Hello everybody! Bill here at QA1 and today we're going to show you how to
measure for a custom driveshaft with just a piece of paper a tape measure and a pen.
Today we've got a scenario with this car that you may run into yourself.
Where this car got a different rear end housing in it when it got all the new suspension and now
because of that the driveshaft that was in there is not really the right length so the question is
how do you measure for a new driveshaf? Well that's what we're going to show you today so
let's get this thing up in the air and we'll go through it. All right well if you want to measure
for your driveshaft the first thing you're going to need to do is print yourself off one of these.
These are available on our website and they're also available if you call us up we can email
you one whatever. But what it is is it's it's a driveshaft measurement sheet and with all of this
information that you fill out we can come up with the right driveshaft for you. Now there are things
on here like year make and model of your vehicle engine max engine speed max speed of the car
rear end drive ratio tire size things like that and what we're trying to do is trying
to get an idea an accurate idea of just how fast your driveshaft will spin in your car.
Now for a streetcar or a you know high-performance streetcar or a show cars and things that might
not be as important to you but it's important to us. Where it's really important is for the
drag racers who know exactly you know I'm going to be doing 167 miles an hour in the quarter mile
at 7500 rpm with a 33 inch tire and blah blah blah. Those scenarios we want to make sure that
we we're getting you covered and you're not going to wind up with something that
doesn't work for you. So let's get under the car and we're really going to go through
the act just the actual measurements. And as I said earlier all we really need
is one of these guys.
Important note. Important note. The car needs to be sitting at ride height when you do this.
If the suspension is hanging your measurement is going to be off because as the suspension hangs
the driveshaft pulls out or pushes into the transmission. So
the car needs to be sitting on its suspension when you get these measurements
and we've got it on the four post lift but you could do this on a set of jack stands or a set of
uh cradles that you put under the wheels however you want to do it.
Just know that the drive the car has to be at ride height. And what we're going to do
is since this car doesn't have a driveshaft in it
it makes things slightly easier but what we're gonna do...Kasey can you see this?
This is our greasy transmission. As you can see. Now there are two things the slip yoke can bottom
out right here on the seal. The slip yoke can also bottom out inside on the end of the output shaft.
So what we're going to do here is we're going to measure how far this is sticking out from
the output shaft and I got about five eighths of an inch. I'm going to go over here to my
deal and I put my pen over here where it should be.
And if we go on here that's measurement C. How far is the tail shaft sticking out of the or I'm sorry
the output shaft sticking out of the tail shaft measurement C I'm going to put that right here.
0.625 now the next measurement we need is this measurement B you see that? And this is just a
measurement from the end of the tail housing to the center of the u-joint in the rear.
Okay so we're going to take our tape measure
and I'm going to go figure out this Rubik's cube of how to get this thing out of here.
Okay and then we're gonna go all the way back
to here. 63.375 Now with those two measurements
you can give us a call and you can say these are my measurements how long does driveshaft need to
be and we can figure that out for you? Okay so now you got your measurement from tail shaft
to uh the rear end pinion yoke. And what we need to know next is how many splines
your output shaft has and so what I do is I use like a pen and I find like you know the top one
I kind of set the pen in the groove and then you just count 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
17 18 19 20 21 22 23 24 25 26 27 27 spline and obviously this is a GM car so we come in here.
Wipe the stuff off on your other hand and we know we gotta this is gonna be a 27 spline
five and a half inch long and if you have your old driveshaft you can kind of get an idea
of how long your old slip yoke was. It doesn't have to be exactly that length because high
quality like nice slip yokes like we use the measurements are slightly different than what you
might see on your stock one. But it's important to know that okay well you don't need a seven
inch long one or an or eight inch long one so you just wanna be in the ballpark of what you had.
In this case 27 spline uh 1.503 O.D. that would be a measurement of here to here.
In this case I don't need no SFI. Driveshaft's just as good either way. And the center to
center u-joint we don't have that because we don't have a driveshaft to measure so
that's why we're using these two. So now we've got all of our measurements we've
got all of our information filled out I'm going to call up the QA1 tech line.
Got her! Let's go put it in!
This is the most fun part of the whole
deal.
Well there you have it! As you can see measuring for a custom driveshaft is really not that
difficult. In fact I'm pretty sure you probably have the tools in your kitchen junk drawer.
If you do have any questions or want to talk to us about these driveshafts or getting the
measurements right give us a call on the tech line send us an email get a hold of us on social media
you know any of the normal ways. And otherwise other than that have a good one and #goDRIVEit!