Spare tire swingaway for Greg Davis bumper?

squirt

Well-known member
Nov 13, 2008
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Los Angeles
I think the population running that bumper and a tire heavy enough to wreck a door is close to 0

If its still made like the picture then I don't see why it can't be done

Mine is not exactly like this - it seems the design has evolved to be smoother, but it may still be feasible. The biggest challenge is that it only sticks out at most 2 inches from the bodywork, so a top-mount hinge would risk interference. A surface-mount hinge on the face of the bumper would work better for the GD bumper.
 

Jeff Blake

Well-known member
May 6, 2016
429
16
Pacific Beach, San Diego
Here's a little mockup. The swing away could be made of 2x4 steel in 1/8 or 3/16 wall thickness, and also match the curvature of the GD bumper, like this:

\-----------/

The spindle might fit if welded to the corner of the swingaway...?, or, shorten the carrier arm so the spindle ends up where the corner of the 2x4 is in this picture
 
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robertf

Well-known member
Jan 22, 2006
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I think youre going to have a problem with it being on that side. The tire is roughly 7” offset from centerline. Switching sides I figure a rough approximation of about 1.5 the bending force applied to that spindle. Theres no room to bolt stuff so you have to weld leaving you with mild steel as your only choice and I wouldnt go thinner than 1.25 dia on the normal side. I dont think there is enough room for a spindle and hub on the drivers side that would be long term durable
 

Jeff Blake

Well-known member
May 6, 2016
429
16
Pacific Beach, San Diego
That's a mighty tight fit

There's plenty of space behind that body panel, so with a little trimming I think it can work - pending actual spindle dimensions, as opposed to toilet paper roll

I think youre going to have a problem with it being on that side. The tire is roughly 7? offset from centerline. Switching sides I figure a rough approximation of about 1.5 the bending force applied to that spindle. Theres no room to bolt stuff so you have to weld leaving you with mild steel as your only choice and I wouldnt go thinner than 1.25 dia on the normal side. I dont think there is enough room for a spindle and hub on the drivers side that would be long term durable

You might be right. The weight is much better handled with a spindle on the passenger side, no doubt about that. If I went with the driver side option, the latch would also need to take weight of the spindle when locked, I think, or a perfectly elevated 2x2" skid plate welded on

If the bumper is made of 2x4" steel, what's the max spindle base diameter? ~1.5"?

Here's a 1.5" spindle: https://www.amazon.com/AtoZ-Fabrication-Carrier-Hinge-Spindle/dp/B01K6JYWK8
 

robertf

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Jan 22, 2006
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Is the bumper made of 2x4 steel? It looks like its the same width as that lumber 2x4.
 

robertf

Well-known member
Jan 22, 2006
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356
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Here's what I'd do. cut the hole where it needs to be. Off center, through a weld, whatever. if you go through the inner wall no big deal, you have a 1.5" solid bar to patch it back up with, itll be sturdier than oem at that point. I would definitely plate the top and bottom. I don't know if the pieces are butt welded or not, but I'd assume the worst, and you need a bigger bearing surface anyway. I'd go with bushings instead of the bearing spindle. You'll never exceed 50 rpm so bearings are a waste of space that a bigger spindle diameter could fill.

I threw your bumper measurements in my model. I don't have a disco 2 so I assumed similarities on a D1. You're missing a couple dimensions to nail it down, but I eyeballed the photos to guess. I also assumed you are running the shittiest tire ever made in 36x12.5x16 on a d1 wheel

http://www.flemcodesign.com/files/gdbumper.pdf
 
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Jeff Blake

Well-known member
May 6, 2016
429
16
Pacific Beach, San Diego
Thanks robert! Looks great, thanks for taking the time to mock that up. It's on the wrong side though, ;)

I haven't seen a spindle with bushings as opposed to bearings. I'll keep looking around. The one I linked above has 2.25" OD on the sleeve, and I'm pretty sure it can fit with a minor cutout in the body panel.
 

Blue

Well-known member
Mar 26, 2004
10,043
856
AZ
Thanks robert! Looks great, thanks for taking the time to mock that up. It's on the wrong side though, ;)

I haven't seen a spindle with bushings as opposed to bearings. I'll keep looking around. The one I linked above has 2.25" OD on the sleeve, and I'm pretty sure it can fit with a minor cutout in the body panel.

But do you really want to hack up your truck? Or hack it up more?
 

Jeff Blake

Well-known member
May 6, 2016
429
16
Pacific Beach, San Diego
But do you really want to hack up your truck? Or hack it up more?

I don't mind. I need to do something about those missing plastic corner pieces anyway (other than getting plastic corner pieces). I've already done plenty of cutting... mantec snorkel, quarter panels, air fitting cutouts, roof holes, firewall is swiss cheese with all the wires...

I don't think 2" vs 2.25" OD is going to make the different either. I'll need ~9-10" of clearance above the hole for the spindle in order to fit the carrier.

The IPOR spindle is 2? od and uses bushings

I talked with the guys at A-Z Fab today, and they were pretty adamant about bearings. They used to do bushings, but the failure rate was really high.

A-Z isn't concerned with the tire load being on the opposite side. He says weight is not the issue, it's stabilizing the carrier from any movement. He recommends a heavy duty plastic pad to go on the latch side, where the arm will rest on when closed. He also said it's important to have something to prevent forward to back movement, (i.e. stopping the car fast)

For those reasons, I liked the concept of 4xinnovations hinge http://www.4xinnovations.com/Swing-Out-Tire-Carrier-Hinge-Assembly_p_109.html
As it has lock-pins for closed, 90 degree, and 130 degree open. But I don't like how it mounts to the face of the bumper, so it's out.

A-Z suggested 2x2x 1/8" wall steel for the carrier.
 

robertf

Well-known member
Jan 22, 2006
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I talked with the guys at A-Z Fab today, and they were pretty adamant about bearings. They used to do bushings, but the failure rate was really high.

A-Z isn't concerned with the tire load being on the opposite side. He says weight is not the issue, it's stabilizing the carrier from any movement. He recommends a heavy duty plastic pad to go on the latch side, where the arm will rest on when closed. He also said it's important to have something to prevent forward to back movement, (i.e. stopping the car fast)

For those reasons, I liked the concept of 4xinnovations hinge http://www.4xinnovations.com/Swing-O...bly_p_109.html
As it has lock-pins for closed, 90 degree, and 130 degree open. But I don't like how it mounts to the face of the bumper, so it's out.

A-Z suggested 2x2x 1/8" wall steel for the carrier.

I'm pretty adamant about not using bearings. Did they say what material or size bushings were failing? I don't believe a bronze bushing in the 1.25 and up shaft diameter is failing when holding up a 200lb tire 4' away

2x2 x 1/8" is probably fine. I went with 3 x 1.5, its slightly heavier but the deflection when open is around half. The extra half inch width adds no strength, only the vertical dimension is significant in this application.

They are right about stabilizing it. Thats one of the reasons I use the roller. When closed it deflects the beam upwards to pre load it, and the heim linkage is adjusted to compress the rubber bumper on the back to pre load it that way.

edit: Looked at their website. I see they have the spindle in double shear, thats how they are getting away with a spindle diameter small enough to trash bushings and not bend. theres no room for that on the top of the bumper
 
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Jeff Blake

Well-known member
May 6, 2016
429
16
Pacific Beach, San Diego
I think they were using bronze.. or was it brass? One of the B's.

My tire weighs in at 80lbs... what are you running, a tractor??

Anyway I haven't made much progress on this lately due to work.

I am still leaning towards the A-Z spindle, as its widely used, and I don't think 2.25" diameter will be an issue.

Next step is to order the hardware and drop by the welder to have a chat. Chuck ( https://www.yelp.com/biz_photos/d-and-c-q-welding-san-diego?select=0d0MRX2aC7fsZNKg6y0Slw ) has a cool outdoor shop by the beach and did the welding for the GD bumper. I want to have the parts in hand so he can better figure out what he wants to do.

I tried to source some 14x1.5 studs for the mount off Mcmaster, but no luck. But then I remembered I have two new wheel hubs sitting around, so I think I'll install one of those and use the old wheel hub for the mount... one less task for the welder.

For the clamp, I think I'll use a toggle clamp like fishEH.

Delrin pad for the carrier to rest on in the locked position
 

fishEH

Well-known member
Jan 26, 2009
6,927
201
Lake Villa, IL
Have your fabricator weld the tire mount at the same angle as the rear door. Not only will it look tight but it will move some of the tire weight back over the center of the carrier.
 

Blue

Well-known member
Mar 26, 2004
10,043
856
AZ
Do you think it makes a significant difference to mount the spare backwards (with the inside of the rim facing out) like Mercedes does on the G-wagon? It certainly makes sense because the weight of the rim's face is held further inboard. What's a Rover alloy rim weigh? About 30 or 40 lbs?
 

fishEH

Well-known member
Jan 26, 2009
6,927
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Lake Villa, IL
Do you think it makes a significant difference to mount the spare backwards (with the inside of the rim facing out) like Mercedes does on the G-wagon? It certainly makes sense because the weight of the rim's face is held further inboard. What's a Rover alloy rim weigh? About 30 or 40 lbs?
That doesn't make any sense.
 

Jeff Blake

Well-known member
May 6, 2016
429
16
Pacific Beach, San Diego
Have your fabricator weld the tire mount at the same angle as the rear door. Not only will it look tight but it will move some of the tire weight back over the center of the carrier.

Good idea, thanks

Alright did a better mockup. This tube is 8" long, 2.25" diameter. The actual outer hinge tube is 4" long, but I figured I'll need twice the vertical clearance to install it.

It's awfully tight... it *might* work if the 1.5" diameter spindle is welded to the inside face of the bumper, so that the outer tube is offset towards the face, as in the picture.

Or... do a little body trimming...

Or...?