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2 posters

GearVendors install


Number of posts : 54
Location : San Francisco, CA
Registration date : 2016-01-18

GearVendors install Empty GearVendors install

Post by Brandon2 Fri Jan 18, 2019 1:10 am

Hi all,

Wanted to post my experience installing a GearVendors overdrive on my 69 A108 with a 318 engine and 727 transmission.  I did this last summer, but have been lagging in getting around to posting...

First, the tools you need and I have, but that you may need to borrow:
- Welder: I use oxy-acetelene, but any should do
- Angle iron bender: You could use a rosebud torch here if you're desperate

More common tools:
- Disc grinder to cut and adjust the angle iron
- Drill press or hand drill

The only other thing you'll need is a marker for the metal, some nuts and bolts, and patience.

So first, I ordered the kit from GearVendors.  When I got them on the phone, they told me these things bolt right up in an afternoon  Very Happy  Very Happy

These units are pricey, and run $3k included shipping.  Took about a week from when I ordered it until it showed up.

Now taking a step back, the GearVendors kit comes in two parts.  The first is an adapter shaft which replaces your tail shaft:

GearVendors install Img_8817

One end fits the specific car, and the other end mounts to the main GearVendors drive.  The second part is the GearVendors drive.  This way they can produce a single main drive, but produce a tail shaft adapter for all the different cars separately.  They have two 727 versions, one for either a short or long tail shaft.  You'll want the short tail shaft.

When I told them the van I had, they said, "Well you have the one config that doesn't bolt right up".  Bottom line is that the 727 kits work with all 727's, "except" the hanging mount we have on these vans, because their adapter shaft has the mount on the bottom like all other 727's.

So I ordered the short kit, knowing that I'd have to fabricate a new crossmember.

While waiting for the kit to show up (which took about a week), I did some prep work.

First I used an angle finder to take measurements of the U-joints and driveshaft so that I could match the original angles.  You'll want to grab the angle of the tailshaft, front of the driveshaft, rear or the driveshaft, and the rear axle.

GearVendors install Img_8816

To instruct building the new crossmember, I took some measurements including it's distance from the ground, distance relative to the crossbar, and angle relative to the crossbar.

I also measured the width of the tailshaft, and wondered if I could re-purpose the existing mount.  The mount is attached with four bolts:

GearVendors install Img_8511

(see more details in

I decided to just unbolt the mount.  With the bolts off, the mount was still attached.  There is something that's holding the mount in place independent of those bolts, because not only does it not pull off, but I banged that thing around countless times with no movement.  This provided the benefit of being able to use the edges of the existing mount for stability and strength.  It also allowed me to keep the hanger up by friction -- which made sizing the brackets and bolting things together easier later.

So my strategy for the new hanger was to fabricate something like this:

GearVendors install Img_9210

Put a truck mount from Imperial Services (IS-140) on the base, and use the existing mounting bolt holes to attach the whole thing to the crossmember.

It's important to note that you need the transmission isolated from the frame by rubber for flex while driving.  In the stock configuration, the rubber between the big bolt going through the mount provides that isolation.  In the new config, the rubber of the truck base from Imperial Services provides it.

Now to get the existing tailshaft off, I jacked up the transmission, and then started to take apart the back of the transmission.  This consisted of:
- Removing the driveshaft
- Removing the truck style u-joint plate off the tailshaft
- Draining the transmission fluid
- Taking out the speedometer gear
- Unbolting the tailshaft
- Removing the large hanger bolt where the tail shaft hangs off the crossbar

Here's what it looked like at this point (sorry about the bad camera angle):

GearVendors install Img_e810

I then pulled off the tail shaft which quickly hit the crossmember, and lowered the tail shaft with the jack (which drops your transmission down lower than anyone would want) until the tail shaft could clear the crossmember.  Once I got the tailshaft off, I returned the transmission to it's original position.

Back to the hanger:

GearVendors install Img_9210

The idea is to weld the horizontal bottom to the vertical pieces, attach the vertical pieces to the brackets with bolts and serrated lock nuts (I considered welding the brackets for strength -- but quickly realized I would never be able to get the mount on/off if I did that), and bolt the brackets to the existing mounting bolt holes.

The hanger is made of:

1 x 12" long 2-1/2" x 1-1/2" angle iron, 3/16" thick (for the horizontal piece)
2 x 10" 1-1/4" angle iron, 3/16" (for the vertical pieces)
4 x 1-1/4" angle iron, 1/8" thick (for the brackets)

I started the vertical pieces at 12" and I made the brackets later to fit by hand.

I bent both vertical pieces at 1-1/2" up from the bottom and bent them to a 14 degree angle to match the existing crossmember/tailshaft angle.  I then welded everything together.

GearVendors install Img_9411

GearVendors install Img_9410

To get the height of the vertical pieces right, I bent a piece of sheet metal like a C, drilled a hole through it to match the large hanger bolt, and then derived this crafty setup to check the measurements I made on the car from the crossmember:

GearVendors install Img_9311

It came out to a 10" vertical height (after the bend), so I cut the vertical pieces down.  I then pushed this up under the van and it fit perfectly on the outside of the hanger mount.  I took some measurements between the vertical bars and the 4 bolts on the hanger mount and went back to fabricate "connectors".

Here's what they look like:

GearVendors install Img_0410

Mine measured 1-1/2" on the short side by ~2-1/2" along the crossmember.  I upgraded the flat bar pictured to angle iron for extra strength, bent it 90 degrees, and drilled it.

Here's the final product...

GearVendors install Img_9412

GearVendors install Img_9413

I put the new GearVendors tail shaft on.

Then I loose mounted the brackets to the hanger mount first, then bolted the brackets into the original transmission mount using 1/4" longer bolts to account for the angle iron thickness. It's worth calling out here that the original bolts were SAE 6 (which existed at one time), so I replaced them and all the bolts I used with SAE 8

Once those were tight, I tightened down the nuts and bolts attaching the brackets to the mounts.

Now I'm specifically leaving out the 17 times I had to take things on and off to measure, cut, etc..  so if anyone actually tries to do this themselves, hopefully you'll spend less time after reading this, but don't feel bad about it.

Once I had the hanger lined up, I took the truck mount from imperial services:

GearVendors install Is-14010

and placed it centered on top of the horizontal base.  I drilled holes to line up with the outside holes of the mount.  I then attached the IS mount to the tailshaft, followed by attaching the IS mount to the horizontal base using nuts and bolts.  After all this, I lowered the transmission back down onto the new mount.

I then finished assembling the GearVendors unit.  This took several calls to their tech support because the manual had some misleading steps and was a bit out of date.  The tech guy I talked to (every time) was super helpful, and relayed that the new guy always gets to write the manual.  Smile  I hope to eventually get around to an updated post pointing out both the missing and un-needed steps from the manual.

Once I had it up, I pushed in the tail shaft and took measurements to the rear axle according to the book.

I took my original driveshaft to my local shop, and was told it would cost me about the same to build a new (much stronger) driveshaft as it would to shorten and balance my old one. He gave me a quote for both, and the price was so close, that I just had the new one made.

Got it back, and it fit great lengthwise, except I had one problem:

GearVendors install Bad-an10

To be continued...

Number of posts : 124
Location : Hayward, CA
Registration date : 2012-09-29

GearVendors install Empty Re: GearVendors install

Post by 68vanman Thu Mar 14, 2019 2:06 pm

Any updates as to what happened next? I have a 69 with a 318 automatic.

    Current date/time is Sun Jun 26, 2022 9:50 am