40 replies to this topic

[lakeside]

loctite will not work. Dowels between flywheel and crank will fix. I broke my crank and block when it happen to me, sheared the heads off 7/16 api flywheel bolts. I had of drove it, i would have lost my feet

Edited by lakeside, 13 May 2007 - 10:16 AM.

[rodomo]

Keep the RPM down til you fix it properly.
If it starts chopping out the end of the crank, its engine out again.

[gtrboyy]

You will have to keep the revs way down till you come up fix a permanent fix,a good harmonic balancer,doweling,loctite & tack welding the bolts is what we did that worked on mine.Used to buzz it to 6000-6500rpm regularly.Never came loose on me but did on the previous owner.

I didn't know what the lock wire method was back then otherwise I would have done that instead of doing the bodgy tack welds of the bolt heads to the flywheel.

[lakeside]

all later model blue motors come with a dowel from the factory.

[dinky48]

Is it a standard flywheel ? I used to have a lot of trouble like u, years ago. Eventually, I took the crank out of the engine, and got a steel flywheel made that was an interference fit onto the back of the crank, and along with 7/16" Grade 8 bolts, fixed it finally !

[piquet]

before you go down the pathways that heae been sugested it may be worthwhile doing a bit of research first.

have you checked out the runout on the flywheel?
this is fairly easy to do witha dial indicator on the clutch face of the flywheel.

There is a tolerance in the workshop manual as to the max allowable runout.
If the run out is within the tolerance it may be a simple fix with a dowell or two.

This is best done with the crank and flywheel out of the car as is also the drilling and fitting of additional capscrews or bolts.

If it is outside the tolerance it could indicate either a warped flywheel or a bent crankshaft. A warped flywheel would be an easy fix, just get another one. A bent crank is a teardown(sorry) and rebuild.

I had a crank that was cracked in the radius of #6 Bigend allowing the whole back of the crank and flywheel to wobble. This caused loose and broken flywheel bolts.


hope its fairly straight forward
cheers
piquet

[Stedz_lc]

oh more money! Anyone got any photos of the dowel's and how/best way to do it

[Stedz_lc]

oh more money! Anyone got any photos of the dowel's and how/best way to do it

[lakeside]

Is it a standard flywheel ? I used to have a lot of trouble like u, years ago. Eventually, I took the crank out of the engine, and got a steel flywheel made that was an interference fit onto the back of the crank, and along with 7/16" Grade 8 bolts, fixed it finally !

don't work

[Stedz_lc]

I take it this will be another job for the machinist

[turbotrana]

I get the machinist to drill and tap 4 extra threads inbetween the existing bolts to accept
4 allen key bolts. Then loctite and it will never come lose.

In the turbo tory I have an alluminium flywheel and I only use the standard holes with Stage8 bolts and loctite and never came lose.

While your on the flywheel end you must also address the harmonic balancer end.
For this I have it drilled and tap to accept a chevy balancer bolt. The most important thing is to have the keyway milled to accept a much larger key. Otherwise you will chew these out. Easiest way is to get a metric key which is slightly wider than the existing one but you machine the top half of the key to the original width. Overall the keyway will be deeper and longer.

Then get a good bonded steel balancer.

I only ever use VK alloy timing gear and you must either weld them on the cam with 3 quick tack welds (TIG) or grub screw them in to they dont come off.

Its all these little bits that get you a reliable engine.

[turbotrana]

The alloy timing gear has a steel hub with the timing gear cast around the steel hub. I've never seen an all alloy timing gear but they may have changed the design of late.

Why the timing gear slides off the end of the cam under heavy usage. I am not really sure but I thought it was a reason why there are straight cut timing gears.It may be that the helical gears are pushing the gear off in either heavy acceleration or deceleration just by the nature of the angle designed. Even crank harmonics may have something to do with it or even high volume oil pump may have something to do with it. The cam thrust plate gets chewed out because of the pressure the helical gears or whatever put it under. Thats why I have a seperate oil feed going to the thrust plate area. Nevertheless the VK timing gear is still the way to go IMO.

Many moons ago I was dealing with big solid lifter camed XU1 type motors that reved out to 7500rpm and once it happened a couple of times I just fixed it permanently.

A bolt and washer is probably the proper way to go but we just welded or scrub screw it. I didn't think there was much room between the cam and timing cover to put a bolt and washer.

If the gear moves forward it actually allows the cam to move backwards before maybe hitting the rear core plug and the gear hitting the front timing cover case. Timing will alter quite a bit also. Thats how you diagnose it.

[Stedz_lc]

More things to add to the list of to do things!! keep it coming!

[lakeside]

Is it a standard flywheel ? I used to have a lot of trouble like u, years ago. Eventually, I took the crank out of the engine, and got a steel flywheel made that was an interference fit onto the back of the crank, and along with 7/16" Grade 8 bolts, fixed it finally !

Greg, what stops the flywheel moving slideway at big revs? His is the way it broke the first time.

[dinky48]

What Broke ? I forgot to add that the steel flywheel was dowelled also, engine was in an FX, so I had no room to run a bigger balancer unfortunately, on Greys they used to use M.F.Tractor balancers sumtimes. That 202 in the FX pulled over 7000 in 1st. & 2nd gears, dragged it heaps, and never had any more loose flywheel trouble !

[TerrA LX]

Flex plates usually just crack