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Thread: pinion depth/backlash english diff cwp rebuild tips and info

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    Tyre Kicker ernos's Avatar

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    Post pinion depth/backlash english diff cwp rebuild tips and info

    Q from CW&P tooth contact area,could it be good thing that pattern have different than the other side (drive/coast),coast side be a bit higher than drive side pattern or is STD pattern one and only.

    How much is axial clearance of carrier side bearings or preloading or torque value to those"plate nuts",what are they by right names

    Pinion rotation/bearing preload,free rotation on 0.2-0.35kg ,is this correct value for english axle

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    Re: english axle CW&P

    Hi,

    The contact height isn't that important if it's not making any noise. If it's got different markings AND is noisy then both gears are probably scrap anyway.

    I could post all the settings for the diff on here, but how you set it is quite difficult to explain. So long as you don't have to put a new pinion in it's not too bad and can be done with just one dial gauge - if it's a new pinion it's much harder to do.

    The adjusters for the crown wheel don't get set to a torque figure, you screw in one until there's a certain backlash on the gears then screw the other one in to spread the bearing caps by a set figure. This opens up the backlash between the CW and the pinion and you measure this again. If it's not in tolerance you take it all apart and start again. I've never had one that didn't come within tolerance.

    Preload figure for the pinion depends on whether it's all new bearings and seal or not, generally used bearings & seal have hardly any.

    Good luck.

    Bernie

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    pinion depth/backlash english diff

    after rebuilding my axle and putting it back under the car i have come across a problem.

    there seems to be too much play when the wheels are turned which gives a bit of a clonking.

    i replaced all the bearings in my diff and has never had the backlash and pinion depth set properly.

    could this be the cause of my clonking.

    i dont intend to connect the prop until iv sorted it as i dont wanna chew my diff up.

    you reckon its best to take the diff to someone that knows what theyre doin when setting it up as i just dont have the equipment.

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    Pole Position Decade Plus User Pushrod King's Avatar
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    Re: pinion depth/backlash english diff

    Provided you didn't remove the spacing shim/washer that's between the pinion Gear end and bearing the depth shouldn't need changing however the is set using a colapsable spacer which can be reused if you're very careful to literally nip the pinion nut up (otherwise you'll crush the bearings)but ideally needs setting with a spring guage,the crown wheel to pinion adjustment is a case of turning the adjuster rings until the diff runs smoothly and the tightening using a spring guage.
    I set mine up by feel and don't use a guage but I've got 25+ years of experience.

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    Re: pinion depth/backlash english diff

    there didnt seem like much play when i set it up, but obviously when this is translated to the wheels its magnified.

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    Re: pinion depth/backlash english diff

    I'll just add to what pushrod says in that if you've put new bearings on the pinion don't run it till you've had it set up, the diff cage bearings are easier to get right - I always do mine with gauges an shit. But I'm a smally boy who's only been doin them for 15 years instead of pushrod's 25.

    You might have a bit of trouble finding someone old enough in a gearbox/diff place to know what the figures are for these anymore.

    Bernie

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    Re: pinion depth/backlash english diff

    i too do most diffs by feel but i have a pukka origonal escort RS1600workshop manual here it says,

    crownwheel/pinion back lash 0.005 to 0.007" (0.13 to 0.17mm)

    to meassure this set a DTI gauge up in the tip of a crown
    wheel tooth and rock the crown wheel back and forth but with out atually moving the pinion.

    pinion bearing preload excluding drag from seal
    20 to 26 LB/INCH new bearings 12 to 18 LB/INCH old bearings

    note the figures of lbs per inch, in other words not much preload at all, you can use a spring balence in a prop flange hole to meassure this, assemble the diff with out the seal, tighten it until you are at the lower end of the tolerance, then mark the pinion nut so you know exactly where it is, undo the nut, fit the seal and do the pinion nut up again stopping exactly on or just a tiny fraction past your mark.

    differential carrier spread, i.e the amount the diff carrier should get wider by when you preload the diff bearings using the screwed colars 0.008 to 0.10 (0.20 to 0.25mm)

    i have a big micrometer which i can meassure this with.

    or on the other hand send the whole lot to Fossie and let him do it see fostek one of the sponsors at top of page
    Last edited by Graham; 15-01-2008 at 13:48.

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    Re: pinion depth/backlash english diff

    Quote Originally Posted by graham bahr View Post

    pinion bearing preload excluding drag from seal
    20 to 26 LB/INCH new bearings 12 to 18 LB/INCH old bearings

    note the figures of lbs per inch,


    Have a think about this.

    lb.in is not the same as lb/in

    I'm sure you've got it right in your head Graham - but if you think about this preload (or Torque required to rotate the pinion) in terms of lbs PER inch then you'll end up with far, far too much preload.

    I don't do English diffs by the way, but thanks for the thought.

    A spring balance is a perfectly good method, by the way. There's a huge tolerance on the preload figures in the books however - i.e. 20-26 lb.in is quite a window. If you can get it bang in the middle, that'd be fine. Too tight and it'll overheat, too slack and it'll rumble/wear out.

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    Re: pinion depth/backlash english diff

    yes fossie your right i should of typed lbs.in,

    in other words if you have your spring balence attached 1 inch away fro the centre of the pinion it should take a pull of 20-26lb to rotate it, if you are using the holes on the prop flange you will need to do some maths to work out how hard to pull, i.e if the flange hole is 2 inch from the pinion center then you would have 10-13lb pull
    Last edited by Graham; 15-01-2008 at 17:41.

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    Re: pinion depth/backlash english diff

    Quote Originally Posted by graham bahr View Post
    yes fossie your right i should of typed lbs.in,

    in other words if you have your spring balence attached 1 inch away fro the centre of the pinion it should take a pull of 20-26lb to rotate it, if you are using the holes on the prop flange you will need to do some maths to work out how hard to pull, i.e if the flange hole is 2 inch from the pinion center then you would have 10-13lb pull
    Spot on.

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    Re: pinion depth/backlash english diff

    I was thinking of putting new bearings and my atb in my spare diff myself so this is all dead handy. I got the figures with the new bearings, plus the figures here so im sorted for that.

    Whats bugging me is....

    If i change the pinion bearings, provided i set the preload right i wont have to mess about changing the shims as its all the same bits in the same casing just with new bearings and seal?!

    Also whats the guages i need, is it an old torque wrench with the needle that swings to indicate the torque? Also whats this spring balance?!

    The rest i think im ok with
    Last edited by dangerousdave; 18-01-2008 at 20:02.

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    Re: pinion depth/backlash english diff

    Modern spring guage

    If you only change the bearings the diff shouldn't need shimming unless it needed adjusting in the 1st place,the crushable spacer will need to be either renewed or hammered flat where it's belled out so the pinion bearing preload can be reset. HTH.

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    Re: pinion depth/backlash english diff

    Cheers, helps lots....just bid on an old fashioned spring balance http://cgi.ebay.co.uk/Spring-Balance...QQcmdZViewItem so that should let me set that bit up.

    I got a new crush washer with the bearings, so its just a case of following the instructions above to set the preload, then apart again and put in the seal, then just play with the twiddly side bearing adjusers until you get the mesh hitting the middle of the tooth as in the instructions with the bearings. Im guessing you have the bearing caps done up tight when you play with the side adjusters?!

    Might crack on in the week if i get a chance and the weathers crap and get lots of pics and do a nice write up for this section

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    Re: pinion depth/backlash english diff

    you may have trouble finding a torque wrench that will read what you need which is why the spring balence is a good bet.

    yes the bearing caps are done up when you twiddle with the side adjusters, dont forget to keep you need to prelaod the side bearing to by streching the diff casing, the side bearing adjustment will effect the backlash too, use a dti gauge on a crown wheel tooth to check, too little backlash the diff will be noisy too much and the risk of stripping teeth dramatically rises.

    if you want new crownwheel bolts use X/flow flywheel bolts they are the same

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    Re: pinion depth/backlash english diff

    Cheers graham, tbh i have not seen an old style torque wrench for sale yet! And yep wont forget to preload the side bearings, got all that written somewhere, either a guide on the net or in the bearing values got the dti from when my dad was an engineer so im all set to build it, im hoping its a lot easier than it seems as its kinda thought of as a black art, but must be on a par or easier than building an engine and i manage that fine

    And the bolts will be fine

    If i use the crown wheel thats on the s/h atb (its the same ratio) then it will mess it all up right as the cwp are a matched pair that have worn to eachother so i need to change it for the original one? Also do you have to heat the crownwheel up to get it on/off as its a tight fit or is that some other manufacturers diffs (the guide was for a hilux!)

    Thanks again

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    Re: pinion depth/backlash english diff

    Definately keep the cwp as a matched pair,no you don't need to heat it up it will tap off but make sure youtap it evenly otherwise it'll be pissed and wont come off.
    What I do to line the crown wheel holes when I'm putting a crown wheel on is use a couple of long bolts the same thread as the c/w bolts with the heads cut off,screw them in oposing sides of the c/w and put them through the corresponding holes in the ATB housing and the tap the c/w back on either with a drift on the inner edge or a block of wood (don't directly hit the teeth)

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    Re: pinion depth/backlash english diff

    cwp's are matched pairs, you must keep them that way, missmatched ones can whine like an old women whos at a car show when she wants to go shopping instead!

    although the crown wheel should go on cold the last one i fitted to an lsd wouldnt go on without either a lot of force or warming it up, i put it in a medium oven and baked it for 15mins! that worked a treat

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    Re: pinion depth/backlash english diff

    Cool cheers for more tips guys, im feeling a lot more confident about doing it now...was contemplating sending it off to someone professional

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    Re: pinion depth/backlash english diff

    Quote Originally Posted by dangerousdave View Post
    Cool cheers for more tips guys, im feeling a lot more confident about doing it now...was contemplating sending it off to someone professional
    If you get stuck or run into trouble, feel free to give me a buzz and I can run through it with you

    How are you planning on getting the old bearings off by the way? Have you got access to the proper bearing pullers? If not, be V careful with the grinder - I've seen far too many pinions and diffs for that matter, with gouge marks from previous attempts to take bearings off.

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    Re: pinion depth/backlash english diff

    Cheers mate, will do if i need to but im pretty sure il be fine, i was just not too sure about the shim and what to use to measure the preload

    Also i have access to a hydraulic press at the garage my brother works at so between us i recon we should be able to come up with something to get them off

    Quite looking forward to this now, i could be the ts sarf london diff builder

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    Dave,

    One bit of advice. If you put it together and the backlash measures up in the middle of the range it's OK. If it's at one end or the other take it all apart and start again - you've skinned it somewhere on the measurements.

    Bernie

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    Fear not, i paid kev16v and wayne wigger to build it for me For the price they charged its not really worth me bothering and potentially messing it up.

    Just got to take up fishing now to make use of the spring balance i bought

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    Info..................
    Attached Thumbnails Attached Thumbnails Diff-Setup-PinkForm-1.gif‎  

    Diff-Setup-1.jpg‎  

    gear_layout.jpg‎  

    Small-Fords-Diff-Gear-Count-1.jpg‎  

    Take it Easy....

    Roger Miller

    Works-Escorts = http://rsmotorsport.com.au/

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    Re: pinion depth/backlash english diff

    Quote Originally Posted by graham bahr View Post



    differential carrier spread, i.e the amount the diff carrier should get wider by when you preload the diff bearings using the screwed colars 0.008 to 0.10 (0.20 to 0.25mm)
    Can someone help regarding the above. Done the pinion bearing preload as above, done the crown wheel/pinion backlash. Could someone explain the differential carrier spread, not quite sure.

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    im pretty sure what youve got there is the measurements for spreading the atlas axle case when loading the diff and shims. i may be wrong and im sure that nice man from FOSTEK will put us right.

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    Re: pinion depth/backlash english diff

    Quote Originally Posted by darrans View Post
    Can someone help regarding the above. Done the pinion bearing preload as above, done the crown wheel/pinion backlash. Could someone explain the differential carrier spread, not quite sure.
    the diff output bearings need some preload on them, you do this by meassureing across the diff bearing carriers and tightening the bearing adjusters so that the diff bearing carriers move appart by the required amount, i have a big micrometer to do this

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    Re: pinion depth/backlash english diff

    Quote Originally Posted by graham bahr View Post
    pinion bearing preload excluding drag from seal
    20 to 26 LB/INCH new bearings 12 to 18 LB/INCH old bearings
    is the above setting for new bearings carried out when diff is built up completely, or with just the pinion?

    (hope its just the pinion...shit!)

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    Re: pinion depth/backlash english diff

    99% sure its when its all stripped and just the pinion

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    Re: pinion depth/backlash english diff

    Quote Originally Posted by graham bahr View Post
    yes fossie your right i should of typed lbs.in,

    in other words if you have your spring balence attached 1 inch away fro the centre of the pinion it should take a pull of 20-26lb to rotate it, if you are using the holes on the prop flange you will need to do some maths to work out how hard to pull, i.e if the flange hole is 2 inch from the pinion center then you would have 10-13lb pull
    Hi Graham,
    Could you help please i have torque dial gauge (lb/inch) wrench i got from the States for little money, what i need to know given the info above if i'm using the pinion nut to measure the Pinion pre-load will that alter the pull reading of 20-26lb if so would you be able to tell me the correct pull reading please?
    Best Regards,
    Adrian
    Last edited by westie1700; 18-04-2009 at 09:13. Reason: incorrect spec

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    if you useing a lb/inch torque wrench directly on the nut then the setting stays 20-26lb/in

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    Thanks Graham & all who contributed for the valuable info
    Adrian

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    Came across this thread when I googled English Axle and used the really useful info to rebuild my English Axle (in a kit car ) last weekend.
    Diff felt in need of attention , with that wind up / clonk when going from 1st to reverse.
    When removed there were no horrors , metal filings etc. However , although the pinion had no perceptible end float, it was very free running ,ie close to zero preload and there was plenty of backlash between crown wheel and pinion, although I didnt measure it.

    So I dismantled the diff and finding no obvious pitting on the bearings decided to re-assemble it using a new crush washer to reset the preload on the pinion bearings. I didnt replace the seal as it wasnt leaking . I used the correct weight of water in a plastic bottle suspended from one of the output flange holes to give me 13lb.in of torque and incrementally kept tightening the pinion nut till it just turned under that suspended load.

    I then reset the crownwheel by nipping up but not fully torquing down the bearing caps and adjusting the side wheels to move the crownwheel across till I acheived backlash of 0.15mm at the tip of a crownwheel tooth . I didnt have a dial gauge , so i set hard stop using a threaded rod and a piece of plate against which I could rotate the crownwheel tooth and used a feeler gauge between the two to determine the backlash.
    I then used some blue to check I had a decent sized central meshing on the gear teeth.
    Finally I measured the distance on a given point across the bearing caps and increased that by 0.22mm by screwing in the adjuster wheels evenly. Torqued up the bearing caps fully and rechecked nothing had changed on the backlash and the meshing.

    Reassembled everything in the car and drove about 10 miles at a steady speed . It felt much better , no noises and no slack as you came on and off the gas .
    Now to the point of the message !
    How hot should the diff get? Its not something I've ever tested before , but this was hot enough that I could only just hold a pressed palm on the front of the casing . I had also installed in the rebuild a drain plug into which I had fitted a magnetic bolt and on draining the oil , I did find some swarf.
    So-have I got a problem and can someone say from the above whether I have dropped a B****** somewhere?
    I would say that I was surprised at how tight I had to do the pinion nut up to achieve the correct preload torque .

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    Quote Originally Posted by Ppuxley View Post
    Came across this thread when I googled English Axle and used the really useful info to rebuild my English Axle (in a kit car ) last weekend.
    Diff felt in need of attention , with that wind up / clonk when going from 1st to reverse.
    When removed there were no horrors , metal filings etc. However , although the pinion had no perceptible end float, it was very free running ,ie close to zero preload and there was plenty of backlash between crown wheel and pinion, although I didnt measure it.

    So I dismantled the diff and finding no obvious pitting on the bearings decided to re-assemble it using a new crush washer to reset the preload on the pinion bearings. I didnt replace the seal as it wasnt leaking . I used the correct weight of water in a plastic bottle suspended from one of the output flange holes to give me 13lb.in of torque and incrementally kept tightening the pinion nut till it just turned under that suspended load.

    I then reset the crownwheel by nipping up but not fully torquing down the bearing caps and adjusting the side wheels to move the crownwheel across till I acheived backlash of 0.15mm at the tip of a crownwheel tooth . I didnt have a dial gauge , so i set hard stop using a threaded rod and a piece of plate against which I could rotate the crownwheel tooth and used a feeler gauge between the two to determine the backlash.
    I then used some blue to check I had a decent sized central meshing on the gear teeth.
    Finally I measured the distance on a given point across the bearing caps and increased that by 0.22mm by screwing in the adjuster wheels evenly. Torqued up the bearing caps fully and rechecked nothing had changed on the backlash and the meshing.

    Reassembled everything in the car and drove about 10 miles at a steady speed . It felt much better , no noises and no slack as you came on and off the gas .
    Now to the point of the message !
    How hot should the diff get? Its not something I've ever tested before , but this was hot enough that I could only just hold a pressed palm on the front of the casing . I had also installed in the rebuild a drain plug into which I had fitted a magnetic bolt and on draining the oil , I did find some swarf.
    So-have I got a problem and can someone say from the above whether I have dropped a B****** somewhere?
    I would say that I was surprised at how tight I had to do the pinion nut up to achieve the correct preload torque .
    what weight of water did you have hanging from the prop bolt?

    My guess is, and apologies if put 2+2 together to get 5, but I suspect you've measured lb/in rather than lb.in in which case you've got far too much pinion bearing preload which will undoubtedly cause the diff to get too hot...

    You need a lot of torque to crush the crush washer - but that doesn't mean you need a lot of preload - you should be able to turn the pinion flange with light-ish finger pressure, and that's with the oil seal in. If you have to grip it hard, it's too tight.

    HTH's
    Tom.

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    Quote Originally Posted by FOSSIE View Post
    I suspect you've measured lb/in rather than lb.in
    Could you explain that bit for me Tom. I don't know what it means.

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    Fossie
    Excuse mixed units!
    Used 3.4 kg of water suspended at bolt hole 45mm from pinion centre line . So I think the calc is
    (3.4x2.24)lbs x (45/25) ins = 13.7 lb.in.


    I would say it takes a normal-not too firm handshake grip to turn . Which is certainly more than light finger pressure.
    But if I got the calc right above , surely 13-14lbs at the prop bolt hole would be described as more than light finger pressure???

    I understand your point about the difference between pinion nut tightening torque and the "resistance to rotation" torque that is developed by pre-loading the bearings.

    So ,if my pinion bearing load is too high is simply backing off the pinion nut a little ,now , an option or ,because the crush spacer is shortened do I need to dismantle and instal a new crush spacer and reset the preload properly.

    Thanks for your help so far
    Patrick

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    Quote Originally Posted by Dave View Post
    Could you explain that bit for me Tom. I don't know what it means.
    Basically Dave, the / sign is short hand for divided by, yes? And just a . means multiplied by. Getting them mixed up could ruin your day, or at least your sums. As it happens I think Patrick is on the right track, I'm in a bit of dash but will have a look at those numbers later...

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    just reading this thread - if anyone wants any help/advice on building english diffs then pm me. im building these diffs for customers with all the proper ford/churchill tooling.

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    These have appeared on Ebay

    Last time they were £70 + p+p

    Now this different seller has em at £40 inc UK p+p

    Makes life easier to set pinion pre-load

    http://shop.ebay.co.uk/classicmotors....c0.m270.l1313
    Last edited by RS2000CUSTOM; 01-10-2010 at 23:00.
    cheeRS

    DAVE



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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    I have sheared all the crown wheel bolts on a trial any idea what the cause was so I can on rebuild stop it happening again

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    Re: pinion depth/backlash english diff cwp rebuild tips and info

    old bolts that are past it that have been re used, or bolts under or over tightened

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