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Today, i got my new Hughes GM25 BPO converter and im confused due its design
i already have a Hughes GM20 BPO in my car, which is quite the same size as the stock converter, has welded-on threaded lugs and came with 3 new bolts to bolt it to the flexplate just like the stock converter:
the new GM25 has a different design. It has a smaller diameter and seems like it has to be boltet to the flexplate with bolts and nuts. It came without mounting hardware:
It also seems like the balancing weight of the flexplate is too thick (or the welded-on spacer plates of to converter are too slim).
what bothers me too is how the weldings on this converter are looking. Some kind of like my first welds i ever did in my life.
- Is this really the correct GM25 BPO converter?
- since that i got no mounting hardware, which size and grade bolts + nuts would you recommend to use?
- does anybody has some pictures of their installed Hughes GM25?
Yeah, that also like my GM20 looks like. Since that on the wrong GM25 is written "GM25-BPO" and even on the label on the box is "GM25-BPO", i think this is a mistake of Hughes. Wrong labeled
Yes, packaged and marked incorrectly. I have a GM 25 BPO and same as Inline said above, it looks like the GM 20 BPO in your picture..
i was able to call Hughes today just to get some informations if it could be that this converter was packaged and labeled wrong, and the guy said that i have the correct "new" version of the GM25 BPO converter. He said, they changed to a smaller diameter converter because the 12 inch converters they use for the outer shell are getting rarer. So they now are using the smaller 10 inch diameter shells from later applications. He told me that now the BOP version is Bolt and Nut style like chevy.
Then i told him that the welded on spacers to clear the balancing weight on the flexplate are too thin to give enough clearance for the weight. He just said use thin washers to give more clearance.
I dont know if i want to use this converter.
i would like to have one with the same style than my "old" Hughes GM20.
This new style seems like a bit a sluggish solution.
Thanks for updating us about the subject. Sounds poor choice from manufacturer to go for bolt and nut-style, plus the jargon for using shims. They didnt redesign it properly.
Thanks for updating us about the subject. Sounds poor choice from manufacturer to go for bolt and nut-style, plus the jargon for using shims. They didnt redesign it properly.
Yeah, i wasnt really satisfied with his explaination. I havent even knew that they are using old original GM shells for theyre converters. Theyre "just" changing the internals.
i think also, that the welding are looking horrible.
Im quite a bit disapointed, since Hughes is normally known for quality converters.
i saw another thread here on classicoldsmobile, where someone posted a picture with the "new" style hughes converter because of the too thin spacers for the balancing weight.
Yeah, really too bad, my Hughes 2500 stall flashed at 2500 rpm behind a 403 and had the lug style. Looks like a converter to avoid now. I believe the base Jegs 2000 to 2300 stall converter is still the lug style and much cheaper. Did you do an upgrade to the motor to need more stall? Sorry about this, a good warning for others to avoid.
Last edited by olds 307 and 403; Dec 29, 2021 at 12:56 PM.
Hmm, Summit shows the original Chevy and BOP part numbers. Jegs shows everything as "GM" now, way less part numbers to carry. It is no doubt the new universal part number, GM is all the same, nope! The B+M 2300 to 2500 stall looks right and is about $100 more. https://www.jegs.com/i/B-M/130/20412/10002/-1
Nobody makes “new” converters, they all start out as converters from a different application. I build a lot of transmissions, occasionally people want a stock 12 or 13 inch converter. My supplier won’t sell one unless they have a core. Who would have thought stock 12-13 inch converters would ever become desirable?!
Hughes makes top notch stuff. I wouldn’t hesitate to use it. As long as you have 3/16 to a 1/4 inch of clearance between the converter and flywheel, your in good shape.
As I mentioned, every aftermarket converter started out as a stock converter from a different application. Most 10 inch converters are based on 245mm converters from fwd 4T60 GM transmissions. They are then modified to fit rwd GM flywheel bolt patterns. Converter builders sometimes have to make custom mounting brackets,rings, whatever to make it work.
Last edited by matt69olds; Dec 30, 2021 at 07:16 AM.
So this is the new norm? I assume it clears everywhere? Most "GM" converters need clearancing around the weights. There looks like room for one really thin washer on this converter. Will it contact the weight when tightened down? Most aftermarket converters with the 3 lugs have about room for 3 thick washers, I put in two, which would give the clearance mentioned. I used no washers with one OPT 2004R converter with probably 4 times the gap pictured, I didn't realize you had to dial in clearance. On startup, it dumped a pile of expensive synthetic ATF on the ground. It was my first aftermarket converter experience, owned 4 of them including a Hughes since. I guess a 10" is more efficient, Matt is the resident transmission expert here. If he says it is fine, trust him.
Last edited by olds 307 and 403; Dec 30, 2021 at 06:13 AM.
Thanks for all the information, specially to Matt!
If someone with a lot of experience in transmissions and converters say that it shouldnt be a problem to use it, i believe it for sure.
I guess that i will use very thin washers, just thick enought to make sure that the flexplate will not be pulled (and bent) to the converter where its interfering with the balancing weight, and use ARP's 7/16-20 - 1.0 or 1.25 lenght Bolts and Nuts with a bit loctite on the nuts to secure them.
The holes in the Flexplate are wide enough for the 7/16-20 bolts, maybe i have to slightly enlarge the holes of the converter.
Don’t shim all the clearance out between the converter and flywheel. As long as you have 3/16 or so of clearance, your good to go.
Make sure the pilot of the converter fits into the end of the crank. Set the converter up to the flywheel, make sure it fits flat against the flex plate.
