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Honda bearing MGB crank

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Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
Well I should be getting my honda bearing MGB 5M crank back today, then I'll move to designing the rods at least .300" longer than stock, and then design my pistons as well, somewhere around 1.300"-1.350" on compression height. The crank also takes #2 and #4 mains and feed extra oil to #2 and #3 rods, that'really not that new of a deal, but this crank has that too. I'll take pictures, and post here of it soon.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


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Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
pics



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


Member Services:
MG/ Triumph Performance Street/Race Engines - Cylinder Head Porting - Modified SU HS Carbs - DIY Engine Rebuild Kits With Free Tech Advice - VTO alloy wheels for British Sport Cars, and others

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Steve64B Avatar
Steve64B Steve Opitz
Phoenix, AZ, USA   USA
1966 MG MGB
Looks like I missed the original post about Honda bearings and MGB cranks... shed some light Hap.

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Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
In reply to # 3734714 by Steve64B Looks like I missed the original post about Honda bearings and MGB cranks... shed some light Hap.

Racers have been fighting #2 ans #3 rod bearing failure for some time now, I, and others think it has more to do with the bearing we have available now, the King tri metal CP bearing has a 6000 psi load capacity, the Vandervell VP2 has 12,000, the King Racing XPC is 17,000, and are factory coated, but not available for the MGB, so I did some research and find viable option in a Honda application available in King Racing XPC racing line that would work on the MGB if I would reduce the rod journal size .100", and that is what you are looking at in the pics. The KIng Racing XPC bearing are also not earth shattering expensive, about $50-60 for a set, they come in two size std and one under size, so it give the same sort options most of us have now, but in much better race quality bearing choice. Dave used to do something similar with Quad 4 bearings, but they have dried up, and these Honda bearings are very popular part number, so readily available.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


Member Services:
MG/ Triumph Performance Street/Race Engines - Cylinder Head Porting - Modified SU HS Carbs - DIY Engine Rebuild Kits With Free Tech Advice - VTO alloy wheels for British Sport Cars, and others
fast-MG.com Avatar
fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
If I was still racing, I would be experimenting with this or something similar on my own engine but I'm not ready to experiment with customer stuff. The Quad4 bearing application was very successful but you had to be very careful with fillet radius clearance. And as Hap notes, supply of the Quad4 bearings in -.020/.030" is NLA. The only risk I see with the Honda bearing is crank strength at -.100" rod journal size. Nitriding the crank would IMO be necessary.


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Dave Headley, dba FAB-TEK offers full service race car parts and preperation for MGB & MGA race cars, SCCA and Vintage. Dave is a mechanical engineer and has raced MGBs since 1963.
Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
In reply to # 3734843 by fast-MG.com Nitriding the crank would IMO be necessary.

It was. thumbs up



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


Member Services:
MG/ Triumph Performance Street/Race Engines - Cylinder Head Porting - Modified SU HS Carbs - DIY Engine Rebuild Kits With Free Tech Advice - VTO alloy wheels for British Sport Cars, and others
Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
In reply to # 3734843 by fast-MG.com If I was still racing, I would be experimenting with this or something similar on my own engine but I'm not ready to experiment with customer stuff. The Quad4 bearing application was very successful but you had to be very careful with fillet radius clearance. And as Hap notes, supply of the Quad4 bearings in -.020/.030" is NLA. The only risk I see with the Honda bearing is crank strength at -.100" rod journal size. Nitriding the crank would IMO be necessary.

Dave I think I remember you telling me the Quad 4 bearing was slightly wider than the MGB, in this case the Honda bearing, they are insufficiently not as wide as the MGB, like .020". None of this is new, big healey guy have modified their cranks for years to use SBC bearings, and those numbers vary way more than these do as for a turning down and width differences. I did a lot of research looking at other engines and how they took on this, so when spotted the Honda bearing I knew I was dealing less of mod than other had done successfully, so leap of faith, more like hours and hours of research. I recently sold a second one of these cranks, but with normal MGB rod journals, he is West Coast racer, who recently broke a MGB 5 main crank, which is super rare for this to happen., he also has suffered #2 and #3 rod bearing failures before. So there ya go Dave, we are now going to get R&D feedback from both applications.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


Member Services:
MG/ Triumph Performance Street/Race Engines - Cylinder Head Porting - Modified SU HS Carbs - DIY Engine Rebuild Kits With Free Tech Advice - VTO alloy wheels for British Sport Cars, and others
fast-MG.com Avatar
fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
Hap, just for info, the Quad4 bearing is 3mm wider than the 5-main MGB. Advantages were better oil film thickness due to the width increase with resulting lower unit loading and the bearings were Clevite 77 composition.

Have you looked at a Honda crank to see what the oiling design is? That can play an important role in the success of the bearing performance. For reference, the Quad4 crank design(oiling) gave nearly indestructable bearing performance at much higher bearing loads than in an MGB engine. These engine would look brand new after 24hour IMSA endurance races as well as 1000hour WOT dynamometer endurance testing. Unfortunately, that opportunity no longer exists unless someone could locate a large stash of these bearings(Clevite CB1388 P-50,p-75). Even in standard or p-25, these could be used with a billet crank having larger journals.

I like the concept of the Honda race bearing and hope the experiment proves successful.thumbs up


Member Services:
Dave Headley, dba FAB-TEK offers full service race car parts and preperation for MGB & MGA race cars, SCCA and Vintage. Dave is a mechanical engineer and has raced MGBs since 1963.
mgracer38 Avatar
mgracer38 James Darby
Rugby, UK, UK   GBR
Your crank does like nice Hap.

I broke mine just a month ago. Let go on one of the straights at Silverstone. Cracked the block under the bearing saddle, but eveything else is ok.


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John Hamilton Avatar
Laurel Hill, FL, USA   USA
1963 Austin-Healey Sprite
1965 MG MGB "The Great Pumpkin"
1968 MG MGB GT "Buck"
1970 MG MGB "Dad's Car"
I have one of those 2 piece cranks tooeye rolling smiley



If I can't be fast, I'll just be obnoxious!

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Dougie Avatar
Dougie Doug Escriva
Portland, OR, USA   USA
In reply to # 3734553 by Speedracer pics

That's about twice the lbs of my big billet Healey crank....ugh.


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Billet Crank 59.7 lbs.jpg

Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
Nice looking crank Doug, yeah the MGB is little lighter, but you got a little more real estate to cover smiling smiley Of course it could get lighter with a billet because on the MGB, it just most don't do that expect three main user, most of time the 5M crank don't break.


OK, back to the MGB steel factory cranks cracking for you that had one do this, looks the above one crack happen at #3 rod and #4 main, about the other, where did they occur, and like the crack above, it most likely started from a filet radius, I would looking and seeing if tell the place where the cracked started, closely inspect the filet radius was properly done if they cranks were turned down, if std. then I find factory filet radius to be always reliable



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


Member Services:
MG/ Triumph Performance Street/Race Engines - Cylinder Head Porting - Modified SU HS Carbs - DIY Engine Rebuild Kits With Free Tech Advice - VTO alloy wheels for British Sport Cars, and others
V8MGBV8 Avatar
V8MGBV8 Carl Floyd
Kinggsport, TN, USA   USA
I thought you were going this route, Hap, to take advantage of the NASCAR take-out Honda rods.

chormy Avatar
chormy Gold Member Shaun Holmes
Norwich, Norfolk, UK   GBR
1963 MG MGB MkI "3330 PE"
1964 MG MGB MkI
1967 MG MGB GT "BABE"
1967 MG MGC    & more
Doug / Hap

You mention modified Healey cranks , I know the C crank is different but I have similar issues with mains not lasting too Long not wear but distortion (squashed )

Do you have any info on the mods to Healey 6 cranks.


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Dougie Avatar
Dougie Doug Escriva
Portland, OR, USA   USA
In reply to # 3737709 by chormy Doug / Hap

You mention modified Healey cranks , I know the C crank is different but I have similar issues with mains not lasting too Long not wear but distortion (squashed )

Do you have any info on the mods to Healey 6 cranks.

The stock Healey crank has it's limitations if your reving past 5500rpm, balance is key. To save the mains, we've gone to a side oiling system to deliver oil from the cooler directly into the main gallery. This is the mod really extends the bearings life, like many seasons.


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