheapo Grade 5 cap screw at your local hardware store, thread it in and measure how much is left when it bottoms out. Figure the length of the Grade 8 from that before you order. Empirical engineeering.

JayJay
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I would do that, but 5/8"-18 isn't a bolt type they carry around here. Also I thought somebody on here might know, save me the trip. :)
 
Russ/40 said:
Just measured two shafts. Threads go 1 1/4" in.
Click to expand...

Thanks folks, I've ordered a 1.25" bolt and a washer with thickness .16". Given that the pulley must be proud of the shaft by at least some tiny amount, I'm betting it won't bottom out. Appreciate the quick help.
 
Kurt in NJ said:
The pulley should be , but some reproductions are not to specifications
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It's my current pulley, which was being held tight by the ratchet nut up till now, so I assume it'll be OK with the hex bolt. This car had the 2-piece pulley when I got it, which has allowed me to remove the ratchet nut and the pulley without removing the engine. Plan is to sand, prime, and repaint the pulley, then put it back in with the new bolt/washer.

It's been very frustrating using the crank to turn the engine over up till now. Not only did the degraded ratchet nut not hold the crank very well, but my A has a flat steel piece welded on top of the front crossmember – I assume as a repair – that precludes installation of the crank guide.
 
I am using a ⅝-18X1" Grade 8 bolt to for my Murray balancer. Works fine. The Murray is a bit tight for the ratchet bolt.

Why don't you want to use a new ratchet bolt?
 
I have the same problem with a deformed ratchet nut so the hand crank slips. What was your nut wrench size? I ordered a 1 3/8" socket and it's too small. Fits the replacement ratchet nut perfectly though.

Is there such a thing as a 1 7/16" ratchet nut?

Can't get my calipers in there to take an accurate measurement.
 
Mister Moose said:
I have the same problem with a deformed ratchet nut so the hand crank slips. What was your nut wrench size? I ordered a 1 3/8" socket and it's too small. Fits the replacement ratchet nut perfectly though.
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I've attached a pic of my ratchet nut. You can see someone's been at it with a chisel. Probably the same person who went at my camshaft nut with a chisel. In your case, you might try doing what I did to get my camshaft nut tool to fit my deformed camshaft nut: I tried to identify the areas where I thought the nut might be deformed outside the socket, then I took a rotary tool with a flex shaft and a little grinder tip, and ground down those areas incrementally until the tool fitted properly. This is the socket that worked for me. I jacked up the engine a bit to get the socket on, let it back down, then I ran an extension bar through the crank hole to a breaker bar. Put it in third gear, put on the brakes, and the nut came off easily.
 

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Y-Blockhead said:
I am using a ⅝-18X1" Grade 8 bolt to for my Murray balancer. Works fine. The Murray is a bit tight for the ratchet bolt.

Why don't you want to use a new ratchet bolt?
Click to expand...

Two reasons, first as I said I can't put a crank guide on this car. Without the crank guide, the crank won't stay straight as you turn the motor, and you end up rubbing on the shell. Second, I'm getting ready to install new valves and set the valve lash, so I want to make turning the motor as easy and precise as possible for right now.

It's a 100% reversible operation. I might go back to the ratchet nut after I've gotten the car "sorted" as they say. Or I might leave it for the next guy to do.

Edit: I mean, sure, I could take a good crank guide, cut the bottom off, and weld the bushing portion onto the steel plate atop the cross-member, but I can think of a lot of reasons I might regret doing that later.
 
alexiskai said:
I've attached a pic of my ratchet nut. You can see someone's been at it with a chisel. Probably the same person who went at my camshaft nut with a chisel. In your case, you might try doing what I did to get my camshaft nut tool to fit my deformed camshaft nut: I tried to identify the areas where I thought the nut might be deformed outside the socket, then I took a rotary tool with a flex shaft and a little grinder tip, and ground down those areas incrementally until the tool fitted properly. This is the socket that worked for me. I jacked up the engine a bit to get the socket on, let it back down, then I ran an extension bar through the crank hole to a breaker bar. Put it in third gear, put on the brakes, and the nut came off easily.
Click to expand...

Yup, that's the exact same socket I just bought. My radiator is on, no way I can get a rotary tool in there. When I slide the socket on, it looks like it's up on the shoulders of the socket, like the nut is at least a 1/16th bigger. So I'm perplexed.
 
Thanks for the links.

Looking with a mirror and a flashlight, the nut looks in really good shape. What's odd is the nose of the nut is shallower, the 'hooks' the crank fit into are shallower, and have way less lip. That's allowing the crank to slip out instead of crank the engine.

But the nose of the nut has a very machined look to it, not an abused look. And it's bigger than 1 3/8. A rotary tool isn't going to help here. I don't get it.
 
Mister Moose said:
Thanks for the links.

Looking with a mirror and a flashlight, the nut looks in really good shape. What's odd is the nose of the nut is shallower, the 'hooks' the crank fit into are shallower, and have way less lip. That's allowing the crank to slip out instead of crank the engine.

But the nose of the nut has a very machined look to it, not an abused look. And it's bigger than 1 3/8. A rotary tool isn't going to help here. I don't get it.
Click to expand...

Per this post from 18 months ago, there seem to be 1.5" ratchet nuts out there.
 
alexiskai said:
Two reasons, first as I said I can't put a crank guide on this car. Without the crank guide, the crank won't stay straight as you turn the motor, and you end up rubbing on the shell. Second, I'm getting ready to install new valves and set the valve lash, so I want to make turning the motor as easy and precise as possible for right now.
Click to expand...

I use a modified 1⅜" wrench to turn over my engine when making adjustments. Or I should say used to. It will not fit in a Murray Balancer as the balancer is much thicker. Now I use a 15/16" socket to turn the engine.

48138076877_737dde30a6.jpg
 
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