Help - Taking accurate (0.1mm) measurements with basic tools

[NavyF350]

I want to design an adapter plate to mate a Nissan VH45DE V8 engine to the 5-speed manual transmission in the Nissan 300zx.

A good friend of mine has a water jet, so if I can get accurate enough measurements I can design and build a prototype to make the final corrections during mock up.

So what can I do to accurately map out each of the bolt hole locations as well as their relation to the input shaft / crankshaft pilot bushing.

I work in a automotive garage, so I may not have access to the most accurate tools...

[mc-motorsports]

I use a bridgeport with a DRO to measure stuff like that. Use an indicator and tram each hole, if they are threaded, put an allen head bolt in the threaded hole and measure the head.

You probably won't have enough travel if you use a BP or similar knee mill, locate off of the crank pilot, measure everything you can, flip it over and measure everything else, measure a couple of them twice so you can match it up when you do your CAD work.

It's a PITA, but it's easy, if you have a mill with a DRO anyway.

MC

[NavyF350]

Originally Posted by mc-motorsports I use a bridgeport with a DRO to measure stuff like that. Use an indicator and tram each hole, if they are threaded, put an allen head bolt in the threaded hole and measure the head. You probably won't have enough travel if you use a BP or similar knee mill, locate off of the crank pilot, measure everything you can, flip it over and measure everything else, measure a couple of them twice so you can match it up when you do your CAD work. It's a PITA, but it's easy, if you have a mill with a DRO anyway. MC

When I put the bell housing under the milling machine I couldn't reach all the holes, as well we didn't have an ideal tool to find the exact centerpoint of each hole because they were unthreaded.

So, would it be better to take a VG block (the engine the transmission comes from) and use it to get the measurements? The lower mounting holes are bolt on brackets that would be simple to fabricate...

I may have solved this myself, well I needed something to redirect my thought path!

[mc-motorsports]

Originally Posted by NavyF350 When I put the bell housing under the milling machine I couldn't reach all the holes, as well we didn't have an ideal tool to find the exact centerpoint of each hole because they were unthreaded. So, would it be better to take a VG block (the engine the transmission comes from) and use it to get the measurements? The lower mounting holes are bolt on brackets that would be simple to fabricate... I may have solved this myself, well I needed something to redirect my thought path!

You don't have a test indicator?

I would use a block if at all possible, would be easier since you should have more surface area for it to lay flat, vs a trans bellhousing.

MC

[NavyF350]

Originally Posted by mc-motorsports You don't have a test indicator? I would use a block if at all possible, would be easier since you should have more surface area for it to lay flat, vs a trans bellhousing. MC

On the Nissan transmissions you are basically splitting the case in half, but the main shaft bearing is part of the housing. I thought this would allow me to easily get center point, but I totally didn't think about using a VG block and crank to get the locations.

I found the bell housing sat nicely on the milling machine, but it is not my piece of equipment so I am not familiar with the tooling for it. I am not that experienced when it comes to machining, I just understand what the technology does... So this is a learning experience for me.

[mc-motorsports]

Originally Posted by NavyF350 On the Nissan transmissions you are basically splitting the case in half, but the main shaft bearing is part of the housing. I thought this would allow me to easily get center point, but I totally didn't think about using a VG block and crank to get the locations. I found the bell housing sat nicely on the milling machine, but it is not my piece of equipment so I am not familiar with the tooling for it. I am not that experienced when it comes to machining, I just understand what the technology does... So this is a learning experience for me.

Hmmm... If you have a milling machine, you probably have a machinst in the crew somewhere? Most guys won't leave a test indicator laying around. They are delicate and rarely loaned out, one of the sacred tools of the machining trades.

Best bet is ask your machinst to teach you how to tram holes, if he weill let you borrow his indicator

Pick a hole, or the crank pilot, make that 0,0 and record the location of all the other holes in relation, and use this information to make your CAD drawings.

[RICHARD ZASTROW]

Just another little hint.. Rather than a capscrew, use a tap. The shank is smooth and ground, more accurate to the thread than a capscrew head. Should also fit tighter in the threaded hole.

$0.02 US

Dick Z

[NavyF350]

Originally Posted by RICHARD ZASTROW Just another little hint.. Rather than a capscrew, use a tap. The shank is smooth and ground, more accurate to the thread than a capscrew head. Should also fit tighter in the threaded hole. $0.02 US Dick Z

So basically thread the tap in, then align the milling head?

[mc-motorsports]

Originally Posted by RICHARD ZASTROW Just another little hint.. Rather than a capscrew, use a tap. The shank is smooth and ground, more accurate to the thread than a capscrew head. Should also fit tighter in the threaded hole. $0.02 US Dick Z

a lot of times the tap is loose and wobbles. I take an allen head bolt, if the outside is stamped or knurled, I turn it down on the lathe to make it smooth and make it finger tight using an allen wrench. Pleanty accurate enough to locate a bolt hole.

MC

[NavyF350]

Originally Posted by mc-motorsports a lot of times the tap is loose and wobbles. I take an allen head bolt, if the outside is stamped or knurled, I turn it down on the lathe to make it smooth and make it finger tight using an allen wrench. Pleanty accurate enough to locate a bolt hole. MC

So it is pretty safe to assume that the allen head bolt will correctly center when it is lightly torqued into place... Didn't think about the free play the tap will have.

The information posted here has been very helpful. Hopefully this weekend I can get both blocks onto the milling machine

[mc-motorsports]

Originally Posted by NavyF350 So it is pretty safe to assume that the allen head bolt will correctly center when it is lightly torqued into place...

Within reason. Pleanty close enough to locate a bolt hole. I've done this time and time again, never failed me yet. Just measure carefully, double check yourself and take your time. It's really a simple process, but one slight error can snowball and screw your whole project and it will be a loss of both time and money.

MC

[handlewanker]

Hi NavyF350, the bolt holes are CLEARANCE, that is they are a loose fit, .010" to .015" clear, but there are two dowel holes on either side of the bell housing that allign the plate with the engine and bellhousing.

You can mark out the bolt holes, using regular marking out methods as they're clearance holes, and the dowel hole positions are picked off the engine block back and bell housing, and transferred to the plate.

Ten to one the dowel holes on the engine back won't match the bell housing so you will have to either drill and ream new dowel holes (2) in each, or drill and ream the plate to suit both existing dowel positions.
Ian.