Setting whipple supercharger gear backlash?

Discussion in 'Mustang Chit Chat' started by palanza7, Apr 29, 2021.

  1. palanza7

    palanza7 forum member

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    Anyone in here ever rebuild a whipple supercharger? Wondering how you set the gear backlash. Dial indicator and just put it in the middle of the play?
     
  2. skwerl

    skwerl tree hugger

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    You'd probably find better answers over on Yellow Bullet. Good luck with it.
     
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  3. palanza7

    palanza7 forum member

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    Thanks for the suggestion I'll give them a shout.
     
  4. palanza7

    palanza7 forum member

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    Boy this must be the most closely guarded industry secret of all time, I can't find a single piece of information on this anywhere. Calling whipple got me their support email and just no reply lol wtf
     
  5. crjackson2134

    crjackson2134 Member

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    What a shame, I’ve read many times about Whipple’s poor customer support. I thought about Whipplizing my 2014, but that specifically was a major factor.
     
  6. skwerl

    skwerl tree hugger

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    I know they don't sell Whipples but I'm sure a few guys at VMP Performance can answer your question. See if you can get Joe on the phone.
     
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  7. stkjock

    stkjock ---- Madmin ---- Staff Member Administrator Super Moderator S197 Team Member

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    I’ve had good support from Whipple

    did u email a general email box or someone specific?
     
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  8. jlmotox

    jlmotox forum member

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    That sucks! I have always had good service with Whipple. See if you can get ahold of Jeff @ Whipple he helped me with my manual swap recently and is a cool guy.
     
  9. Flusher

    Flusher Member

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    I can't say about the Whipples specifically. If the Whipples are like PSI screw blowers, which are similar to 71-series Roots blowers, you can't adjust the gear lash because the center-to-center distance is fixed.

    The gear teeth are helical. Installing shims behind one gear or facing the back side of one gear will advance or retard one rotor in relation to the other. This is so the rotors interlock together properly and don't hit each other.

    I'm not saying that it is beyond my capabilities, or yours, i chose to have Littlefield Blowers do my 71-series because I wanted it to be the best it could be and I didn't want to risk a first-timer's mistake on a complex and expensive setup that would destroy an expensive engine.

    There is a service manual, from GMC, that describes how to set each clearance and what they should be. Maybe you could find just such a manual for your application.

    I definitely would not just set it in the middle and let it rip.

    As far as Whipple's customer service, if I am correct, clearancing your blower is more complex a procedure than a simple phone call or casual email can describe.
     
  10. palanza7

    palanza7 forum member

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    So I recently found an interesting youtube video in which a guy does pretty much exactly this. I learned a good bit just from watching that video like how potentially measuring the rotor gap with a feeler gauge and adjusting via shims like you mentioned. I've actually already fully rebuilt a 2.9 before by just setting it in the center and didn't have any disaster but I also agree there is probably a more specific number I should be shooting for.

    Unfortunately no idea what specification I should be aiming for since whipple hasn't responded to my support ticket in any form. A simple "you want .008 between the rotors" would be a pretty easy and doable reply, or actually any reply would have been cool.

    Anyway I found a book on this I ordered off of amazon the other day hopefully I can find some more information here and apply it. There seems to be some "rules of thumb" out there for blowers, its not like whipple is the first and only person to ever build them, but who knows what sort of special coating or design they added.

    But yeah, thanks for taking the time to add your thoughts! So far you are the first human who has been able to add to this conversation in the last week of searching on every social media/forum/internet platform I could find LOL

    Oh here is the youtube video if anyone is curious.




    The lady on the phone just had me email their support, I figured this is either something they keep to themselves or they are just too busy to reply.

    This is a cool idea I did not think of, thanks man.
     
    Last edited: May 3, 2021
  11. Flusher

    Flusher Member

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    Thank you

    Please post the link to the book you found.

    I will reply later with some more information from personal conversations with the guys and Mrs Littlefield at Littlefield Blowers. It's not as easy as just saying, Set it at .XXX clearance.
     
  12. palanza7

    palanza7 forum member

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    I haven't gotten the book yet but the guy in the video mentioned getting clearance info from SA book so I think this is it

    https://www.amazon.com/gp/aw/d/1613251319?ref=ppx_pt2_mob_b_prod_image

    Update whipple finally emailed me back after I sent another follow up. Basically said "sorry can't help you but you can send it in for us to rebuild" lol

    Definitely interested in hearing what info you find. If you watch the video when he sets the tolerances it's basically " well we are at .01 I'd like it .008 so I'm gonna take a little off the hub" I dont have an issue measuring these dimensions or adjusting the hub and ring gear to lock them in, I just would like to know what value whipple sets them at.
     
  13. Flusher

    Flusher Member

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    That's an 'okay' book. There is a short section on Gene Mooningham setting up a 4-71. Basically, it's an overview of supercharging. I have yet to see a book with any real meat and potatoes.

    Corky Bell's Supercharged! Design, Testing and Installation of Supercharger Systems has the most extensive calculations I've seen yet. Been trying to work through and proof out the formula.

    https://www.amazon.com/Supercharged-Testing-Installation-Supercharger-Systems/dp/0837601681

    I'm always looking for something that contains the next piece of the puzzle of the answer to the universe.
     
  14. palanza7

    palanza7 forum member

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    haha thanks for this. yeah i mean i guess ultimately it probably just comes down to trial and error these companies/people have done over the years to squeeze the most efficiency out of their setups without blowing them up. i figure these gaps in the rotors are similar to like advancing timing, the smaller the gap probably yields a little more air flow at the cost of rotor longevity. i have a feeling just ball parking it wont get you into too much trouble worse case the blower moves less air than it can and you lose potential HP
     
  15. Badd GT

    Badd GT forum member

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    Try/Google Jon Bond performance. I once had a question on low vacuum bypass valve and called him directly. He was easy to reach/contact and he rebuilds these i believe and might just be the unicorn your looking for
     
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  16. Flusher

    Flusher Member

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    I'm going to do the best I can to recollect conversations from the past 20 years. Again, these are for Roots 71-series blowers.

    The 6-71 in the video above is what we refer to as a "street blower" that has upgraded bearing plates and the PTO is omitted, otherwise, it is basically right off a trash truck. Here is a video of a 6-71 Detroit Diesel ().

    In the video, he is only checking the rotor to case clearance. If you look closely, you will see dowel pins installed in the bearing plates, to align the plates with the housing. To adjust the rotor to case clearance, (outlined in the book you ordered) the dowel pins would be removed, the entire assembly would be mocked up and clamped together. After the desired clearance is achieved, the cover, bearing plates, and housing are reamed for the next size larger dowel pin.

    The initial difference between the "street blower" in the video and a performance Roots blower is that the tips of the rotors are machined for a strip of Nylatron to be installed. This allows tighter rotor-to-rotor and rotor-to-case clearance. The Nylatron actually comes in slight contact with case, this is why 70+% of the fuel needs to be run through these blowers for lubrication.

    I did not see the end clearance being set in the video, or even checked. He did say that this was the "second time." I would expect that the end clearance had previously been set, but it should have been checked. You either need to face the rotors or mill the ends of the case to achieve the desired clearance.

    What should those clearances be? That largely depends on the application. For example, a blower for gasoline or street use generates more heat and requires more clearance because of thermal expansion of the rotors. In a blower for methanol, the cooling effect of the fuel actually causes the rotors to contract.

    The rotor to case clearance is not consistent around the circumference of the rotors. For example, the rotors are tighter at the 6-o'clock position than at 3 and 9 o'clock positions, with even more clearance at 10 o'clock. You have slight control over this by moving the bearing plates.

    The rotor-to-rotor clearance is a bit more complex. This is what I think I understand (again, I'm glad that I had Littlefieldset up mine, I didn't want to go through the learning curve this go around). A longer rotor (14-71) will have more twist than a shorter rotor (6-71), from the mass of the rotors themselves. Higher boost will also cause more twist because of the resistance against the rotors. Longer rotors have more leakage because of greater clearance areas rotor-to-rotor and rotor-to-case. The RPM range that the blower will operate needs to be compensated for. For example, my boat, turned ~7200 RPM and blower is overdriven 10.9%. A fellow competitor at NJBA turns his well into the 8Ks or higher with 78% overdrive!

    Don't know if this is helpful or more confusing. I don't know if any of this applies to a Whipple.

    Good luck
     
    Last edited: May 4, 2021
  17. Flusher

    Flusher Member

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    Hard anodizing the case and rotors will help to tighten up the clearance. We constantly see .001" buildup on every surface, .002" on the diameter. You would need to compensate for this where applicable.

    I'm curious to try https://www.line2linecoatings.com/, but I didn't want to experiment with my life's savings this go around. At least, Littlefield didn't even want to entertain the idea. I will discuss line2line coating with Brian Moreland of CP Pistons when I get to that stage of my rebuild.
     
  18. palanza7

    palanza7 forum member

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    Yeah I tried them my last rebuild even having bought the kit from him and they didn't want to part with any of these secrets either. Just send it in and we will do it type conversation. They even file the bearing numbers off the races in the rebuild kits so you can't look them up and see they only cost 20.00 lol



    Thanks for sharing that info. I appreciate it man. Definitely some stuff to learn here. I'll keep investigating as well. Worse case I'll just send it in if I don't feel confident in nuking my built engine and this 4.0 whipple lol
     
  19. eighty6gt

    eighty6gt forum member

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    can't you measure total clearance and then just set it at close to zero on the drive side and call it good? Put all of the slack on the back side.

    the rotors on my TVS touch each other - just the coating, though, that's meant to wear to fit.
     
  20. palanza7

    palanza7 forum member

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    So that's sort of what I did on my last one except we set in the middle of the clearance. I'm wondering just how much efficiency you lose by having a little larger gap than necessary? Maybe it's really just that simple haha
     
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