is this "safe?" (Fungineering steering parts)

shameless plug from my build thread but I wanted to pick the hive mind on this. 

this is how we ended up on the last rally, only a few miles into the first stage: the co-driver side was pointing straight ahead btw...

right on the edge of the cliff (picture doesn't do it justice, luckily there were small enough trees to catch us and we weren't going super fast at that spot)

which happened from a rock + dip/bump in matter of seconds:

It below BELOW the pickup point and this was a brand new OEM outer tie rod, it was a bit tricky getting it out as I couldn't pull the bolt through the top because of said taper but by lowering the jackstand onto a stick it was enough for the impact to do its ugga dugga and retrieve the failed bolt. After the stages were swept we had our crew bring us parts and fixed it then drove back to service. With rallies, you always have/need spares. I am pretty good about this as I can't rip parts off another subaru with a blown headgasket like everyone else (theres always one) at a rally.

So this brings us to steering version 3 (or possibly more, IDK - I haven't really kept track so lets just say V3)

I have been told by the facebooks drifty boi's that caravan outer and inner tie rods (roughly 2006 era) work and are far beefier, and they weren't kidding, it upgrades from an m12 bolt to an m14 thread on top of a beefier inner tie rod shaft

From Left to right: OEM/Stock Rx7, S14 240sx, dodge Caravan

lots more material and thread engagement (current knuckles only give about 12mm of engagement on stock tie rod ends) 

these mini van ones are beefy, don't let the rx7 one fool you (square flange) as that flange drops off quick. top is 240sx

my only concern is that the taper on the Nissan and Dodge outer tie rod ends leaves a similar gap before the start of the boot to the bottom of the knuckle but it has very similar overall engagement depth as stock one does, but maybe this is no issue as the boot on the stock one covers more taper but the taper portion on both of these are quite a bit longer than stock. 

(left rx7, right dodge caravan)

The thought behind all of this is the added force of the electric power steering and the shortened knuckle pickup points are causing more force/stresses in this area. The dodge ones are greasable too which is nice and has ALOT of depth to have the outer tie rod end eat up:

is there a guideline on outer tie rod ends? How much taper to base is acceptable? if I bore out the knuckle it will have a lot more gap between the threads of the outer tie rod and knuckle end but I can get more engagement on the spindle part of the balljoint of the tie rod. 

furthermore I don't feel like putting my life in my own hands out of idiocy. with that much gap am I just asking for it to sheer?

Technically, what you've done if you don't seat it all the way is potentially change the arc of the tie rod end from stock. Which can create bump steer, or correct it, depending.

Which is also part of the problem with using the longer Caravan rod end. That longer rod end changes the arc as well. In most cases longer tie rods don't induce bump steer like shorter ones do. But realistically if the car doesn't have bump steer now, you don't want to change anything that might induce it. 

I would measure the RX7 end and call Howe and see what they have that would fit from the circle track bin. The studs on Howe's tie rod ends are replaceable by removing a circlip and threaded base (with grease zerk fitted as well). Bonus there is you can get a few rod studs to adjust height and correct any bump steer in the future. 

Are the tapers the same degree? If not, you should be able to ream it to the needed spec. I'll be doing that on a street driven car because of a disc brake upgrade.

is there a chance that the tie rod end ran out of articulation? 

Recollection is that the ball joint will run out long before the tie rod end does, but weird things happen I guess.

It is just bizarre for the stud itself to break, and not just pull the ball out of the socket.

DocRob said:

Technically, what you've done if you don't seat it all the way is potentially change the arc of the tie rod end from stock. Which can create bump steer, or correct it, depending.

Which is also part of the problem with using the longer Caravan rod end. That longer rod end changes the arc as well. In most cases longer tie rods don't induce bump steer like shorter ones do. But realistically if the car doesn't have bump steer now, you don't want to change anything that might induce it. 

I would measure the RX7 end and call Howe and see what they have that would fit from the circle track bin. The studs on Howe's tie rod ends are replaceable by removing a circlip and threaded base (with grease zerk fitted as well). Bonus there is you can get a few rod studs to adjust height and correct any bump steer in the future. 

This is the missing data point, I don't have a bump steer gauge and I don't know who does/knows how to use it. I'm sure I could dig someone up in my area (Metro Detroit). From a setup perspective the car never felt better with the new knuckles/power steering out on stage, so if I am experiencing bump steer now is and I don't notice it/aware is bump steer a bad thing? 

After all in a rally car its bumpy all the damn time, I usually don't even mess with tire pressures throughout the day. 

As far as the caravan setup goes, I can get the lengths with inners/outers matched up pretty well with the rx7 one. 

In reply to Pete. (l33t FS) :

Possible? Not really sure how to tell or diagnose that, full droop seemed okay and it only has 7" of travel. The failure is the weird part as I would have expected them to snap at the nut end and fall out, rip out threads & etc but not like this. 

I can't really tell from the picture how that joint failed.  Did the tapered stud shear at the bottom of the hole in the knuckle?  If that's the case then I can't help but wonder if there wasn't something wrong with the stud or if, as Pete suggested, it ran out of articulation so that it experienced an unusual bending force.  That's a really bizarre failure mode.  If there steering forces are too high I would expect the inner tie rod to buckle long before the stud bent and sheared and I would expect an impact sufficient to pull the stud outward enough to shear would cause other damage like a bent wheel.

An easy way to test if the joint is running out of articulation is to install the stud but don't tighten the nut so the stud can still be moved up and down in the hole.  Jack the car up so the suspension is at full droop.  Move the steering through it's full range and make sure you can still slide the stud up and down.

I like that the Dodge tie rod end has more thread engagement in the inner tie rod but that's not where you're experiencing failure so I don't know how much value that really has.

Due to the fundamental nature of the tapered joint unless you ream the hole larger both the Nissan and Dodge ends are going to have the exact same cross section at the bottom of the hole in the spindle as the stock part.  Additionally the longer stud will increase the leverage on the stud, reduce available suspension travel before binding and change the bump steer characteristics.  There's no way to know without measuring if it makes it better or worse. 

If you ream the hole so that the stud goes deeper into the spindle then the spindle will be weaker due to the loss of material.  My suspicion is that there's plenty of material there but that's just a guess.

I would almost be willing to chalk this failure up to an improperly hardened stud than just about anything else. 

I would try APEowner's advice on checking for binding throughout the steering range at full droop. If there isn't any. I think I would source a tie rod end from another vendor and try that. 

Otherwise, you might be fixing something that isn't truly broken. 

Do the Driftykids get similar broken studs? 

In reply to APEowner :

That is a good way to test, I can definitely check that out - thank you!

I will have to find the broken piece as it broke about 4mm below the knuckle - I think part of the reason is probably over torqued  (ugga dugga) on install then so it got stretched out and with the right impact it went snap. The wheels are braids so they "don't" bend easily at all, very beefy. 

I haven't had tie rod issues before and ive done 15 rallies on these inners alone so I am a bit hesitant to just go off the deep end here but the last thing to get changed was within the steering system and then this failure occurred but I can't say for certain its just a bad outer tie rod end fault. 

ideally I need to get the car aligned on both tie rod setups and measure bump steer to be sure, like DocRob said I don't want to fix something that isn't truly broken. I have actual broken things on the car I need to attend to. Not sure about the drifty folk failures, I think theirs are more from hitting walls and bending inner tie rods. 
 

If this failed part way through the steering arm, not top or bottom, the taper was wrong and it was over tightened, or the hole has ovaled out some. Everyone else who commented is also correct..! All of the standard road car tie rod ends tighten at least to the base of the boot, and many somewhat farther. 

I've been running this setup, on my fc champcar, for 3 years.  Beefy!  I will say that there can be some bind at the end of travel for bump and especially droop.  These tie rods have dealt with it amazingly.

Not sure how much travel you use, but when switching these MAY become your travel stops.  Not good.

Check for bind at full bump, full lock- it's a rally car.  Easy if you take the springs off. I would bet that the driftyboi knuckles were designed with about 3" of travel in mind. 

In reply to ¯\_(ツ)_/¯ :

Good point, although the ball joint to tie rod end relationship looks very similar to stock.  I found with stock struts that the ball joint was fine at absolute max compression, but with my 8" travel struts that the ball joint would lock at full droop unless I had a small amount of positive camber dialed in, but this also was with his subframe/suspension in a different chassis with different strut tower height, and the body would hit the tie rod at max bump/steering, so *shrug*

Or maybe it just fatigued?  Naaahhhhh

If this is a competition car, you can always drill the tapered hole out to the larger diameter and use a high strength bolt through a Heim joint as a tie rod end.  More maintenance work - needs to be kept clean and lubricated, but the high tensile bolt will be stronger than the OEM taper pin the tie rod end uses.

In reply to wspohn :

i have been looking into this option for the ball joints for "Colin" for various reasons.  The thing that you run into is that for rod ends, you can have high strength, or high articulation, but not both.  Even the high articulation units have very little excess articulation, if any excess at all, when considering how much travel you need vs. how short the arms are.  That is a design limitation from having to have a straight fastener that goes all the way through.

For as unsexy as regular old ball joints and tie rod ends are, they are remarkably good for strength AND articulation, because they do not have that limitation.

wspohn said:

If this is a competition car, you can always drill the tapered hole out to the larger diameter and use a high strength bolt through a Heim joint as a tie rod end.  More maintenance work - needs to be kept clean and lubricated, but the high tensile bolt will be stronger than the OEM taper pin the tie rod end uses.

a heim joint for rally steering would be replaced nearly every day of competition, I don't see this being worthwhile. besides where we race in BFE you can always find garbage car parts at the local parts shops. exactly why I have LS coils on the car

I kind of skimmed so forgive me if this has already been covered. One real potential problem I see is the angle of the tie rod ends. The stock rx7 tie rod end has what appears to be angled up about 15-20 degrees where as the other replacement options look to be pretty much square. This leads me to think that binding at full droop would be a problem.

gearheadmb said:

One real potential problem I see is the angle of the tie rod ends. The stock rx7 tie rod end has what appears to be angled up about 15-20 degrees where as the other replacement options look to be pretty much square. This leads me to think that binding at full droop would be a problem.

I think that the considerations will be a bit different on a rally car than a track car. I used Heims on my track car that had much less suspension travel on a smooth track than a rally car needs.   I have also seen Heims used on quite a few sports racing cars that also run with limited suspension travel.

Rod ends may well not be useful in rally cars where that sort of range is needed - maximum angles seem to be around 17 deg.