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MGB Flywheel - worth the upgrade?

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catlotion Avatar
catlotion Toby M
Leeds, West Yorkshire, UK   GBR
As my clutch is slipping and gearbox has to come out I'm considering changing to MGB flywheel, pressure plate and gearbox front cover.

I've read a few things about this being a worthwhile upgrade but not sure whether it's worth the expense. I realise I'll gain a better clutch and input shaft seal but are the gains worth it for road use?

thanks

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billjamesSTJames Avatar
billjamesSTJames Bill James
Southport, NC, USA   USA
Seems like a lot a work to change one rotating mass for another. You could have the old flywheel resurfaced and maybe cut a few pounds off the backside to make the car a little faster off the line.

Bill

riley1489 Avatar
riley1489 Gold Member Bruce H
Great White North, QC, Canada   CAN
1953 Jaguar XK120
1959 Riley 1.5 "King George"
1973 MG MGB
So if you need a clutch assembly this cost is a wash out, B for A type. The diaphragm style clutch of the B is smoother action.

As long as you use a 3 main MGB flywheel this is a straight bolt on. The B flywheel is already lighter than the A one, will bolt onto the A crankshaft and the inertia type starter will still work.

I think the throw out arm needs to match the transmission front cover to keep the geometry correct.

Ensure the splines of the driven plate is compatible with et input shaft of the A transmission.

Have fun

B



Check your ego Amigo!

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dominic-ch Dominic Clancy
zurich, zurich, Switzerland   CHE
You need the following parts to make it work

1. Gearbox front cover from a 3 synchro B box, AND
2. The matching fork
3. Clutch cover and release bearing for a B - steer well clear of the AP roller release bearing, the one Basil sold me lasted 30km and I got no response to my email to him to ask his reaction. The standard carbon one has already done 1500km in a few months without any further change to the setup.
4. MGB flywheel from 3 bearing engine, or have your existing one modified to the drawing on MGAguru - the locating pins are placed differently, and it needs to be rebalanced after being modified.
5. make sure you buy a clutch driven plate that matches the number of splines on your gearbox input shat, most MGA are 10 spline, MGB standard is 23 spline IIRC, and won't fit

It's a worthwhile change, and as a B clutch kit costs less than the A, will be pretty much the same cost overall if you can find the B parts used (apart from the clutch bits).

Basil Adams Avatar
About 12 miles from Sears Point, CA, USA   USA
Dominic, I am emailing you a copy of your email of May 6, 2017 and my response on May 6 of 2017. I always respond. It may not be the answer you always want to hear but you did receive a thorough response - check your email and contact me privately if you like. Thanks. Basil

PS, when you see the response I sent 5/6/17, feel free to apologize here as publicly as you complained!



Basil C. Adams
1956 MGA Coupe (Show Car)
1957 MGA Roadster (Driver)
1958 MGA Coupe (Racecar)
1959 MGA Coupe (unrestored)
1960 MGA Coupe (unrestored)
1960 MGA Roadster (Driver)
MKIII Elva Courier (E1056)
1967 427 Cobra
1972 Alfa Romeo Montreal
A coupla late MGBs
1960 Austin Healy BN7
More Cars than Brains

catlotion Avatar
catlotion Toby M
Leeds, West Yorkshire, UK   GBR
thanks, I've got the list of required parts and someone to supply them but just wondering what people's experiences are of the upgrade..?

Is the clutch noticeably better? Can you really feel the lighter flywheel? Is the seal on the front cover a big upgrade?

My gearbox is leaking quite a bit but I think it might mainly be from front cover and rear seal...

Basil Adams Avatar
About 12 miles from Sears Point, CA, USA   USA
The rear crank of an MGA is going to leak 99.9% of the time. I have a race engine with a custom back plate and a custom crankshaft that uses a Ford F-150 rear manin seal and it does not leak but the expense was high. The MGB Clutch with finger springs instead of coil springs is a better piece and there are more varieties available. A lighter flywheel does not add any power but does allow the rpms to spool up faster. Lightening the flywheel is one means but simply switching from an MGA flywheel to an early MGB flywheel reduces the weight by about 8 pounds without doing any machining. There are those that say over-lightening the flywheel on a 3 main engine removes the damping effect of the flywheel but I've seen no proof of where the tipping point is on reciprocating mass vs driveshaft oscillation. If you make the change, you will have to relieve the inside of the bell housing for the MGB fork. Regardless of the issues anyone tries to blame on the roller, I used it successfully in my race car for years at 8000rpm before finally switching to a double-disk 7.25" racing clutch and an annular throw out bearing and a dog-ring transmission. And I have every intention of putting that transmission, clutch, fork and roller bearing in my Elva if I ever get done with the two MGAs in process and the big Healey :-) I did have 5 paddle clutch discs made with the ten spline hub just for that set up. Let me know if pictures will help, Here's a little eye-candy for you smiling smiley Thanks. Basil 707.762.0974 basiladams@yahoo.com



Basil C. Adams
1956 MGA Coupe (Show Car)
1957 MGA Roadster (Driver)
1958 MGA Coupe (Racecar)
1959 MGA Coupe (unrestored)
1960 MGA Coupe (unrestored)
1960 MGA Roadster (Driver)
MKIII Elva Courier (E1056)
1967 427 Cobra
1972 Alfa Romeo Montreal
A coupla late MGBs
1960 Austin Healy BN7
More Cars than Brains


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dominic-ch Dominic Clancy
zurich, zurich, Switzerland   CHE
The lighter flywheel gives you a faster pickup from a standing start, and your acceleration will improve. Effectively the clutch becomes much sharper.

In my experience you do not need to relieve the gearbox bell-housing for the fork.

Basil is going postal in my email because he says correctly that it is not his fault that his response wasn't delivered. So I apologize for saying he didn't respond at all. But I am still waiting for a substantive response to the fact that the release bearing gave up the ghost immediately. The bog-standard carbon successor has survived over 1500km problem free without any other changes in either setup or hydraulics. I still stand by my negative report on the roller release bearing.

Basil Adams Avatar
About 12 miles from Sears Point, CA, USA   USA
Dominic, I appreciate that you corrected your mis-statement because I did respond at length and within a couple of hours. And I'm sorry that I can't diagnose your failure from 7000 miles away - even I'm not that good. I shared some analytic insights based strictly on your representations but that's insufficient information to determine if the operation was lacking, the installation was lacking or the part was lacking. That's what I have repeatedly said and it's all I can offer. I have been exceedingly polite but I am insistent in the fact that your statement that I never responded was false and intended to injure me. I don't appreciate that kind of falsehood and find it unprofessional. I'm happy your car is fixed. Basil



Basil C. Adams
1956 MGA Coupe (Show Car)
1957 MGA Roadster (Driver)
1958 MGA Coupe (Racecar)
1959 MGA Coupe (unrestored)
1960 MGA Coupe (unrestored)
1960 MGA Roadster (Driver)
MKIII Elva Courier (E1056)
1967 427 Cobra
1972 Alfa Romeo Montreal
A coupla late MGBs
1960 Austin Healy BN7
More Cars than Brains

Speedracer Avatar
Speedracer Platinum Member Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
OK, for educational purposes, what failed on the AP roller bearing, is it the plastic bodied one? Not trying to get into your, and Basil's debate, but in his defense he didn't make that part, and all us vendors are the mercy of the quality of the manufacturer. So with that said, what I, and the community would benefit from most is seeing a picture of the failed roller bearing.



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


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dominic-ch Dominic Clancy
zurich, zurich, Switzerland   CHE
The part is a plastic bodied one. it *looks* fine, but the rotating part is flopping around as the internals appeared to have collapsed. There is 1/8" movement from front to back, and a similar amount sideways. That can't be seen in a photo.

I have also received the Moss roller part, which looks more substantial and also has a teflon facing to the rolling part like the plastic one that Basil sold me.

As I didn't relish the prospect of another engine in/out before my Croatia trip, I just used a standard carbon release, which works just fine.

barneymg Avatar
barneymg Barney Gaylord
(Somewhere in USA), Pick one (or more), USA   USA
1958 MG MGA "MGA With An Attitude"
I'm with Hap on this one. I too would like to see a picture of the failed roller release bearing, and know how it failed. Some people have good luck with them, while others have very early failures (within 1000 miles of installation). Pretty sure there are at least two different types of roller release bearing. Story is that the ones with plastic housing are prone to failure, but I haven't personally tested any of them.

Due to geometry of the MG release arm, the release bearing will regularly run slightly off center, almost never perfectly concentric with the shaft. That in itself may or may not be a problem (just rubs me the wrong way).

More important, the clutch slave cylinder contains a spring that will keep a constant small force on the release lever, intended to prevent the release bearing from backing off away from the clutch cover. When the bearing is constantly in contact with the rotating clutch cover, the roller release bearing will be spinning constantly. Resulting heat may be the cause of its early demise (especially with the plastic housing). To prevent this it is recommended to install a pull-off spring and adjustable mechanical stop on the release arm. This in turn calls for occasional periodic adjustment of the mechanical stop as the clutch friction disc wears.

I recon this is all a bit of unnecessary pain. My experience has been that the carbon release bearing will last about as long as the friction disc. It is a relatively cheap part and easy to change when the friction disc is being replaced. So it seems like the roller release bearing is a solution looking for a problem (that does not exist). I have been using original type carbon release bearings for decades, and they serve the purpose well.



Barney Gaylord - 1958 MGA with an attitude - http://MGAguru.com - barneymg@mgaguru.com

dominic-ch Dominic Clancy
zurich, zurich, Switzerland   CHE
I emptied the trash on Friday and it was hauled on Monday, so I am pretty certain it's gone. There were no signs of wear at all on the face, there was no visible distortion of the body, but it was definitely toast. I'll look for it next time I am in the workshop

MGAdavid Avatar
MGAdavid David Werblow
Portland, Connecticut, USA   USA
1954 MG TF
1959 MG MGA
I've used a roller release bearing that I got from S.F. for years. No problems at all.

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fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
Barney X2!smoking smiley


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