• The Roadster Factory Recovery Fund - Friends, as you may have heard, The Roadster Factory, a respected British Car Parts business in PA, suffered a total loss in a fire on Christmas Day. Read about it, discuss or ask questions >> HERE. The Triumph Register of America is sponsoring a fund raiser to help TRF get back on their feet. If you can help, vist >> their GoFundMe page.
  • Hey there Guest!
    If you enjoy BCF and find our forum a useful resource, if you appreciate not having ads pop up all over the place and you want to ensure we can stay online - Please consider supporting with an "optional" low-cost annual subscription.
    **Upgrade Now**
    (PS: Subscribers don't see this UGLY banner)
Tips
Tips

TR4/4A Flywheel... Lightened or Stock, that is the question

TriumphantMan

Freshman Member
Offline
I have a 1963 TR4 that I am rebuilding the engine from the block up. I have a new Findanza aluminium flywheel. I am increasing the bore to 87mm, and installing a very mild cam, otherwise it is a stock engine. What are the pros and cons of the lighter flywheel?
 

HarryL

Jedi Trainee
Offline
Concerning the issue of the flywheel; the lighter flywheel will allow the engine to rev up faster,
taking less power from the engine to do so. It'll be a little easier on the synchros as the revs drop a bit faster.
To really get the full benefit you would need to do a whole bunch more work on your engine proper. Balancing
crank,connecting rods,pistons,flow the head & more. I did most of what I just said; but wanted to maintain the reliability.
Lightened the existing flywheel a bit so when I dropped it on my foot only 2 toes would break !
You'll get a bunch more responses.
Good Luck
Harry
 
OP
T

TriumphantMan

Freshman Member
Offline
I am balancing everything crank, rods, pistons, however, I can not find a shop that will flow test my head, so, I'm probably leaving it stock. I want a peppy, smooth running engine. A fun weekend street car. Will the lighter flywheel affect the idle? Suggestions
 

tdskip

Yoda
Country flag
Offline
I have that basic set up on my TR4a, noticeable and nice difference. I shaved my flywheel but similar end result.
 

TexasKnucklehead

Jedi Knight
Country flag
Offline
I did not see much hair on my head, so did not have it shaved.

Will the lighter flywheel affect the idle?

I did have my flywheel lightened per Hermans diagram and installed the larger pistons/liners. I think it's peppy enough but wonder if my idle would not be a little smoother with the added weight on the flywheel. The idle has no lope, but does flutter up and down a little -probably due to the significance of the mechanical advance at low RPMs. If I turn it up a few hundred RPMs (to over 1000 or so), it smooths out very well. Since I never drove the car before the changes, I can't say what difference it made, or if I'd do it again. The 'roughness' of the idle doesn't really bother me much, and most probably would not notice it, but it's just one of those things I find myself wondering about.
 
OP
T

TriumphantMan

Freshman Member
Offline
Would you mind telling me what size pistons, 87mm, 89mm or... and did you change the cam, if so, what are you using, did you remove the heavy "weights" fan extension, on the front of the crank and replace it with an electric fan and a harmonic balancer? or any other modifications. The main reason I'm asking is that I do not want an engine that has a lope to it.
Any advice is appreciated
 

TFB

Jedi Knight
Country flag
Offline
I think the major con of the lightened flywheel will be a more sensitive clutch at low speeds and lower rpm.If you like keeping the revs up you may not mind.
How do plan to drive the car.
I have more hod rod friends than sports car friends but some similarities are that I am surprised at the expense,not just money but dercreased longevity,milage,etc., that some go thru,that didn't drive the car to the max when stock.If your racing different story.
Have fun,

Tom
 

HarryL

Jedi Trainee
Offline
When I rebuilt my engine I went with the 89mm pistons, had the flywheel balanced & lightened, crank balanced. Went up on the
cam just a little bit. Fancy new connecting rods and pistons. Like my race engine I try to make the bottom end as bullet proof as possible.
I'm using a Macy fan to keep things cool. With the oversize liners it tends to make the engine run warmer. Probably no advantage with
the 89mm. Very very little done to the head and intake. It does not lope; but kicks in strong around 2000rpms. Don't forget you've
got and old gearbox and rear diff back there.
Harry
 
OP
T

TriumphantMan

Freshman Member
Offline
Harry, did you use the uprated Moss Motors cam or TS Automotive's "torque" cam or something else? Do you recall the lift and duration? The TS Automotive cam is suppose to be a mid RPM torque cam. And, are you saying that the 89mm pistons are not worth the extra heat in the engine. Would you have rather gone with the 87mm?
 

HarryL

Jedi Trainee
Offline
All my engine build up material is not readily available(out of state).
But believe it was the Moss cam. If I had to do over would go with the 87's esp. since you already have them.
Harry
 

TexasKnucklehead

Jedi Knight
Country flag
Offline
I have 87mm pistons and a stock TR4 cam. I have a plastic yellow fan (mounted backwards) on the stock extension, as well as an electric fan controlled by a thermostat (but it does not block the crank hole in the radiator). I have 3/8" push rods installed. 5lbs was removed to make my flywheel weigh 14.5lbs. I have a pair of H6S's (not H6's). I have a uprated (DOT5 tolerant) hydrolic T-O bearing in my HVDA 5-speed. I have 195-65-R15 tires mounted on TR6 wheels.

I can dump the clutch without giving gas to pull out, but generally rev a little and feather the clutch to make it smooth. I can rev it up a lot, dump the clutch, and spin the wheels easily. The last time I auto-crossed, I stamped the brake so hard at a hair pin turn, that I killed the engine. I didn't notice until I let off the brake, and noticed the engine had to restart before taking off again. My course times were very good (I was only behind a TR3B and a TR6 -both driven by excellent drivers) -and not by much.

Although I have yet to drive in Texas 'hot' weather, I have not overheated in temperatures around 90.

I am happy so far, but am looking forward to a real test in heat. I drove it to Pa last fall and am planning a longer one later this month. I'll let you-all know how it goes and hope this information is useful.
 

TexasKnucklehead

Jedi Knight
Country flag
Offline
Which T/O bearing did you use in the HVDA that is Dot 5 tolerant?

I wish I could answer that more specifically, but I don't really know. I do know I spoke with Herman about it, and he knew the (original stock) one I had would not stand up to DOT5. I think the new one he sent specifically warns against DOT5, but I was assured it would work. -Something about a difference involving a square cut o-ring, and a round one. I'd imagine the material it's made from is different too. The bearing I used required shims, instead of turning a collar. I see a lot of "not for dot5" warnings, that seem to be ignorable. My issue in the TR3, was the single can reservoir, and I really wanted it all to be DOT5. The bearing cost a little more, but I think it was worth it. I also have the McLeod (TR6) pressure plate Herman recommended.

6,000 trouble free miles so far... And today I was caught in some red light traffic, humid, 90 degrees in the hot hot sun... so I got to see the temperature go up a little for the first time.
 

PeterK

Yoda
Offline
McLeod? 1st generation used the shims, 2nd generation bearing used in the HVDA kit uses screw in out method (MUCH easier) for setting the clearance. Clearly "not for Dot5" by the manufacturer's instructions. Reason: I don't know why but not recommended so I still use Castrol GT LMA in mine.
 
Similar threads
Thread starter Title Forum Replies Date
davidk Lightened Stock Flywheel Triumph 26
DerekJ Lightened flywheel options Austin Healey 62
F TR4/4A Lightened Flywheel for TR3A/TR4 engine Triumph 12
rjc157 lightened flywheel Austin Healey 9
G Lightened 1500 Flywheel? Spridgets 4
6 Pics of Lightened Steel Flywheel Spridgets 5
cjm lightened flywheel,best fixing? Triumph 3
C WHO HAS A LIGHTENED FLYWHEEL - AH 3000 Austin Healey 2
P Crankshaft and Flywheel Lightened ?? Triumph 4
P Lightened Flywheel Austin Healey 10
Y MGB Flywheel saga continues.... MG 24
tr6nitjulius For Sale TR6 tail light assemby & Resurfaced/New Ring Gear Flywheel Triumph Classifieds 0
Y MGB Flywheel resurface? MG 2
KVH General Tech Flywheel Bolts Too Long For Main Seal Triumph 13
Michael Oritt 100 Flywheel Weight Austin Healey 16
BoyRacer 6 cylinder flywheel on a 100 engine? Austin Healey 0
WHT Denis Welch CENG635SO Flywheel Austin Healey 0
R For Sale Fidanza Aluminum Flywheel for 1275 A-Series Spridgets Classified 0
D 1.8 2007 Toyota Avensis Clutch & Flywheel Torque Settings? Other Cars 0
J BJ8 flywheel take some pounds off Austin Healey 17
roscoe Flywheel orientation question Austin Healey 3
R TR6 Pilot bushing clearance and Fidanza flywheel Triumph 0
AUSMHLY Shifting into 2nd, problem because of the Flywheel? Austin Healey 21
M TR2/3/3A What Flywheel is this? Triumph 3
J TR2/3/3A Flywheel-Crank Dowel Alignment Triumph 6
R Wanted BJ8 FlyWheel Austin Healey Classifieds 6
M TR2/3/3A Starter and Flywheel Combinations Triumph 2
Rut Crank/flywheel dowels Spridgets 3
JimLaney Flywheel Pitting Spridgets 4
S TR2/3/3A Alloy flywheel Triumph 13
K TR4/4A TR4A clutch pressure plate to flywheel bolt "torque value"? Triumph 2
TRopic6 For Sale Flywheel for TR250/'69 TR6 Triumph Classifieds 0
drooartz ID a 1275 flywheel Spridgets 2
D TR4/4A flywheel bolts maybe too long Triumph 15
trotti Flywheel removal Austin Healey 4
drooartz Looking for a 1275 flywheel Spridgets 17
A 1955 100/4 Flywheel Info Austin Healey 4
T Post-War Other Herald flywheel Triumph 3
B Clutch disc - which side goes towards flywheel? Austin Healey 8
abarth69 1275 Flywheel Wanted Spridgets 7
CJD TR2/3/3A Clutch/Flywheel Bolts Triumph 28
T TR2/3/3A How many guide holes in TR3 flywheel for crank pin? Triumph 2
J TR2/3/3A Flywheel bolts Triumph 1
DNK General Tech Flywheel Bolts Triumph 6
K TR6 Flywheel installed without the locating dowels? Triumph 5
K TR2/3/3A Lightening a stock TR3A flywheel..... Triumph 13
O TR2/3/3A TR4 Flywheel Triumph 4
toysrrus TR6 TR6 & GT6 Flywheel, Clutch question: Triumph 4
RedTR3 TR2/3/3A Moss [ARP] Flywheel Bolts Triumph 16
K TR2/3/3A Torque value for TR3 clutch cover to flywheel bolts....... Triumph 2

Similar threads

Top