• 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

Crankshaft Rotational Freeplay - What's going on with this engine?

gonzo

Jedi Warrior
Country flag
Offline
In the process of tightening the fan belt and some rotational freeplay (about +/-10 to 12 degrees) in the damper / big crankshaft end nut was observed - early BJ-7. There is little to no "lash" or thrust - back and forth movement, only this rotational movement. The nut is secure and damper pressed fit nicely to crankshaft with no leaking oil from seal. Also, there is no movement of the distributor that corresponds the degree of freeplay. Other than this, the engine runs smoothly through RPM range.

So the question: Is there an acceptable tolerance for crankshaft rotational freeplay? What's going on here with the engine?
 

dklawson

Yoda
Offline
It sounds like you are describing delamination of a harmonic balancer. There are places that say they can rebuild them. I think it's more common to replace them. On other makes of cars where this happens the owner is typically advised to stop running the engine until a fix is implemented. I don't know if the same holds true for A-Hs.

See this old thread:
https://www.britishcarforum.com/bcf/showthread.php?53008-Harmonic-balancer-repairs
 
OP
G

gonzo

Jedi Warrior
Country flag
Offline
The BJ7's Harmonic Balancer is comprised of two parts, the laminated piece is bolted to pulley. Fanbelt runs off pulley and the entire assembly and nut have some degree of clockwise and counterclockwise movement.
 

vette

Darth Vader
Country flag
Offline
Gonzo, I don't believe you should run the engine till this is fixed. I have never heard of rotational "play" in a crankshaft pulley or damper. If the whole assembly is moving then I would have to believe that the key in the keyway is sheared and the hub is not really tight on the snout of the crank.
 
OP
G

gonzo

Jedi Warrior
Country flag
Offline
Understood and I'll be investigating this further. First order of business is to spin off the nut, then check the pulley for movement. Thanks, GONZO
 

red57

Jedi Knight
Country flag
Offline
Gonzo, Vette is right, I would not run it as is. I have heard of this and I know of one fellow racer that had one 'fret' itself loose - the key and keyway can easily allow the rotation you describe. The pulley should be so tight that you need to boil it in a pan of water to install and ram home quickly. You may have the pulley worn oversize the crank snout worn undersize, or a combination of both. If indeed it is loose, it will get progressively worse.
Are you certain the movement is between the pulley and the crank? I ask because sometimes there can be a small amount of rotational 'free' movement due to rod bearings clearances until you hit the resistance of rings in the bores. I can usually get some small relatively free movement back and forth with mine.
Dave
 

Keoke

Great Pumpkin
Country flag
Offline
:iagree:: Engine should not be run in its current state.

Either the rubber is failing or the keying on the shaft is defective.
 

elrey

Darth Vader
Country flag
Offline
I would pull the balancer and check the crankshaft nose and the bore of the balancer. Generally if the balancer has been loose on the crank the woodruff key shows wear where it sits in the slot. All of this wear can add up to a fair amount of slop. It is my understanding through hearsay that the expensive Australian harmonic balancers on the market are tight as a "tick" on the Healey crank and coupled with a new key may solve the problem. I believe the crank end is harder than the balancer so it may not wear as fast as the hole in the balancer. One of these more competent fellas here may have the specs for the crank end circumference. As I am but a simple carpenter my word is suspect but I have seen this before. Best o luck, you are in excellent hands here. We are truly fortunate to have such knowledgeable folks in our midst! :yesnod: :cheers:
 
Last edited:

Michael Oritt

Yoda
Gold
Country flag
Offline
"tight as a condom"


​I didn't know they were supposed to be tight!
 

Frameman

Senior Member
Offline
\I would suggest you loosen the fan belt and reach down to the lower pulley, if it rocks freely this would mean it is worn or come off the wood drift key. If it is not loose than I would suspect worn timing chain or timing chain gears or worn timing chain tensioner. It will be one of these issues.
 
OP
G

gonzo

Jedi Warrior
Country flag
Offline
Great ideas. Thanks all for sharing. Here's an update: crankshaft rotational movement is no more than 2 degrees with fan belt removed. When I replaced the seal last year the damper took some effort to remove with a three arm puller. It checked out OKay along with the crankshaft snout. The damper was warmed up (110F summer heated driveway), aligned it to the key and quickly drove home with a lead mallet. This took some effort as well. 75 ftlbs to tighten the crankshaft nut. I'm confident the assembly is secure.

From your ideas, I believe the movement could be due to rod bearing clearances or timing chain. I'll investigate this further. GONZO
 
Similar threads
Thread starter Title Forum Replies Date
B TR6 Crankshaft long seal surface Triumph 5
MKIII_Joey Crankshaft Bearing Austin Healey 7
BT7 Owner Rear Crankshaft Bearing Cap Austin Healey 4
K TR2/3/3A " do not remove the fan as it is essential for establishing crankshaft balance" Triumph 9
B General MG Crankshaft Nut Removal MG 4
W Crankshaft Oil Seal Austin Healey 3
Popeye TR4/4A Crankshaft pulley recommendations: One piece alloy, two-piece steel, wide, narrow...? Triumph 12
B MGB Mgb crankshaft end play shims MG 2
M TR2/3/3A 1958 TR 3 , crankshaft nut for hand starting Triumph 7
M TR2/3/3A Crankshaft Sludge Plug Removal Triumph 6
T crankshaft (rear) bearing leak Spridgets 2
T Wanted Wanted - 1956 TR3 Crankshaft Triumph Classifieds 0
R Wanted 3 main crankshaft MG Classifieds 0
glemon TR2/3/3A Crankshaft Question Triumph 3
J Crankshaft dog nut and timing chain cover removal advice Austin Healey 30
AUSMHLY Crankshaft Starter Nut Austin Healey 10
S For Sale Mg t-series crankshaft tb tc td tf 1250 1500 MG Classifieds 0
K TR2/3/3A Anyone have a picture of the crankshaft pulley.... Triumph 1
S Wanted Looking for a new/used crankshaft for a 100-4 Austin Healey Classifieds 0
P TR2/3/3A Crankshaft Thrust Washers Triumph 4
M TR2/3/3A Crankshaft Pulley Configurations Triumph 3
M TR2/3/3A Crankshaft Oil Galley Plugs Triumph 7
S TR4/4A Fair price for a crankshaft? Triumph 2
charleyf TR2/3/3A crankshaft hardening Triumph 2
Gerard Wanted: 1275 Crankshaft Spridgets 3
T can't find timing marks on 1275 crankshaft pulley/damper Spridgets 8
O Wanted TR 3 Crankshaft please... Triumph Classifieds 1
P Replacing the crankshaft damper [harmonic balancer] Austin Healey 15
GTP1960 TR2/3/3A Moss Crankshaft pulley failure Triumph 23
C Tough Bolt on front of Crankshaft Spridgets 16
TRMark TR4/4A Prepping Crankshaft Triumph 4
D TR2/3/3A crankshaft shims to align timing sprovkets Triumph 4
KVH General Tech Crankshaft Main Bearing and Oversize Puzzle Triumph 5
tinman58 TR5/TR250 Front crankshaft seal Triumph 0
2billydavies TR2/3/3A removing con rod from crankshaft Triumph 4
J TR2/3/3A Crankshaft thrust washers. Triumph 2
C Crankshaft pulley / damper Austin Healey 5
HJR TR2/3/3A Crankshaft crank bolt head[108498] Triumph 10
M For 1974 MG Midget - Crankshaft pulley bolt is 1 5/16"? Spridgets 4
M Spitfire need a crankshaft pulley for 1978 Spitfire Triumph 0
M_Pied_Lourd TR2/3/3A TR3A Crankshaft Question Triumph 3
B crankshaft/cam timing Austin Healey 10
RedTR3 TR2/3/3A TR3 Crankshaft Options Triumph 10
Gerard 1098 10CC crankshaft Spridgets 14
vette Timing Cover crankshaft pulley seal Austin Healey 6
AHS TR2/3/3A Which way does the TR3 front crankshaft oil seal face? Triumph 8
M Healey Crankshaft Thrust Washer Thickness Austin Healey 3
Tugboat Crankshaft Pulley Question Triumph 4
J How bad do Spridgets leak oil from the crankshaft? Spridgets 18
M Healey Crankshaft Bearings Austin Healey 21

Similar threads

Top