TR4/4A TR4 vs. TR4A flywheel question

[TR4A_IRS]

A local guy is selling off some TR4 parts, leftover from his restoration. (Anyone here?) One of the things he is selling is a lightened and balanced flywheel.

Does anyone know, offhand, if the TR4 and TR4A flywheels are the same?

Thanks,

Ian

 

[TR4nut]

Not exactly - the 4A flywheel will be set up for the later style diaphram clutch, same as on a TR6. The TR4 flywheel will be drilled for the earlier finger style clutch from a TR3. Other than that, you can use them in either car.

ps. and if needed you can have the 4 flywheel drilled to accept the 4A clutch

 

[TR3driver]

and if needed you can have the 4 flywheel drilled to accept the 4A clutch

Might be worth asking if that has already been done. The TR4 clutch is quite a bit heavier than the 4A clutch, doesn't make a lot of sense to keep it with a lightened flywheel.

 

[TR4A_IRS]

Thanks Randy and Randall!

 

[TR4A_IRS]

Well, I picked up the flywheel. Lets hope it will work if/when I ever get around to swapping it out.

Here is a picture of it:

I weighed it, because it still seemed awfully heavy to me. It weighed in at 22 pounds. I guess the originals are 31 pounds, so I guess that is a bit of an improvement.

 

[FordFiesta]

From this side, it looks like a stock TR2/TR3 style flywheel, which may or may not have been lightened below factory-spec.

Is the ring gear the press-on or bolt-on type?
If it's the early type flywheel, you will need the correct starter to properly mate with the ring gear.

 

[TR4nut]

I weighed it, because it still seemed awfully heavy to me. It weighed in at 22 pounds. I guess the originals are 31 pounds, so I guess that is a bit of an improvement.

That sounds about typical for the ones Joe Alexander does too. Somewhere around 21 lbs without the ring gear.

 

[TR4A_IRS]

From this side, it looks like a stock TR2/TR3 style flywheel, which may or may not have been lightened below factory-spec.

Is the ring gear the press-on or bolt-on type?
If it's the early type flywheel, you will need the correct starter to properly mate with the ring gear.

It's the shrink fit type, from the earlier cars.

 

[TR4nut]

Its from a TR3 then, not a TR4

 

[TR3driver]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Its from a TR3 then, not a TR4
[/QUOTE]
FWIW, if you have one of the lightweight gear-drive starters, it is apparently not too hard for a shop to change the drive gear to suit the early flywheels. 9 teeth instead of 10.

That sounds about typical for the ones Joe Alexander does too. Somewhere around 21 lbs without the ring gear.

I think the billet steel ones are lighter than that, around 14 without the ring gear. At least that's what Joe said, I didn't try to weigh one.

 

[TR4nut]

I was just talking about Joe's lightening service he does on stock flywheels - easy to shave 9-10 lbs off. Anything more and you need one of those fancy ones you have!

 

[TR3driver]

I was just talking about Joe's lightening service he does on stock flywheels

Ah, I didn't realize he was still doing that. Thanks for the correction.

 

[TR4A_IRS]

Its from a TR3 then, not a TR4

I am now also assuming it was only balanced, and not lightened, since the early flywheels were lighter.

Anyone looking a for a never used TR3 flywheel?

Good thing he had a few other parts in the lot that I could use, so I didn't totally waste my money...

 

[FordFiesta]

I could use the TR3 one, as I have a very strong preference for the early-style clutch mechanism,

 

[TR4A_IRS]

I replied to your PM.

- Ian

 

[JerryVV]

Years ago (early 80's) Moss Motors was cleaning out their remaining stock of Factory Competition parts and they had 4 or 5 lightweight flywheels among those parts. The story was that they got the parts from Cal Sales which is where I believe Kas Kastner worked as the Triumph Competition Manager. I bought one of those flywheels as did a good friend. Mine is drilled for a TR4A clutch (it was originally only drilled for the TR3 and 4 clutch assembly) and has been in my car for several years. As I recall the engine side of it looks very much like the photo above. So you may well have an original factory lightened flywheel.
Also if one wants to lighten a flywheel there are instructions in the black Competition Preperation books that are available as re-prints from many sources.

 

[TR3driver]

Also if one wants to lighten a flywheel there are instructions in the black Competition Preperation books that are available as re-prints from many sources.

Do you have a page number, Jerry? I can't seem to find any instructions in my copy of either the black TR4/4A Comp Prep or the earlier dark blue TR3/4 Comp Prep.

The earlier one lists the lightened flywheel with a part number; the later one just says to use an alloy flywheel.

The closest thing to instructions that I could find was in the much later "Triumph Preparation Handbook" with the white cover. But it only says that you can mount the flywheel in a lathe and remove about 4 pounds, no specific instructions on how to mount or where to trim.

It also mentions that there are two flywheels for the TR3 and TR4, with the earlier one weighing only 21 pounds. I think this must be a reference to the optional lightweight flywheel (P/N 132766) as I recall the early "press fit ring gear" flywheel being heavier than that.

 

[JerryVV]

The only edition I have handy is 5 but I do have an earlier one that only covers the 3 and 4. By 5 it included the 4A. It must be in that early edition that my brother gave me in 1969. He bought it in the early 60's. What edition do you have? As I recall there was a drawing showing where to remove material from the back side. I need to dig deeper into my stuff and find it.
JVV

 

[TR3driver]

The TR4/4A version I have is marked 5th edition. The TR3/4 version does not have an edition number, but I believe it is a first edition. Copyright date is 1963.

 

[JerryVV]

Still looking for my reference. I'll let you know once I find it.