Installing a new Detroit TrueTrac Limited Slip Differential in your Crown Vic

By: Charlie "Metroplex"

 

Warning:
It takes 24 hours for the threadlocker to fully cure, and its best to do this by keeping the TrueTrac with the ring gear indoors near a heater (if its cold in your house) to help accelerate the curing process. Try to prevent debris from reaching the insides of the differential and bearings by wrapping it with plastic bags or clean rags/towel (use bags for the bearings).
Threadlocking compound may take 5 minutes to fixture (with the activator) or 20 minutes without the activator, but it will fully cure in 24 hours. You do not want a ring gear bolt falling off and rattling around.

You can get the install done within a day if you work fast and have someone to help you. In addition, it helps if it is above 20F! I did this in an unheated garage below 20F. My extension cord insulation froze and when I accidentally stepped on a segment, it just popped.


Parts required:

-Dyneer Detroit TrueTrac, TT913A361 (about $283 from DTS btw, you need to call them for their updated prices)

its for a Ford 8.8" rear end with 28 spline axles

-Timken Carrier Bearings and Races (about $30 total, ask if the store can press the bearings onto the TrueTrac for you, DTS will do it for $10 labor)

-Adjustable Carrier shims (The adjustable differential shims directly replace the stock non-adjustable cast iron shims. Adjustable differential shim kits consist of thin shims of varying thickness sandwiched between two hardened interlocking steel flanges forming a single insert able unit. Thickness adjustments as small as .001" are thereby attainable for correct setting of ring gear backlash and carrier bearing preload.) About $27.75 from DTS

-Two Victor Reinz Gaskets, Part #: P27608TC –or-

-Permatex “The Right Stuff” gasket maker and one Victor Reinz Gasket


Tools required:

Dial indicator with magnetic base, 0.001” precision

Slide caliper, 0.001” precision – make sure you calibrate it

½” drive torque wrench

3/8” drive torque wrench (or a ½” drive that reads 20 lb-ft)

¾” long socket

5/16” box ended wrench

10mm socket (3/8” drive)

½” box ended wrench

½” socket

Punch tool (I used an impact hammer punch, the one that looks like a stake)

Cheater bar and ½” drive ratchet

13/16”, ½” drive long socket

Two jaw heavy-duty gear/rotor puller

Mallet (soft mallet)

Heavy steel hammer or mallet

Needle nosed pliers

90-degree bend needled nosed pliers (easier to pull out C-clips)

Snapring pliers

Brake drum star adjuster spoon

Heavy-duty vise (around 5.5”)

Quality gasket scraper

A helper (you need someone to spot you under the car, as well as help with moving the carrier, adjustments, etc...)

Crowbar

Wooden blocks (small ones)

Ziploc bags (at least 10)

Music (helps make the whole install go quicker)

China marker


Equipment required:

2.5 ton or larger capacity hydraulic jack (or if you have a lift…)

2-4 jackstands (I use two to hold the frame, 2 as backups)

Creeper (I used cardboard boxes)

Chemicals required:

-Permatex Red Threadlocker (High Strength, NOTE: 24 hours needed to fully cure)

-2-3 cans of Brake Parts Cleaner

-Liquid Penetrant or Diet Coke

-Nickel anti-seize compound

-3 quarts of inexpensive 80W-90 gear oil for 500-mile break-in

-3 quarts of quality synthetic 75W-90. I bought three quarts of Redline Synthetic 75W-90 Gear Oil. You will need about 2.25 to 2.5 quarts, so buy three quarts.

A short summary of what I am going to cover:

The gist of it:

Removal of the open differential carrier

Installation of the new Detroit TrueTrac.

Break-in of about 500 miles is needed to properly wear in the case surfaces where the helical planetary worm gears grind. Refill with good synthetic gear oil.

Dyneer states that there is low friction between the helical gears and the case surface, but the first 100-200 miles will make you think otherwise. Do not worry – so long as you do not run 400+ lb-ft at the rear with 5000-7000 RPM clutch dumps w/ Nitto drag radials, you will be fine. Otherwise, be prepared to grenade one after another. Zexel’s T-2 differential is almost the same thing, except it will grenade itself before the TrueTrac will give away – AND the T-2 is not available in 28-spline form. You will need 31 spline axles to use the Ford 8.8” model!

Anyhow, the 500-mile break-in is done so you can dump the oil that will contain metal shavings and any other debris that flew in during the install so use whatever cheap 80W-90 you can find. Save the Redline 75W-90 for the post-500 mile run, or use whatever synthetic gear oil you usually use. Redline and TrueTrac recommends the 75W-90 because it reduces temperature and friction of the helical planetary gears. Unlike clutch based LSDs such as the Ford Traction-Lok or Auburn, the TrueTrac relies on these helical worm gears for LSD action. Once you pass the 200-mile point, the noises should go away and the operation will almost be invisible.

Theory:

The Detroit TrueTrac is a torque sensing limited slip differential. It uses helical planetary worm gears to bind the wheels together before slip occurs, but allows some speed difference while turning. They apply more torque to the wheel that has the best grips. Paul Hogan could not have said it better, “it transfers power from the wheel that slips, to the wheel that grips” of course he was talking about an AWD Subaru so replace “wheel” with “wheels” if you have AWD.

Here is a short comparison between clutch type LSDs (such as the Ford Traction-Lok) and the torque sensing differentials (such as the Detroit TrueTrac and Torsen), from HowStuffWorks.com:

The Torsen differential is a purely mechanical device; it has no electronics, clutches, or viscous fluids. The Torsen (from Torque Sensing) works as an open differential when the amount of torque going to each wheel is equal. As soon as one wheel starts to lose traction, the difference in torque causes the gears in the Torsen differential to bind together. The design of the gears in the differential determines the torque bias ratio. For instance, if a particular Torsen differential is designed with a 5:1 bias ratio, it is capable of applying up to five times more torque to the wheel that has good traction. These devices are often used in high-performance all-wheel-drive vehicles. Like the viscous coupling, they are often used to transfer power between the front and rear wheels. In this application, the Torsen is superior to the viscous coupling because it transfers torque to the stable wheels before the actual slipping occurs. However, if one set of wheels loses traction completely, the Torsen differential will be unable to supply any torque to the other set of wheels. The bias ratio determines how much torque can be transferred, and five times zero is zero. The AM General Hummer (or HMMWV) uses Torsen differentials on the front and rear axles, and the owner’s manual proposes a novel solution to the problem of one wheel losing traction: Apply the brakes. By applying the brakes, torque is applied to the wheel that is in the air, and then five times that torque can go to the wheel with good traction. The Detroit TrueTrac torque biasing ranges from 2.5:1 to 3.5:1

The clutch type LSD has all of the same components as an open differential, but it adds a spring pack and a set of clutches. Some of these have a cone clutch that is just like the synchronizers in a manual tranny. The spring pack pushes the side gears against the clutches, which are attached to the cage. Both side gears spin with the cage when both wheels are moving at the same speed, and the clutches aren't really needed -- the only time the clutches step in is when something happens to make one wheel spin faster than the other, as in a turn. The clutches fight this behavior, wanting both wheels to go the same speed. If one wheel wants to spin faster than the other does, it must first overpower the clutch. The stiffness of the springs combined with the friction of the clutch determines how much torque it takes to overpower it. Getting back to the situation in which one drive wheel is on the ice and the other one has good traction: With this limited slip differential, even though the wheel on the ice is not able to transmit much torque to the ground, the other wheel will still get the torque it needs to move. The torque supplied to the wheel not on the ice is equal to the amount of torque it takes to overpower the clutches. The result is that you can move forward, although still not with the full power of your car.

What this means is that a clutch type LSD will most likely work better on ice and snow than the Torsen-type differential, however the clutches can wear out but will handle driveline shock a lot better. However, in a situation where one wheel has lost all traction (off the ground, mud, ice, etc) applying the brakes will definitely help if you have a Torsen. In fact, the electronic all-speed electronic traction control on the Panthers might actually help out by applying the ABS at speeds under 35 mph (applies torque to the slipping wheel automatically, and bam 2-3 times that torque goes to the gripping wheel – this way you won’t need to apply the brakes manually).


(Notice the Pairs of Helical Worm Gears. Some models will contain 2, 3, or 4 pairs depending on application)

Removal Procedure:

Before you even do anything, make sure your new carrier has new carrier bearings pressed onto the sides. If not, get a machine shop to do it for you – all that is required is a flat steel plate that can rest on the inner bearing race, a hydraulic press, and wooden blocks to prevent marring of the gear and carrier mounting surface. I HIGHLY recommend you ask the store to press the bearings prior to shipment. Keep the bearings and races free of debris!

If you have air suspension, switch it OFF.

Loosen the lug nuts on the rear wheels by using a ½” ratchet + cheater bar or use a crossbar with some extra effort. I prefer not to use an air impact wrench because the chances of messing up the threads on the studs are substantially reduced when you do it manually. Chock the front wheels.

Place the jack underneath the pumpkin (NOT on the cover, find a good spot. Make sure you center the jack (you can use a lift if you have access to one). Once you get it high enough, place jackstands underneath the frame side members. I added two additional jackstands (that do not contact the frame) as backup jackstands in case the first two fail (this way the vehicle collapses on the backups, giving you SOME time to bail in case of an emergency). Once the jackstands are secure, slowly drop the differential. WARNING: the jack will move back a bit so be sure to chock the wheels on the jack itself. Once everything is stable, remove the jack and secure it elsewhere. You will notice the anti-sway bar is no longer blocking most of the differential cover.

You will now remove either the wheels with a 13 /16” socket using the ½” drive ratchet or a crossbar with a 13/16” socket. The next step is to remove the brake calipers. The bolts are 10mm, use a 3/8” drive ratchet to remove them. Tie the caliper to a frame point – do not let it dangle by the hose. If you have ABS, you must remove the ABS sensor. Find the sensor on the back of the dust shield. The black sensor is mounted next to the ABS exciter ring behind the axle flange (shiny zinc coated deal). The bolt is also 10mm. Remove the sensor and clean the metal shavings/gunk.

The next step may or may not be tricky: you want to remove the calipers. Sometimes the emergency brake shoes groove themselves into the inner drum of the rotor. If this is the case, you will see that the rotor itself tries to move a bit off the axle flange but is somehow stuck. Remove the dust plug in the back of the dust shield near the top. Stick the spoon in there and push the star adjuster with a downwards stroke. There is a spring on top of the star adjuster so if you hear a PLOING sound each time, you are doing it right because the star edges are pushing against the spring.

Newer cars will have two or more serrated clips mounted on the studs to secure the rotor. These are easily removed by rotating them off or cutting them.

Unfortunately, sometimes the rotor becomes meshed with the axle flange – you can tell this is the case when the rotor and axle flange studs move TOGETHER and you do not feel any binding from the brake shoes in the back. If this is the case, you must use a gear puller to extract the rotor. Once you do this, it will not hurt to apply a LITTLE anti-seize to the hub of the axle flange to prevent galling.

With the rotors removed, you can start work on the pumpkin area. Remove the differential cover bolts (1/2” hex head, ten of them) and place them in solvent. For cars that use RTV as the gasket: gently pry the bottom part of the cover to allow the fluid to drip out. Eventually tear off the cover. Be prepared to scrape RTV for a while though. Make sure none of it is lodged into the differential or ring and pinion area.

For those who use Victor Reinz steel shim + cork gaskets (or similar), simply remove the gasket and wipe the surfaces clean. You may re-use the gasket if it is in good condition. These things are TOUGH. It helps to use these gaskets because if you have to tear down everything in a worst-case scenario, you will not be spending most of your time scraping the black rubbery stuff off. It took me a whole half second to remove this gasket.

Let the gear oil drain, and after you are done – go into the car and shift into Neutral. Here you want to rotate the differential so that the pinion shaft retaining bolt is visible. It is a tiny 5/16” bolt that is on the passenger side of the carrier. Remove it, and extract the pin ONLY when you have rotated the carrier so that you can remove the C-Clips. BE CAREFUL: if you rotate the axles with the pinion shaft removed, the spider gears may fall out along with their thrust washers.

With the pinion shaft removed, and the C-Clip access port in view, re-insert the pinion shaft and slide in the retaining bolt. You do not need to torque the bolt down now, but since you will not be using this open differential in the near future, snug it down. Push in one of the axles and remove the C-Clip. Use a 90-degree needle nosed pliers or a suitable tool to extract it. Pull out the axle about 12” and clean the shaft and seal being careful not to nick it. Repeat for the other side.

Now you want to measure the gear backface runout and the backlash. The gear backface runout is recorded using the dial indicator with the indicator probe pointed at the back of the ring gear (smooth side, not the teeth side). Rotate the differential (using the driveshaft) and record the maximum needle movement. As a comparison, my reading was -0.001” at one point, the other parts of the gear were at around 0.000” The maximum allowable runout is 0.004”

Measure the backlash: aim the indicator probe at the edge of a ring gear tooth making sure it is as perpendicular as humanly possible. The backlash is the amount of slop in the ring gear – you will notice that you can rotate the ring gear by hand by just a hair before it engages the pinion gear and hits the resistance of the transmission and driveshaft. You are measuring that distance. For normal cars and trucks, 0.007” to 0.010” is preferred while a maximum of 0.015” is allowed. For drag racing cars that run special gears, 0.006” to 0.008” is preferred. However, erring on the slightly tight will not hurt anything much. As a comparison, I measured my backlash to be 0.013”, which might explain the clunking I experienced at low speed takeoffs (due to too much slop).

 

Now mark the bearing caps. I noticed that my bearing caps have different part #s, so I just used that as my reference. The bottom of the left cap starts with W3 while the bottom of the right cap starts with W10.

Use a ½” breaker bar with a ¾” long socket to loosen the bearing cap bolts. It requires SOME effort to remove, so as usual be careful, and loosen them. Remove the bolts and the bearing caps. Use a wooden block and a crowbar to remove the carrier. Place the wooden block across the differential cover sealing surface (to prevent the crowbar from messing up the machined surface) and use the 90 degree bend of the crowbar to grip onto the ring gear bolt or one of the grooves on the carrier. Pry hard and have someone spot you in case the carrier shoots out. I have heard that some people remove the carrier by hand while others need to pry it out. I had the luxury of experiencing the latter. As the carrier comes out, you will reach a point where the crowbar no longer has any space to apply enough torque. This is where you grab hold of the ring gear and tug with all your might. The carrier will come out so do not lose hope! The shims and races will drop, so note which is which. My left shim was 0.26” while the right shim was 0.288” so the difference was noticeable.

With the carrier out, you can do some extra cleanup work in the pumpkin bay as well as sort out your bearing caps, bearing cap bolts, and carrier shims. You will now remove the ring gear and transplant it onto the Detroit TrueTrac. Secure the open differential (with a rag or covering around the body to prevent damage) in a vise, then use a breaker bar w/ a ¾” long socket and proceed to remove the ring gear bolts. Once you loosen them all, clean them with solvents to remove the old threadlocker. Use the punch tool along with a heavy hammer to tap the ring gear off the carrier. Hammer it down the center to avoid damage to the boltholes, and hammer along the entire ring gear. It will drop out so cushion the fall using either rags or wooden blocks. Do NOT damage the ring gear teeth.

Once the gear is off, clean it with solvents. I used 500 grit and 2000 grit sandpaper to clean up the backface to prevent any crud from messing up the runout or backlash during re-installation. I also polished up the inner ring surface of the ring gear where it would contact the carrier, hoping it would help with installation.

Installation Procedure:

Note: I had Drivetrain Specialists press the bearings onto the carrier for $10 labor. If you plan to do this yourself, then please refer to Mitch’s Install procedure (http://www.shizzot.com/rear.htm) or the Factory Service Manual. I figure that I would pay about the same at a machine shop, but rather than do a lot of extra legwork and driving around, I had DTS pre-install the bearings.

You made it this far, the journey will become a lot easier right after this mini-task.

Take your new TrueTrac differential and clean up the exterior using brake parts cleaner. Wrap the bearings with Ziploc bags and tie wraps to keep out dust and dirt. When my TrueTrac arrived, it was covered in some kind of oil or resin. In fact, most of it was on the machined surface where the ring gear would contact the carrier. Make sure you use LOTS of brake cleaner to clean the mounting surfaces. Make sure NO DEBRIS gets in there. Even a strand of human hair can throw out the gear backface runout or backlash. A single hair strand is approximately 0.001” in diameter. I first placed my TT differential upside down (the ring gear part of the differential was on the bottom) resting on two blocks of wood in the vise (the wood prevents the teeth from getting nicked) I had the vise jaws opened up to allow the bearing to hang loose. I could clean the mounting surface as well as mount the ring gear. The ring gear will not drop in, so you will have to align the bolt holes as best as you can, then proceed to start 2 bolts (one directly opposite another). Once the bolts are relatively secure, I flipped the differential around and wrapped the carrier body with a rag. I clamped it in the vise making sure the vise jaws did not damage the carrier body. I placed a rag pad under the lower bearing to prevent damage. I started tightening the two bolts to seat the ring gear, and then I installed two more bolts for a cross-pattern to evenly tighten the bolts. Others experienced that the bolts were too short to fully seat the ring gear. The trick here is to lightly tap the gear with a soft mallet (rawhide) and make sure it goes into the carrier evenly. Anyone that has worked on U-joints should know about this. If the ring gear body goes in evenly, it will seat quicker than if you try to jam it in. Once you seat the ring using the four bolts, REMOVE the four bolts and use brake parts cleaner to clean the boltholes again. Use towels to soak up the excess cleaner in the ring gear holes and let the whole assembly dry. Clean your ring gear bolts using parts cleaner and dry them. Apply the threadlocker to the threads and seat each bolt by hand – just snug them down. Take your ½” drive torque wrench and set it to 60 lb-ft and torque all ten bolts in a cross-pattern (pretend you have a 10-lug wheel and you are tightening it). Use the vise jaws to keep the carrier from rotating. Afterwards, set the torque to 77 lb-ft and finish the job. It takes 20 minutes for the threadlocker to fixture, and 24 hours to fully cure. I would wait at least 12 hours before installing and using the differential especially if it is cold in your area. Use this time to clean the work area, focus your thoughts, and go over your notes.

I used this time to re-organize the workshop and re-do the math on the shims. Here is a backlash specification chart:

 

Say your backlash was 0.013” and you want a new backlash of 0.008”. The change required is 0.005” so you will need to change the thickness by 0.006”, simply add 0.006” to the original shim thickness on the left, and make one using the adjustable shim. Subtract 0.004” from the original shim thickness of the right shim and make one using the adjustable shim (the 0.002” discrepancy allows for bearing pre-load).

The backlash tolerance is 0.008” to 0.015”, with Ford’s preference between 0.013” to 0.015”. I say, “Screw that.” Many people agree that 0.007” to 0.010” is where you want to be with a light-duty truck or passenger car, with 0.006” to 0.008” for racing gears. A backlash of 0.006” to 0.008” would have less slop and once your new bearings start to wear in, the backlash would increase slightly. It is better to err on the tight side than start with a lot of slop and end up with more slop.

I had some difficulty in installing the adjustable shims, because it was comprised of two shells with lots of small pieces inside. There is no locking mechanism for the shim, BUT the cool part is that it is adjustable down to 0.001” to 0.002”

I calculated for a backlash reduction of about 0.007” so I added 0.010” to the left shim to make 0.27”, I reduced the right shim by 0.008” (there is a 0.002” discrepancy that I added for bearing pre-load) to make 0.281”. Now comes the tricky part.

Clean the pumpkin interior; make sure there is no debris on the bearing cap and race surfaces. You will need two people for this part, unless you are very strong yourself. You will be carrying a 30 lb. object into a tight compartment where you cannot utilize your more powerful muscles. It is best to have someone helping, because you will need to install the different WITH the bearing races on the bearings – making sure they do not fall off. Load in the differential w/ bearing races. If you do not install at least one of the bearing races, you will have some difficulty in installing the second. There's not enough room to simply slip the race over the bearing. You want to install the carrier "lose" right now. Install the shims so that its snugged in with almost no sideplay. Record the shim thickness that you used to obtain this point. Now you need to add 0.012" for proper bearing pre-loading. It is essential to get the right amount of pre-load. Too much and you risk burning the carrier bearings if you use run of the mill dino gear lube. Too little bearing pre-load, and you can also run the risk of premature wear among other things. Think of them as ordinary wheel bearings. You apply preload by tightening the jam night, you reduce preload by loosening the nut.

Distribute the 0.012" to obtain the proper backlash (for example, add 0.008" to the left for proper backlash, add 0.004" to the right). If you need more than this amount for the right backlash, then add the difference to one side, subtract that difference from the other side so you maintain the pre-load while obtaining the correct backlash.

Use a hammer with a drift or punch to tap in the left shim all the while making sure the differential bearings are seated properly and that the ring gear is meshing with the pinion gear. I ended up with a backlash of 0.002”; I was 0.004” off from my estimated new backlash! Therefore, it is important to be conservative with your new shim sizes.

With the bearings, races, and shims in place – its time to torque down the bearing caps. Torque the bolts to 77 lb-ft in a cross pattern so that the entire differential is seated evenly. Start on the top left bolt, then the bottom right bolt, bottom left bolt, ending with the top left bolt.

Rotate the differential so that the C-clip and retaining plate is facing downwards. Here is a tricky part. I used a pair of Lisle Snap ring pliers with the gold 0.060” diameter pins. The smaller ones snapped off so I had to use largest one I had on hand and even then, it was rather tricky. The snap ring is very tight and thick. Moreover, it is in a deep recessed location so you will need the aid of a heavy-duty flat head screwdriver to pry out the snap ring. Once you remove the ring, remove the plate and pinion shaft. Start inserting the axles one by one and inserting the C-Clips. Pull the axle outboard to seat the C-clip, repeat for the other axle. Re-insert the pinion shaft and retaining plate, then re-install the snap ring making sure its seated (when you can rotate it using the snap ring pliers).

Check to see if you have any spare parts remaining. Clean the gasket surface and apply RTV or a new Victor Reinz gasket. I highly recommend you use a Victor Reinz gasket for the break-in period because it will make less of a mess the next time you add gear oil. If you're a diehard RTV user, then stick with RTV. Torque down the differential cover bolts to 30 lb-ft in an even pattern. Remove the rear fill plug and dump in 2-2.5 quarts of your break-in gear oil. During this time, it would be a good idea to re-install your ABS sensors, clean the brake shoes, adjust the brake shoes, apply anti-seize on the shaft flange and hub, and start installing the rear brakes.

Torque the ABS sensor bolts to 8-9 lb-ft, and the rear caliper bolts to 20 lb-ft.

Install the rims and tighten the lug nuts (you will torque them when the car is on the ground). After you finish filling the axle lube, re-tighten the fill plug and check to see if there leaks. Clean out the tools under the car and drop the vehicle. Torque the lug nuts to 90-100 lb-ft. The TrueTrac will sound like its falling apart for the first 100-200 miles, and you will get minor tire scrubbing in turns. After 500 miles, change out the axle lube and refill with quality synthetic 75W-90, 80W-90, or whatever gear lube you desire along with a new differential gasket. This procedure is done so that you can remove excess metal shavings, grime, or other stuff that fell in during the differential swap process. TracTech states that the OEM specified gear lube is to be used for proper torque bias performance. I am going to stick with a quality synthetic 75W-90 for maximum protection and efficiency such as Redline 75W-90. If you plan to do racing or subject the rear to excessive shock from using drag radials or clutch dumps (I do NOT recommend the TrueTrac or Torsen for competitive high torque/high driveline shock drag racing), use thicker oil like Redline's 75W-140 or 80W-140.

Post-Install Notes:

I found that if you break the tires loose in REVERSE, you would experience an intense and violent vibration from the rear of the vehicle. According to Torsen, TracTech, and several people, this is wheel hop. However after examining the physics of the Torsen differential, it appears that the gears were designed for mainly FORWARD operation. The pinions grind against the covers while the side gears push towards the covers as well.

Now if you applied a lot of torque in reverse (gunning the throttle, breaking the tires loose), the pinions would grind against the case while the side gears would grind against the pinion shaft and cause some type of cavitation to occur which isn't good for the car or the differential.

So do NOT gun the throttle in reverse. Gently accelerate. I got the Vic up to about 15 mph in reverse without hearing anything abnormal, so it is not how fast you go but rather if you get any of the tires to lose traction causing the TrueTrac to start working in reverse gear. Overall, this was my single most anticipated mod since the day I got the car. I was always disheartened to see "3.55/non-locker" on the window sticker. Ford just simply refuses to make the Traction-Lok an option for civilian Panther platform cars, except for the Mercury Marauder.

UPDATE: 5/26/03
I did the 250 mile oil change to get rid of the metal shavings. I found quite a bit of debris in there, only two or three large pieces of metal otherwise everything else appears normal. The large pieces of metal look something like strands of metal shavings, I will be keeping an eye on this but as with all new differentials a bit of wear early on is normal, especially considering the TrueTrac uses helical worm gears instead of the normal beveled spider and side gears.

Important Specs:

Questions? Comments? Email Me: coldfusion@redpulsar.us