Double nut those TABs

[Bitsyncmaster]

I had replaced my TABs about 7 years ago with the stock bolts from DMCH. I bought EU TABs a few years back to install on my next replacement.

The drivers side single nut was not very tight removing that TAB. Very little effort to get the nut backing off. So I have to say Grady is correct to use a double nut. Now maybe the bolt stretched. The very thick 4130 washers I made the first time don't show any compression damage that the OEM washers did on the first replacement.

The DMCH bolt was still straight with no bending. That bolt is marked 10.9 grade. The EU bolts are marked 12.9 and a little longer which should allow the double nut that is shipped with the TABs.

[Christian Dietrich]

So you get to nuts per Bolt? That's definitely a good idea and I wonder if it's wise to put a mild Loctite on the threads as well? You know just to be on the safe side. My suspension is the next thing I want to do within the next month and I'm glad that you posted this Dave!

Sent from my SM-N920P using Tapatalk

[Bitsyncmaster]

So you get to nuts per Bolt? That's definitely a good idea and I wonder if it's wise to put a mild Loctite on the threads as well? You know just to be on the safe side. My suspension is the next thing I want to do within the next month and I'm glad that you posted this Dave!

Sent from my SM-N920P using Tapatalk

Yes the EU TABs came with a standard nut and a locknut for each bolt. The bolts are hex head and plated.

[Christian Dietrich]

Yes the EU TABs came with a standard nut and a locknut for each bolt. The bolts are hex head and plated.
Nice! By the way thanks for showing pictures also and I didn't notice the Nylock nut on there!

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[Bitsyncmaster]

Nice! By the way thanks for showing pictures also and I didn't notice the Nylock nut on there!

Sent from my SM-N920P using Tapatalk

The removed nut from the first change was a nylock. The EU has a Nylock for the second nut.

[Christian Dietrich]

The removed nut from the first change was a nylock. The EU has a Nylock for the second nut.
Well that's definitely good to know and thanks for posting this buddy!

Sent from my SM-N920P using Tapatalk

[Bitsyncmaster]

What we need on the forum is an easy to find table of torque values for all the bolts on our car and engine.

I have the manuals somewhere but I know the chart was in a recall notice of new values.

Does anyone know the torque for the TABs?

[novadmc]

What we need on the forum is an easy to find table of torque values for all the bolts on our car and engine.

I have the manuals somewhere but I know the chart was in a recall notice of new values.

Does anyone know the torque for the TABs?

Houston basically says "as tight as you friggin' can"

http://support.delorean.com/kb/a72/trailing-arm-bolts.aspx

[David T]

Houston basically says "as tight as you friggin' can"

http://support.delorean.com/kb/a72/trailing-arm-bolts.aspx

The trailing arm bolts have been known to stretch. A lot depends on what the bolt is made of and what it is torqued to. If it stretches, double nutting is not going to help. The very best insurance is to check them once a year or 10,000 miles. Overtighening them is as bad as too loose. Over torquing them will collapse the tube in the bushing and now it won't hold any torque. Proper torquing is essential so that the bolt is never subject to cyclic loading. By stretching the bolt under torque you are inducing a stress in it which should be higher than the stress it would see without the torque. That way the cyclic stress is always less then the induced stress. Since the induced stress is not cyclic the bolt can handle it. Think of a paper clip. If you bend it back and forth eventually it breaks. That's cyclic stress.

[Drive Stainless]

Rather than making these important decisions based on conjecture, someone could send a nice e-mail to Guy T. Avellon. Mr. Avellon is the proprietor of www.boltfailure.com and also a DeLorean owner. He could provide a qualified opinion on torquing the trailing arm bolts.

43686
http://boltfailure.com/wp-content/uploads/dynamik-gen/theme/images/article_book.jpg

[Bitsyncmaster]

Looks like the book torque value for the TABs is 55 ft/lbs. Seems a little light for a bolt that large.

[DMCMW Dave]

Looks like the book torque value for the TABs is 55 ft/lbs. Seems a little light for a bolt that large.

If you overtighten them the sleeve in the bushing will crush. When that happens all of a sudden they will tighten at a constant torque, i.e. they will feel like they are not tight no matter how much you tighten them. And then you'll see the bushing mushroom a bit.

[David T]

If you overtighten them the sleeve in the bushing will crush. When that happens all of a sudden they will tighten at a constant torque, i.e. they will feel like they are not tight no matter how much you tighten them. And then you'll see the bushing mushroom a bit.

That joint moves in several planes and is subjected to different and varying loads. The sleeve, aka tube, inside the bushing must also be taken into account. It is not as simple as just considering the size of the bolt. Toby did an analysis and came up with the Toby Tabs, too bad they are NLA. What I do to inspect the TAB is to loosen it and rotate it if I suspect anything wrong. If the trailing arm moves up and down the bolt is bent. If it won't turn it is bent or the bushing sleeve is crushed. I then retorque it. I also count the # of shims and write it right on the frame by each bolt. That way if any are missing I know right away there is a problem. You can also put a dab of paint on it and the nut as an inspection mark.

[PJ Grady Inc.]

Is there an easy way on this forum to search old threads instead of periodically revisiting the same exact subject with no easy access to past threads? I commented extensively on this subject about a year ago and tried to use the search bar to pull up the material with no luck. I don't have time to rehash old threads from scratch every time they come up and the advanced search bar seems rather ineffectual. I'll have to let this one go for now but it would have been nice to point out past references.
Rob

[DMCMW Dave]

Is there an easy way on this forum to search old threads instead of periodically revisiting the same exact subject with no easy access to past threads? Rob

Kind of the nature of internet forums. . . .:t2:

[content22207_2]

Search terms have to be 4 or more characters. "TAB" doesn't work. I'm pretty sure it's a vBulletin limitation, not Talk specific.

Toby Peterson's analyses were all post-production. He used a Boeing supplier (same company that makes bolts that hold the jet engines on). They did the testing.

Bill Robertson
#5939

[EdR5150]

I have my best luck using the advanced search, with the "Search Single Content Type" tab.
That, or Google is pretty good at finding results on dmctalk.


I commented extensively on this subject about a year ago and tried to use the search bar to pull up the material with no luck.

[mr_maxime]

Google is pretty good at finding results on dmctalk.

I frequently do this

[David T]

I frequently do this

It would be a lot of work but you could put the answers to frequently asked questions in the FAQ's. Every time a newbie comes into the forum he thinks he is the first to have, what to us, is a common problem. Then we all chime in hashing it all over again. Even with complete and up to date FAQ's it is so much easier to post a question than to look through the FAQ's or do a search.

[Nicholas R]

Looks like the book torque value for the TABs is 55 ft/lbs. Seems a little light for a bolt that large.

It's because the intent is not to stretch the bolt (as is the normal intent of bolt torque). Proof load on a class 12.9 M12 occurs around 100ft/lbs (dry) (though the stock class 10.9 is closer to 90 dry). In the case of the TABs, you're going just be torquing against and deforming the rubber bushing, and then if you get tight enough you'll crush the sleeve before you actually reach the proof strength of the bolt. As such the locknuts/double nuts/loctite methods are all good ideas.

[Tillsy]

Houston basically says "as tight as you friggin' can"

I presume that's metric ;)

[PJ Grady Inc.]

I presume that's metric ;)

Whatever it is it isn't good advice. Are we sure someone there actually said that?
Rob

[Bitsyncmaster]

I was able to use the torque wrench on the bolt head (inside frame side) holding the nut with a wrench. I would not think you could get much more than 55 ft/lbs just wrenching the nut tight with a standard length wrench. Maybe that is what they meant for as tight as you can.

[David T]

Saying "as tight as you can" has way too many variables. The length of the wrench, the strength of the person, etc. 55 ft/lbs is not all that tight and much more than that and you crush the sleeve inside the bushing. That is why there is a torque spec, so you do NOT crush that sleeve. Admittedly the design of that joint leaves much to be desired but serviced properly it has a good track record. Many of the failures can be attributed to age, lack of regular inspection, use of inferior parts, or improper assembly by others. As with just about any part of the car it is the product of engineering compromises. At this point in time, when most Deloreans are not used regularly, the best thing you can do is regular inspections of known problem areas like the TAB's, the fuseblock and relay area, the fuel system, all of the grounding points, and the front suspension.

[content22207_2]

As with just about any part of the car it is the product of engineering compromises.

Lotus didn't have to compromise -- they chose to be cheap. Volkswagen Beetle has trailing arms too, but their pivot bolts are 17mm, not 12mm. They also sit in Bauerle like cages so if the bolt ever does break (usually it's the Baja racers doing that -- Beetle trailing arm bolts normally last half a century and hundreds of thousands of miles in street use, without any inspection or maintenance whatsoever) the rear wheel won't fold back under the car:

43767

By Lotus engineers' own admission (BBC Car Crash documentary) they didn't give DeLorean their best work.

Bill Robertson
#5939

[content22207_2]

the rear wheel won't fold back under the car

Spring plates (torsion unit) also would help hold the wheel in place.

Bill Robertson
#5939

[David T]

Spring plates (torsion unit) also would help hold the wheel in place.

Bill Robertson
#5939

Every car is built to a price-point. Obviously the Lotus engineers designed the car just the way Delorean wanted or they would have asked for changes. Now, 30 years later to say they built a crappy car, it lasted a LONG time, much longer than anyone designed it to.

[content22207_2]

False argument. The only reason many DeLoreans survived to this day is because they spent most of their life sitting idle.

Even the world's worst car could survive 35 years just sitting in a barn.

Very uncommon to find a DeLorean that has accumulated 100,000 plus miles of use.

Moreover, most DeLoreans now are pampered and babied -- hardly average use.

My money's on Mike Loasby: he found significant flaws in Lotus' engineering. Summer/Fall 1981 Loasby sent a car to Porsche to see if they could make improvements (see Sarah Heasty's DCS'12 presentation). When Porsche declined to get involved, Loasby set about making improvements himself -- that's the source of Rob Grady's lower wishbones. Veterans of the .com site should remember Loasby's posts documenting weaknesses in the car's design (for example, swaybar pulling out of the lower control arms the first time he slammed on the brakes). Loasby also pointed out flaws in a presentation to a European DeLorean gathering that has unfortunately been pulled off YouTube due to copyright violations.

No offense, but anybody who argues that Lotus gave DeLorean their best effort, or that Lotus' design is not ripe for improvement, is rather naive.

Bill Robertson
#5939

[content22207_2]

Don't get me wrong: for everyone involved to have pulled off DMC-12 production at all, much less in the truncated development window available, was a tremendous accomplishment. But you can't rush a job like without flawed results.

Basically we're driving the automotive equivalent of a school paper written the night before it's due.

Bill Robertson
#5939

[David T]

Don't get me wrong: for everyone involved to have pulled off DMC-12 production at all, much less in the truncated development window available, was a tremendous accomplishment. But you can't rush a job like without flawed results.

Basically we're driving the automotive equivalent of a school paper written the night before it's due.

Bill Robertson
#5939

There were some significant flaws in the design of the front suspension, hence the recalls. As for the rear, yes they could have done it other, perhaps better ways, but what we have is what was settled on. As for mileage, in some ways less use is harder on a car then regular use. I call as an example a fuel system that is little used but must be replaced because it is all f-cked up. For the weight of the car the design was just good enough without being over-designed. From what I see of the fleet the bigger problem with the suspension is when the frame rots out and there is nothing left to hold the parts in place. That would scare me more than the design of the TAB's. Bill we are going to have to agree to disagree. Mile Loasby is not the only engineer who worked on the car and he was not the final authority. Hindsight being 20/20 he can now claim that he would have done it differently but that is not how it went down. Ultimately you can place the decision for it on JZD and Colin Chapmin. They had to approve the car for production after the engineers designed it.

[content22207_2]

There were some significant flaws in the design of the front suspension, hence the recalls.

Front suspension flaws go far beyond some bolt on plates. That Lotus itself decided to start triangulating its own lower control arms speaks volumes.

If you want your DeLorean to perform like one of the new & improved Loti, triangulate the LCA's.

Any DeLorean owner who acts like the world froze in time in 1981 denies him or herself of later improvements. For example, Volvo revised its PRV oil spec in 1985 -- 3-4 years after DMC bellied up -- retroactive to all previous PRV's.

Closing your eyes to post-production improvements is like saying whatever you learned in high school is as good as it can get, so why bother with post-secondary education.

Bill Robertson
#5939

[Tillsy]

Volvo revised its PRV oil spec in 1985 -- 3-4 years after DMC bellied up -- retroactive to all previous PRV's.

What did they change it to?

[David T]

Your arguments for changing the car get to the heart of the controversy of what to modify on a classic car. At what point is it still a Delorean? How original do you want to keep the car? Most purists will only do things that directly improve safety but some won't do anything. I say the car is more than safe enough as long as you properly maintain and inspect it.. The recalls must be done and all of the service bulletins. After that it is up to each owner how he wants to treat his car. Some want more power. Some want more reliability. Some want to play with it and change things just to make it more individualized. For me a priority is any changes should be reversible and able to return the car back to it's stock configuration so I won't drill or otherwise cut up my car. If you desire a car with more handling or power maybe you should look at other cars. More modern Lotus's can give you much of that but of course they won't be a Delorean.

[content22207_2]

At what point is it still a Delorean?

Taking all the wiggle out of the lower control arms does not make the car less of a DeLorean. Actually quite the opposite: it makes it a much better DeLorean. That certainly is what Mike Loasby was shooting for.

Bill Robertson
#5939

[David T]

Taking all the wiggle out of the lower control arms does not make the car less of a DeLorean. Actually quite the opposite: it makes it a much better DeLorean. That certainly is what Mike Loasby was shooting for.

Bill Robertson
#5939

My point to when it is no longer a Delorean has practical implications. Let's use your front suspension mods as an example. An owner goes ahead and makes the changes. He sells the car. The new owner has a problem with the front suspension and orders some parts. Because of the modifications none of the parts fit. The vendor has no idea what is going on and the owner did not realize the front suspension is not original and has no idea now what to do. You can imagine the order of magnitude when a Delorean has an engine swap! Especially if the seller did not provide the buyer any documentation on the changes. One thing to keep in mind, typically a classic car is worth more the more original and untouched it is, before "improving" it.

[content22207_2]

I bought my Uding brackets through DMCMW -- Dave at least knows exactly what they are.

Dave also has installed Heninger control arms -- he knows exactly what they are as well.

If Dave were ever to work on my car, I 100% guarantee he'd take one look at my front suspension and say "Of course: Uding brackets on Heninger control arms -- next order of business please."

Bill Robertson
#5939

[content22207_2]

Mike's pretty adept too -- a carbureted owner just sent his car to Midwest to have some work done (not fuel delivery -- other maintenance and repair). Mike didn't come all unhinged when he saw the carburetor -- he simply drove the car into the garage and set about fixing the other things.

Mike also has worked on an EFI'd car (that was misbehaving at the time, since fixed). Again, he didn't come all unhinged -- he drove that car into the garage and set about fixing its other things.

Bill Robertson
#5939

[DMCMW Dave]

Mike's pretty adept too -- a carbureted owner just sent his car to Midwest to have some work done (not fuel delivery -- other maintenance and repair). Mike didn't come all unhinged when he saw the carburetor -- he simply drove the car into the garage and set about fixing the other things.
--
Bill Robertson
#5939

Needing to pump the accelerator a few times (the carb version of a cold start valve/thermo time switch) on cold start-ups caused some initial head scratching.

[content22207_2]

Don't go crazy pressing the accelerator pedal. Each time you do that you shoot unatomized gasoline into the venturis (accelerator pump, intended only to compensate for heavier than air fuel lag when the throttle plates open). Enough pumping and you'll flood the intake manifold, requiring propping the choke plate open and holding the throttle plates open to clear the manifold out.

All you need do is press the accelerator pedal slightly. That moves the fast idle screw out of the way so the fast idle cam can rotate back around. In its fully warmed up position the fast idle screw sits underneath the fast idle cam, preventing the choke mechanism from returning to its cold engine settings. That's why the choke plate is still open before pressing the accelerator pedal slightly.

Bill Robertson
#5939

[content22207_2]

This is how easily a [properly tuned] carbureted DeLorean should start:


https://www.youtube.com/watch?v=3sFEpe9N1dQ

Bill Robertson
#5939

[David T]

How do we get from a thread on TAB's to starting a Delorean with a carburetor?

[content22207_2]

The vendor has no idea what is going on....

Evidence is vendors are smarter and more adaptable than you give them credit for.

Bill Robertson
#5939

[Lou and "Boo"]

How do we get from a thread on TAB's to starting a Delorean with a carburetor?

Around here we call that the "Robertson Effect". But what do I know? I'm just a bad apple. ;)
LMAO

JK Bill. :)

[David T]

Evidence is vendors are smarter and more adaptable than you give them credit for.

Bill Robertson
#5939

The vendors, unless they are the ones selling the mod, don't stock parts unless it is for a stock Delorean. As "clever" as a particular vendor may be, if he is not familiar with a mod it will take him more time to familiarize himself and figure out what is going on and how to fix it. Then he has to source the parts. Not the kind of service you can expect if your Delorean is stock. It will take longer and cost more money.

[content22207_2]

Post #35: David argued against modifying DeLoreans not only by saying vendors won't know what's going on, but also by implying that engine swaps are the pinnacle of not knowing what's going on ("You can imagine the order of magnitude when a Delorean has an engine swap!")

Post #37: I pointed out that a vendor has in fact successfully worked on *TWO* different modified (more or less "swapped") engines: one carbureted and one EFI'd (EFI car had a 3.0 engine swap BTW).

Post #38: Vendor responded about one of the modified cars with potentially misleading info (pumping the accelerator pedal to start the car).

Posts #39-#40: I corrected potentially misleading info from Post #38 -- don't need anyone misinterpreting that info and pumping their accelerator pedals unnecessarily, because that creates problems (if you're still K-Jetted go ahead and pump your accelerator pedal to your heart's delight -- that doesn't do anything).

Post #41: David complained about the Pandora's Box he opened.

Post #42: I defended vendors as smarter and more adaptable than David gave them credit for being in Post #35.

Bill Robertson
#5939

[David T]

Post #35: David argued against modifying DeLoreans not only by saying vendors won't know what's going on, but also by implying that engine swaps are the pinnacle of not knowing what's going on ("You can imagine the order of magnitude when a Delorean has an engine swap!")

Post #37: I pointed out that a vendor has in fact successfully worked on *TWO* different modified (more or less "swapped") engines: one carbureted and one EFI'd (EFI car had a 3.0 engine swap BTW).

Post #38: Vendor responded about one of the modified cars with potentially misleading info (pumping the accelerator pedal to start the car).

Posts #39-#40: I corrected potentially misleading info from Post #38 -- don't need anyone misinterpreting that info and pumping their accelerator pedals unnecessarily, because that creates problems (if you're still K-Jetted go ahead and pump your accelerator pedal to your heart's delight -- that doesn't do anything).

Post #41: David complained about the Pandora's Box he opened.

Post #42: I defended vendors as smarter and more adaptable than David gave them credit for being in Post #35.

Bill Robertson
#5939

I get it Bill, no one is as smart as you and whatever anyone says, you have a come-back line for. This thread will never end until you want it to. At least talk about TAB's in it?

[content22207_2]

I'm no smarter than anyone else.

I do think the vendors are smarter than you give them credit for.

Bill Robertson
#5939