TR6 Flywheel security above 6000 RPM

From: "kas kastner"

I guess we'll go over this again for the tenth time. The problem is that the harmonic of the TR-6 engine causes the flywheel to move back and forth (wobble) and this prys the bolts out of the crank or STRETCHES the bolts. When this happens the bolts are found bent over or loose or even out of the threaded crank. Larger bolts, yes, but the main thing is that the bolts must be of a type that do not STRETCH.

The only way to solve this on an immediate basis is to lower the revs below 6000 as the secondary vibration occurs at 5800 and is so strong it moves the flywheel edge back and forth over a 1/2". Lots of hardware companies sell the type bolt you need for this crank. Buy the best you can find. REMEMBER hard not stretching bolts. NOT strong, but hard. Grade eight is not near good enough for the TR-6.

The GT-6 is a totally different crankshaft and does not have anywhere near the problem. What fixes the GT-6 will no doubt FAIL with the TR-6. The only similarity of the engines in this department is that they are both have 6 cylinders.

In the end you want the lightest flywheel and the lightest clutch you can come onto. My TR-6 had a total weight of BOTH these components of 13 pounds. I also had six bolts in the end of the crank and of an improved diameter and quality. You can fix it, but is takes some little doing.

Kas

----- Original Message -----

Subject: Re: Flywheel woesTo add to the good advice by Russ.

ideally you want a bolt with a large underhead bearing area & correct grip length. Also make sure that the register in back of wheel & rear of crank is pefectly clean & flat, & make sure there are no raised spots around bolt hole chamfer. Also make sure that the locating dowel is a tight fit in the wheel, the fasteners clamp the wheel, the dowel takes the shear load. If the wheel is loose on the dowel the bolts will be subject to shear load & they WILL fail!  Some people add a second dowel for increased shear strength.

Glen

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