CV Workshop
Courtesy of: Mance Etheredge


I had SOOOO many inquiries on LWCV's yesterday/last night I thought I'd create a CV Workshop...


as there is so much misinformation/disinformation out there regarding CV's I think the only way to approach these is by information sharing.

I'll start by saying CV's are not the "cake" when it comes to chassis-building. They are icing on the cake. Some have asked "why would I pay $1700 for 6 CV's when I can buy a big behonking turbo and have change left over?" Well, ya wouldn't silly and the question is more ridiculous/rhetorical than valid. You build motors for HP/Torque, you buy lightweight/motorsport CV's to augment and enhance the driveline that motor is bolted to and the chassis it's going in. And yes, of course there's several, if not many things you will want to consider before CV's unless budget is unlimited and allows EVERYTHING be bought up-front and that only occurs in fairy tales and on factory race teams. And I don't know of even a single instance where "something" didn't always get added later.

Another concern some have had with lightweight CV's is that they may be weakened in the lightening process. Admittedly that is a concern I shared early-on. However the outer CV's provide a lot of insight into this dilemma. By doing some Rockwell C-standard testing on both inner/outer CV's as well as wall thickness measurements it was determined that the outer CV would fail catastrophically/explosively 12% sooner than the inner CV "after" lightening. Even after lightening the inner LWMSCV's have a thicker and narrower wall thickness than the thinner/wider outer CV wall thickness it's connected to via a common axle. Without exception a stock outer CV will fail first in EVERY instance with the "possible" exception of collision which I'm unable to emulate on the bench. And this dynamic holds true for both 100mm and 108mm CV's and their mated outer CV's.

Many/most think LWMS CV's are just for making power and little could be further from the truth. They don't make power so much as they allow faster acceleration/decelleration EXACTLY the same way a lightened flywheel does, ie; they make your "pre-existing" power more fun, efficient, friction-free, feelable and enjoyable "thru-the-gears" and it doesnt come at the cost of additionally stressed engine componentry. You cannot at-once agree with flywheel/driveshaft lightening while simultaneously poo-pooing lightweight CV's. Done correctly it's not a one-or-the-other choice. They are part-&-parcel to the same end. Choosing only one just leaves some performance on the table that is otherwise available. Definately an "if I'm gonna be a dog, why choose Chihuahua" item. But yes, sadly it does cost money and and it's a smaller ROI but that doesnt mean there's no place for finesse and subtle nuance in race cars or daily drivers. Hell, Formula Fords were using these in 1970. It was one of the best kept secrets in SCCA. It wasn't "illegal" mind you... just a very closely held secret initially known to only a few. Not uncoincidentally the "few" that somehow always managed to finish in the top 10, race after race... season after season. People went to GREAT lengths to hide their inner transaxle CV weight-reduction by filling the weight-relieved areas with foam fillers, sealing then painting so no one could see it on those open-wheeled cars. Same with Brabhams, Lolas, Royals, Indy cars, Formula 1 and other Hewland transaxle equipped cars. None of those cars have bigger/heavier than absolutely necessary CV's. And if there weren't a damned good reason for that no one would ever have used them! You can argue with almost everything. Success however is NOT among them.

Another thing many don't consider is that LWMS CV's arent "just" for faster acceleration as that's only maybe 20% their overall benefit. You must also consider the law, ie; "for each and every action there must be an equal but opposite reaction!" LW driveline components are quicker to slow when you let off the go-pedal. And this while the drag racers nemisis is the road racer's blessing. A drag racer will likely offset some potential benefit by a race lasting only a few seconds and the slowing that occurs between upshifts (even when power-shifting if clutch is depressed). But does that mean there's no benefit to LWMS CV's in ALL of motorsports!?! Of course not! A road racer on the other hand gets the benefit of letting off the gas deeper into a turn and increased parasitic drag due to reduced rotational inertia in the time that lapses between letting off the gas and getting on the brake... a faster/more efficient "pre-brake" slow-down accompanied by an additional quicker exit out of that same turn due to faster acceleration. Now granted it's not gobs of time but it's cumulative and it COUNTS!! On a 12 turn 2 mile road course even if it only averages 12-15 thousandths of a second faster in/out of EVERY corner thats a .144-.180 second faster lap time! In 10 laps thats a 1.44 to 1.80 second enhancement! There's been times I woulda given a testicle for a tenth of that!! Road race, auto-X and rally events are usually won/lost in sub-seconds.

On high HP or mega-boosted turbo applications much of the benefit goes unnoticed on acceleration. But it remains as high profile noticeable on deceleration as a lowly sub-200HP car weighing about the same. However that same lowly sub-200HP car owner has no problem feeling the benefit on both acceleration/deceleration. Learn to use and modulate that faster deceleration on auto-x, road course or dirt and it can become even more addictive/beneficial than the "equal but opposite" benefit in acceleration. You let off & brake later and less going into a turn then accelerate faster upon exiting... the single biggest key to success in EVERY form of automobile racing except straight-line!! It's an entirely different dynamic than most have experienced before since it doesn't involve the usual parts and components normally associated with those benefits. Now none of this is "best-handled" via LWCV's alone. Most benefit with any driveline loss of rotational mass are best accompanied with tons of other related modifications including, but not limited to lighter tires, rotors, wheels, driveshafts, axles, cranks, flywheels, harmonic dampers etc. LWCV's are not a replacement/substitute for any of those. They're the "go-to" parts when everything else has been addressed. As I said early on, they're the icing. And any good icing is best served on a great cake. Sure you can eat icing alone with nothing else but it's nothing special in and of itself... sweet but unfufilling.

Other benefits of LWCV's are that they are precision blue-printed and this is a "no-short-cuts" hand crafted, laborious and meticulously carried out affair. After lightening CV's will shrink in 4-7 days due to stress relief. Without honing, lapping and polishing they risk seizing if mounted directly on a car after lightening and driven hard for any extended period. You don't even want to hear the kind of driveline damage a seized CV can cause let alone experience it!! Lapping/honing can only be done accurately after the lightened CV outer mass has relaxed over a period of a week or more after weight removal. And even then only in VERY precisely measured tolerances. This requires the use of plug gauges and laps and hones in 3 different sizes and grits on EVERY CV modified thusly. That means 6 each ULTRA precision plug gauges, 3 laps and 3 hones are used in 3 different sizes on EVERY 100mm driveshaft CV, 100mm inner axle CV's and 108mm inner axle CV's all require 18 different plug gauges and each inner outer bearing race must be lapped/honed in 3 stages as a mated pair and then a final "polish" is applied to the inner/outer bearing races. To do a single CV is over a 3.75 hour process from lightening-thru-polishing/assembling//balancing/testing. And each CV's inner/outer ball race is indexed so that it is reassembled with "matched" races where all races are "paired" as they were lapped/honed upon re-assembly. Additionally the plug gauges also insure each CV inner race is perfectly centered within it's outer race while honing/lapping. Something that is nowhere close to perfect even on a brand new right-outta-box-CV. In fact on a new CV the inner & outer races never even come into contact with each other during manufacturing until they are assembled and placed in the box you buy. There's no time spent mating, matching, or otherwise insuring the inner/outer parts are perfectly matched/mated to each other.

A lapped/honed CV runs cooler, smoother, quieter requiring a LOT less power to operate as so little is lost to parasitic drag and/or friction/heat. They can run over 90*F cooler than a new OEM CV and average over 50*F cooler than a well-worn but "good" CV. They are also exceedingly smooth when run thru their orbital, axial and radial deflective axis by hand after "dry" (before grease-packing) assembly. They exhibit no high/low/loose or tight spots and feel ultra-smooth in EVERY axis. Just the difference in "hand-feel" is incredible but where they truly shine is on the car. You'll be amazed how much noise a CV can make even in a straight line as well as how much driveline NVH they tend to make and transmit thru the chassis. But the funny thing is ya don't even notice it until it's GONE!! And usually one of the biggest and first-experienced reactions and comments to me by people buying these is how quiet and smooth the car is now. Yet they never thought it was loud or suffered any NVH before.

They also come with a lifetime replacement guarantee as does everthing I sell. And I don't care if it's used on a track in a professional race, off-road or otherwise. Anything that doesn't dent, gouge or break the CV outer body as in a wreck gets a replacement if it ever fails, PERIOD!!

Each matched pair of CV's also come with a 14.4 oz tube of Redline CV-2 red moly grease for packing the CV's. Redline claims this will extend the life of CV's by 2-8 times on their site. I dunno if thats true but it's all I use and I wouldn't pawn anything less off on anyone running these.

Now with all this said I want to add that this is not some sales spiel. I know precious few of these will ever be sold. I actually count on that! Truth is I DO NOT wanna do these 8 hours a day, day in day out. I would come to hate them if that were the case. Exclusivity has it's own merit and privelages. But I also know there's a few that want em and a few that already have them. I'm ok if I never sell another one. But I like doing them in spite of all that. Just something about making the most efficient, lightweight, ultra-precision, balanced and bullet-proof Audi CV's available ANYWHERE that pumps a lot of cool breezes up my skirt! And of course ya can't see all that high-tech, nerdy, polished/lightened and precision geekdom when installed. Bling is a dish best-served top-side while LWMSCV's languish "at-the-ready" beneath the cool shade of the chassis in total under-stated anonymity. They don't telegraph their punch!

I'll complete the workshop with a few subsequent posts showing step-by-step procedures involved in the evolution of an OEM CV to a full-fledged lightweight/motorsport CV.

Pic shows a new Lobro driveshaft CV with 1st step plug gauges installed. All gauges used in this process are Myer Guage Pins in Class "XX" series with inch tolerances of .00002" and a metric tolerance of .0005mm and VULGARLY expensive!! But they insure each inner/outer bearing race has exceedingly good concentricity and sphericity in their assembled relationship. far, Far, FAR higher tolerances than stock OEM specifications and fit the ball bearings they're mated with PERFECTLY after honing, lapping & polishing.

CV Workshop Part 2...

In this pic you can see where a new "real deal" Audi/Lobro driveshaft CV has been ultrasonically cleaned and then lightened. Some CV's may exhibit additional "light" machining marks where they are also trued for axial/radial run-out at the same time. This will show up as "shiney" machined areas on the front face, OD or rear face and in some cases, all 3. Goal is "0" indicated run-out on all 3 outer surfaces. Inner race is also checked for run-out and concentricity and corrected if present. Any run-out found in these parts will have a dramatic affect on CV dynamic balance and operating smoothness once assembled. Zero imbalance/run-out is the "only" accepted number at 10k RPMs on driveshaft CV's and 6k RPM's on all inner axle CV's after modification. If it can't be achieved by shuffling balls and/or roating inner race 120/240 degrees within the outer race then it's done assembling parts for least imbalance then chamfering bolt holes for absolute balance. No brand new CV to-date has been found by me that outta-the-box will sustain even 800 RPMs without "some" measureable imbalance! And no CV is placed on the balance machine that is not a fully assembled unit! This particular CV and its opposite-end driveshaft counter-part as well as all 4 inner axle CV's being sold in this set will also be cryogenically treated like those on my car per customers request (add $15 per CV) after machining/balancing. All stock ball bearings provided with new CV's are discarded and replaced with new "Grade 10" ball bearings being ultra-close tolerance balls with enhanced sphericity compared to the Grade 8 balls provided by Lobro and are weighed down to .001 grains (not grams) so they don't contribute to or exaggerate any existing imbalance once assembled. And don't think for a minute that ball bearings all weigh the same or are even close!! Out of 100 balls I'll usually get 3 identical tho slightly varying weight "sets" of about 30-31 balls per set which I can usually assemble 14-15 CV's with a matched ball set weighing EXACTLY the same in all 6 CVB races. 2-3 ball bearings out of every 100 will inevitably be tossed as they simply cannot be weight-matched to each other or any other balls in the box. I will also substitute the ball cages in EVERY CV I'm not satisfied with as that relates to it's fit to ball bearings and/or the CV inner/outer races with special cages made specifically for me and this application. If stock cage is a good, tight fit it stays. If I'm unhappy with it for any reason it goes in the trash. Too much time/effort put into these to compromise on a $20 part!

Lightening these involves the use of radiused corners to prevent stress risers forming. Weight removed is 12ozs (3/4lb) per 100mm inner axle/driveshaft and 14ozs per 108mm inner axle CV's. This makes the larger 108mm inner axle CV's after conversion to LWMS specs even lighter than a stock 100mm inner axle CV!

I try to keep 12 driveshaft CV's lightened and on the relieving bench for 10 days to two weeks before further work so that they take their "set" and relieve themselves. This means they will shrink over a period of 4-5 days and I like to afford them some additional time. I can't do anything to them as it relates to lapping, honing and polishing until "after" they've taken a measureable and confirmed .xxxx" amount of stress relief.

More on this as this CV is massaged into LWMSCV spec.

CV Workshop Part 3...

Today I'll show the final pre-assembly results of the same driveshaft CV I showed in Part 2. I finished both driveshaft CV's yesterday which took a little over 6 hours to complete. And thats about as much work as I can tolerate on this phase of CV work in a single day. And I don't want to do that more than once/twice a week as it's very meticulous and fidgety work requiring a LOT of focus and mental concentration. Additionally it's messy work as these are lapped/honed either completely submerged in coolant or when out of the "soup" under a heavy spray of coolant. Without cooling these during lapping/honing they get hotter-n-hell and will warp/deform a thousandth or so if one area gets hotter than another. Only way to retain the concentrricty of the part attained during lightening and run-out correction is to insure nothing gets above room temperature during this process.

You can see a slight tinge of "rosiness" in this CV that wasn't there in yesterday's pic. That comes from the final polishing using jeweler's rouge on the bearing races. That stuff is nigh-on impossible to remove completely with standard brush & soap cleaning but every individual component of a blue-printed/lapped, honed and polished CV is ultrasonically cleaned a 2nd time before assembly and balancing. Ultrasonic cleaning scrubs the rouge right off (something about a quadrillion tiny bubbles with an internal temp approaching 1,000* F that rouge just can't quite stand up to ;-). They are then moved to a "clean-room" (a spare bedroom) where I keep all my ultra-close tolerance precision measuring tools. There they are wiped down with a lint-free cloth, then assembled with a weight-matched set of upgraded "Grade 10" ball bearings and again blown out with compressed air. They are then checked for "rough" imbalance on a cone balance ball setup to sub-1 minute of absolute "static" balance, measured from both sides. They are disassembled/reassembled as many times as necessary to accomplish this. Once sub-1 minute angle of imbalance is attained on my table-top machine they are blown out again, this time with filtered/clean air and dipped in WD-40 and placed in individual plastic "zip-lok" type bags and stored until 6 or more at a time can be taken to the balancing shop as my special pricing for balancing is based on "6 per visit" and I retain the special balance jig arbors I CNC'd specifically for this purpose that is required for balancing. The 3 jig arbors used for the 3 different LWMSCV's have been balanced to 14k RPM's with no measureable imbalance so they cannot influence or affect CV balancing. And each balancing arbor is re-checked and corrected if necessary for zero imbalance at 14k RPM's every visit to the balance shop before any CV is balanced on it.

This pic also shows the stock inner ball cage on left and one of my ultra-close tolerance custom ball cages I have made for all LWMSCV's I offer on right in pic. If I can't get the perfect fit I'm looking for with the stock ball cage then I opt to use a custom cage in that LWMSCV. Most stock cages are perfectly acceptable/useable. Maybe 1 out of 18-22 is slightly too large/loose-fitting for my liking and doesnt provide the ultimate fit I'm seeking. When that happens I go for one of the known-good ones. And even then I "sometimes" get a loose one tho the ratio is closer to 1 in 60 that are slightly "outta whack" and subsequently tossed.

The polishing on the ball bearing races is purpose-designed to have the same micron finish as the Grade 10 ball bearings used. I want a true "glass-on-glass" surface bearing/race relationship. If my polish is rougher or less than the ball micron finish then all I've achieved is "glass-on-cinder block" and that just doesn't suit me or the goal with these.

After balancing they are put back in their plastic bag and returned home or sent out for cryogenic treatment if specified then home where they undergo a 3rd ultrasonic cleaning while fully assembled "as-balanced", blown out again with filtered/clean air, dipped in WD-40 again and placed in a new zip-lock where they remain until shipped to end-user. It is of utmost importance they remain sealed/unopened until such time as they are to be packed with grease by the purchaser and that too should be done in a meticulously clean area so as to avoid contamination of grease and CV. And they should NEVER be dis-assembled without all 9 parts, ie; outer ring, inner race, ball cage and all 6 balls be marked/indexed so they can be re-assembled EXACTLY as they were before disassembly. If you don't you've ruined a LOT of work and wasted a ton of money. Sure it's smoother than a stock CV but it's a LOT less CV than you paid for!!

The pic above would appear that the outer mass internal ball races have a lesser/duller polish than that on the internal splined race. It's an illusion caused by the outer ring internal races picking up the reflection of the silver table underneath. Both are mirror-finish pieces. They are identical in every way... they have to be as they are lapped, honed and polished while mated together and both have the same Rockwell C-hardness of 60-62. Funny thing in all this is that the outer weight removal area has no polishing done to it.. just touched with a ScotchBrite pad before turning the lathe off removing from it's centering fixture. Thats EXACTLY how it come off the lathe after lightening. It's nowhere near as polished as it looks in this pic and the races are a LOT more polished than they appear. Capturing polished mirror surfaces in pics is tricky bidness!