Anyone ever priced out the reworked CWP option for a group buy?

 

Yes, I did RFQ in March 2015.

Since then, I tried to "persuade" OEM chaps to provide me with copy of the CWP blueprint. Old blueprint would be useless in this case, but it could have been used for tracing some general dimensions.
To no avail, though. I think they probably tossed it decades ago.

Long story short:
including cost of reverse engineering, tooling made for the cutters, lappers, tester/proto and production set up, the cost would be $1,850 per set, not including cryo, taxes, shipping and insurance. Not expensive, comparing to prices charged by the "usual suspects" for the similar "weak" parts.

What say you?

 

At one time R&Ps were scarce.

Now you can get them from Harry Martens in the Netherlands:

Home

 

ESPRIT GEAR RATIOS

Standard OE Citroen C35 CWP ratio of 8/35 (4.375:1) x gear ratio are shown in black.
Red shows favorable 1st/2nd gear ratio step of the UN1 Holloway upgrade kit.

Beefed up CWP would open an ample opportunity for all G-car+88 US ET engine upgrades!
It could be achieved by reducing teeth count of the pair increasing their flank thickness.
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Here's a few pictures of the aforementioned tool (in action) that I made for removal / installation of the speedo gear:

The flats on the speedo gear are on the back side and very narrow. The tool makes access easy and in the limited space and, with jaw closure bracket mounted, it keeps the jaws of the tool from spreading when applying loosening or tightening torque, thereby eliminating the probability of rounding off the flats on the gear.

When I rebuilt the box on my S1, I sourced several parts from SM World. And a used Citroen CWP from Harry Martens. Both sources were extremely helpful. The used CWP, by virtue of its previous reverse rotation life in a Citroen, was brand new for my purposes. And since I don't dump the clutch from standing stops, the Citroen box has proven fully trouble-free in my hot rodded S1, and likewise, in both of my '84 Turbos.



Here's another nice tool that I made that has proven helpful. A nice little flywheel locking tool:

Removal of the starter motor provides clear access to the flywheel and the lock drops right into place. Easy peezy.

 

I just remembered something about the Citroen gearbox that is important to distinguish early Esprit units (S1 & S2) from the later cars: The shift lever on the gearbox (fore/aft lever as opposed to the side/side cross-gate cable actuator) is on the left hand side on the early cars. The S3 and Turbo cars had a new Lotus specific gearbox top cover with the lever relocated to the right side. This moved the shift linkage to the engine intake side and away from the exhaust. Heat from the early cars exhaust system would cook the plastic bushings in the mechanical shift linkage in short order. The result would be very sloppy linkage after only limited exposure to the heat.

 

Nice tools Ron!
Thank you for sharing your ingenious ideas. "Need is a mother of all inventions"

2 yrs ago, I missed these tools on eBay. Somebody got them for a song.
What are they for?

 

I have a rebuild toolkit that has all of the stuff you need to dismantle and rebuild a Citroen gearbox. It included clamps for the bearing saddles, a CWP height tool, a socket for removing the speedo drive gear, plus various modified tools to make the job simpler. It also contains a selection of spacers, shims, circlips and other service parts (no bearings or gears) that you can use when rebuilding your box - just replace them with the good parts out of your box that you won't be using. I don't guarantee that every spacer or shim you need will be in the kit - you probably will need to order some of your own, but if you can use them - great! It has been sent around the country at least a dozen times and is available on request. All you pay is shipping both ways.

 

WOW, good to know!

Thank you Mike.

I'm wondering, if you could share with us some other tricks in caring/rebuilding C35 transmission?

I started this one because a thread dedicated to Citroen transmissions would definitely benefit earlier Esprit owners. There was a thread like this on (now defunct) Lotus Buzz, but no more.:crying:

PS. THANK YOU RON for great pictures!

 

As far as care goes, don't rush your shifts. That is probably the most important thing to remember. The gearbox is running at the top end of its spec in an Esprit, and hammering it with power shifts is the quick way to problems. They will last a good long time if you take that extra half second between gears.

Rebuilding is a time consuming, futzy process that requires several disassembly/reassembly cycles of subcomponents - like setting up the preload on the differential and then adjusting crownwheel backlash once the pinion height has been set. Even with good measuring tools and a spreadsheet, you are looking at a minimum of 3 cycles to get everything dialed in. Having the proper tools helps a lot, but expect to place an extra order for an oddball shim or spacer, or running down to your local machine shop to have a thicker one ground down to what you need. It also makes all kinds of sense to replace bearings while you are in there, particularly if you suspect or find CWP damage.

There are some quirks about them. For example, the bell housing is also half of the bearing race for the differential bearings. This means that the bell housing was machined with the rest of the gearbox case as a unit. So, you can't just swap the housings around, as the bearing races will most likely not be round. It is also impossible to determine if you have a buggered pinion with the shaft installed in the box. The teeth are arranged such that you just can't see the working face even with a mirror. If you are faced with replacing the CWP, it is very worthwhile to spend the time dialing in the proper pinion height and crownwheel backlash - getting these right has a direct correlation to future failure.

One of these days I want to make a series of videos that detail how to work with the thing, but it seems I never have the opportunity to do a "leisurely" rebuild - I always want to get it back in the car in a hurry. Someday...

 

$1,800 is a bit much for my budget for a potential need, but if the price comes down with a group buy I'd be in, as the true cost comparison is with a transaxle swap to a Renault or better alternative. Of course if/when it breaks (without taking out the case) 1,800 may look cheap after discounting the cost of another used backwards Citroen CWP.

When I put in my LSD, I could see marks of a past failure, so it does have my attention!

 

When I put in my LSD, I could see marks of a past failure, so it does have my attention!

The circular 'polish' marks to the right side of your picture are the result of crownwheel carrier bearing failure.

@mike.griese is correct, the preload and backlash adjustments are REALLY finicky. I had my output shaft housings in & out more than 15 times (prob because that was my first time) getting the preload correct. :wallbang: And, that was using Mike's handy tool-set.

 

Dean Smith (medida lotus) has rebuild his C35 and Cryogenically treated them!
See below:


1986 Lotus Esprit Transaxle by Medida | Photobucket

Whilst you're there, check his supercharged engine !

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Does anyone know the PN# for the pinion shaft bearing (it is an INA (Schaffler) roller bearing , I think)?

 

US Citroen parts supplier
SM & Maserati, Engine & Gearbox

 

After reading all this, it makes me want to
build an electric/battery version of the esprit. What
a headache!

 

After reading all this, it makes me want to build an electric/battery version of the esprit.

So that the maximum torque will be applied at zero RPM?




Replacing the input shaft circlip with the more robust one (at ~45K miles), and at the same time replacing the differential carrier bearings (again, with the more durable SKF or Timken bearings made today) goes a long way to prevent the common Citroen transmission issues.

These repairs are no more involved than replacing a clutch.

The trial-and-error preload adjustments commonly needed to be performed on the solid rear axles of older rear-wheel-drive cars too, so it's not reasonable to complain. That's how it was done 'back in the day'.

 

FYI:
Maserati manuals and parts lists
The Car Nut - Maserati Manuals and Brochures

 

Switching to a Renault gearbox is not a cheaper solution by any stretch of the imagination. Remember that the Citroen cars have inboard rear brakes. If you change gearboxes you need to either reengineer the Renault gearbox mounts to accept the rear brakes, or change out the rear suspension to outboard brakes. Outboard brakes mean new halfshafts, new upper and lower links, as well as new rear hubs, calipers, rotors, and plumbing. And don't forget rear wheels. The offset for the rear wheels will be different with brakes crammed in there.

The shifter will need to be changed, as the Renault shifter is a two cable system with translator or a direct shift depending on the type of rear housing your Renault gearbox has, and the Citroen is a cable and shaft system.

Finally, the muffler support bracket on the Citroen cars bolts to the rear housing, along with a heat shield. Renault cars have an exhaust hanger that supports the shifter cables as well as mounts to hang the muffler. This muffler support bracket mounts to the transmission mounts, which makes an inboard brake solution that much harder to implement.

That $1,800 is looking pretty cheap now...

 

You're right! Harry used to charge 1650 euro for the "weak" Citroen OEM used one!

 

now, please mr Dangerous, don't spread any fairytales!!

I ask for a very, very nice used cwp set, wich is for the Esprit like new, because of different rotation, 1200 euro. Nowadays, 1350 USD!!

I have some brandnew original CWP sets. I ask 1800 euro.

I did have a quotation from Tandler 3 years ago. German gear manufactorer for Ferrari, Maserati, Porsche etc. 1500 euro for one set, minimum order 50 sets.


You go for it mr Dangerous.


I still can supply the Esprit community for many years with parts or complete rebuilds.


cheers,


Harry

 

Dear Harry,

No one can change the fact that old Citroen OEM profile teeth, if run "backwards", are inherently weaker, which you repeatedly denied in the past!
It doesn't matter if crown and pinion gears are old or "fresh" from the cutter. Geometry still is wrong for the application because the tooth flanks incline angle is wrong and promotes over-stress fractures.

I hope you agree with the fact, that thicker teeth are stronger. Therefore my redesigned crown has only 31 teeth and pinion 7, which makes possible cutting teeth 2.5-3mm thicker.
ALSO, my profile has more favorable line of action and tooth pressure angle allowing more efficient teeth meshing.

The pressure angle exists between the tooth profile and a radial line to its pitch point. In involute teeth, it is defined as the angle formed by the radial line and the line tangent to the profile at the pitch point. This moves the path of contact closer to the root where tooth is much thicker and can carry much higher loads.

In conclusion:
Why waste money on making duplicates of the original inferior CWP? They still won't be "right", (still driven on the wrong side of the teeth). Additionally, using coast side to drive CW contributes to fatigue failures.
Common sense dictates that new parts should be designed with an objective to withstand hi torque, internal impact AND should have a reverse-cut to allow correct gear meshing in Esprit application.

It is obvious that thicker teeth are stronger
So..., clearly, we're can not compare these two, it's like apples to oranges.


PS.
Additional strength can be achieved by Deep Cryogenic treatment.

~~~~~~~~~~
Cryogenic treatment, can effectively increase gear box (or any other component) strength and durability. Actually any part can be treated, camshafts, diff carriers, heads, pistons, con rods, etc.
Cryo-service companies are more and more common and getting less expensive every day. For example in US one can get crank shaft treated for under $150 !
Cryogenic treatment, also known as cryogenic tempering or freezing, utilizes ultra-cold temperatures (-301 to - 317F) to modify the micro-structure of metals and other materials.
Cryogenic treatment promotes additional crystalline transformations in metals. Deep cryogenic freezing ultimately improves the performance of the metal parts. Improvement in durability is around 100 percent (that's double !!!). The typical increase in strength is 30 to 50 percent. As you might imagine, these results can dramatically reduce broken part expenditures.
Home - The Lotus Forums
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Dear mr DANGEROUS,

I fully understand your point and wish you all the best with your project. I would make the sets mostly for the Citroen DS and SM and will not make them work " backwards".

Cyro treatment is indeed very good option. Have myself done some work too.


cheers,

Harry

 

Harry's point about making parts for the larger market is valid. The use of this gearbox by Lotus are small numbers compared to the other applications. I am not aware of any other applications that use it like the Esprit, but if there are any, they probably don't contribute much to the overall number. Add to that the number of Citroen based Esprits remaining, the number of miles they are driven, I suspect that the potential market is pretty small year to year.

Re-engineering parts these days isn't quite the chore it was in the past - all you really need is a good digital model of the parts and let computers do the conversions to swap direction of rotation for all of the surfaces involved and send it off to the NC cutter. Even so, those parts need to be tested, and those costs amortized over the number of sets you want to sell, in addition to raw material cost, machining, and any treatments you want to do once they leave the cutter. Don't forget the opportunity cost of tying up money in slow moving inventory.

I would be very surprised if you could get to a $2000 price point with fewer than 50 sets, and even if you could, who is going to finance upwards of $100k and then sit on the parts waiting for gearboxes to fail and for people to prefer your parts to Harry's?

 

Harry's point about making parts for the larger market is valid. The use of this gearbox by Lotus are small numbers compared to the other applications. I am not aware of any other applications that use it like the Esprit, but if there are any, they probably don't contribute much to the overall number. Add to that the number of Citroen based Esprits remaining, the number of miles they are driven, I suspect that the potential market is pretty small year to year.

Re-engineering parts these days isn't quite the chore it was in the past - all you really need is a good digital model of the parts and let computers do the conversions to swap direction of rotation for all of the surfaces involved and send it off to the NC cutter. Even so, those parts need to be tested, and those costs amortized over the number of sets you want to sell, in addition to raw material cost, machining, and any treatments you want to do once they leave the cutter. Don't forget the opportunity cost of tying up money in slow moving inventory.

I would be very surprised if you could get to a $2000 price point with fewer than 50 sets, and even if you could, who is going to finance upwards of $100k and then sit on the parts waiting for gearboxes to fail and for people to prefer your parts to Harry's?

Mike,
Where did you get the 2000 number? Did you get it from someone else? What company?
Please read my post #4 and #35, again.

I'm NOT scared spending money (wisely)!
BTW, there are almost 6,100 Esprits with Citroen trannys, so market is there.

 

While it is true the diff gears are running "backwards" it doesn't seem to affect the longevity.They also run backwards in the Renault box in the Lotus AND the Delorean. What does seem to kill the gears is abuse or failure of the carrier bearings (probably from abuse). Using good fluid, changing it often and not flogging the car are all that is necessary to keep the parts going for a long time. Another point to be made, NEVER touch the adjusting nut on the carrier bearings without going through the whole pre-load check. Once disturbed and not properly reset you WILL kill the carrier bearings and then the gears. It is not necessary to remove that nut to change the seal but all too often is is turned anyway.
David Teitelbaum

 

While it is true the diff gears are running "backwards" it doesn't seem to affect the longevity.They also run backwards in the Renault box in the Lotus AND the Delorean.
David Teitelbaum

Not true! It adversely affects longevity!
OE CWP driven on the "wrong" side of the teeth (coast flank) generates vector towards the cone center "jamming" the gears together, which should be avoided. See below.

PS: UN1 box/CWP rotates in the "right" direction.

 

NEVER touch the adjusting nut on the carrier bearings without going through the whole pre-load check. Once disturbed and not properly reset you WILL kill the carrier bearings and then the gears. It is not necessary to remove that nut to change the seal but all too often is is turned anyway.

^^^ David, that is Renault 'box advice.

The Citroen's carrier bearing preload and CW&P backlash are both adjusted by installing and re-arraigning shims.


There is no adjusting nut on the carrier bearings.

 

^^^ David, that is Renault 'box advice.

The Citroen's carrier bearing preload and CW&P backlash are both adjusted by installing and re-arraigning shims.

If you can't figure out if your shims are innocent or guilty, you can always put them in a holding cell overnight

Sorry, just a little humor!

Scott

 

Mike,
I financed the EMCO UN1 single shaft/1st/2nd gear conversion kit group buy out of my own pocket to the tune of $140K and sold all kits in 2 months. I'm NOT scared spending money (wisely)!

FYI:
Flank breakage in cylindrical and bevel gear applications typically initiates in the active flank, approximately in the middle of the active tooth height, and subsequently propagating to the tooth root of the unloaded flank side.
Crack initiation can be localized below the surface in the region between the case and core of surface-hardened gears.
This failure mode cannot be explained by known causes such as tooth root breakage or pitting. Even bevel gears in truck/bus applications are at risk of damage from sub-surface fatigue if an optimum utilization of material is not achieved. In such instances a balance between the flank breakage and pitting risk must be considered.

 

I vote guilty?