Flexplate balance

Discussion in 'Race 400/430/455' started by chrome yellow, Oct 2, 2021.

  1. chrome yellow

    chrome yellow Well-Known Member

    So, I’m done messing with this jw the wheel flexplate. Cant get proper engagement with stock or the robbmc mini starter no mater how many shims or nose cone shims on the mini starter i use. Engine is together in the car and was balanced with this flexplate but they did not alter flexplate or balancer, no weight taken or added to either. What are my options for a new flexplate besides taking engine apart and having it rebalanced with new flexplate? Any options? Thanks.
     
  2. Bens99gtp

    Bens99gtp Well-Known Member

    I have a jw wheel and have had no issues with starter alinement. Have you sent it back to them to be checked or called them to talk to them about the issue.

    I've used 3 different wheels over the years with no issues
     
  3. Jim Weise

    Jim Weise EFI/DIS 482

    Brad,
    If they used the JW flexplate in the balance process, then your kinda screwed.. Those historically have been all over the place on weight placement and amount.. It's also a flat plate, with no bevel, so the converter mounting as well as the ring gear are not in the correct spot. Those plates are a disappointment, and give American made products a bad name.

    It's why years ago I adopted the policy to balance everything with a stock flexplate. And then correct the aftermarket flexplate, by adding or removing material as required.

    I had to replace a JW plate for a customer one time, so we actually corrected two plates on one assembly.. and the correction was considerably different between the two otherwise "identical" parts.

    The new SFI Plate from PEP is and exact copy of the OE flexplete.. just thicker.. it has the correct bevel and weight/amount and placement. We still balance everything with the "master" stock flexplate, but are more often than not are pleasantly surprised when we bolt on the PEP plate, and the balance does not change.

    I can hook you up with one of these plates, I keep them in stock.. UPS has a good flat rate deal going now, so shipping is cheap.. the plate to your door will be about $115 bucks..

    Bolt it up and give it a try.. if it's far enough off to be an issue, you will feel the shake..

    JW
     
  4. chrome yellow

    chrome yellow Well-Known Member

    If you thi
    If you think it would be close enough to not ca
    If you think it will work im all for giving it a try. Just dont want to trash a new engine with an out of balance situation at 6000 rpm.
     
  5. dan zepnick

    dan zepnick Well-Known Member

    I had a problem with jw flywheels years ago that they had a batch that were backwards. Maybe yours is too.
     
  6. chrome yellow

    chrome yellow Well-Known Member

    The ring gear off set is right although it could be offset too much or to little. It is several years old and ive always had issues with the starter with it.
     
  7. BQUICK

    BQUICK Well-Known Member

    Since it is an older piece, I seem to remember JW had a known issue with their Buick flexplates at some point. I believe TA Performance may remember exactly what the issue was, like Dan said made backwards......
     
  8. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    Your best bet is to find a machine shop that will “match balance” your old and new PEP flexplate. This will find out where if any there is extra weight in the 360 degrees of the wheel and then weight is added or removed as needed to match the new plate to the old. Not an uncommon issue to have.
     
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    What kind of starter problems? The shims that go between the starter and mounting block (Robb Mc Starter) adjust the clearance between the pinion gear and flex plate. Is the pinion too close or too far away?

    Pinion Clearance.JPG
     
  10. Jim Weise

    Jim Weise EFI/DIS 482

    Yes and no... with a neutral balance flexplate, this is relatively easy.. but with an external balance deal, you now have an offset weight. The exact position and exact mass of the weight has to be duplicated, as well as the exact mass of the base flexplate, and any holes that are drilled in it. Balancing equipment is not designed to do this.. your not balancing anything.. to properly match balance am external balance flexplate, you need to have a crank with the correct bob-weights on it. Then you can actually achieve balance of the assembly, with as many different flexplates as you like.

    I have always recommended that if your going to visit the machine shop for balancing, that you have your crank and harmonic balancer with you.. Hopefully, if you go to the same shop that just did your balance work, they will have the bobb card, so you don't have to take the whole motor apart, to get the rest of the weights..

    You can get the crank out without disassembling the complete engine..

    As to the starter issue, the main problem is the Buick engine is designed to have a flexplate on it, that is beveled away from the starter.. any flat plate will have the ring gear in the wrong position, we have had to make provisions for this in the past, but the new SFI plate eliminates this issue all together.


    JW
     
  11. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    Agreed on everything. Yes not a normal engine balancing setup with the crank and Bob weights.

    For clarification though there are machine shops that have a proper tapered mandrel that holds just the flywheel centered...and then they will spin it up and see what where the weight is placed all around the flexplate. Similar to a tire balancing machine. Then they take the other flexplate and repeat, drill to remove weight or weld on tabs to add weight.

    I’m not sure how many machine shops have equipment like this, but it is possible.
     
    Last edited: Oct 3, 2021
  12. chrome yellow

    chrome yellow Well-Known Member

    A machine shop thats has that capability to match balance a flexplate was my worry. I had the round shims in the mini starter setup correctly, tried every imaginable combination of shims under the starter pad. My friend rob stopped by and was under the car as i turned the key and said it looks like it needs to be tilted! What? This is what i found, the mounting block on the starter was hitting the corner of the engine block. Cant see it to well laying under the car. A file and 15 minutes later it works like it should. This car gives me so many weird problems that shouldn’t happen from a broken magnet in the hei to this.
     

    Attached Files:

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  13. dan zepnick

    dan zepnick Well-Known Member

    Yes now that I see that ,I did that too years ago!
     
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  14. Bens99gtp

    Bens99gtp Well-Known Member

    We gets builds like that, I this summer has a boat distributor issue......the boat at some time had newer style distributor that like early 90s chevy trucks used. Full electronic cranked at based timing shoukd had jumped up near 20* at 600rpm then liner to 30 by 2500 rpm. This one would idle near 22, go up to 16 stay till 4000 then get ad high 23. So the customer opted for the better msd marine style to match. This was a nightmare, it stayed on base timing till about 900rpms then jumped up to 20s......the issues was to get the boat to idle with the bigger cam it needs at least 12-14 at 600/700 rpm....so to make it idle you gave it that....when we went to troll the timing kick up and he had no trolling speed control, then of course top end timing was way too high. Bought a more traditional msd distributor with springs and weights, now we have a controlled timing curve that works, but within a mile or so it would foul out #2 plug.....never did that b4???? So with the timing light you could see #2 firing. Just would carbon ash black foul, well after wires and all sorts of the other ****, I replaced the new cap that came with the new distributor and no more #2 issue.........freaking crazy........so your not the only person in this boat of buying things designed and built for a very specific fit, and not actually be what is should......welcome to our hobby
     
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  15. Daves 71 GS

    Daves 71 GS Well-Known Member

    Jeff Strube has the best flex plate made for sale.Meziere 1 piece chromolly,hardened.They are internal balance flex plate.It would not be difficult to balance and attach weight for external balance.
     
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  16. slimfromnz

    slimfromnz Kiwi Abroad

    Yep I second the Meziere flexplate from Jeff. No issues whatsoever.
    I had sooo many issues with my JW wheel
     
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