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MG MGA - MGB flywheel conversion

I am currently converting my clutch and flywheel to the "B" set up. I have what I thought was an early "B" flywheel but it does not fit the crank (bolts don't line up and the holes are not the same size and the ring gear sets toward the back or block side of the flywheel)) I think I might have a later "B" flywheel. Does anyone have a picture of the early flywheel for the 18G/18GA engines they could post or send me. I would like to have a reference to go by as I have never seen the early flywheel. If you happen to have one available for sale lets talk.

Thanks.....Norm
Normd55

Yup, you have a later 5 main flywheel for the all synch trans.

The 3 main MGB flywheel looks like an MGA flywheel that has been hollowed out at the back. Mk 2s also had somewhat lighter flywheels.

Why not just have your flywheel redrilled for the locating dowels for the MGB pressure plate? Cheaper than buying a new flywheel.

Don't forget to get the front tranmission cover with realease fork from an early MGB too, or it won't work.
Bill Spohn

Am I correct in assuming that you can use the early 3 main flywheel with a standard 1600 and MGA trans configuration with changing the fork?
WMR Bill

Norm,

Presumably your changing the flywheel to save weight.

Remember flywheels are balanced to your crank and on the MGB front pulley.
Not sure how much weight saving is to be had between the two, but it's probably not much.

I converted to diaphragm clutch with MGB front cover and fork.
Have you considered just sliding off the back half of your MGA gearbox with the large MGA mounting bush and sliding that onto an early MGB gearbox.

Then you get enhanced ratios and if you pick the 66-67 MGB MKi gearbox you get the thicker and stronger 4 hole layshaft.

If you have a 1500 gearbox with sliding universal joint then not such a good idea unless you get the later seal type MGA rear housing.

Hope this helps
Mark.
Mark Hester

Norm-
"Yup, you have a later 5 main flywheel for the all synch trans."
Mebbe not, though the ring gear position means probably.
On the end, 5 main cranks are different from 3 main, but all 5 main are the same. So all 5 main flywheels are different from all 3 mains in the bolt circle and location flange.
Magnette, MGA, MGB 3 main are interchangeable to the early no seal cranks.
MGB 5 main early through '67 is the same OD, ring gear, and clutch as MGB 3 main, but all of these are different for '68 on 4 synch boxes.
Early or 3 synch flywheels are just a shade over 12" across the 120 tooth ring gear, 4 synch are noticeably bigger, maybe 12 1/2+", with more teeth - forget the exact number, maybe 127.

WMR Bill-
MGB clutch, front gbx cover, and fork are a set. There are said to be release bearings that will adapt the MGA fork to suit the MGB clutch without changing the cover, but I don't know what bearing (Different offset pivot to face). Some squirrel might have an old B&B catalog - all mine got lost or destroyed over the years.

Mark-
"Presumably your changing the flywheel to save weight."
Sounds as if his main objective is to use the B clutch without redrilling for correct dowel pins.

"Remember flywheels are balanced to your crank and on the MGB front pulley."
Not from the factory. Flywheels and front pulleys are service parts and are balanced alone. Any decent aftermarket balancing should be similar, the crank being balanced alone, and the other parts added singly and balanced each alone, despite being on the crank when it's done. Anybody who tells you they have to be balanced as a set is incorrect or sloppy. The exception being engines that have pulleys or flywheels with counterweights, like some V8's.

"Not sure how much weight saving is to be had between the two, but it's probably not much."
Depends on which exact flywheel, but it can be a lot from say an early 1500/Magnette type to a 3 main B. Barney says 28lb for early MGA, 20 for 1622/MGB. And the inertial effects are greater and more important than just the weight - it isn't static inertia.

Norm-
Read Sandy's thread re flywheel on MGB General, maybe you guys can play frisbee and both be happy.

FRM
FR Millmore

FMR, thanks for the clarification on several of the comments. I am, in fact, changing the flywheel for the weight reduction and the ease of assembly of the clutch plate. Since the "B" clutch is a superior clutch I figure why pay to drill a flywheel that will not help with the performance of the clutch upgrade. I have already converted the front cover of the tranny to the "B" set up. Now all I need is the correct flywheel. I will look at the thread in the "B" section, thanks for the info (I better hit the Gym if I'm gonna play Frisbee with a 28 pound disk).

Thanks all for the input.

Norm
Normd55

Norm-
There are not a whole lot of 1622/B flywheels around, so it might be quicker ans easier to drill for dowels and machine the MGA one to the later spec. Barney gives the drawing for this.

http://www.mgaguru.com/mgtech/clutch/ft_202.htm

Check the ring gear before you send it to the machine shop.
And I erroneously said Sandy's post was in MGB/general, but it's MGB/tech.

If you start playing Frisbee with 28lb plates, you ain't agonna need no gym! Especially once you can catch 'em in your teeth.

FRM
FR Millmore

I know about the 1622 flywheels, already tried that route. One of the guys in our club here believes he has a very early "B" flywheel, he has several older B's on his property. Hope that pans out, if not, I'm sure I'll be able to locate one through this site or the MG Experience site. If he doesn't have one I may contact Sandy in Florida for a Frisbee toss......

I can't make up my mind, should I catch it with dentures in or out???

Norm
Normd55

This thread was discussed between 25/10/2009 and 27/10/2009

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