60th Birthday - Winter Work - '07 & '08





Locating Dowels

I can't believe that I'm doing one page on my site about locating dowels. What the heck are they and why do we need them or even care about them. What I learned from my friends on the Triumph and 6-Pack Mail Lists are that locating dowels are precision ground to ensure "perfect" alignment of critical components. Specifically, in my case, the transmission to the engine. Some people say to just use an appropriate sized bolt and you'll be fine but, for example, a 3/8" bolt is made to "acceptable" tolerances. They're not made to align things, they're made to hold things together. And there's a big differences in those two needs. The shoulder on a 3/8" bolt is made to a rather wide + or - variance when compared to a locating dowel. So where do you have locating dowels on a TR6?

Well, as I was assembling bits and pieces I was surprised at how many I found and how many were missing! The ones I'm addressing are critical in the alignment of the transmission to the engine and it all starts at the rear of the engine.......obviously :-)

These two align the back plate to the block This one sets the flywheel to the crank shaft

Once you get the back plate aligned to the engine block and the flywheel to the crank, it's time to add the pressure plate......yup.....more locating dowels.

This time there's 3 of them

And with the Pressure Plate on them

Seeing as I'm doing the Toyota 5 speed conversion it was important to save the dowels that came with the 5 speed. These were located between the tranny body and the bell housing.

Here's two different views of the Toyota tranny dowels: with & without the bell housing.

And then there's the "BIG ONE".............the dowels that mate the bell housing to the back plate. If your car is like mine, these two dowels are long gone..........having been replaced by plain old 3/8" bolts. However, they are easily replaced by going to www.mcmaster.com and ordering part# 98381A624.

Red arrows are back plate to engine block dowels & yellow arrows are bell housing to back plate

So there you have all the locating dowels that are required to ensure perfect alignment from the engine block to the transmission. If you're missing any of these DO NOT replace them with a bolt of the appropriate size. Get a dowel that is precision machined for this purpose.