Shift linkage pivot bolt

[82DMC12]

Well I'm currently sitting here waiting for a flatbed tow truck to get my car home because I believe my linkage pivot bolt has sheared off. This is part number 17 on the manual transmission linkage diagram. This happened to me once before about 20 years ago. My transmission shifts very nicely so it's not like I have to jam it into gear or anything.

My shifter is just flopping around and I'm stuck in neutral.

Is this just a really common problem or is there something else I should be looking at to figure out why this has happened to me twice now?

I'm buying two pivot bolts this time.

Once I get home I'll get underneath and confirm.

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[82DMC12]

Sure enough, pivot bolt is the problem, but it didn't break off. It somehow unscrewed itself from the frame. Looks like I need a new jamb nut (missing) and I'll use blue loctite this time.

How do I know when the bolt is tight enough? Seems like I can make it so tight that the arms will bind?https://uploads.tapatalk-cdn.com/20211121/e3134dcf4a812f7aa4fed6f3b464c0fc.jpg

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[82DMC12]

Oh - and thank God the threads in the frame are fine! This will be an easy fix, really only for the price of the tow. And all I wanted to do tonight was watch the Chiefs game!

And fortunately the tow driver has towed DeLoreans before :-)

[Bitsyncmaster]

The bolt should seat on the frame and therefor should be torqued tight. Mine the epoxy on the frame in that area was all gone and it had a lot of rust. I machined my pivot arm with a new bearing and seat for the bearing so I just use a standard bolt. Probably something DPI should produce and sell.

The third photo is the stock bolt. So it looks like you can grind or file some of the pivot arm so your bolt will not bind.

[82DMC12]

Dave, thanks.

I'm confused though. In the fourth picture, what is all that? An O-ring? And a stainless bush? I don't think I have any of that. I just have the bolt I posted above with a single thin washer, which is what that parts book is also showing.

I just got a new jamb nut at the hardware store. I'm going to put this back together good enough so I can get to my alignment appointment on Tuesday, but I will do a thorough job of replacing the bad bushings on the ends of the bellcrank ASAP.

PLUS - looking at your picture - seems like my bolt doesn't have long enough threads. I remember I got this from Hervey way back in the day, he was kind enough to overnight it to me when my car was broken down at a shop for the exact same thing. Maybe this bolt isn't the right thing at all.

Going to order all new everything tomorrow I guess.

[82DMC12]

I put the pivot bolt and washer back in just to get the car mobile. Interesting to note that the Parts Manual I have (Grady physical copy) shows the washer directly under the bolt head (above the bellcrank) with NO washer between the bellcrank and frame.

delorean.com shows the washer UNDER the bellcrank with no washer under the bolt head.

Which is "correct"? I see delorean.com has a superseded part for the pivot bolt so is the new design/part reflecting in the revised diagram online? I will check with DMCMW tomorrow.

I really do not like this bolt I have because the jamb nut I bought tonight barely threads completely onto the bolt. This bolt must be too short. I have to tighten the jamb nut fairly tight to keep the bellcrank from turning the pivot bolt right out of the frame again. WTF?

[Bitsyncmaster]

Dave, thanks.

I'm confused though. In the fourth picture, what is all that? An O-ring? And a stainless bush? I don't think I have any of that. I just have the bolt I posted above with a single thin washer, which is what that parts book is also showing.

I just got a new jamb nut at the hardware store. I'm going to put this back together good enough so I can get to my alignment appointment on Tuesday, but I will do a thorough job of replacing the bad bushings on the ends of the bellcrank ASAP.

PLUS - looking at your picture - seems like my bolt doesn't have long enough threads. I remember I got this from Hervey way back in the day, he was kind enough to overnight it to me when my car was broken down at a shop for the exact same thing. Maybe this bolt isn't the right thing at all.

Going to order all new everything tomorrow I guess.

Mine is modified. That last photo is a new part I machined which gets bolted tight onto the frame. I needed a larger surface area where it contacts the frame because of the damaged epoxy. So the new bearing (not stock) uses that new machined part (not stock) to rotate around. That gives me a design so the bolt has very little lateral force so the bolt just holds it onto the frame.

The OEM design the bolt is the surface of the rotating part of the bell crank. So the bolt must be tight since it is the pivot with all the lateral force on it.

[DMC-81]

I replaced mine in 2018 with a new bellcrank assembly (100549) from DMC and an improved grade 12.9 Shift Pivot Bolt & Hardware from PJ Grady.

Here is how I put it together:
http://dmctalk.org/attachment.php?attachmentid=55742&d=1521686172

I lubed the assembly with a 50/50 mixture of anti-sieze and axle grease, and applied red loctite to the jam nut:
http://dmctalk.org/attachment.php?attachmentid=55758&d=1521806394

[82DMC12]

I replaced mine in 2018 with a new bellcrank assembly (100549) from DMC and an improved grade 12.9 Shift Pivot Bolt & Hardware from PJ Grady.

Here is how I put it together:
http://dmctalk.org/attachment.php?attachmentid=55742&d=1521686172

I lubed the assembly with a 50/50 mixture of anti-sieze and axle grease, and applied red loctite to the jam nut:
http://dmctalk.org/attachment.php?attachmentid=55758&d=1521806394Excellent, thanks! I have all new hardware and bushings for the rods coming tomorrow.

Andy

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[DMC-81]

Excellent, thanks! I have all new hardware and bushings for the rods coming tomorrow.

Andy

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You are welcome. Here are the details when I replaced the part as posted in my transmission rebuild thread:

http://dmctalk.org/showthread.php?14544-5-Speed-gearbox-flaw-repair&p=232838&viewfull=1#post232838

and here is the service bulletin with more details and torque specs:
http://dmctalk.org/attachment.php?attachmentid=67479&d=1637718065

As I recall regarding the sequence of the washers, the thick washer goes on top of the bellcrank as pictured, but the 2 wavy washers go on the bottom between the bellcrank and the frame, leaving no washer between the jam nut and the frame. I would test the arrangement out for proper movement before using loctite in the final assembly.

[82DMC12]

Great resource, thanks for the link. Are you sure there's supposed to be a washer under the bolt head though? The bulletin mentions the bell crank having a chamfered edge for the bolt which makes it sound like a washer would defeat it. I haven't pulled my crank out yet though so not quite sure I can confirm?

My front and rear rods seem to have zero bushing remaining - they are loose on the crank. I guess it all deteriorated over the years and perhaps that slop contributes to binding of the crank which in turn unscrewed my pivot bolt out of the frame? I did find that bulletin and I'll check to make sure it's within spec before reinstalling.

Slightly worried about using red loctite as it seems you need either an impact or heat to remove whatever was fastened. Is that what Grady recommended? I was going to use blue loctite.

I'll post some pictures and an update tomorrow afternoon.

[DMC-81]

Great resource, thanks for the link. Are you sure there's supposed to be a washer under the bolt head though? The bulletin mentions the bell crank having a chamfered edge for the bolt which makes it sound like a washer would defeat it. I haven't pulled my crank out yet though so not quite sure I can confirm?

My front and rear rods seem to have zero bushing remaining - they are loose on the crank. I guess it all deteriorated over the years and perhaps that slop contributes to binding of the crank which in turn unscrewed my pivot bolt out of the frame? I did find that bulletin and I'll check to make sure it's within spec before reinstalling.

Slightly worried about using red loctite as it seems you need either an impact or heat to remove whatever was fastened. Is that what Grady recommended? I was going to use blue loctite.

I'll post some pictures and an update tomorrow afternoon.


You're welcome.

Are you sure there's supposed to be a washer under the bolt head though?
This Pivot Bolt was an upgrade from Grady and as I recall, it was slightly longer, so it needed the 3 washers as shims. It was discussed here:
http://dmctalk.org/showthread.php?13255-Pivot-Bolt-Depth
Now that I think about it again and remember the shoulder bolt concept, perhaps all 3 washers were placed on top with the 2 wavy washers between the larger washer and the bellcrank (to add slight tension to the assembly to prevent the slop discussed in the thread). I can't honestly remember definitively, but I know the final installation had the washers in a different sequence than they were in the picture I took. Regardless, I remember being able to draw full torque on the pivot bolt without binding the bellcrank. It was free moving but not sloppy. That should be the goal.

If you are using the stock setup with DMC's superceded pivot bolt, I would follow the Bulletin/DMC instructions and ensure the chamfer is in spec etc. and you have proper movement without binding or excess play.

I guess it all deteriorated over the years and perhaps that slop contributes to binding of the crank which in turn unscrewed my pivot bolt out of the frame?
Perhaps. By replacing the parts above and cleaning, lubing and installing the bushing kit, it made a world of difference in my shifting performance.

Is that what Grady recommended? I was going to use blue loctite.
I can't remember, and maybe it was my choice to avoid a tow because of this part failing, so I would recommend using whatever you're comfortable with.

Good luck with the project.

[82DMC12]

I fixed my bell crank yesterday. First, here's a comparison of a John Hervey-supplied pivot bolt (over 20 years old) vs a current DMCMW pivot bolt:

67483

Hervey bolt on left, DMCMW on the right. As you can see, the Hervey bolt doesn't have as many threads. This means you cannot get a normal nut or nyloc nut on the threads sticking out of the frame - you can barely get a thin jamb nut to hold on. The turning of the bell crank with each shift has the effect of loosening this bolt if you cannot secure it on the back side. So, to the trash can it goes.

There is some debate regarding how to install the crank and with what washers. The printed part manual I have from Grady does not agree with the illustration on delorean.com in 4-2-0, and of course there is also the service bulletin discussing the crank and adding washers under it. I ended up using a washer under the bolt head (between the head and the crank) as shown in the original parts manual (delorean.com does not show this washer) and NO washers under the crank. I consulted with Mike at DMCMW on this. He also mentioned this is a common failure area and advises checking the tightness of the pivot bolt and nut every year or / each oil change.

Anyway I greased the pivot bolt and top and bottom surfaces of the crank with a mixture of lithium grease and copper antiseize, tightened the pivot bolt to a medium tightness (no way to get a torque wrench in there) and then secured a standard nut to the bolt threads coming out the other side with blue loctite. I also replaced the rubber bushings, washers, and nyloc nuts on the levers so everything is fresh.

My shifter is butter smooth, snickety-snick now and I'm sure this will be a lasting repair.

So, if you have a Hervey pivot bolt - better check this out!!!!

[cis6409]

Most excellent thread, very interesting!

I will be refurbishing my gear linkage soon and it will come in very handy for it , great timing :)

Shane

[82DMC12]

Most excellent thread, very interesting!

I will be refurbishing my gear linkage soon and it will come in very handy for it , great timing :)

Shane

First I tried to add two washers under the bellcrank as per the service bulletin but I was getting a lot of binding when trying to turn the crank to check for smooth operation. After talking to Mike, he didn't think they were necessary so I took them out and just set the crank in without the washers. After tightening the bolt, it felt a bit stiff while moving it by itself under the car, but once the levers were attached and I used the shifter in the car it felt fantastic. So tight and precise once again. I will make sure to remove it every couple of years and give a good grease as it's just going to have to be another maintenance item.

I have been bad about fluid changes (antifreeze and brake, mostly) so I'm committed now to be on a 2-year schedule where I just go change every fluid and do all the greasing of ball joints, bell crank, silicone grease on bushings, etc.