Hot Rods AD_NAPCO's 39 GMC Rocket 324 Build

Frank it certainly seems that you are correct in that the spring is pinned on the one side to force it to one side and probably the neutral gate. Upon closer inspection of the pin, there is a nail head on the opposite end, that seems to be pretty well covered by the spring coils. I guess the spring has to be compressed to be able to get at the pin? Only think I can think of to compress it would be a C clamp. I have one that's big enough but it doesn't want to catch bottom coil to compress, and even if it did, I'm not sure I could get in there to back the pin through the stick.
Man... They sure made this thing a pain in the ass to take apart! I wish it were easy like the SM-420's from the 48-87 Chevy trucks!

 

Never had one apart but aim to soon as my spring is broken. I know on the Lasalle that the 5/16 pin is easily driven out and wondered if that would be the case here to get a bit of slack in the stick travel to help lessen the pressure on the spring.
Frank, I sent you a pm on a Lasalle issue.

 

That nail head on the pin rings a bell. And I do think the coils keep the nail end from falling out. I am almost positive the pin is slip fit once that end is exposed.

As I recall, I had the top cover upside-down in a vice maybe. Then I think I made a flat bar with one end hooked to a topcover bolt hole with a link of some sort.

Then something attached to the bar above the spring, to press down. It may have been a length of pipe with a side window notch at the bottom, to expose the pin head after the spring is pushed down? The long end of the bar is your leverage.

 

I win!!! Send my check to me Josh! Lift the small end of the spring tang just enough to get it over the end of the pin when you rotate the spring ccw and the spring will screw right off. Those gm engineers are pretty smart. When you screw it back on the tang snaps back into place and holds the spring from rotating while the small coil holds it firmly in place. The nail head pin will fall out so watch out you don't loose it. Now to find a replacement spring.

 

Alright... I believe you Walt... I just wanna make sure I know what you're talking about. You say the 'lift the small end of the spring tang just enough to get it over the head of the pin' are you talking about the tail end of the spring coil? If you look at the pic I posted of mine, the tail is captured under the pin. I was able to rotate the spring ccw enough to free the tail end and it seems I can keep turning it ccw... I think that's what I need to do but the spring is still bound. I just don't want to break it. I'm not sure about the lifting over the head of the pin part. I think of the head as the nail head, and the end as what is sticking through to capture the spring coil. Are we then talking about lifting the tail of the spring over the end of the pin?

 

Walt, is that info from a service manual? As I recall, there is a ton of pressure there from the compressed spring. Have you tried that with an unbroken spring that still has full tension?

.

 

I see now that I misread the original post... You did say "end of the pin" so... I guess that changes things but I'm still concerned about breakage... I'll wait for you to clarify/answer Frank's question.

 

Do either of you have the 37 Buick service manual? I'm contemplating purchasing, but I don't want to do that unless I know it actually covers the removal process... I'm guessing if they do however, that the procedure involves a custom fixture/tool for compressing the spring.

 

I don't have one, and I doubt it would cover that. I say that because I've had three 1934 LaSalles to fix up for an estate, and there were factory Cad/LaS service manuals inside the LAST 34 I just finished. I tried to find cylinder head torques and sequence...the freaking book said "tighten as firmly as possible without stripping the head studs" I'm serious.

I'm knee deep in garage revamp/cleaning/reshelving... If I had time, I'd show you how easy it would be to make a tool to press the spring down. Think of a pipe with notched windows directly 180 across on the end. That would be 2 windows, one to fit around the tail of the exposed pin, the other to get access to the nail headed end, after the spring is pushed down.

Maybe I can whip something up later tonight with a pic. Not sure if I have a good top cover handy, with the original spring and pin though. But it would show the basics

 

Yeah, I think I know what you're talking about, Frank. I'll see if I can figure something out with a piece of scrap tubing. Thanks for all the help!

 

HA! In my rush to get the "prize" I neglected to recall that I did have a broken spring. The last coil is separated from the rest. It seemed to me that one could just go ccw after clearing the end of the coil and it would come off. Admittedly, yours will have more pressure. Frank always has a better idea so I would go with his plan if it looks like it will not budge.
I do not have a manual but I do have a service disk for old trannies and I will look on there but I doubt they cover it. Back at you later.

 

Don't have an unmolested 37 shifter.. The only loose one came from a package deal for 2 37 Buicks that were modded with Olds stuff back in the day. The seller said he had "some oldtime trans go-to guy" , "go through them to make sure they were all set"

Well, one had this cover with screw-in "rivets", because it apparently had a broken spring. They had the wrong spring, and a weird retainer you can see...... and I am waiting for Walt to find out where we can get a substitute tapered spring.. Walt can find stuff

Anyways, all I had right on the bench was a bent piece of 5/8 EMT.. So I used it despite the bend. Ground two windows with a 4-1/2" grinder.. Then an eye bolt... and a super long 3/8 extension. You can get the idea from the pics. I think that size EMT should fit the small end of your stock 37 spring perfect.

Back to the threaded rivets on this trans. I have no idea if they were from something else, or made by a machinist, OR if they might be an old Buick "Service-replacement part" from back in the late 30s..if it broke a spring, how would the factory suggest dealing with rivets?? IDK, just a guess

 

I see. Good idea. I was thinking about slotting an old metric socket ( I have TONS of duplicate metric sockets from my dad's shop) and and seeing if I could use a clamp to press it down. I gotta say i like the threaded pins a whole lot better than these pressed and staked versions! I might get to sneak out to the shop and see about freeing this sucker up tonight after work.

Thanks for the detailed pictures! If the slotted socket doesn't work I'll see if I can dig up a piece of pipe and an eye bolt. I may need to run to the store the eye bolt.

 

No need to "must use" a eyebolt. I use what I have in a five foot distance from the vise..

You can use flat stock, L shape with a hole at both ends. One hole on the short leg to bolt to cover, then a bigger hole up top for the bar. Or a short piece of light duty chain, whatever.

Really would help to have it in a vice, but no matter how you try to hold it, the shifter will move around a bit as you fulcrum it. Nice to have one guy "two hand" the spring compressing, and another to grab the pin before something slips

 

Yeah, it would be nice to have help, but I unfortunately have to work alone. We are new to the area and I don't really have any hot rod buddies here. I know I don't have to use an eyebolt but I like the idea. If I don't have one I'll probably grabe a chain or something else like you say. Whatever gets it done without injury and fastest. Besides I'll probably not be done with work in time to hit the hardware store anyway.

 

So ? Frank about the "retainer" shown in the pic on top of the spring. Did the pin go across both sides?
On mine which appeared to be factory correct as it had the original rivets the pin end was caught on that side but the head of the pin was under the top coil. Couldn't depress the spring as it caught on the head leading me to believe that the only way it was going to come out without damage was to turn the spring ccw. There are witness marks on the spring where the end laid on the top of the coil and looking underneath the coils there is another where the head laid against the side of the coil. With it attached in this fashion there is little chance that it would ever fall out but I wonder how the factory installed these. Perhaps in my case the pin had slid over from years of use complicating this removal process. If I had a good spring I could play with this to figure it out. All the spring guys want to know what material to make the spring out of???????????????? Have no idea. And further they need to know the spec on the tension when fully compressed so I wonder Josh if you could find someone to check the spring rate thru compression???? Would be a big help to get the right spring set up.

 

I'm hoping to get the spring out this morning. My pregnant wife and my 2 year old son should be awake shortly. I'm sure they'd appreciate it if I didn't start up the angle grinder just yet. I'll see if I can find a way to check the spring rate. There must be a formula. As far as material goes... I have no idea. My guess is that there wasn't a lot of exotic material usage in a 1937 Buick. It's probably a fairly standard grade of spring steel.

 

Good news... I got the spring out. Based on what I see here, I don't get the impression that the spring is meant to be twisted out, or that the head side of the pin is meant to bind on the spring. The pin sits in a counter sunk hole and the head is ground to where it is flush with the tapered portion of the shifter. When I compressed the spring, it slipped right past and the pin pushed out with nearly zero effort. The grease in there was the only thing keeping any kind of tension on the pin allowing me to grab it with a pair of needle nose pliers rather than have it fall out. Thanks for the ideas on tackling this part of the job. Walt, if you can get info from your 'spring guys' about what they need, I will get you measurements, coil counts, etc. Maybe they can tell you if there is any way to discern the material as well?

 

I could use the relaxed length measurement of your spring.
Took a break from shelf work.. 3 H's here..Too humid.

I just took apart a 34-36 LaSalle top cover to see if the spring was the same as Buick. Despite that these 2 transmissions look so alike, the cast tower at the shifter base is a different height. I just can't get the pin back into the Buick shifter, as the LaS spring is "coil bound". The LaSalle spring is 2.25 " relaxed.

Also, the 34/36 LaS does not use the pin with a head. It uses a normal cotter pin, straight through, with neither end hidden under the coils.

I also now see a huge difference in why the Buick shifter feels so different than the 34 LaSalles I had here recently. Look in the pocket where the big end of the spring sits on; you will see a casted wedge shape on one side only, like a 2 sided pyramid. That forces the spring to tilt to keep spring tension on the shifter, towards the right side. It is wedge shaped, so that when the shifter goes forward or backwards, the spring can't try to pop it out of gear? Look at it awhile to understand what I think it does.

...The LaSalle casting bore is flat bottom for the spring. That's why they feel way different to me.

So, it is not the angled pin on Buick that favors the shifter to the right side. That pin design must just be a quicker factory install, and perhaps stronger than a cotter pin?

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You are right Frank. It's definitely not the pin that's doing the cocking action on the shifter. It's that hump that's cast into the collar bore. Also... I went to spot blast the top cover... I don't know if you were talking about the top cover or just the retainer collar when you mentioned chrome. I thoughtyou were talking about the retainer only.. .Anyway, the damn top cover on this trans was chromed! It was so rough I thought it was just silver paint. Damn stuff won't come off with sand. I don't even know if wire brush will take it off considering it went onto a rough casting. Any ideas on removing that crap or should I just etch prime and paint over it? The other thing is that you can see just barely on the left side of one of my pics from earlier that there is one ear broken off the top cover where a rear bolt goes into the case. Should I worry about trying to repair that? I don't like the idea of not having good clamping pressure on a gasket in that spot. I suppose a piece of bar stock could be drilled, shaped and mig welded to that ear, but it'd probably have to be preheated, right?

 

Frank, the relaxed on mine holding it together looks to be around 1.890. I looked in mytower and I see the hump although it is covered with old grease but it is their which explains the pressure on the shifter for sure. Working on a source for the springs but everyone wants to know the compressed pressure thing!

 

Yup.. I mic'd mine at 1.885" relaxed. The only think I can think of that might tell compressed pressure would be to set a washer on top of the spring coil, and somehow hook a pretty stout spring scale, like you'd use to weigh a really big fish, to it from the bottom and then pull on it and see what the scale read at full collapse... Unfortunately I'm fresh out of heavy duty spring scales... Any other ideas? Maybe stacking weights on it until it collapses and then figuring the cumulative weight?

 

The broken ear is not completely in view, but the break looks like you ended up with a slot shape, with enough circumference remaining to support a thick flat washer? Meaning, that if the washer has enough to sit on, without tilting as you tighten it, it should be like a washer over an adjustment slot on a alternator bracket?

You could fashion a small piece of steel to replace what's missing, but weld it to the washer, instead of the cast cover. That would support the washer just fine as it tightens.

Yes the cover could be brazed or welded, but it seems like you get embrittlement adjacent to the repair, so it might crack when you tighten it against the compression of the gasket there.

Etch the chrome with the blaster or acid, then paint. I kinda thought the cover looked chromed. I wonder if they dunked the whole deal assembled? Who knows

Valve springs are checked by compressing to a pre determined height. So, how can we tell what a spring company wants to know? Unless... maybe we are supposed to measure the installed height (spring installed back in the tower), then take it back out on the bench and see how much weight it takes to compress to that distance??

 

So... Like I mentioned in an earlier post, we are pretty new to this area, and I'm still trying to locate businesses like machine shops, radiator shops, etc. that will do business with people that have our particular sickness. Anymore, it's difficult to find a place that, wants to work on, much less knows what to do with something that doesn't have On Board Diagnostics, EFI, etc. Well, not long after my last post I decided to drive around and I actually struck gold. I found a shop called Paradise Driveline about a five minute drive from my house. Super junky looking from the outside, and probably worse inside, but... There was a FOREST of driveline parts hanging on the walls, lots of them clearly old, and there was a whole bunch of vintage metall working machines for making whatever you'd need made. So, I got to speak with the older guy that owns the place. He's been in that spot for over 40 years now, loves working on the old stuff, and he said he could weld up that ear using 'cast weld' and an acetylene torch, and it'd be good as new. I was specifically hoping he'd say that. My dad who is 79 now, and can't really see worth a crap from all the years of welding, is the only person I'd ever seen use cast iron rod and repair cracked manifolds with acetylene, and even split manifolds with the same process. So this guy also said he could make me a couple new retainer pins with threads out of some bolts he knew he had from many years ago that have 'goofy big heads on'em' and that'll save some time and labor. This guy, 'Vern' was almost giggling, he was so enthusiastic about doing this kinda work. Said he LOVED working on the old stuff. Said he had a '29' he was working on... I didn't get a chance to ask what make or model his '29' was but that'll be good conversation for later. I have told my wife before that she doesn't have to worry about me ever cheating on her because I already know I got really lucky finding her because under normal circumstances, I'm an old man magnet!

 

Well you can't beat having a shop like that close by..

Here is a pic of the 34 LaS trans. Sure looks like a Buick that was converted to open drive, but it was open drive in the 34-36 LaSalles. The motor for 34 LaSalle was borrowed from the Olds straight eight. So, I wonder if this is an Olds straight eight design trans, and if so, how far back in years was this trans designed.

There are just too many small differences in these to be useful for Buick type transmissions

But....Tracing the roots of the GM selector style trans that was still in use in 1964!

 

My thoughts exactly!

That's really interesting that LaSalle was making open driveline cars that early... Did you just happen to pick that up for fun, or are you working on it for someone?

 

Frank, another thing I noticed is that the there are two humps cast into that shifter bore on the Buick cover. A tall one and a short one opposite. Must be to keep the spring cocked to the one side, but also allow the whole coil to pivot along the axis it creates rather than have the one side get bound up and buried in a hard corner. I'm sure that does make for a dramatically different feel...

 

check out this site...........www.thespringstore.com as they have a good description of what is required to spec out a spring. Perhaps your new contact may be able to offer up some insight???

 

Here are the specs as best I can tell that The Spring Store needs.

End type: Closed and Ground

A: Small Outer Diameter = .91"
B: Large Outer Diameter = 1.65"
C: Free Length = 1.85"
D: Wire Diameter= .148"
E: Total Active Coils = 5
F: Solid Height = .85"

I didn't see anything regarding material type or calculating the spring stiffness, etc. Let me know if there's anything else I can get you.

 

Thanks Josh. I will see what I can find out there.