U-joints (DSM vs. Evo3 vs. Aftermarket)

[DSSA]

I was emailing with another OG DSM owner tonight, who is rebuilding a 1G AWD for his son.

He contacts me when they're working though another segment of the car (MUCH appreciated, and I'm honored), and today, we've been working on rebuilding the driveshaft on said car.

He's already purchased OEM carrier bearings through me, but was looking to rebuild the shaft itself, so we're talking u-joints, yoke, lobro joint boot kit, and mounting bushings at this point.

We went back and forth with the list and what is actually available (meaning---there are some in the U.S., and can be had), and pricing.

The yoke--well, that's a captive audience. We have/have had them on constant back order status with Mitsu for the last 2-3 years. We order 20, we see 4-5 per evey 2-3 months. We typically have a waiting list of people who want them, but for once, we have 5 of them on the shelf as of last week. Mitsu's U.S. inventory is at 0 again which is typical, so this is making me feel like a kid at my 8th birthday party and I just got a RedRyder BB gun!.

The Lobro joint on this car is missing the boot--"no beuno". These things RARELY go bad without a ripped (or in this case, "missing") boot, and dirt/debris getting into the joint and someone driving on it. I can probably count on two hands the number of these joints going bad over the last 25+ years of doing this without a ripped or missing boot. If they *do* (for either reason listed above), Mitsu VERY rarely brings these into the country (going back over 20+ years here), so you're looking at a monthS long wait, and they were quite "proud" of them (MSRP was $380.05). They're now another discontinued part, but even 20 years ago, I would have suggested finding another propeller shaft (used) to rebuild.

The propeller shaft boot kits are still (for now) available, but no matter how many I order, we typically only have one on the shelf per month--and once again, typically a waiting list of customers. Point being, if you have a ripped boot, take care of it NOW. Don't let it kill that joint and become a BIG headache.

Bringing us to the elephant in the room....the u-joints.

These are the same as the above. I order 20. Mitsu brings 10 into the U.S.. I order 20 more, wait a couple of months, and get 5. I order 20 more...rinse, repeat.

Part of my job these days, is trying to find in-roads to Mitsubishi's actual suppliers. If they're not willing/wanting to keep a part around, I try to make contacts with the company that supplies/supplied them the parts, then order them in bulk to meet their purchasing requirements for a vendor, then ship a crate from Asia of them. That's why we're able to offer things like the "White Box" idler and tensioner bearings (among other things) for some of these parts at 1/2 the cost as buying them from Mitsu, but they're the SAME OEM part.

This hasn't happened with the u-joints though.

They're expensive now that Mitsu has discontinued the MR470072 recall kits which Mitsu intentionally priced ridiculously low to keep "recall costs" low. Look that part number up...they were DIRT cheap for almost 3 decades, while the u-joint part numbers (MB837300) and the Yokes (MR111611) were twice the cost...EACH. No one bought the u-joints and yoke part numbers for decades. Why would you? You can get them combined for 1/10th the cost!

Turns out, that Mitsu let that run the course (legally--and a lot longer), and the Suzuki Samurai guys were buying them left and right as they were stonger than what they could get from aftermarket companies (Dana/Spicer/etc.).

Back in the 90's/early 2000's, people (DSM people...), tried going with aftermarket u-joints. It was quickly found that even 13 second/high 12 second cars were shearing aftermarket u-joints regularly. So, for 20+ years, no one would touch them. The biggest issue was that the cross shaft itself was failing (they are all drilled internally so that you can grease them via a zerk fitting).

Over the last two years, we've been trying to find a replacement. If it's got a zerk (grease) fitting..PASS. This weakens the cross shaft itself (hollowed). On top of that, the cross shaft design is weaker as well on everything I've found thus far.

With one of my own cars (GVR4) that I pulled out of storage, I ordered some Evo 1/2/3 u-joints into the U.S., thinking that I'd found a cheaper version to rebuild it. Turns out, Mitsu actually understood that DSM's, despite the slight power defecit, were heavier (U.S. B.S.) and increased the strength of the cross shaft itself. See below, how they reinforced them (Evo 1/2/3 on the right/DSM unit on the left):

You must be logged in to view this image or video.

 

[Junglejim23]

I was emailing with another OG DSM owner tonight, who is rebuilding a 1G AWD for his son.

He contacts me when they're working though another segment of the car (MUCH appreciated, and I'm honored), and today, we've been working on rebuilding the driveshaft on said car.

He's already purchased OEM carrier bearings through me, but was looking to rebuild the shaft itself, so we're talking u-joints, yoke, lobro joint boot kit, and mounting bushings at this point.

We went back and forth with the list and what is actually available (meaning---there are some in the U.S., and can be had), and pricing.

The yoke--well, that's a captive audience. We have/have had them on constant back order status with Mitsu for the last 2-3 years. We order 20, we see 4-5 per evey 2-3 months. We typically have a waiting list of people who want them, but for once, we have 5 of them on the shelf as of last week. Mitsu's U.S. inventory is at 0 again which is typical, so this is making me feel like a kid at my 8th birthday party and I just got a RedRyder BB gun!.

The Lobro joint on this car is missing the boot--"no beuno". These things RARELY go bad without a ripped (or in this case, "missing") boot, and dirt/debris getting into the joint and someone driving on it. I can probably count on two hands the number of these joints going bad over the last 25+ years of doing this without a ripped or missing boot. If they *do* (for either reason listed above), Mitsu VERY rarely brings these into the country (going back over 20+ years here), so you're looking at a monthS long wait, and they were quite "proud" of them (MSRP was $380.05). They're now another discontinued part, but even 20 years ago, I would have suggested finding another propeller shaft (used) to rebuild.

The propeller shaft boot kits are still (for now) available, but no matter how many I order, we typically only have one on the shelf per month--and once again, typically a waiting list of customers. Point being, if you have a ripped boot, take care of it NOW. Don't let it kill that joint and become a BIG headache.

Bringing us to the elephant in the room....the u-joints.

These are the same as the above. I order 20. Mitsu brings 10 into the U.S.. I order 20 more, wait a couple of months, and get 5. I order 20 more...rinse, repeat.

Part of my job these days, is trying to find in-roads to Mitsubishi's actual suppliers. If they're not willing/wanting to keep a part around, I try to make contacts with the company that supplies/supplied them the parts, then order them in bulk to meet their purchasing requirements for a vendor, then ship a crate from Asia of them. That's why we're able to offer things like the "White Box" idler and tensioner bearings (among other things) for some of these parts at 1/2 the cost as buying them from Mitsu, but they're the SAME OEM part.

This hasn't happened with the u-joints though.

They're expensive now that Mitsu has discontinued the MR470072 recall kits which Mitsu intentionally priced ridiculously low to keep "recall costs" low. Look that part number up...they were DIRT cheap for almost 3 decades, while the u-joint part numbers (MB837300) and the Yokes (MR111611) were twice the cost...EACH. No one bought the u-joints and yoke part numbers for decades. Why would you? You can get them combined for 1/10th the cost!

Turns out, that Mitsu let that run the course (legally--and a lot longer), and the Suzuki Samurai guys were buying them left and right as they were stonger than what they could get from aftermarket companies (Dana/Spicer/etc.).

Back in the 90's/early 2000's, people (DSM people...), tried going with aftermarket u-joints. It was quickly found that even 13 second/high 12 second cars were shearing aftermarket u-joints regularly. So, for 20+ years, no one would touch them. The biggest issue was that the cross shaft itself was failing (they are all drilled internally so that you can grease them via a zerk fitting).

Over the last two years, we've been trying to find a replacement. If it's got a zerk (grease) fitting..PASS. This weakens the cross shaft itself (hollowed). On top of that, the cross shaft design is weaker as well on everything I've found thus far.

With one of my own cars (GVR4) that I pulled out of storage, I ordered some Evo 1/2/3 u-joints into the U.S., thinking that I'd found a cheaper version to rebuild it. Turns out, Mitsu actually understood that DSM's, despite the slight power defecit, were heavier (U.S. B.S.) and increased the strength of the cross shaft itself. See below, how they reinforced them (Evo 1/2/3 on the right/DSM unit on the left):

You must be logged in to view this image or video.

To the best of your knowledge is there a replacement U joint that's as strong ? What company produced the joint to begin with ? GMB ? .

 

[DSSA]

To the best of your knowledge is there a replacement U joint that's as strong ? What company produced the joint to begin with ? GMB ? .

The first part of your question is answered in the above post--"not to my knowledge", otherwise the post above would be moot. ;-)

The second part, the cross shafts are seemingly a proprietary part.The bearings themselves, I can track down, but the cross shaft itself is the missing link. All of the aftermarket units (as noted above) are either port-drilled (most common), or of the weaker cross shaft design without the grease ports (and THOSE are hard to find).

If Mitsu discontinues these, and cuts us off completely (which is looking like it will happen sooner than later), it may be a case of someone stepping up to the plate and making a large investment on having the cross shafts replicated to spec.

 

[EC17PSE]

is just a rough sketch and no actual sizes to compare but its doable for sure. if these break in stock form they can be made stronger still and / or a better material even

You must be logged in to view this image or video.

You must be logged in to view this image or video.

 

[greddy_1700]

Looking on RockAuto, the GMB U-joint seems to have the same design as factory, however, it does look like its cross drilled. This might be a silly comment, but has anyone contacted GMB regarding these U joints, and see if they can produce without the cross drilling? I would assume that these are cast solid then drilled after the fact, so if anything it would reduce their machine costs (unless I am wrong about that and if they arent cast solid.)

 

[diambo4life]

When I worked at PepBoys years ago, this is what we sold for our cars. The GMB. It was definitely beefier than all the other aftermarket ujoints I had come across to that point. The Galant had a healthy appetite of chucking other ujoints with no disregard to my feelings....

Also very interesting the EVOs had a smaller cross shaft. I never ever broke a ujoint in my old mid 10 second Talon. Everything including the tcase was bone stock from the factory....and that thing must have been at the track 500x with a healthy 3100lb with me. No sticky tires though. Just street radials.

 

[jdxnc]

I've had this GMB saved in my Summit wish list for a while, was told it works on a DSM and isn't cross drilled, similar to the OEM

GMB North America 220-0107 GMB U-Joints | Summit Racing

Free Shipping - GMB U-Joints with qualifying orders of $109. Shop U-Joints at Summit Racing.

www.summitracing.com

 

[Mech Addict]

is just a rough sketch and no actual sizes to compare but its doable for sure. if these break in stock form they can be made stronger still and / or a better material even

You must be logged in to view this image or video.

You must be logged in to view this image or video.

At some point there is a limit to how much room between the yokes will allow for more cross material. The next move would be to start with a stronger allow of steel, I suppose.

Looking on RockAuto, the GMB U-joint seems to have the same design as factory, however, it does look like its cross drilled. This might be a silly comment, but has anyone contacted GMB regarding these U joints, and see if they can produce without the cross drilling? I would assume that these are cast solid then drilled after the fact, so if anything it would reduce their machine costs (unless I am wrong about that and if they arent cast solid.)

Probably forged, not cast, but your point is worth exploring. If Mitsubishi stops offering completely, then another manufacturer could compete on quality, and not just cost.

 

[EC17PSE]

At some point there is a limit to how much room between the yokes will allow for more cross material. The next move would be to start with a stronger allow of steel, I suppose.

If the evo ones fit and the dsm ones are this much reinforced it might have enough room even if its anothef MM or two its enough to help and agree on material! They can be made from material like EN24T or EN30 which is very very strong

Probably forged, not cast, but your point is worth exploring. If Mitsubishi stops offering completely, then another manufacturer could compete on quality, and not just cost.

Cost would require hundreds to be made and possible testing. A forge die of this size in a package of 4 would be about 30k as an est based on what we have worked on before then machine time and then testing on batches. Long term would be fine if it could be made in thousands but likely wont be so cost might be a problem as they would be a small quantity likely.

 

[bastarddsm]

Going hog wild on the cross is silly. It's pretty easy to twist the yokes as is. A decent replacement is all that's needed. If you need more, time for a better driveshaft.

 

[greddy_1700]

Cost would require hundreds to be made and possible testing. A forge die of this size in a package of 4 would be about 30k as an est based on what we have worked on before then machine time and then testing on batches. Long term would be fine if it could be made in thousands but likely wont be so cost might be a problem as they would be a small quantity likely.

I would agree, but it looks like the photos of the GMB joint already mimics the factory design better than anyone else. They may already have the design right, just need to eliminate cross drilling. Likely a bit optimistic as they likely use a lower alloy, but you never know I suppose.

 

[EC17PSE]

I would agree, but it looks like the photos of the GMB joint already mimics the factory design better than anyone else. They may already have the design right, just need to eliminate cross drilling. Likely a bit optimistic as they likely use a lower alloy, but you never know I suppose.

Yeah i dont know if they will devolge the material but they may look at non cross drilling. They likely went for optimal strength as drilled means it is less likely to bend as its 2 surface areas so acts stronger then a solid. More deflection can be had with less cracking. Material plays a role also in the design

 

[Mech Addict]

I was imagining getting them machined from billet, and not a new forging. I’m not knowledgeable enough about the materials to say it would work or not. Entirely new shafts with everything upgraded is certainly one option, and after rebuilding my entire driveshaft with oem, the price is not all that much more. I wonder if there is a slightly larger existing cross in common use that could be suitably machined down to fit properly and be stronger than the current aftermarket.

 

[EC17PSE]

I was imagining getting them machined from billet, and not a new forging. I’m not knowledgeable enough about the materials to say it would work or not. Entirely new shafts with everything upgraded is certainly one option, and after rebuilding my entire driveshaft with oem, the price is not all that much more. I wonder if there is a slightly larger existing cross in common use that could be suitably machined down to fit properly and be stronger than the current aftermarket.

Im not sure if one will cross over. The age of the cars it might of been stumbled across already but i could be very wrong on that if no ones looked properly. Anything is possible for sure though if one body will fit turning down the race sections would be ok if nice and smooth

 

[Mech Addict]

Yes, I thought about your last point after I posted that. It’s not only a matter of machining the part, but also would need to polish it to a very smooth finish to act as a bearing surface. I suppose that’s not too different from what some shops do with cranks and cams, but a much smaller diameter might require more specialized equipment. Presumably one could then use the needles and caps from typical aftermarket joint.

 

[bastarddsm]

what about heat treating? The needles will just brinnel the soft steel after you machine the case off it........

 

[Mech Addict]

Yeah, that makes sense too. Do cranks and cams receive that treatment? I assume trans gears and r&p sets must, for their high load pressures. Sounds like machining down u-joints from larger ones would take a lot of processing.

 

[EC17PSE]

what about heat treating? The needles will just brinnel the soft steel after you machine the case off it........

will likely be through or induction hardening to avoid making it to brittle for the remainder of the material as thats the last thing you want is the body cracking as its now to brittle. different materials effect this process also and you can do things like grinding the bearing surface and this will greatly make a different vs turning it finely.

 

[bastarddsm]

will likely be through or induction hardening to avoid making it to brittle for the remainder of the material as thats the last thing you want is the body cracking as its now to brittle. different materials effect this process also and you can do things like grinding the bearing surface and this will greatly make a different vs turning it finely.

Are you high? The cross is the INNER RACE, it needs to be a bearing surface, rockwell c 60+, that doesn't happen without carbon. It needs to be case hardened. And with the correct temper the core will still be ductile. This is like metallurgy 101 boss. You can't through harden it, cause the whole thing will end up at hrc60, or if you leave it say 30 to stay ductile it'll be too soft and the needles will embed. There is a small possibility that it could be induction hardened to get a good case, but again it needs carbon, IIRC most steels that would be induction hardened only go to about hrc50 or maybe a little higher.
Nitriding could be another possibility, but I'm not sure if you could get a deep enough case that way to avoid case crushing.

You need to do some research before you start trying to solve the worlds problems.

The end all for brutal strong u joints is to do away with the needles and just be lubricated steel on steel. They are popular in 4wd front axles as they are space constrained and need all the strength they can get, they are making yokes and joints out of vascomax and the like. Most of this stuff is slow speed, but high displacement. We have high speed, but minimal displacement, might be some obstacles to overcome, but not insurmountable. In the end though we don't need that, like I said before you can twist the stock yokes with a stock u joint.

Yeah, that makes sense too. Do cranks and cams receive that treatment? I assume trans gears and r&p sets must, for their high load pressures. Sounds like machining down u-joints from larger ones would take a lot of processing.

cranks sometimes nitrided. That has to do with wear and fatigue resistance. They don't have the point loads of a needle roller beaing. Motorcycle/2 stroke ect that does use needle rollers are in fact case hardened. Lots of crank pins are 8620 with a 0.060"+ deep case.

Roller cams are iron and induction hardened, or 8620 and case hardened. Some are tool steel and through hardened. Again in general they don't have the point loads, but when you get up there in ramp rate and spring rate they do and ind hard iron don't last. 8620 barely lasts and the good ones are tool steel or 9310 case hardened. Gears are case hardened usually as well. There are some studies of using nitriding alloys or through hardening such as vascomax, but case hardened 9310 is KING of fatigue life. Lots of NASA papers out there on this stuff. It's not a mystery.

The only way turning down another cross would work is if you could find one very close in size. shooting from the hip like take max of 0.010" off. You'd have to calculate the loads, then get a coupld example crosses to cut apart polish the cut and etch to see the case depth, and decide if there is enough after machining (grinding)

 

[EC17PSE]

Are you high? The cross is the INNER RACE, it needs to be a bearing surface, rockwell c 60+, that doesn't happen without carbon. It needs to be case hardened. And with the correct temper the core will still be ductile. This is like metallurgy 101 boss. You can't through harden it, cause the whole thing will end up at hrc60, or if you leave it say 30 to stay ductile it'll be too soft and the needles will embed. There is a small possibility that it could be induction hardened to get a good case, but again it needs carbon, IIRC most steels that would be induction hardened only go to about hrc50 or maybe a little higher.
Nitriding could be another possibility, but I'm not sure if you could get a deep enough case that way to avoid case crushing.

You need to do some research before you start trying to solve the worlds problems.

The end all for brutal strong u joints is to do away with the needles and just be lubricated steel on steel. They are popular in 4wd front axles as they are space constrained and need all the strength they can get, they are making yokes and joints out of vascomax and the like. Most of this stuff is slow speed, but high displacement. We have high speed, but minimal displacement, might be some obstacles to overcome, but not insurmountable. In the end though we don't need that, like I said before you can twist the stock yokes with a stock u joint.

You do realise that through and induction hardening is just a version right and its not set to just 1 thing. You have many forms of either or. We dont know whats been done to them exactly. Those are the 2 most common ones i just mentioned, im not saying 1 is set but just a general idea that is all.

Love how you always go on one makes life so funny you getting ya knickers in a twist haha.

Im not a hardening specialist and would consult on one for the job anyway so we work together to get the correct harness and finish without making it to brittle etc etc.

 

[bastarddsm]

It's scary that you make the parts you make with such a lack of understanding of these engineering and manufacturing principles. You best figure out how to test it so you don't dump some fail prone junk on your customers.

 

[Mech Addict]

Informative and colorful discussion. It brings up a point that I have wondered about for some time. Why do ujoints use needle bearings at all. Sounds like some don’t, from what bastarddsm alluded to. Under the typical few degrees of articulation (even less in the essentially fixed dsm prop shaft), the joint is barely rocking back and forth. All the load is transferred through only a few of the needles, with all the others just keeping the spacing correct. Unless they have some way of circulating that isn’t obvious, I have a hard time understanding how those few unfortunate needles don’t end up distorted from the constant loading. Seems like with such minimal movement the lubricant wouldn’t be that critical.

 

[EC17PSE]

It's scary that you make the parts you make with such a lack of understanding of these engineering and manufacturing principles. You best figure out how to test it so you don't dump some fail prone junk on your customers.

My current parts are not heat treated nor need to be so thats why i make them. So im not an expert on hest treatments and hows that a reflection on other items i make? You know how this makes you look right! Anything like this that requires any hard surface would be sorted properly with people who are in that sector and as i said before if you read it!!! So we get it right!!

 

[DreamChaser7]

It's unfortunate that some people find the need to attack people constantly and don't understand that their good points and information get lost in the messaging and vitriol. The exact reason I've never had any social media, don't have the time or energy for the bs. I would, and sure most would, like to be able to get new information and knowledge without having to weed through rude comments. Just sayin.

 

[Mech Addict]

There is a point where lively discussion and razzing crosses into hostility and public shaming. It’s better to state what you know or think rather than what someone else doesn’t know. Ujoints are getting scarce as are lots of parts. We need to find ways to address these issues if our hobby with these cars is going to survive. Supporting vendors, freelancers, and directed pleas to manufacturers are really our best shot.