Topic: 25mm Knuckle Pin Upgrade Kit Review

[BigMike]

So.... what do you guys think about this awesome kit?
Full article may be found here: http://www.marlincrawler.com/tech/axles/25mm-knuckle-upgrade-kit-review




When we sought to build Toyota pins as large as Dana 60 lower pins, we never knew the results would be this fantastic.
The image to above clearly defines the 47% size increase of the 25mm Marlin Crawler Knuckle pin.
By replacing your stock 17mm pins you are increasing the durability and also the safety of your Toyota-axle 4WD vehicle.
Also of interest is that the stock component is a 1-piece cast setup whereas the Marlin Crawler component uses a Chromoly pin that is pressed into a solid billet cap, just like our High Steer arms.


Here we have our new updated High-Capacity 8,500 pound-force 25mm KOYO knuckle bearing.
The inner diameter literally dwarfs that of the stock NSK bearing.
Can you believe that our KOYO bearing is 54% stronger than the stock Toyota bearing? You better believe it baby!
Not only is our pin 47% larger, but our bearing is also 54% stronger to boot! It is a total upgrade package!


Knowing that no steering linkage is attached to the lower cap, designing stronger fasteners wasn't a high priority of this upgrade kit. But then again this kit is designed by Marlin and he only wants the best parts for your rig! Without compromise, the kit includes high shear and high tensile strength 12.9 grade cap bolts along with high quality serrated conical washers made in Germany.


All Billet Steel parts along with their 25mm Chromoly pins are all made in USA. As you can see on the lower caps, we are quite proud of USA made parts!


Another impressive feature of our Billet Rock Guard lower cap is how much ground clearance is gained. As shown to the left, ground clearance is cut by a massive 60%.
Put yourself in a rocks shoe: Would you rather hit an exposed single stud or go face-to-face with our Solid Billet Rock Guard lower cap?
Stop risking bent studs with damaged delicate and exposed threads. Switch over to our Heavy Duty Knuckle Bearing Upgrade today!




Discuss!

[*** YELLER ***]

OK a couple things about this kit....

1.  way to think outside the imaginary box this is great

2.  how am I gonna convince the wife I gotta have it

3. THIS IS AWESOME

AS USUAL MARLIN AND TEAM COME THRU FOR US AGAIN 




 

[blackdiamond]

I guess I'll go first...make that second.

My initial thought is that this appears to be a pretty slick product.  I like the idea of eliminating the four studs hanging out the bottom, but I've never had an issue with them contacting the rocks (I know some wheeling terrain will certainly cause this to happen) and am not convinced that it has $500 worth of value to me.  I'm sure there are a lot of people that will greatly benefit from this upgrade.

Is this upgrade related in any way to a 5 or 6 knuckle stud or ARP knuckle stud upgrade?

[Nothingface5384]

i purchased this in late feb...the complete kit is 500..but most people all ready have some things that's why they also offer just the steeromg pin upgrade for 279

[BigMike [OP]]

Thanks for the comments guys

but I've never had an issue with them contacting the rocks

The ground clearance advantage really only becomes an advantage when you run 1.5" or larger wheel spacers.

Please remember that the real need for this product is to combat blown up knuckle bearings and sheared steering pins. The benefits of the lower cap design is icing on the cake and it looks really, really good on any truck.

Is this upgrade related in any way to a 5 or 6 knuckle stud or ARP knuckle stud upgrade?

Negatory ghost rider.

most people all ready have some things that's why they also offer just the steeromg pin upgrade for 279

I just came across a nice pic of the upgrade kit installed on our F-Toy

[OOPS]

Very easy install. Pins for the steering arms went in fine with the 20-ton press, nice and tight in the Marlin Billet six-hole arms that I have (yes you read that right, MARLIN six-hole arms). Gives me piece of mind since I have broken two trunion pins and two trunion bearings (no-name piece of crap, made in China------JUNK.)

[kiyul4130]

this setup looks really good. my buddy matt won a set of these at the raffle last year an blew up the bottom bearing first trip out to the rubicon this year in may. maybe it was a bad bearing??? the pins look really strong.

[BigMike [OP]]

Yup I spoke to Matt a couple of times on the phone as well as meeting him in person at the round up last year.

We happily replaced Matt's bearing free of charge, but I want to mention, not to say Matt installed it wrong, but it is critical to follow the factory service manual's instructions and have the proper knuckle preload. For future reference, if the knuckle is setup improperly with a peload that is too loose OR too tight, bearing failure will be inevitable.

We tested these upgrade kit out for over a year before releasing the product at last years round up. We stand behind everything for sure

BigMike

[Duffil]

I fail to see how the upper steering head bearing for an 82 YZ250 (as per the numbers I was given by Matt directly off of his unit) is designed to handle more load than a stock Toyota trunion bearing.

[Sluice Box Hero]

Hey mike, can you post the bearing number for that bearing. Not to say rex is wrong, but an 82 yz250?  Also what is the taper difference between the stock bearing and the big one! Also, how many more individual bearings are in there, and how much smaller are they?

As for proper set up, not to bash but I would guess maybe 1% of the people who purchase these will have the tools or the know how to get the preload perfect, and if such little imperfection will cause failure then I see a lot of these having issues.....

Has anyone looked into a premium grade stock sized bearing? If so, what is it rated at?

Now, I love the idea of not having the studs stick out the bottom, wish someone made a lower cap like that for my d60 for sure. How did you overcome the clamping force loss from using a bolt over a stud? Heard it's something like 40% loss using a bolt compared to a stud at the same torque spec.

[BigMike [OP]]

Thanks again for all the great comments guys!

I do not know the application(s) of the bearing we are using as this is generally not how we design products. We first come up with the idea, then we build a couple in-house prototypes using on-hand parts, and then we determine the desired specifications such as diameters, thickness, etc, and then we simply refer to a large bearing reference book to see what bearings are readily available. Of course not all bearings are applicable for an intended purpose. With this application we must use a tapered bearing due to the axial loads present.

We have load ratings for many different manufactures, but beings how this is a KOYO bearing, we went with their own published static and dynamic load ratings -- straight from the horses mouth. Regardless of the application, the bearing we are using is much stronger both statically ("not in motion" - more practical here as we are likely to slide of a rock ledge with our hands firmly gripping the steering wheel) as well as dynamically ("in motion" - less practical of a measurement here, it's not like the knuckle is going 2,000 revolutions per minute about the trunnion pin LOL).

I fail to see how the upper steering head bearing for an 82 YZ250 ... is designed to handle more load than a stock Toyota trunion bearing.

So in other words, if you are right, then the dirt bike's headset components are INDEED stronger than Toyota knuckle bearings. As crazy as it sounds, you'd better believe it! Perhaps that is why Yamaha's are so expensive! Gotta love Japanese quality!!

Here is the only pic I have comparing the two bearing tapers and pin count:


It is true the taper angle of our bearing is less, but notwithstanding, it's load ratings are still better. The increase number of pins account to its improved mechanical performance. The length of each pin appears to be the same - I need to mic them to determine precisely which is longer/if longer. In my personal opinion, the only thing I dislike is how small the landing area is of the inner race. But once again, I feel the increased load ratings make up for any shortcomings, and of course there is no way around this short of forcing everyone in the world to make modifications to their stock housing. And we won't have that! This is a pure bolt-on product!

Has anyone looked into a premium grade stock sized bearing? If so, what is it rated at?

We already sell premium grade stock sized bearings: Japanese KOYO or NSK bearings in all our axle rebuild kits!

How did you overcome the clamping force loss from using a bolt over a stud? Heard it's something like 40% loss using a bolt compared to a stud at the same torque spec.

The best way to answer this is to say that 1) the threads will fail before a stud or bolt will fail in tension, and 2) there are no lateral loads on the lower cap so it is not as much of a concern as say the top steering arm.

It is really nice to have such a great test rig to support and back-up this product Check out this recent picture - fully get'n it!!

[Sluice Box Hero]

I see the failure in the design being that the taper on the bearing could be a little too much.....time will tell. As for the bolt vs stud debate it's not about the breaking force, it's about how much, and in what ways the blot/stud stetches.....which it will not matter what. When. Bolt is torqued down it you have to create a fairly significant twisting force on it to get the threads to engage, so when it stretches it not only stretches along it's vertical axis it will also twist the head causing it to loosen. A stud that is propertly installed will only stretch along the vertical axis because the force used to tighten the stud is not a twisting force.

[Sluice Box Hero]

Gaurenteed the reason Matt lost that bearing is because the bolts loosend becaues when torqued to the same spec as the factory stud it is not nearly sufficient.

[-Matt-]

Supposedly I was one of the only ones to have an issue with the bearing blow out. I was sent a new bearing and a pack of shims for fine adjustment, free of cost.

I do admit, and even told John when I talked to him that i did not put anything to specs. like most people I am aware of the preload specs, but just guesstimated on the final outcome.

at the time I was having death wobble issues, so I most likely overtightened it due to taking out one more shim than i should have, to try and get rid of the wobble. I finally concluded that the death wobble was from bad caster angle. so once i fixed that, wobble was gone, so im going to assume that if I hadn't of pulled one more shim out, it would have been fine.

[-Matt-]

Gaurenteed the reason Matt lost that bearing is because the bolts loosend becaues when torqued to the same spec as the factory stud it is not nearly sufficient.

it wasn't from loose bolts trust me on that one. I always make sure all the knuckle bolts are tight, I periodically check on the trail, since i have seen so many people sheer them once they even remotely get loose.

[Duffil]

So in other words, if you are right, then the dirt bike's headset components are INDEED stronger than Toyota knuckle bearings. As crazy as it sounds, you'd better believe it! Perhaps that is why Yamaha's are so expensive! Gotta love Japanese quality!!

No.

I see no way that a dirtbike steering head bearing would be stronger than a bearing designed to carry steering load on a 4800-pound truck. I do see a shear strength increase over stock on behalf of the pin, but this isn't really the issue at hand. Although I do know that you guys have had some high-steer arm issues related to the pin.

what I am getting at, is that the load the bearing is designed to see is lower than what it will see in your application, and it is a light duty bearing.

[Sluice Box Hero]

it wasn't from loose bolts trust me on that one. I always make sure all the knuckle bolts are tight, I periodically check on the trail, since i have seen so many people sheer them once they even remotely get loose.

you check your lower kingpin bolts. . . . i know everyone checks their highsteer arms, but ive never seen anyone check the lower bolts.  either way, bolts are NOT the way to go on anything that, under the possibility of them loosening, could cause catasrophy.

[-Matt-]

you check your lower kingpin bolts. . . . i know everyone checks their highsteer arms, but ive never seen anyone check the lower bolts.  either way, bolts are NOT the way to go on anything that, under the possibility of them loosening, could cause catasrophy.

ya i checked them all the time because they're hard to see if they were to come loose or not. I never had to re-tighten them after the first installation. which surprised me because I thought the threads would stretch a bit, but they didn't on my setup.

[kiyul4130]

maybe they were tight but the preload was wrong............

[Jud]

I don't see how having a bigger pin with a smaller bearing will cure our problems of our stock (which are beefier) Toyota bearings going out. Think about it, when something on a Toyota front end goes bad, what is it? Either knuckle studs or trunnion bearings. So why upgrade the pin (which very rarely breaks) making you run a smaller weaker bearing?

I'm with Callen on the lower cap bolt/stud issue 100% also.

[kiyul4130]

i think the preload was wrong.

billy blew up his pin the after his first day at the hammers. lots of people break them.

[slabcs]

I've broken one.  A friend of mine sheared one too.

[Sluice Box Hero]

i guess matt wasnt a test.

as far as im concerened matt is the perfect real world test, and they failed for him.  something is up, maybe our searching will help a flaw surface and the MC crew and work it out.  its pretty immature to think that a new product is perfect at its initial release.  the 2008 Ford 6.4 powerstroke had over 5 million miles of testing on it, within the first 3 weeks of sales they were already making recalls.  nothing is perfect until you let a standard retard try it for himself.

give it time, if there are more than a few failures then there is "something" wrong with the design, and it needs revised. which im sure it will be.  gaurentee its not perfect. . . .

[cruzila]

I see the failure in the design being that the taper on the bearing could be a little too much.....time will tell. As for the bolt vs stud debate it's not about the breaking force, it's about how much, and in what ways the blot/stud stetches.....which it will not matter what. When. Bolt is torqued down it you have to create a fairly significant twisting force on it to get the threads to engage, so when it stretches it not only stretches along it's vertical axis it will also twist the head causing it to loosen. A stud that is propertly installed will only stretch along the vertical axis because the force used to tighten the stud is not a twisting force.

Wow, tough read but here goes. On the bottom cap the stud is not held in place by a cone washer therefore it really is moot whether it is stronger or not. The tightening force is applied the same. On the top, of course the cone washer captures the stud, locking it to the arm. A bolt simply will not work in this arena as torque will be applied to the tapered surfaces locking and not to the threads.

Matt, failed to use the proper procedure for installing the parts. THAT is the reason for failure. I have been running the stock stuff for years and it does not loosen. Maybe after a few trips though the Rubicon I will need to retorque. Simply said, follow the directions and you can't go wrong. If that can not be done, a person should not be working on these parts.

Upping the pin diameter is a simple, obvious strengthening solution. More pins in the bearing equals more contact to the inner race. Again, math says it should be an improvement. Failing to apply the proper torque and preload WILL result in failure regardless of the above.

[Doof]

after a quick re-read i retract my statement.... guess i should read better

[Rockcrawlintoy]

you said it yourself... bolts should not be in this app


and its Matt, not math




real professional 

no he said bolts wont work in the steering arm application, and that the math goin to figure out loads and what not shows an improvement

[blackdiamond]

 

[COToy91]

you said it yourself... bolts should not be in this app


and its Matt, not math




real professional 

Reading comprehension is also professional

[OOPS]

Lets keep this on topic or I will start deleting posts---THIS IS NOT PBB!!!!!!!!!!!!

[Doof]

THIS IS NOT PBB!!!!!!!!!!!!

sometimes it should be