Tranny Tunnel Knocking

[Steve1970]

The stress testing of the tr6 continues... After three weekends of fairly hard driving, I figured tonight I would take it out for an easy pleasure cruise. Just when I thought I shook out all the bugs... the knocking started

It's a faint knock, occurs on the right side of the tranny tunnel, just before the radio console leg. I can feel the knock with my hand on the right side of the tunnel. Seems to occur mostly in third gear around 2200 rpms.

I would venture to say driveshaft u-joint, but I had them replaced last yr when I had the gearbox out during the mighty clutch job of '08 (must have less than 300 miles on 'em). Anyhow, noise seems to be coming from closer to the radio console than the driveshaft flange Maybe the gearbox mount has come loose? Maybe the fiberglass tunnel is too small?

Anybody have a similar experience?

 

[BobbyD]

Steve.......I had a similar experience but the knocking was just behind the passenger seat. It turned out to be the u-joint hitting the side of the drive shaft tunnel under acceleration. I had to realign the diff to stop the knocking. I'd check that there was proper clearance all around the drive shaft and that tranny & diff mounts were nice and tight.

 

[Steve1970]

man i bet thats it. i had the diff out last yr to get access to removing the prop shaft.

so you can actually align the diff? do you just kinda shove it into place and then tighten the diff mount nuts?

thanks bob

 

[Steve1970]

i just read something about shaft bind/slip which can occur when the splines aren't lubed enough. basically (from what i gather), at certain loads the half shafts go into cycles of binding then slipping free, causing imbalance in the prop shaft.

can't quite remember, can the splines of the tr6 propeller half shafts be greased??? id be happy as a pig in mud if i can get away with just greasing up the splines

thanks!!

 

[swift6]

Yes, and make sure the rubber boots are in good shape to keep the dirt out of the grease.

You have to take them apart to do it.

 

[Steve1970]

it was a clearance issue!!

the speedo cable was sandwiched between the tranny and the tunnel, so that even the smallest level of vibration caused a knocking against the tranny tunnel walls. i've been able to push the cable slightly free from where it was lodged, but i'm sure it will find its way back to getting stuck in there again. i will need to take off the tunnel and properly route the cable to do this right.

thanks to all for the good info. with this issue resolved, and with the punishing driving over the last few weekends, i'm pretty confident that i've finally got a good straight reliable driver on my hands.

now i get to move on to the more 'fun' issues, like making it look nice. gotta settle on a color. blue vs. green? hah i wish it were that simple... mallard blue vs. french blue vs. laurel green vs. emerald green vs. conifer green... heavily leaning towards laurel green at the moment. green with redline tires, too christmas-ey??

-steve