Thursday, December 1, 2016

Tech Tip: Torque Your Dang Wheels - Carefully!

Keeping your wheels attached to your car is critically important. The most obvious opening statement for a blog post ever, I know. However, I do believe that familiarity breeds contempt and the little studs (or bolts) that hold your wheels to your ride do not get enough respect. The torque spec that your manufacture recommends is actually pretty important when it comes to wheel bolts and studs. There are times where "good and tight" is acceptable, your wheels are not one of those times.

As discussed all across the internet (including in this BLOG), and in fine books and pamphlets all over, fastener torque is critical to the strength of any joint. Also, the torque applied to a bolt is not the critical bit. What is critical is the amount a bolt is stretched (stained) when it is installed (ever wonder why rod bolts in an engine are not just torqued, but measured?). A torque value is just a handy way to measure and apply a set amount of strain. The torque value for a fastener is calculated by estimating things like the friction factor between the fastener and its mating part, or experimentally where strain is measured for a specific application and the torque required is noted.
When working on cars here, we often see studs that have obviously not been properly torqued. Usually this means they are WAY too tight and this happens for 3 main reasons:

  1. Use of an impact gun
  2. Torquing hot wheels
  3. Stud lubrication

Leave this tool in your box
when working on your sports car.
1. Impact Gun 
The first most common mistake is that people put wheels on with an impact gun, this crime is committed most often (oddly enough) by wheel/tire shops. You would think that people that specialize in putting wheels on cars would do the task correctly, but they do not. It is such common practice to just buzz the lug nuts/studs/whatever on that no one bats an eye. If you are using an impact gun, how do you know that the torque is correct? Too much torque puts too much strain on the stud and the wheel itself, worst case, the stud snaps. Too little torque actually puts too much strain on the stud as well and severely lowers its fatigue life. Worst case, stud snaps. Nothing good has ever happened after a wheel stud failure. We NEVER use an impact to install wheels here. We also never use one to remove wheels either. Using an impact is hard on the wheel lugs/nuts and doing it by hand with a breaker bar allows you to feel if something is not right (over/under torqued, bad threads, etc.)

2. Torquing Hot Wheels
The second most common offense? The habit of torquing wheels right after a track session. In this scenario, the wheel studs and everything else associated with the hub are pretty hot, hot enough to change the strain in the system. So sometimes you can turn the bolt a little bit farther with the same amount of torque. You have now tightened the bolt further than you did initially (when it was cold), and now when everything cools back down, the bolt is strained more that originally intended. We think that this is minor but we still never recommend torquing hot wheels.

For peace of mind, you can check for loose bolts but wait till the wheels have cooled before checking torque.  Do it just before your session starts.

3. Stud Lubrication
The third reason why wheel bolts get over torqued is lubrication of wheel studs. As mentioned early, the torque applied to a threaded fastener is meant to produce an ideal amount of pre-stress or strain in the fastener. Most of the force (torque) applied to a fastener (about 90%) while you were tightening it is not stretching the bolt, it is overcoming the friction between the two mating threads as well as the friction generated under the head of the bolt. So then the amount of friction between the parts is critical in determining the correct torque to produce a given strain. The friction can vary wildly depending on the bolt plating, thread class, materials, and lubrication. Most torque values given by manufactures are for dry threads unless stated otherwise. So if you have a torque spec for a dry thread, then you lube it with something like anti-seize or thread locker, you are going to reduce the friction and you will end up with much more strain in the fastener for the same amount of torque applied. If a fastener does not call for lubrication, it is usually best not to lube it.

So if all these mistakes are being made and people are over torquing the hell out of wheels all the time, why aren't wheels flying off cars and people dying in fiery crashes 24/7? Safety factors. Engineers always design things with a safety factor and make things able to withstand loads usually 2-10 times higher than what is expected (air craft and race car engineers usually use safety factors under 2 to reduce weight). This covers things like over torquing, misuses, accidents, etc. However, the wise (wo)man respects the safety factor she is given and does not try to push his luck. Wheel studs CAN and DO fail from improper torque.

We Recommend:
1)Torque your studs/bolts/lug nuts with a torque wrench and according to the manufacture's specifications.
2)Tighten your lug nuts in a criss-cross or star pattern for even torque with a torque wrench
3)Check your wheel torque at least twice a day at the track - when the wheels are cold.  We like to check before every session.
4)Use a torque wrench (was repetitive enough?)

Monday, November 14, 2016

Tech Tip: Suspension Bump Stops Will Degrade!

The bump stops are an overlooked and underappreciated piece of the suspension system. Some people look at the bump stops as a nuisance because they lowered their car and now it is the bump stop's fault that they do not have as much suspension travel as before. The fact of the matter is that the primary purpose of a bump stop is to prevent suspension or chassis damage when you do run out of available travel. The secondary purpose of the bumpstop is to provide a progressive transition between your normal spring rate to the fully bottomed condition.
Standard bump stop on a
Nitron 40mm Single Adjustable Shock

The bump stop prevents damage by absorbing and dissipating a huge amount of force when your suspension bottoms out. If the bump stop was not present, a large (and harsh) impact force would be transferred into the chassis and into the lower suspension arm. In this scenario, the chassis and/or the a-arm can be damaged.  In other words, not good. You can have a bottom out condition without damage but it is still highly stressful to all the components and passengers involved.

The second, and more subtle job of the bump stop is to be progressive. When the car is normally going around a track, the suspension is working with what ever spring rate you are running (resulting in some wheel rate). When you run out of travel and fully collapse a shock with no bump stop, your spring rate (and therefore wheel rate) goes to infinity. Infinity is a very high spring rate indeed and is the least compliant you can get. Tires do not like to stick to the ground when there is no compliance. This situation does nothing good for handling. When a bump stop is in place, rather than an immediate spring rate to infinity transition; there will be a progressive ramping up of the spring rate. This is much more forgiving on the suspension and chassis and results in much more predictable handling.

Bump stops do wear out over time. The life is going to be determined mainly by the environment in which they live. Severe weather and track use will accelerate degradation and wear. Miles are pretty much irrelevant unless your car is "stanced bro" and you are riding on the bumpstops constantly. Evidence of this can be seen on a car we currently have in the shop. It is a 2006 Lotus Elise with 14,000 miles on it. Luckily this customer is getting a nice set of Nitron 40mm Single Adjustable Dampers to replace these tired units.
This is not an effective bump stop...
These stops crumble when touched, they will do nothing to help the vehicle and must go. If your bump stops look like this, get them replaced. You can send your stock shocks to Bilstein to be rebuilt or get an UPGRADE.

Tuesday, November 8, 2016

Struggles of Design: Alfa Harness Bar

We developed our 4Corsa Harness Bar for the Alfa 4C knowing that people would like to track these cars.  This blog entry discusses our harnessbar development process, a mistake we discovered AFTER we had began production and the solution that we came up to fix it.  We are happy with the final product but it took some extra effort to finally get it 100% right.

Brainstorming A Solution
Getting a bar into the Alfa presented some challenges as the chassis and seats did not give us much latitude.  We've designed harnessbars for over 10yrs for Lotus Elise/Evora and Mini Coopers.  Some of our design requirements for the 4C included:  be economical, 100% reversible, require minimal modification, and most importantly, be safe. Safe means it must be strong AND correctly position the shoulder belts.  Solutions we've seen in various cars, including the 4C, position shoulder belts too high.  After MUCH head scratching and going through a number of concepts, we landed on the one you see for sale today.  We hit our targets for safety and reversibility. 

Joe (our engineer) earning his paycheck.

Measurements were taken inside the car, a rough 3D model was made, and a prototype was fabricated. Making a one off piece is actually relatively easy. However, we needed to take this part and make an accurate 3D model for our fabrication vendor so they could make a batch of bars. We took measurements from this bar and had some tubes laser notched, they were off a bit, so we had some more tubes laser notched, these were correct. We basically remade our prototype with these laser notched tubes (the originals were notched by hand) to verify the design. It fit so we kicked off production.

Prototype bar in place. It fit our car!
Fitment Problem
Great! Right? Well, when dealing with these low volume cars, sometimes it is difficult to get your hands on a single car for testing, much less multiple cars. Before production, we identified a potential issue. We assumed there would be some variation in the distance between the seat belt mounting points that the bar bolts to. We did some estimation that the variation would be 1/8" or less which the bar was designed to deal with.  We were wrong.  After we started selling our bar, we found out we were wrong. It turns out the variation from car to car is more. This may be due to the introduction of a new model called the 4C Spider - though we are not sure.  Regardless, small volume cars generally have much more car to car variability and that must be considered in the design of any hard parts.

Problem Resolution
 We needed to get creative again and come up with a solution to take up the car to car variation. Our current bar fit some Coupes but not Spiders (2 so far). Most cars have 'slip joints' to take up build tolerances.  This gave us an idea.  We decided that the best way to allow the bar to accommodate the width variation is to allow it to telescope.  We brainstormed several different approaches to make this happen and finally landed on a solution.  Obviously safety was critical and we are happy that it is probably now even stronger than before.

TSSJ Technology
Our solution is a slug and sleeve arrangement to give the bar some telescope ability in the width direction. We cut the bar in half, insert and bond a slug inside the tube and slid a sleeve over the top. This sleeve is also bonded to one side of the 4Corsa.  The other side of the 4Corsa bar slides into this joint.  This arrangement is total overkill. The slug in the center is a piece solid steel round bar and the sleeve, being bigger than the tube it is covering, is even stronger. The both of these parts combine make sure that the bar is not any weaker than the original design.  We came up with the acronym, TSSJ (Telescopic Slug Sleeve Joint) because necessity is the mother of all invention and why shouldn't we have some fun at the same time?!
TSSJ Technology:
Section view of slug and sleeve retrofit.
Slug is red, sleeve is blue, original tube is grey.
Though we had considered adding additional adjust ability, earlier in our development, we ended up tabling it.  In hindsight this proved to be a mistake.  Ultimately our TSSJ solution makes our bar a product that will work on both models and offer a degree of adjustment that a small volume car truly needs.

Thursday, October 27, 2016

Safety Reminder: Fuel Systems and Plumbing

We love modifying cars as much as the next guy but things need to be done properly. Original Equipment Manufactures (OEMs) go through a lot of testing to ensure that flammable liquids stay inside their respective systems. Not only does a car run better when fuel and oil are kept in the correct places, but it is much much safer as well. When we modify our cars, we need to make sure that we are paying attention and respect the systems we are working with.

In a recent blog, we mentioned the merits of good practices when plumbing or wiring a modified car but the safety aspect needs to be addressed as well. Fuel and oil lines are not places to save money on cheaper parts, they are not places to save time while building, and attention needs to be paid to how these systems are routed and secured. Too many times have we found loose oil or fuel lines in a vehicle that were about to cause an issue. We even had a problem during our Drakan testing when an OEM fuel connector came off the hard line it was attached to because too much movement was allowed. A simple ziptie fixed any future problem.

Below is an example of what a fuel fire can look like inside a car. This video shows the speed at which a fuel fire can start, the importance of safety gear (it is not all created equally by the way) and the importance of practicing getting out of your car in an emergency. While we do not know the cause of the fuel fire in this vehicle, it is a very eye opening look at the seriousness of a fuel fire, no matter the cause.
This is especially relevant to the Lotus Elise and Exige community because the design of the stock fuel tank allows the engine to be fuel starved in left hand turns when low on fuel. In our opinion, there are two ways to safely take care of this issue.
  1. Keep your tank topped up.
  2. Use a baffled fuel tank like our V2 Tank .
We like a baffled fuel tank because it retains OEM wiring and fuel plumbing. Another solution is a surge tank, but we do not recommend them.  Surge tanks require that you make modifications to the fuel system and wiring system to install them. We have seen 2 cars that have caught on fire from issues related to the surge tank. No matter how well designed a product is, all things being equal, more points of failure mean more opportunity for failure.

Here another video of a Lotus Exige on fire:

Here is less alarming (actually quite funny) video from another fire. This one is more likely oil related than fuel, but the lessons still apply.

So please remember:
  1. Pay attention when modifying fuel, oil, or wiring systems.
  2.  Wear your safety gear! 

Monday, October 24, 2016

Shifter Update 10/24/16

Original concept/prototype.

We have been busy working on our shiftR111 for the Lotus Elise/Exige. The first prototype has been in the car for a while now and we are happy with its function. It is much improved over stock and anyone who has sat in our car has said as much. Almost everyone has gotten out of the car and asked "when will you have production parts" and "how soon can I get one!". The issue we have with the first iteration is it just costs way too much. Figuring that no one wants to buy a $2,000 shifter no matter how good it is, we have put a great deal of time and brain power into simplifying the design.

We redesigned the shifter while keeping the function and core concept the same, and reduced cost and complexity. After much discussion with our manufacturer and much internal brainstorming, we were able to come up with a lot of solutions. Version 2 has 73% less machined parts, 79% less welding and costs 35% less to make. The upside to this is that the shiftR111 is now much less complex which makes it much more cost effective and reliable. The downside is that we now have to spend another large chunk of money to get the machine shop to make us a new prototype. In the end, we think all this time, effort, and money will be worth it.

Here is a side of the new concept that has not been seen before.
Little treat for you blog readers. 
Eagle eyed readers will notice a number of changes. Note the retention of the stock reverse lockout collar and the provision for the hand brake. When the center console and shift boot are installed, the shifter will look stock. This setup can use any stock or aftermarket shift knob, but of course we recommend The Bollock. It will also be compatible with stock cables, our TRANScables, and our Shifter Re-Enforcer. The ultimate solution is combining all of these parts with the shifter to really bring the shifting to another level.

We have also tested the prototype with the LETSLA short throw shifter and it looks to be a good match. (Look for a kit coming soon to adapt our TRANScables to the LETSLA shifter.)

We will also have parts available that will facilitate running the shifter without the center console and/or without the handbrake. These parts are in development and we expect to have them shortly after the shifter is available for sale. The second prototype is currently being made, we will have to test it and then make production parts. We are shooting to have production parts done by the end of the year.

It also looks like with a few tweaks, it will fit in the Evora...

Thursday, October 20, 2016

Evora Track Car Bodywork Mods

WIn our previous post we talked about an Evora track car we have here in the shop. In an effort to focus the car more for track use, it was decided to do a few modifications to the bodywork.
     The goals were:
          1) To make the clam easier and faster to remove.
          2) To improve air flow and heat extraction from the engine bay.

After looking the car over (and taking most of it apart to do the clutch replacement), we decided that rather than do a true race car quick release style of system, we keep it more simple. The basic plan was to essentially eliminate some attachments that we feel are just not needed on a track only car. We also switched out some attachment methods. For instance, in the trunk, we replaced 6 bolts with a 4 studs and nuts. There are a few advantages to this: the studs capture the shims so they don't fall out and they help align the clam when it is installed. We deleted the two in the center for simplicity.

We also had to address the things that attached the clam to the vehicle other than the fasteners. Namely the battery, coolant tank, and truck release cable.

The switch can be reached from the driver
seat or through the passenger side window.
We decided to relocate the battery to the passenger compartment behind the passenger seat. This setup has a number of advantages besides making it simpler to remove the clam. We are able to reduce weight, better weight distribution, and increase reliability with this modification. Moving the battery inside the car reduces the vibration and thermal stresses on it, it also gets a large bundle of wire out of the already crowded engine bay. Moving the battery gets weight off the rear of the car which helps with the polar moment of inertia of the vehicle. The battery switch we installed will also prevent the car from draining the battery while stored.

Nice little unit from Moroso really cleans up the
engine bay and gives a high performance look.

The coolant expansion tank was another issue we encountered as it too is attached to the clam. We looked into relocating the stock tank but opted to replace it entirely with a nice offthe-shelf unit from Moroso. This tank fit cleanly against the firewall and should last the life of the vehicle. Here again we were able to move weight off the rear of the car and increase reliability by getting rid of the stock plastic tank.

The truck release cable that runs inside the cabin to under the rear seat was the final small thing that we wanted to move to make clam removal simpler. We decided just to re-route the stock cable so it can be pulled from the rear of the vehicle. In the future, the hatch will probably be replaced with something a bit lighter and we may do away with the stock latch, but for now, this will work great.

Stock heat shield in place.
While we were at it with these modifications, we wanted to do something that would help reduce engine bay temperatures. We decided to reconfigure some of the heat management. Since this is a track only car, we do not have a trunk to keep cool, we were able to get rid of some heat shielding and do some ventilation. Lotus obviously had a tough time controlling engine bay temps with this "big" V6. Our plan was to remove all this heat shielding and ducting and allow the heat to escape out the back of the car, rather than through just a few small ducts.
Much cleaner.
We drilled several holes in the clam and also removed an access panel in the truck to vent the engine bay to the trunk area. We then removed the bumper and drilled several holes in it to vent the trunk/engine bay area to the rear of the car. Since this vehicle also has a muffler delete setup on it, we vented the floor of the trunk to give the hot air another option for exiting. We aligned the holes that we cut with the holes that were in the subframe.  These mods were inspired by the GT4 version of the car and should help lower engine bay temperatures. We also happen to think it looks pretty cool.
Deburring the edges with sand paper
is a pain but gives a finished look.

Rear bumper vent holes.
Swiss cheese.  We also painted the rear black so the orange would not show through the rear bumper holes

Luckily, the only thing this car will be
hauling is ass around the track.

The end result of all this is a car that is lighter, more reliable, and easier to work on. 

Thursday, October 13, 2016

Evora Track Car TLC

One of our clients requested that we bring in his Evora for a little TLC. His clutch was not disengaging which prompted this work. Clutch replacement is a 40hr job on an Evora so he asked us to take care of a few other items at the same time.  This blog lists some of the items we found and fixed or upgraded.  

One key client request was that we make his rear clam easier and quicker to remove. The rear clam has to be removed along with the engine to do a clutch replacement on the Evora. This will be the second time the engine has been out of this particular car and the owner wanted to reduce the costs of any future service. As this car lives at the track, this is a smart move.

This was the first time we worked on this car so we needed to get a good handle on it's condition.  As we dove into the car we found the following:
  • Broken clutch
  • Loose exhaust
  • Missing rear engine mount bolt (!!)
  • Broken engine mounts (left and rear)
  • Broken/heat damaged shifter cables 
Here's an Evora with it's heart removed. Look familiar?
We found several other issues, some of which were mentioned in our last blog entry. At some point, the rear engine mount bolt fell out, and the resulting excessive engine movement caused or contributed to all the other problems (besides the cables). With the knowledge that this car is now a dedicated track car, we decided to take the opportunity to do some worthwhile upgrades including simplifying and adding lightness - who needs AC in a track car - right? 

First order of business was removing the clam and engine. One of those things that is easier said than done. This is definitely a time intensive job.  We came up with some ideas to speed up reinstallation/removal.  Since the client still wanted to keep the stock rear hatch (for now), we were limited in some of our ideas.  Certain items, like the battery was relocated to the passenger compartment to help speed up the R&R process.  

Broken disk = no bueno
The first thing we swapped out was the clutch.  The original clutch failed because a spring broke free from the disk.  We took this opportunity to visit our clutch supplier to discuss options for the Evora.  We landed on a couple of different balanced clutch/flywheel packages that we think will work well on Evoras.

New Clutch/Flywheel Bits
The clutch we chose is a heavy duty solution but the pedal effort is just as light, if not lighter than stock. The hub plate is much stronger and should retain the springs very well.  We also threw in an aluminum lightened flywheel for good measure. This combination should last a long time, which is a good thing considering how involved a clutch replacement is on this car. 
One of the broken mounts.
  When we discovered 2 of the 4 engine mounts were in bad shape, we called up our engine mount supplier to try our their upgraded solution. These mounts should be an improvement over the soft stock ones. Reducing engine movement helps with throttle response and shift feel.  They will be available for sale as soon as a few fitment issues are resolved.  We had to modify the mounts to get them to fit correctly. 

New TRANScables
The shift feel on this car was also terrible. One push of the gear lever let us know immediately that something was not right. After a very short investigation, it was apparent that the cables were causing excessive drag. We think that the stock cables are being damaged by high engine bay temperatures and the housings are shrinking around the cables. The cable housing/sheath was also cracked and broken near the ends (see pic).  

Since we have had great performance from our TRANScables for the Elise/Exige, we contacted our supplier to make us a prototype set for this Evora. The difference is astounding. The improvement in feel is apparent even when compared to the other Evora we currently have in our shop. That car has good cables and the shift quality is fine, but these cables bring it to another level. Expect to see this on our site soon as well.

Another interesting area that we were able to study is the actual shifter mechanism.  It is very similar to the Elise shifter which means our shiftR111 should likely fit with some minor tweaks.  First we need to get it released and running on the Elise/variants.

Wiring was a bit lack luster in this car. The interior was gutted and caged so much of the wiring was exposed.  There was so much unsecured wiring that it gave us anxiety. Wiring failures are a very common problem on race cars and that simply does not need to be the case. A few well placed zip ties or p-clips go a long way to preventing damage or failure.  Anyone who has ever had to trace a wiring related issue will agree that preventing an electrical failure is almost always easier than fixing one.

More details on the modifications we did to the bodywork on the next blog.... 

Thursday, September 22, 2016

A Note on Exhausts and Shoddy Work

In a matter of 1 month, two different Lotus have come into the shop that had serious exhaust related issues that frankly, pissed us off!  We are writing this article to just raise some awareness.

Most people do not view their exhaust as a maintenance item, but it is, especially if you run the car hard. Packing material can break down (this is accelerated with poor tunes and track use) and the metal can fatigue and crack from heat cycles and vibration. If you are shooting flames from your exhaust, it is only a matter of time before your exhaust breaks and/or your car catches on fire. 

Exhausts can break under normal conditions, but when you have a low quality exhaust or a low quality installation, wear and damage can happen relatively quickly. This is important as not only does it make your car sound bad and affect performance but it is a huge safety hazard. Exhaust gasses are HOT. We have seen these cars catch fire from only from two things, fuel related modifications and exhaust system failure.  

Case #1: Lotus Elise
Poor install and repair attempt :(
A customer recently brought his Elise in for a SMOOTHoperator install.  He complained that his exhaust seemed rather loud. We thought this complaint was odd because even though he had an aftermarket muffler, the can was pretty large and this is usually an indication of a quiet system. However, a quick inspection revealed the reason for the sound. The bracket that was welded to the side of the can had broken off leaving a large hole in the side. Looking inside the muffler we could see that much of the packing material had blown out through this hole. The entire system was loose and spewing hot exhaust gas out this hole. This failure can probably be traced to a less than ideal installation. The aftermarket cat pipe was cut (poorly), then some sort of adapter piece and muffler tape as used to attach the can to the cat pipe. There is also evidence of an extremely poor attempt to re-weld the hanger to the can. It is hard to say what came first or caused the failure but the point is that this exhaust was poorly installed and should have been replaced a long time ago. We were glad to get this customer setup with a Larini GT3 (formerly known as 8" side exit). He was happy to have a quiet car, yet still sporty and we were happy he had a safe car.

Case #2: Lotus Evora
Halloween is quickly approaching but it came early for us here.  We found something scary under an Evora we are working on for the first time - it came here from the SouthEast. This car spends most of it's time at the track so it has been stripped of interior and has a cage and race seats installed. It has received some "interesting" work during its life that we are finding and fixing as we go. 

One of these interesting things is the 'custom' exhaust and hanger. This car has a muffler delete system with some custom work done to it. It looks like a sheet metal hanger originally was fixed to a rivet nut in the subframe but that rivet nut loosened up. The previous shop's solution was to stick a bracket from a safety harness in one of the holes of the subframe and tie the exhaust to that with some bailing wire. We do not recommend this as a way to attach anything to any part of your vehicle. This is probably the most ghetto fix we have ever seen!  This type of "fix" belongs on a jeep stuck 20 miles out in the woods, not something that will be run on track. I am sure this was meant as a temporary fix, but it was obviously run like this for longer than was necessary.

The horror! 
Fixes that may happen in the middle of a race can be sketchy but are meant to last the duration of the race.  Most of us are not racing so it is important to take the time to fix the problem correctly.  We have a great network of reputable Dealers around the country.  Mistakes can happen but please inspect your cars - especially track driven cars - regularly.  Be safe out there!

Monday, September 19, 2016

Lotus Rear Inner Toe Links

The Lotus Elise and Exige have a few unique items that should be addressed by anyone pushing the limits of their car, especially on the track. One of these items is the often talked about rear toe link. Some of these cars are over 10 years old now but there are still those who do not know about this or may not know the full story. This blog will attempt to explain the issue as well as what we do about it.

The inner toe link is on the left side of this image.

The Problem:

OE inner toe link
The inner rear toe link on these cars is a ball joint similar to other cars with a key difference. Most ball joints are a tapered fit to eliminate any relative movement in the joint. Lotus could not use a tapered fit here because the balljoint pulls double duty as the pivot for the lower control arm. That means the balljoint shaft is more like a bolt. This bolt (especially on early cars) has a tendency to loosen slightly. This allows excessive movement and fretting between the balljoint and subframe. Once this happens, the balljoint gets a notch worn in it and the strength is severely reduced. Failure of the joint usually happens when the link is loaded (going around a corner), this is an exceptionally bad time for one of your rear tires to have a severe and rapid toe change. 

The Solution(s):

Lotus had a few solutions to this problem, the first was to increase the torque spec on the nut on this joint. This seems to be fine for those who have not driven on a loose joint and do not push their cars particularly hard. The other solution they came up with was replacing these ball joints with rod ends and putting a cross brace between the two to bolts to increase the rigidity of the joints and help stabilize the bolts. 

"Track Pack" toe link brace and ball joint

A visual representation of double shear (top)
vs single shear (bottom)
We enjoy the ability to come up with solutions to problems - especially since we don't have the same cost constraints that the Lotus engineers must manage.

We attack the problem in two ways. The first is to prevent the bolt from loosening up. We do this by using a Top Lock nut, this nut has threads that are not exactly round, they are a bit distorted so they really grip the bolt once tightened. We also use special lock washers called Nord-Locks, these fancy things actually tighten as they loosen up which makes it extremely difficult for the joint to loosen on its own. Watch the video below to show how these washers stack up against other methods of bolt retention.

The second thing we do is to put the joint in double shear, this makes the joint less likely to loosen as well because it eliminates the bending force that would tend to "rock" the bolt in its joint and cause it to loosen up. Creating a double shear joint also greatly increases the strength.

Nord Lock Demo 

We have 4 different kits that solve these toe link issues to meet a wide range of needs.  Our first rear toe link brace was introduced in 2006!

TLUkit- This kit is for cars with the factory "Track Pack" brace. It retains the factory brace but replaces the expensive factory rod ends with our own high quality units. The factory rod ends do not last very long. This video below shows the movement in one of these rod ends after 25K California street miles.

DSbrace - Our most popular and economical solution. This kit replaces the factory ball joint with a strong bolt and rod end. The whole system is put into double shear (hence the DS), by using two sheet metal brackets that bolt to existing holes in the frame. We ran this solution for a long time on several race cars with slicks and aero, this solution is plenty strong and up to the task of street or track use. 

RTDbrace - This brace uses the same rod ends as the above solutions and uses a brace similar to the factory track pack. The key difference with this setup is that our brace also attaches to where the transmission mounts. This creates a very strong joint and has the added benefit of stiffening up the subframe a bit. This setup is acceptable for both street and track use. We introduced this is in Aug 2006 and it has been the gold standard in the North American market.

RTD2brace - The ultimate solution. This kit includes everything in the RTDbrace with the addition of Nitron's S99 outboard rod ends. This replaces the outer toe link ball joint with a high strength rod end for reduced deflection and toe change under load. We recommend this as a track only solution.