Upper A-Arm Problems (Taco/4Run/FJC)

[ntsqd]

snip....
Good to know the Total Chaos stuff is correct. It does look like that spacer could be just a bit longer to fill the total depth of the steering arm/upright. But it appears there is plenty of contact (certainly more than the Icon part!).

No, it is better off the way it is. The reason is that the wall thickness would make any further depth useless due to the thru-bolt design. If it were brought all the way down to a sharp end it wouldn't add much more strength and it would promote cracks in the part.

The design alters the way that the original system works. The original system requires that the taper not only positively locate the stud, but also offer bending strength.

The TC system uses the adapter for the location, but the bolt's tension combined with the adapter's shape offers the bending strength.
It's a hard concept for me to explain in words. Think of a 2" OD tube 12" long. You put it in a postion where it is held on one end only and bending is the largest loading, and it bends under load.
So you put another one in place, only this time you also make some end caps and run a 5/8" stud down through the middle - and tighten the snot out of it. That assembly's bending strength is remarkably higher than just the tube's was because of how the stresses flow through the parts. The tensile load of the bolt puts the tube in compression. So now to bend the tube in the application the load first has to overcome the compression of the tube, and then it has to overcome the bending strength of the tube.
Clear as mud? Pre-Tensioned Concrete works in a similar way.

The TC design is working like the latter example.

 

[Redline]

I do understand, it is quite simple and clear to me.

I like it, more good news about Total Chaos.

No, it is better off the way it is. The reason is that the wall thickness would make any further depth useless due to the thru-bolt design. If it were brought all the way down to a sharp end it wouldn't add much more strength and it would promote cracks in the part.

The design alters the way that the original system works. The original system requires that the taper not only positively locate the stud, but also offer bending strength.

The TC system uses the adapter for the location, but the bolt's tension combined with the adapter's shape offers the bending strength.
It's a hard concept for me to explain in words. Think of a 2" OD tube 12" long. You put it in a postion where it is held on one end only and bending is the largest loading, and it bends under load.
So you put another one in place, only this time you also make some end caps and run a 5/8" stud down through the middle - and tighten the snot out of it. That assembly's bending strength is remarkably higher than just the tube's was because of how the stresses flow through the parts. The tensile load of the bolt puts the tube in compression. So now to bend the tube in the application the load first has to overcome the compression of the tube, and then it has to overcome the bending strength of the tube.
Clear as mud? Pre-Tensioned Concrete works in a similar way.

The TC design is working like the latter example.

 

[xcmountain80]

Well now I'm worried, my brother just bought the Allpro kit for his 06 Tacoma and well dang. The only course of action I could come up with was call them Tuesday, the kit will arrive Wednesday. Worst case scenario send the whole kit back or just install the lift and leave the UCA off and see if they will credit it. Long term this is a liability issue if it were to fail. Imagine if you will if yours has snapped while going 70mph on the interstate.


Aaron

 

[xcmountain80]

Anyone?

Aaron

 

[ntsqd]

Anyone?

Aaron

If A-P won't do anything, then your best bet is to replace their bolt with an F911 of the same size and torque it properly. Note that F911's have a taller hex head, so check the fit & clearance before calling it good.

 

[DaveInDenver]

The Toyota FSM calls it a "steering knuckle"

On torsion IFS it's steering knuckle and axle hub. Although it's confusing since they call the front half shafts 'driveshafts' rather than axles, too.

 

[Redline]

Yesterday I spoke with an engineer from Light Racing/Specialty Products Company. I also received an email response from another engineer to an online question I had sent regarding the taper of their ball joint for the 4Runner/FJC.

Firstly, I was impressed by the informative & professional manner of these gentlemen. They informed that their ball joints have the correct taper. They learned during the development of their replacement A-arms that the ball joint taper is slightly different for the 4Runner/FJC to that of the Tacoma. I'm guessing that the taper that I have seen that is ‘wrong’ for the FJC/4Runner may be correct for a Tacoma?

The other positive advantages of the Light Racing design seems to be their sealed-type joint and OEM quality design. Some are concerned about extra travel and droop. According to one engineer, although the joint looks like a stock ball joint, the travel is substantially more than stock. He explained a few other things regarding the design and I’m sold. I have cut & pasted some info below that he shared on the FJ Forum.

Over the the past week I was told by two knowledgeable guys (one shop owner/tech, one machinist) that they don't like Heim joints for street driven applications due to lubrication/wear issues.

I have decided that the Light Racing arms are worth a try and my money. I ordered a set from Toy Tech Lifts ($400.00) while they have their group buy going on for the FJC Forum (until May 30).


• Our Upper Control Arms were designed work with a wide range of coilover shocks; from the stock Toyota units to long travel aftermarket shocks similar to the Light Racing or Icon units. This includes shocks that allow for a slight increase in droop travel.
• The increased travel was accommodated by using a ball joint with a higher range of travel. The stock Toyota ball joint has a 77° included angle (or 38.5° off centerline). Our design allows for a 90° included angle (or 45 ° off centerline. A spherical bearing (monoball) with high angularity inserts rarely has more than a 35° included angle. The angle of the ball joint plate is optimized for this increased ball joint travel.
• The sliding off-set ball joint that we use allows for a huge range of alignment adjustment rather than designing an arm with a static off-set and relying on the Lower Control Arm cam bolts for adjustment. This means the camber of our arm can be adjusted to the stock upper control arm geometry or it can be adjusted for proper camber in a 4” lifted vehicle. The caster can also be adjusted from stock numbers up to a 4° increase in caster for better high speed stability.
• Using a standard ball joint (instead of a monoball) and molded rubber inner pivots (instead of urethane) gives better ride quality, better longevity, lower maintenance, and quiet operation.
• We as a company have 30 years experience designing ball joints for aftermarket and OEM use. The design and quality of the ball joints used on these arms is top notch.
• Our arms are coated using E-coating. This is a process where the coating is electro-statically grown on the part. This is used for many OEM suspension components and gives superior corrosion protection to zinc plating, paint, or powdercoating.

 

[Jacket]

This is a very interesting thread. Thanks for all the great information.

So it sounds like I am to conclude that although many front IFS parts are interchangeable between the 05+ Tacoma, 03+ 4Runner, and FJC, the design of the upper control arm is slightly different, at least the specific taper of the ball joint. And because of this, some of the after market UCA makers have a generic design that accomodates all 3 models, but doesn't necessarily match the OEM specs.

So did LR leave you with information that their UCA has a different part number for the 4Runner and FJC versus the Tacoma?

 

[Redline]

You are welcome. When I learned of these 'issues' last week I knew others needed to know before they spent money on expensive parts that were not completely designed for their vehicles. Or even worse, had a dangerous failure on something that involves steering and suspension. I think the differences might not be known by all designers/sellers and therefore the errors are unintentional or not completely understood.

What you conclude is exactly what I have concluded. The basis for this opinion is my observation of the parts which are not correct for my '06 4Runner or my friend's 08 FJC (they take the same parts), and my discussion with the LR engineer who verified the difference between the 4Runner/FJC A-arms (taper) and those for a Tacoma.

Light Racing does have different part numbers for the Tacoma & 4Runner/FJC.

http://www.lightracing.com/v1b/lightracingToyoArms.cfm

If you click on the buy it now button on the the LR site the price will scare you (922.00!), but Toy Tech in Colo. is selling for $399 right now!

This is a very interesting thread. Thanks for all the great information.

So it sounds like I am to conclude that although many front IFS parts are interchangeable between the 05+ Tacoma, 03+ 4Runner, and FJC, the design of the upper control arm is slightly different, at least the specific taper of the ball joint. And because of this, some of the after market UCA makers have a generic design that accomodates all 3 models, but doesn't necessarily match the OEM specs.

So did LR leave you with information that their UCA has a different part number for the 4Runner and FJC versus the Tacoma?

 

[Jacket]

The price of UCA's has always scared me, which is why I'm still running stock. :smilies27 My alignment specs aren't great, but the truck still drives pretty well at highway speeds. And my FJ40 always makes me feel better about how the Tacoma drives

$399 is an unbelievable price - good for Doug for negotiating such a sweet deal. Its tempting....

 

[Redline]

I'm very particular about how my vehicles drive. I'm happy to have found what may be the best A-arm now available (design, longevity, travel, etc.) and for a relatively inexpensive price during the group buy.

The price of UCA's has always scared me, which is why I'm still running stock. :smilies27 My alignment specs aren't great, but the truck still drives pretty well at highway speeds. And my FJ40 always makes me feel better about how the Tacoma drives

$399 is an unbelievable price - good for Doug for negotiating such a sweet deal. Its tempting....

 

[Jacket]

And it won't squeak like all the uni-ball designed UCA's

 

[ntsqd]

snip.....

Over the the past week I was told by two knowledgeable guys (one shop owner/tech, one machinist) that they don't like Heim joints for street driven applications due to lubrication/wear issues.

A point that I've been making since about '97 or '98 that only recently seems to be more accepted. I don't say it as often any more as I'm sure people are tired of my broken record. The kids on rdc don't want to hear it at all.

 

[jbs]

I installed my Light Racing UCAs Thursday, and the taper appears to fit as well as the OEM part. I forgot to take pictures, but I am confident it is made for the 4Runner's spindle's taper.

The ride is much better with the increased caster. I am glad I waited and got the good deal, but probably should have done the UCAs at the same time as the OME lift a couple years ago. My wife even commented on the improved stability at speed.

 

[xcmountain80]

Austin (my brother) got his All-Pro lift in and they seemed to fit rather tight. He had plenty of thread and the tension from tightening seated the piece that we were worried about. I checked it, looks good feels solid, nothing like what was described.

Aaron