Flywheel dimensions

(ledo) #21

Hi Mike,

My flywheel matches the one on the right.

The part number for that flywheel is
proving difficult for suppliers to come up with any info on them.

Would a machined standard flywheel,
machined to match the original one be safe to use, or would that be a bit

Just a thought to overcome the supply
problem, or composite al/steel is another alternative. Any thoughts ?



(Paul Wigton) #22

If done by a good machinist, it will be safe.

(Mike Spoelker) #23

Yes. To keep from doing it more than once, I typically count the teeth then write the number on the engine side of the flywheel with a paint pen.

(Mike Spoelker) #24

Should be safe to use, but unless you get your machine work done for free, wouldn’t be very economical. The lightweight units became the standard issue, so there should be plenty of good ones around second hand.

(Morris Barnett) #25

Here is a shot of my 3.4 150 flywheel with 132 teeth, but I cannot figure out the VS1119! Is this from an 'S ’ or just coincidental that it has a VS prefix. This weights 28-29lbs IMG_2199|666x500

(Morris Barnett) #26

Shot #2 VS 1119 /

(Mike Spoelker) #27

VS prefix would be a 3.4L S model XK150.

(Morris Barnett) #28

Mike. So why does my non S 150 have a 150 S flywheel. Are you saying all flywheels have engine numbers on them.

(Mike Spoelker) #29

Actually, I knew that E-Type flywheels were stamped with a chassis number, but I was not aware that XK150 flywheels were stamped. Given that at least this one was, I would have to conclude that if your chassis number was not VS 1119, then sometime in the last 50 years, a previous owner replaced the flywheel with a used one.

Now, why would they do that? We know that you have measured the thickness of this flywheel and found it to be very much thinner than what we would normally expect to find. My guess would be that someone attempted to make a heavy flywheel lighter by shaving a BUNCH off of the face. This would have been largely a fools errand. It is really a gross simplification to refer to the “lightweight” as only that. On an engineering level, the weight is really only of secondary importance. What you REALLY want is a flywheel with a minimal polar inertia. Since the inertia of a rotating body increases proportionally to the square of the distance from its centroid, WHERE you remove the metal is much more important than how much is removed. 4 grams removed 400mm from the centroid is as effective as 16 grams removed 200 mm from the centroid.

(Mike Spoelker) #30

Is the reason you are considering replacing the existing flywheel because you are having issues with clutch engagement because it can’t be adjusted to compensate for the very thin flywheel? Shaving the face moves the closer to the block and away from the throwout bearing. Combine the relocated face with a well worn carbon and I would bet you could run out of adjustment.

(ledo) #31

Hi Mike,

Yes, certainly all that you mentioned was
not helping. I replaced the clutch set up including a new carbon thrust race.
Still problems and a metallic sound when clutch was used. Never got to drive it
on the road. Pull the engine and gearbox out again and start looking at
everything. The 10” replacement kit had burn marks on the release bearing
face. Three heat spots in between the fingers that hold it in place. How did
this happen, don’t know!!

The clutch plate had a very slight “kiss”
on the cage that holds the spiral springs in place. The cicular marks lined up
with the bolt heads holding the flywheel onto the crank.

So, how thin is my flywheel? It seems
29.8mm is very thin, average measurements that I have been able to receive for
s/h wheels are in the range of 32/33mm.

Have just received a measurement today
taken on an original lightened flywheel of approx 33mm. I can buy this flywheel
but is 33mm enough meat left on the wheel?

Lightened flywheels are fairly scarce
around here, this one is said to of come off a special equipment 120, did they
make them for 120/140‘s as well as “S” 150’s? New
lightened steel wheels are available so I will soon have to make the decision which
way to go. We have a 50th Anniversary Rally to attend to at the end
of March as well as my fiftieth year of ownership of my 150.

Thanks for all your inputs.


John Ledbrook


(Paul Wigton) #32

Learn something new, every day!
I never knew that!

(Morris Barnett) #33

This thread has myself [Morris]and John discussing flywheels with you, I hope its not getting confusing as to who is who.
My old flywheel numbered VS1119 must be a replacement as my orig. engine number is V yes it must have been a replaced but if it came from an 'S ’ why is it not a lightweight ?.
On another matter I recently I installed a 5 speed, after clutch bleeding my slave cyl.piston popped out. after a second removal and inspection I could find nothing wrong , the same thing happened again after installation, I then made a 1 inch longer adjustment rod ,this cured my s/cyl popping out.
Next time I remove the motor I will change the 150 carbon thrust with the E type carbon thrust model as its pivots push the carbon closer to the pressure plate , this would enable me to install the original adj. rod. Why did this happen ? I was using the existing pressure plate and bell housing the only change was adding an adapter plate which comes with the gearbox…
Your comments about running out of adjustment are so true.

(peter balls) #34

The thickness of the flywheel is ,of course, relevant, but the pertinent dimension is the
measurement - rear block face to flywheel face. The flywheel shown has not been ground.
The measurement at 2 5/16" will inform how much has been removed from your flywheel.
Peter B.

(David Langley) #35

I’m assuming that Mike meant to say Engine Number, not chassis number. I’ve seen that several times on E-Types - it’s visible through the hole in the bottom of the bellhousing if the flywheel happens to be in the right position. The VS1119 is certainly an XK150 engine number, not a chassis number.

(Paul Wigton) #36

That makes more sense!

(Mike Spoelker) #37

Yes, of course, engine number. Duh. That’s what I get for posting after midnight.

(ledo) #38


My engine is on a stand but I have been
able to take a few measurements which are a bit confusing.

My block to flywheel face is approx 2 3/16”.
That says I have very little wear ??

(peter balls) #39

John your measurement of 2 3/16" compared to mine of 2 5/16", shows a difference, of course,
of 1/8", quite a lot! I have checked the dimension - flywheel face to retaining bolt with tab washer
fitted, which on my setup is 5/16" (8mm) approx.
Perhaps some posters will inform their block face- flywheel face measurement.
Peter B.

(Phil.Dobson) #40

I just measured my mk2 3.8 as 60mm