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heim joints on wcm ultralite /xr7 and other 7s


RGTorque

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hey that's very slick, jerry!

you have your own lathe? that must be handy.

i see you've mounted the control arm inboard of the shock, which seems the more intuitive way of putting the components together, yet all of the ultralites i've seen (including mine) have the control arm between the shock and upright. i'm sure there's a reason for it but it's not obvious to me.

 

I actually have no idea why I mounted it inboard, perhaps because the main load on that bolt is the car weight, I wanted it as close to the mount as possible.

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I actually have no idea why I mounted it inboard, perhaps because the main load on that bolt is the car weight, I wanted it as close to the mount as possible.

 

right. it's the way that it's typically done -- shock far away from the upright and creating a large moment arm -- that's counterintuitive to me.

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  • 2 weeks later...

well i finished replacing all the rod ends this weekend. wow, what a difference! no squeeks, not rattles! and it really feels buttoned down now. what a transformation! i thought any change in handling would be very subtle, but it's really a remarkable improvement.

 

thanks to all who have posted on this topic, especially roman for starting this thread and providing the part numbers.

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well i finished replacing all the rod ends this weekend. wow, what a difference! no squeeks, not rattles! and it really feels buttoned down now. what a transformation! i thought any change in handling would be very subtle, but it's really a remarkable improvement.

 

thanks to all who have posted on this topic, especially roman for starting this thread and providing the part numbers.

great to hear that the result was worth the work in your case. we are completing the heim swap, installation of crosswise diff brace and other repair and upgrade work on my wcm s2k this week, hopefully in time for an alignment on thurs. after the alignment, i will promptly report my results - hope they are salutary as yours!

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well i finished replacing all the rod ends this weekend. wow, what a difference! ... especially roman for starting this thread and providing the part numbers.

 

Congrats Scott, glad it turned out so well. Now if only there were some way to make a car work great without all the time, effort and attention to detail ! (other than spending a ton of money, of course) :-)

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While replacing the heim joints on my ultralite I came across the two upper control arms (both front wheels) that are using 5/8" bore holes on the heim joints but that have 1/2" bolts. See pictures below. That means there is "slop" unless the heim ball is pinched within the bracket, and even then that is a scary thought that the alignment could move so drastically if say you hit a bump/pot hole.

 

http://i197.photobucket.com/albums/aa105/joshsalvage/IMG_0929_zpsdaada330.jpg

http://i197.photobucket.com/albums/aa105/joshsalvage/IMG_0930_zps08926f7c.jpg

http://i197.photobucket.com/albums/aa105/joshsalvage/IMG_0931_zps2eb8e80e.jpg

 

 

My question to you other Ultralite owners, especially the ones who have now replaced all of the heim joints... did you notice the same issue? (or is mine just extra special?)

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joshesh,

 

i think maybe yours is special! it's interesting the things you find when taking these cars apart.

 

the parts list in roman's original post was correct for my car -- 28 rod ends with 1/2" bore and 4 with 5/8" bore (all 4 of these on the rear). all of the rod end bores on the front are 1/2".

 

also, your shoulder screw is too long -- by about 1/4" from the looks of it. i initially ordered screws that were too long myself. most of the brackets required screws that had 1 1/4" long shoulders (as i recall the spherical bearings were 0.75" thick and the spacers built into the brackets were ~0.5" thick). i believe there were 2 in the rear that required 1" long shoulders.

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My upper control arms had the right sized bolts but the only real "failure" I had was the drivers side upper rear heim joint, really pounded out the actual ball and enclosure and had imprinted the thread pattern into the bore from the constant movement. Really makes you want to check everything on your car when you find something as obviously miss-done as a 1/2" bolt in a 5/8" bore.

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  • 1 month later...

Last year I had an off that was compounded by the failure of the long bolt that holds the lower rear control arm. Off was fairly minor but I was sliding sideways and the bolt sheared at the hub carrier making the wheel just kind of flop around and rub quite a bit. Did the repair(right side)myself and while I was at it I pulled the left side and it was perfectly straight.

This past Thursday I was at Thunder Hill running the course "backwards" and very late in the day (open track all day and a lot of laps) had the left side bolt fail while on track. Have the whole thing on GoPro video and it is pretty weird. Late in the day, not even pushing hard as was catching some traffic, just completed turn 3 and on the short straight into turn 2 let off on the gas (no brake) and the left rear tire just went sideways. You can hear it fail with the car dead straight and into an immediate spin. Locked it down and when the car went spinning backwards the tire went from "out" to "in" and the end of the broken bolt, the spacer,the heim joint and the end of the aluminum control arm jammed into the tire and sheared the whole thing off.

The car has a lot of track miles but this was the first time I had run slicks. I do take a lot of passengers on track (some pretty heavy) but don't use the berms all that much as it upsets the car so don't quite know why the failure happened. I haven't seen anything about this as a regular failure point and RNR is running an older S2K with lots of track time and his seem to be OK.

I'll get a couple of pictures and post them. Not an expensive fix car parts wise but I did just have to spend over $300 to replace the brand new slick :-(.

I'll be looking at what I can do to beef up this part of the suspension as it will be in my head whenever I'm on track from this point forward.

Anyone else have this problem before?

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Bolts are grade 8, hardest that should be used because a grade 8 is supposed to bend before it brakes, harder will be stronger but will shear, like this one seemed to.

I replaced the bent shock mount bolts when I first got the car and made a spacer to prevent it happening again. Going to try to think of a solution to this one that doesn't add too much weight.

There are a few other post about the shock mount spacer but mine was dead simple and cheap and the bolts are now 3-4 years old and not a hint of a problem. I'll find the drawings for it and post it when I get a chance. you can see it in the photo.

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Hi Jim,

Just read your post and looked at the photo of the broken long bolt and the control link end. It would be good to see the part that broke off and a close up photo of both to see if one can determine if the arm failed first or the bolt failed causing the arm to break and bend. Just a thought but the long bolt seems to be under a lot of load stress by having the hiem joint so far from the hub carrier. I would make the spacer that is shown in rnr's photo larger in diameter and out of steel and not aluminum as the aluminum will tend to flex more and help cause a shear failure at the hub carrier but that is just my belief and with out seeing the parts first hand is just a guess on my behalf. Also make the spacers thru bore as close as possible to the diameter of the bolt so the bolt has as little slop in it as you can. You might have to add shim material to the bore once you install the spacer to take up the slop needed to get over the threads if you stay with that setup.

Hope this helps.

:driving:

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interesting. and my spacer's even longer than rnr's -- over 2". :^o

 

mhkflyer: do you have any suggestions for "shim material"? when i recently replaced the heim joints on my car, one place i was unable to remove slop was on these "long bolts" (the other was the shock mounts). i used shoulder bolts everywhere else, but there is slop where the bearing slides over these threaded bolts. i wrapped the threads with enough teflon tape to make it feel snug, but i wouldn't think that will help with much beyond making it a bit quieter.

long bolt.jpg

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I have never seen those bolts break. We pulled a heavy trailer for 8k miles that often bottomed the shock out on hard bumps and I had them bend a little from that but never had a complete failure. I also used a tapered spacers on my bolts.

 

How long are the spacers on your car? Jim said his were 3-4 inches in length while rss and I also have different lengths.

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