DMI midget drive line problems
 

i was wondering if anyone else has had problems running the dmi billet u-joint with the dmi torque tube/ball in the steel dmi bell housing? i ran my midget for the first time this year up at ventura and had some bad luck with a car flipping in front of me. we got back to the shop and the next day took the rear end out to check everything over. the u-joint welded it self to the drive shaft as did the torque tube to the ball.

after sitting down to think about what went wrong i took a look at the part number for the dmi u joint in my sprint car and the one in my midget and came to find out that there are the same u joint. no my question to anyone out there is how can you have the same size u joint when the torque tube on both cars (sprint and midget) are completely different.

good thing i had no where to go on the track except to stop because the u joint had started to melt from the begining of the splines back which i think is around 1200 degress. talk about possible hot feet


if anyone has had the same problem let me know obviously i wont be running a dmi u-joint in my midget from this point on.

Re: DMI midget drive line problems
 

The DMI and Winters Alum. U-Joints are too big for the midgets to use. They are oversize compared an MPD/Sander to take the strain of a Sprint Car. When I first got the DMI joint's in I sold one to a midget customer without checking the size and it did much the same as what happened to you, but didn't tear up as much.(That cost me a little money) We made it right for them, but I learned a good lesson.

The best u-joints for a midget are still the MPD or Sander(Although the Sander will barely rub as well) or a l/w steel-Alum. None of the companies listed have a different part number for sprint and midget u-joints unless it may be for the Esslinger.

I would still use a DMI Oversize ball, steel housing(To protect the feet) if you wish, and the DMI Tube because they where not the cause. I really like the housing and oversize ball. The ball eliminates any chance for u-joint rub on the shoulder/cup area.

To answer your question, Yes I have seen that problem.

Sorry to hear of your problems, but at least you weren't hurt.

Best of Luck

Re: DMI midget drive line problems
 

To harken back to the old days, and it hasn't been that long ago, and I'm assuming you are talking about the "yoke", guys would actually cut the length of the yoke down, and only use maybe 2 inchs or so of spline, and then shorten the torque tube length, so only the drive shaft was in the tube, but that was real scarey. What I considered the wise move, was to turn the OD of the yoke to about 1.650, and use it full length, that kept it from wearing out the inside of the tube, and kept the driveshaft from wobbleing. Another thing that will help, is try to keep the pivot points in line, where your torque ball pivots, your rear radius rods should pivot, that keeps the torque tube from moving in and out of the torque ball. It may not be the best for forward bite, but it does keep the tube and stuff happier. On the Tq,s, I've turned the od of the aluminum yokes to actually a smaller od, and they've lived. Going back a bit further, there were several torque ball's available, that had a bearing, right behind the yoke, that supported the driveshaft, in the tube, and that worked really good. I just sold one the other day, to a fellow restoring an older midget, it was the first one I'd seen, made out of aluminum, most were steel. Hang in there, someone will have the answer that suits you best. Bob

Re: DMI midget drive line problems
 

The least amount of trouble is to use an MPD Alum. U-joint or l/w steel yoke u-joint and forget about it. The MPD yoke is a smaller o.d. than the others. You can take some of the I.D. of the tube(some people do that) but it's just basically a clearance issue with the "oversize" u-joint/yoke and the i.d. of the tube.

The bearing in the ball deal was known to cause the drive shaft to break due to the flexing in the driveline. It couldn't flex the same as the rest of the driveline.

Re: DMI midget drive line problems
 

The u joint i swear by is the DMI with the alum base and the lightened steel slip yoke. i have been running it exclusively for about 7 years, ever since my last sander yoke exploded between my feet taking the torque ball with it. it is plenty small to fit in the midget tube and is really a nice peice. the first one i bought is still in use in car i sold a few years back. it has never had a problem and is in its 7 season of use.

I had to give up on the alum. slip yokes after splitting two in one season. i'm no engineer but it was my opinion that the four cylinder harmonics, especially when pushing off were too much for the alum joint. i think they say it comes out about a 1/4 lbs. heavier than the all alum. and use to be less expensive. not a bad trade off for the reliablity you gain.

Steve

Re: DMI midget drive line problems
 

That brings up a good subject Steve.

I do agree that a steel yoke is the easiest to run. I try to always suggest to my Weekend Warrior Sprint customers to use steel because it is easier to care for and less likely to fail. An hour here and there a week is a big deal for someone with limited time and help. A $100 part doesn't become a $600 expense during the year. My midget customers though mostly prefer Alum.

I can only go by my own personal experience: In our Midget we never had the problems with the alum. slip yoke splitting or exploding. We ran one 4 years and another 5 years. We damaged one because we didn't put the spring in the driveline after servicing the driveline and the other we changed when we sold the car. I am not endorsing running one that long, but we were able to.

Although I have seen some incredible explosions in other peoples cars. Shane Hollingsworth at Lawrenceburg and J.D Turner also at Lawrenceburg both come to mind. I have also seen others with parts that fractured, but didn't explode.

It's a funny deal because in reality the yoke and the driveshaft should run pretty much inline with each other. Obviously there is flex and driveshaft "whip" to some degree, but unless the rotating assembly is unbalanced I find harmonics not very likely. I know that when a midget starts up it can chatter, but unless the driver isn't doing it right or if the ignition isn't working properly, it shouldn't shock it to that point.

When examining the causes of a problem we try to get as much information as possible. We try to find out if it's a new car or if they have had a crash or recently replaced some parts.

-I would never run an Alum. yoke w/the end plug welded in. I know some people who have done that or purchased a car that way and it doesn't end up well.
-Unbalanced rotating assembly can cause a problem(Rare as it may be)
-Firewall and Housing misalignment
-Out of square/bent torque tube or driveshaft
-Wrong part for the application(The basis of this thread)
-Yoke rubbing tube for some reason
-Mismanaged maintainence. Alum. yokes need alot of care. A good anti-seize as well as grease needs to be used. They need to be cleaned and relubed regulary.

Like anything else, even when you try to do your best, sometimes a part fails. You just have to try and find out why and move on.

Re: DMI midget drive line problems
 

i appreciate the info leaders edge and i definitly know that this all came down to the ujoint being to big. i only thought that matching a dmi u-joint with a dmi torque tube would work and i was definitly wrong. maybe ill take some poictures of the disaster and post them for you to have a laugh at....just a bummer that somebody would keep selling/promoting the ujoint when all iv heard is problems.


dennis

Re: DMI midget drive line problems
 

Originally Posted by howell62:
i appreciate the info leaders edge and i definitly know that this all came down to the ujoint being to big. i only thought that matching a dmi u-joint with a dmi torque tube would work and i was definitly wrong. maybe ill take some poictures of the disaster and post them for you to have a laugh at....just a bummer that somebody would keep selling/promoting the ujoint when all iv heard is problems.


dennis

I fully understand what you are saying about keeping the parts together. I wouldn't feel too bad, hurts the wallet and pride more than anything.

I have also run across a problem with their front brake mounts. They may work with their spindles, but with any other brand they usually cause the caliper to hit the wheel. I like many of their products, but some of their midget stuff isn't quite right for most applications.

Good Luck!

Re: DMI midget drive line problems
 

Originally Posted by howell62:
i was wondering if anyone else has had problems running the dmi billet u-joint with the dmi torque tube/ball in the steel dmi bell housing? i ran my midget for the first time this year up at ventura and had some bad luck with a car flipping in front of me. we got back to the shop and the next day took the rear end out to check everything over. the u-joint welded it self to the drive shaft as did the torque tube to the ball.

after sitting down to think about what went wrong i took a look at the part number for the dmi u joint in my sprint car and the one in my midget and came to find out that there are the same u joint. no my question to anyone out there is how can you have the same size u joint when the torque tube on both cars (sprint and midget) are completely different.

good thing i had no where to go on the track except to stop because the u joint had started to melt from the begining of the splines back which i think is around 1200 degress. talk about possible hot feet


if anyone has had the same problem let me know obviously i wont be running a dmi u-joint in my midget from this point on.

Yeo just had the same thing happen. It started to melt the torque tube and welded the tube to the yoke, 8 laps from new on new engine warm up only

Re: DMI midget drive line problems
 

Originally Posted by rmb077:
Yeo just had the same thing happen. It started to melt the torque tube and welded the tube to the yoke, 8 laps from new on new engine warm up only

Looks like an obvious case of they don't ck the application, or run their own stuff. That has always been an issue tho, even with the steel yokes, if ya don't turn em down, they're gonna rub, I go so far as to pack some grease inside the tube right there, because even if you do clearance it, and get things in a bind, it's still gonna rub a little. I have also gone to the big ball, but you still need to clearance the yoke, and tube, if you can find someone with a lathe with a big enough hole thru the spindle, just bore the inside out about 5" deep, there is enough wall thickness in that area, to not worry, even if you only take out .060 on each side, that will help. Think you can also buy "thin wall" tubes, but I'm not sure I'd trust one. JMHO. Bob:)

Re: DMI midget drive line problems
 

Funny thing is i thought i had checked it all. (You know what happened to thought) If the guy that sold me the bits or the manufacturer had a statment in the box "torque tube modification required" i would simply have done it and i would be racing on saturday night. Now $400 for all new parts to change the thing that i changed only for the sake of changing it errrrrr. Thanks DMI i,m now the owner of MPD again!

Re: DMI midget drive line problems
 

Originally Posted by rmb077:
Funny thing is i thought i had checked it all. (You know what happened to thought) If the guy that sold me the bits or the manufacturer had a statment in the box "torque tube modification required" i would simply have done it and i would be racing on saturday night. Now $400 for all new parts to change the thing that i changed only for the sake of changing it errrrrr. Thanks DMI i,m now the owner of MPD again!

Well, welcome to the school of hard knocks, to assume, is to err, and you are correct, a simple slip of paper, with just those few words on it, would have kept another loyal customer. Good luck, if it happens again, ck the snout on the rear, it could be bent, or out of alignment. Bob:)

Re: DMI midget drive line problems
 

Wow, this was a fascinating post. I learned a lot from this post.

I have friend in the central valley,Ca and until last year he ran a lot of winged sprint cars. Last year he had four brand new sprint cars sitting in his garage. Two 410's and two 360's with motors ready to go sitting on stands. I was amazed to say the very least. He asked me if I wanted to see his brand new toterhome. I said "no". I know he was baffled why I didn't want to see his brand new toy. I hate looking at things I will never own. It kind of makes you sick to your stomach, so I bypassed the opportunity, if given the chance...lol!

I did happen to notice he had about 10 yokes (?)/"u" joint assemblies, sitting on a shelf. They all looked used. I questioned him about it. He said he replaced the assemblies after ever 10 races.

You guys talked about aluminum "U" joints. Not knowing anything about sprint cars, I got to figure that is the most craziest thing you could own. I can think of a lot of thinkgs made of billet aluminum, but a "U" joints, never. I don't understand it. It don't make sense to me, but then again I don't know anything about sprint cars...lol!

But I will tell you this. If I ran a billet aluminum "U" joint, it would be replaced on a regular basis, religiously.


Sincerely,

And best of luck to Dennis I have watched him a few times from the stands. Definitely a hard charger.

Larry "O" and best to wishes to all and be safe!

Re: DMI midget drive line problems
 

LarryO, the "cross", u-joint, or whatever you prefer to call it, is still an automotive product, the "yoke", which is what he had been replacing, is either steel or aluminum, not the actual "joint, cross", the movable part that connects the yoke to the driveshaft. Bob

Re: DMI midget drive line problems
 

Bob,

Question for you. In general is steel 4 times as strong as aluminum?

So if you replace a steel yoke with and aluminum piece of the exact same size you have just lessened your strength by 75%.

After doing some thinking about this subject, The answer is steel is the better choice. Since everybody has a million dollars to put in a midget, go with Billet steel, since it seems money is no object when putting money in a race car. Machine the billet steel yoke to as small as you want it. The billet will be stronger than billet aluminum and will at least be smaller in diameter for less inertia or energy it takes to turn the yoke, during acceleration. It seems acceleration is what people want, so make a yoke out of billet steel and keep the diameter as small as you can, like the journals on a SBC, Honda crankshaft journals?

Wasn't try to steel this post and thanks for correcting me on the misunderstandings of this post and the "U" joint in a Yoke assembly ? I was trying to learn something at other people expense. Sorry for that!

Yeah, I think an aluminum yoke is way less stronger than any steel piece you can buy.

Sincerely,

Larry Otani and God bless you all!

Re: DMI midget drive line problems
 

Larry, I think it's about 6 of 1, and a half dozen of the other, I've run both, and it's usually something else takes them out, before they wear out. I'm assuming the aluminum ones are made out of T7, which is pretty close in strength to steel, in this application, I've seen some pretty ragged looking one's of both materials. Yes, you can machine the steel one's down and get them light, but not as light as the T7, and by then, the strength is gone. I've actually turned the T7 one's down, quite a bit, to get clearance in the tube, and they've held up OK, like I said, something else usually gets them first. Bob:)

Re: DMI midget drive line problems
 

I had the same problem when they 1st came out years ago.The od. is too big. I called DMI and got the old "we never heard of that before".... Call winters they make a billet alluminum u-joint assembly for a midget.Iv'e had the same one in for 2 yrs with no problems. It's the same part number as the sprint u-joint but add -M after the number. Steve Buckwalter

Re: DMI midget drive line problems
 

Steve, I have an internal coupler, lower shaft, that is ONE piece, but no one will admit to making it. Winters didn't even bother to reply to my question about it, it eliminates the leak up the torque tube, I'd like to find another one, but can't find out who, or why they only made one, the tooling marks look just like Winters, but they deny it. Bob:)