# VW attach points

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#### fly scared!

##### Guest
Can someone provide me with some references about the VW engines attach points' (threaded bosses) coordinates/offsets? (front, rear, side et c.)
I guess they will be different for the various versions (or not?)
Thanks!

#### Hot Wings

##### Grumpy Cynic
HBA Supporter
Log Member
Both the Tp 1 and the Tp IV have the same bolt pattern where they bolt to the transmission. All threads are 10mm x 1.5mm. I don't have one handy now, or can find my own measurements, but a quick internet search turned this up:

"The motor is located with a centering ring that is 11.100 inches in diameter...................The top 2 bolt holes are located 4.328 inches above the horizontal centerline and 3.897 inches to either side of the vertical centerline (42 degrees to either side of the vertical centerline.) The bottom 2 bolt holes are located 4.117 inches below the horizontal centerline and 4.117 inches to either side of the vertical centerline."

I'll leave it to you to convert to the closest metric dimensions.

F

#### fly scared!

##### Guest
Thank you!

I'm afraid converting to metric will be difficult with those figures... 4.117" = 104.571 mm ... very unlikely!
What about the flywheel side ? There must be at least two used in the rear, bed mount configuration.

#### Hot Wings

##### Grumpy Cynic
HBA Supporter
Log Member
Thank you!

I'm afraid converting to metric will be difficult with those figures... 4.117" = 104.571 mm ... very unlikely!
What about the flywheel side ? There must be at least two used in the rear, bed mount configuration.
That's why I left it up to you to convert to metric.

I've never had the need to put these dimensions into CAD. I've found that when reverse engineering this kind of thing if you put the dimensions into CAD just as measured and then try to overlay a nice idealized drawing with simple angles using whole numbers something is going to fall into place. Back in the day when the VW was designed it mad things far simpler to use such "idealized" dimensioning unless there was a real need for some odd number. I'm betting if you do this you will find that the 4.117" = 104.571mm really equals 105mm.

I just did a quick sketch this way and using an angle of 48 deg for the top bolts and 45 for the bottom, a bolt circle of 295mm the bolt hole centers come out 0.338mm from the inch dimensions I found and referenced above. I can't say either set of numbers are actually correct.

F

#### fly scared!

##### Guest
That's why I left it up to you to convert to metric.
.
Fact is, the real figures are metric.

#### TFF

##### Well-Known Member
Might be a Metric system built but to Americans, metric is just another set of tools you have to buy. We will still measure in inches.

#### N8053H

##### Well-Known Member
My VW uses a rail mount like a Rotax.

Tony

F

#### fly scared!

##### Guest
Might be a Metric system built but to Americans, metric is just another set of tools you have to buy. We will still measure in inches.
I'm not that patriotic: I use inches when working on US plans. Easier and bullet-proof.

#### bmcj

##### Well-Known Member
HBA Supporter
Speaking of conversions, I'm not sure if everyone is aware that the Windows Calculator has a conversion function (as well as some other functions like date converter, fuel milage, vehicle lease, etc). Just open the calculator, select the VIEW menu drop down, and choose the function you need. In cases like this where you are on the computer, it saves you from manual calculations or having to get a separate calculator.

#### Topaz

##### Super Moderator
Staff member
Log Member
Speaking of conversions, I'm not sure if everyone is aware that the Windows Calculator has a conversion function (as well as some other functions like date converter, fuel milage, vehicle lease, etc). Just open the calculator, select the VIEW menu drop down, and choose the function you need. In cases like this where you are on the computer, it saves you from manual calculations or having to get a separate calculator.
Or just type "unit conversion" into Google search. You'll get a very nice unit converter at the top of the results. Not a link, an actual conversion applet appears in the browser.

If you simply type, "How much is 4.117 inches in millimeters?" into Google search, it'll pre-load the units and values into the converter and you'll have the answer instantly.

##### Well-Known Member
HBA Supporter
What about the flywheel side ? There must be at least two used in the rear, bed mount configuration.
The stock Type 1 motor only mounts from the flywheel side, and does not have a bed mount. The dimensions Hot Wings gave surround the flywheel.

For typical, new T1 cases, three of the four mounting holes have 10mm threads. The bottom two holes are in the lower corners of the case, and are threaded. These are "blind," open only to the flywheel end. (In the car, studs are threaded into this location.) On the top, the holes go through the rounded flange surrounding the flywheel. If you are facing the flywheel, the hole at the upper right will be threaded, and the one on the left is open for the bolt to pass through.

Older, single-relief cases don't have threads in either of the top mounting holes. If you are building from a new case, you are not likely to encounter that.

#### Matt G.

##### Well-Known Member
Or just type "unit conversion" into Google search. You'll get a very nice unit converter at the top of the results. Not a link, an actual conversion applet appears in the browser.

If you simply type, "How much is 4.117 inches in millimeters?" into Google search, it'll pre-load the units and values into the converter and you'll have the answer instantly.
Or use this. Probably the best conversion program I've seen. I've been using it since high school, and my employer uses it, too.

#### Hot Wings

##### Grumpy Cynic
HBA Supporter
Log Member
I've been using it for well over a decade. Even have a quick start icon in my tool bar it's so handy. I just wish "speed" was labeled "velocity".

#### BJC

##### Well-Known Member
HBA Supporter
[QUOTE said:
I just wish "speed" was labeled "velocity".
I guess that I missed something. All the units I saw for speed were just that, not velocity.

BJC

#### Topaz

##### Super Moderator
Staff member
Log Member
I guess that I missed something. All the units I saw for speed were just that, not velocity.

Ayup. "Velocity" is a vector, so it would need a direction component. "Speed" is scalar. Most people use them interchangeably, but the use of "speed" in the program is appropriate if you want to be strictly accurate.

Looks like a cool program. Thanks for the link and recommendation!

#### Hot Wings

##### Grumpy Cynic
HBA Supporter
Log Member
Ayup. "Velocity" is a vector, so it would need a direction component. "Speed" is scalar. Most people use them interchangeably, but the use of "speed" in the program is appropriate if you want to be strictly accurate.
Hadn't thought about it that way, but you are correct. I'm usually thinking in vectors when I use the conversion:ermm:

#### Topaz

##### Super Moderator
Staff member
Log Member
Hadn't thought about it that way, but you are correct. I'm usually thinking in vectors when I use the conversion:ermm:
You, me, and everyone else. But the physicists had to have it their way...