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MG Midget and Sprite Technical - 1275 Alloy Flywheel

I am building up a 1275 engine and have a Fidanza alloy flywheel to fit.
I am unsure what to do about fixings to the crank. Do I go with aftermarket flywheel bolts or standard?
Daniel Stapelton says you must use locking tab washer on an Alloy flywheel. Yet elsewhere I have been told that the tab washer is too soft and will cause the bolts to fret. So do I use a hardened steel washers and Loctite?
Any thoughts .. Roy
R Mcknight

who was the 'elsewhere' who gave conflicting advice? Why would the standard tab washer and bolts behave any differently from when used with the normal flywheel?
Is the Fidanza all ally or a steel centre and ally outer?
BTW do you know the weight of the Fidanza flywheel please?
David Smith

Oh good god !!!... im the expert on this one

Give me some time to address this... theres some things your going to want to know before any wrenching takes place

If you want, we can go out back, you give me the flywell.and.$100, then ill kick you in the nuts as hard as I can, we go back inand laugh about it over a beer....and will call it a day

Prop and the Blackhole Midget


The Fidanza Flywheel is all Alloy construction except for the steel insert for the clutch wearing face, It weight is 3.4 kg.

Now the following information is from Daniel Stapelton's book How to Pwr Tune midgets .Quote . A point to note about the Alloy flywheel is that you must use the bolt locking plate irrespective of what flywheel bolts you use, and whether or not you have thread locked them. The reason is that the bolts are in direct contact with the flywheel, and they will fret into the alloy, resulting in an increasingly loose fit, eventually a serious problem.

Now In Vizards Tuning the A series on a section on Fasteners he states . Do not use lock tabs, They are usually made of material that is too soft for the loads generated by higher tensile bolts . This eventually starts to squeeze out and pre load is lost.

So If I use Arp 12 Point flywheel bolts a lock tab will not lock the bolts. Could I use hard steel washers and Loctite them in . Or do I use standard bolts and locktab washer. Or standard bolt and no locktab but hard steel washer and loctite . Any advice from engine builders?

And Prop, bet you itching to tell us about your woes. Just give us the shortened version .

R Mcknight

I use ARP bolts on my flywheel (standard iron one) but I don't use the tab washer. It just squashed up and distorted so I decided to use locktite instead. It's been fine for years like that.

But I wouldn't do the same if it were an alloy centred flywheel, I'd probably either use the normal tab washer or make a one piece spreader plate out of something harder. I'd use locktite either way.

Roy, is the Fidanza flywheel drilled for a standard Midget clutch?

john payne

I see you are quoting from the 2000 edition book rather than the 2008 edition book.

Both books say not to use lock tabs (page 11 and page 14 respectively) though the 2008 edition expands a bit on why their use is not recommended.

However, the 2008 edition omits the wording about the tab used on an alloy flywheel - probably a lack of space for that chapter and other more widely relevant material squeezed it out. Nonetheless the advice is good and probably came direct from the manufacturer and as aside I was personally discouraged from using an aluminium flywheel and generally their use is scarce in the UK.

The use of a locking plate with an alloy centre flywheel is a necessary compromise in that not using a plate is worse than using one. You could make a plate out of 1/8" plate and get it heat treated and use that in preference to the soft metal standard tab plate. The objective is to prevent the flywheel working loose because of inadequate clamping of the flywheel bolts because of soft metal compression (alloy or soft steel of the soft lock tab)

You don't say if the car is road or or race car. Most if not all race cars have the engine removed at the end of the racing season if not a couple of times during the season as well so there is opportunnity to see how the flywheel bolts are holding tension or if the fywheel is compressing leaving the bolts loose onthe flywheel but loctited tight in the crank. Even then if on a race car are the races all short 15-20 minutes or some of the MGCC/whoever endurance races of 30 minutes or an hour?

Finally, ask Fidenza - who I'd have thought would have had enough feedback over the past 13+ years to provide expert advice.

Daniel Stapleton

While we are on the subject and apologies for a bit of thread creep but is there a lightweight steel flywheel available that is a straight fit? In other words one that uses the standard clutch. All the ones I've seen have been for drilled for the bigger clutch.

john payne

Why not drill the bolts and wire lock them?
Chris Hasluck

John , The flywheel takes a standard clutch
Daniel , Thanks for the info , You need to put you books into reprint, mine was a 2004 reprint
Chris , I could drill and lockwire its just that its not good practice to do the flywheel bolts up onto the crank straight onto Alloy without some kind of washers. Daniel came up with the beat advise in making a steel plate to sandwich the flywheel.

R Mcknight

You need to ask one question that will determine everthing for the fredenzia flywheel

What are you building this new engine for ??? What is its primary application?

And this is a big question with no right or wrong answers

As to bolting it my experiance and for my purpose...I used grade 8 arp hex headed flywheel bolts with locktight and a new bolt ring from.moss that has tabs that fold up onto the bolt heads...and for my purposes thats perfect and more then enough... because my set up is just primarly normal spirited driving with very limited short burst racing in between, plus because my engine is very high performance and im a fiddler and constantly modifing up grading and engine will no doulbt be pulled ever 10,000 - 15xxx miles, so loose fly bolts are not a problem as they will easy be noticed

So id say bolt on for the purpose of the engine....if its 24 hour grand prix at a maxed out rev range...then id persue the drilled bolt and wire approach

As the split lock washers... im not a fan for this application but if you do...I would ONLY use grade 8, to elminate the (mr. Softy) issue

Prop and the Blackhole Midget


The fredinza flywheel... is NOT an exact replica of the regular factor flywheel... I mean it has variations built in

The huge lesson ive learned about performance moddification... its that plug and play without issue is a rarity... one modification at step.3 will bite you in the biblical donkey at step .7

And the fredinzia will take a huge chunk out of your fun hole if your NOT using the ribby 4 speed with the stock starter

Where I got burnt was the back spacing of the fredinza is deeper then stock.

so because I was using a rivergate 5 speed datsun transmission and a high torque modern day starter... it became a challange of creaivity

I had to (groove) the oil pump cover, replace the starter ring hardware with grade 8 button hardware, bevel the inside edge of the starter ring, replace the engine black hardware with counter sink hardware

And that was just to make the fredinza fit the river gate 5 speed

Next a high torque stater... if its a datun back plate...thats an issue if its on stock, you should be okay, a ford 5 speed I cant say

The high torque starter on the datsun plate pushes the starter backward away from the plate by 3/16 of an inch and as a result the starter gear ring on the fredinza because of the incorrect back spacing only hits the high torque gear a total of 1/8 inch...NOT enough

So on a datsun plate you will need to machine the back plate deeper by an extra 3/16 in the shape of the starter mounting plate or have the starter mounting plate machined 3/16 inch so that the starter motor can fit further down in side

So, unless your doing a stock 4 speed tranny and a stock lucas starter your best friend is going to be your imagination and a DTI measuring device

I cant offer any assistant on setting this up for a ford type 9 5 speed or a toyota T2/3 5 speed transmission but I have to belive, because of the fly back spacing and the postion of the ring gear....

there will be some issue to resolve
Prop and the Blackhole Midget


what is the primary purpose of this engine....the answer my show that the F. flyweel is of little to no value

You have to remember a lightened flywheel will NOT make your car go any faster, not even by 1/2 mile an hour

What it does do and its hard to explain and harder to comperhind, is the lightened fly redistributes the engine power making the engine more efficiant....vizard does a great job explaining this

THERE ARE SOME SERIOUS with using an aluminum flywheel (real or arm chair implied)

When you lighten a flywheel esp this much other problems arise, here are the ones im aware of so far

1. Valve bounce...
2. Harmonics being moved to a new bad place

1&2 can be solved by lightening and balancing the crank pully, in fact id say thats a at the very least the crank needs to be indexed, then lightened and balanced, and id even have the clutch assembly balanced as well...because the fly wheel weighs next to will feel ever bit of engine instability... and if you have a crap worn out ignition system it will play havoc there as well density and mass over comes alot of evils

Next big issue is driveability....

You better be driving a clutch on a daily basis and can shift gears without thinking like you breath air in and out

Because there is no flywheel momentum,it is super easy to kill the clutch when taking off from a stand still and to miss shifts because the rev range has changed

Also.... long hills and mountains are a challange to say the least, because you have no flywheel momentum its hard to keep the engine turning and you contantly have to down shift to find extra power then upshift to maintian speed...the steeper and longer the grade the worse it is

If the engine is fairly stock, I dont think its worth it, a lightened fly is more the whip cream topping on a very high performance engine...its definatly not a big performance upgrade to a basic stock engine

If your engine is slightly upgraded and you want big performance... id invest the time and money into peter burguss and a proverbial completely tricked out stage 3 head....that will do alot more for you then a fredinzia flywheel

Btw... there are machine shops that can modify and lighten the stock flywheel and that might be a better option if your using a 5 speed tranny and high torque starter

Thats my experiance with a fredinza...give it lots of thought for what the return your looking for

Prop and the Blackhole Midget

Prop its a roadcar and its going into frogeye with a 5 speed type 9 box . It says on the box its a direct replacement !

R Mcknight


Direct replacement .... but I bet the details are if its a pure stock set up..I . which with a orginal ribby 4 speed and a lucas factory starter... I have no doulbt it will fit without any issues

The 2 main issues are its not the same back spacing and the ring gear is not in the same location as it relates to the backspacing.... but its off only slightly

Unfortantly i dont have experiance with the ford type 9... I cant say if it will be compatible or not, but its not plug and play connection with the rivergate datsun without some modification to the rivergate kit and the F. Flywheel

Like I said a DTI measuring device and lots of mechanical creativity is your 2 best friends

It took me about 6 weeks to figure it out

Im not wanting to be an enemy, im just saying this is my experiance, and this is what i learned....please be warned and keep us posted . And I hope it is a direct fit to the type 9 without issues

Best wishes and good luck


Prop and the Blackhole Midget

This thread was discussed between 03/01/2014 and 06/01/2014

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