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Author Topic:   3rd member ?
steamatic racer
Dirt Full Roller

Total posts: 35
posted July 17, 2002 07:57 AM
I've been running a 4.11 gear & a 168 box comb. all season. I desided to run a 1 to 1 6.50 setup now. I bought different 3rd member & installed new gears and stuff, but the darn thing viberated me to death at 3000 rpms. Thought the driveshaft was the problem but I had the other 3rd member w/ me at track, threw it back in and NO viberation! I've checked the back lash, its set at 10 still. Any ideal's? THANKS TERPS

Dirt Full Roller

Total posts: 47
posted July 17, 2002 03:45 PM
I didn't do the math but if your final ratio is lower with the 6.50 then it probably is your driveshaft. i switched from 3.08 to a 4.56 in a truck and the thing vibrated like crazy. the gears were the only change i made. i had to have the driveshaft balanced, and added about two inches due to a lift the lentgh was fine until i went to deeper gears then it became a problem. after that everythng was fine. So i'd say check your length and get it balanced.

[This message has been edited by nwracr (edited July 17, 2002).]

Dirt Full Roller

Total posts: 69
posted July 18, 2002 06:50 AM
It is probably the fact that you are turning your drive shaft almost twice as fast as before. A stock driveshaft will work fine in low gear but when you start turning it at engine speed it bows in the middle and returns to normal when you stop.

Tim Weiss
Dirt Roller

Total posts: 12
posted July 18, 2002 02:24 PM
We have cut and rewelded many driveshafts for race cars and street cars. We never had a vibrating problem but we always line up the u-joints

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