Building a Mustang Rotisserie

Disclaimer

Notice. The author is not a structural engineer. The author is not liable for any damage resulting to your car if the plans on this page are used and the device is used to suspend your car.
Caveat Emptor.
This page is for entertainment use only.
Your mileage may vary.
My spelling may too.

The Original Rotisserie

While at a local car show, a friend asked what was going on with the Shelby restoration. I replied that while I was tackling certain sections on the 65 Restomod (Raven) project I was trying to finish the same section on the Shelby. For instance, I was busy taking paint and grundge off of the Raven's undercarriage getting it ready for paint. At the same time I had the Shelby up in the air next to the Raven finishing off its floors too.
My friend then offered to lend me his rotisserie, frankly because he actually wanted to see the Shelby back on the road. Ok, so do I, but there have been other matters...
So I took the truck over to his place and loaded up the rotisseries.

This little adventure ended up with me doing a full blown 100 point floor restoration on the Shelby. The welded in replacement floors were not done to my liking. I ground down the welds, added more weld, more grind, etc until the bottom of the car looked factory stock.
Of course, this took over 4 months to complete, but the floors are gorgeous. Here are some pictures of the Shelby on the first rotisserie.
(Click on any picture to see a much larger image in a new window)


Old rotisserie Front	Old rotisserie Rear	Shelby Floor

Shortcomings of the Original

The original rotisserie had some notable shortcomings:

It was huge and impossible to store. You'll notice the rust on the rear section because this thing had to be stored outdoors
It was heavy and required a truck to move.
Although it was made up of 4 x .18 square rectangular tubing it swayed like a drunken sailor. The lack of gussets at the intersection of the horizontal and vertical members caused this.
The rear plate was built to handle 67-70 cars (more on that below)
It was difficult to get a car up to the 48" high level required. Yes, you can use a cherry picker, but if you look at the first Shelby pic above you'll notice there is little room left over in the 24x24 area the Shelby sits in. Do you have enough room in your garage?
This unit had an incorrect front offset. The front bumper bolts on Mustangs are not at the same height as the rear bumper bolts. Take a look at your bumper bracket and see the 's' shape it has. If the support tubes on which the rotisserie rotates are not parallel to the floor AND if the tubes of the rotisserie bolt-on brackets are not parallel to the sill plates of the car, then the rotisserie will tend to squirm or walk when the car is rotated. Now that is scary!

The New Rotisserie

While down at the metal yard, the salesman showed me 'receiver hitch' material. The receiver section is 2.5x.25 thick rectangular tubing. The hitch section is 2x.18. My idea was to use the smaller sections for the towers and 'feet extensions' and use the bigger material for the base and the vertical slider. Although this is much smaller than the original, I had plans to stabilize the tower by using tension rods on the sides (as viewed from the front or rear of the car) and a large gusset on the other (as viewed from the car's side). As it turns out, the hydraulic rams used to raise and lower the vertical slider acts as another gusset (on the car's side).

All right already, what does it look like?

Here are a few shots of the new rotisserie in use.
All thumbnails, when clicked, will show up in a new window.
And, any hyperlink to a picture will also show up in a new window.


1) End View	2) End View at an angle	3) Looking toward front stand

The Plans

Below are links to the plans. I've also number them so that later, as we explore the details, you can reference them.

The Details

Now that you've seen the overall picture of the rotisserie and the plans, let's get into some of the details.

The main support post

Using the dimensions supplied in Plan 1, cut the main support tube to length. The main vertical tube is 2.00 stock. Drill the hole that holds up the slider such that the slider's mid-point would be at 48". Be sure to take into account the 2.5" cross tube the main support sits on. In other words, place the hole at 48 - 2.5 - 6 or 39.5" from the bottom.

The picture at left (click to enlarge in new window) shows where the 48" mark ends up. It also shows how the 7/16x3.75" bolt holds up the slider as well as providing a location for the turnbuckles on the side guy supports.
Drill both posts.
Cut the lower tubes to length as well. The lower tubes are of 2.5 stock so the cross and front legs can slide into or through them.
Drill the holes for the nuts that will hold the lower bottom cross-leg in position. Cut the 2.5 tube for the fore/aft supports and drill holes for small leg too.
Tack weld the vertical tube to the bottom cross-leg tube (at its center). Tack weld the fore/aft support tube. From scrap 2" tube create and tack weld the 45 deg support tube.
The end result should look like the picture at left (click to enlarge in new window)

less the side pieces for the ram. We deal with the ram in another section.

The bottom cross-leg and fore/aft support leg

The cross leg has 4 holes in it. Refer to Plan 1. Two of the holes face away from the car and are near the end of the leg. By placing the nut inside the tube you can determine where to place the nuts so that you can still weld them to the tube. I placed mine 1.25" inches from the end. The nuts are to hold 1.25" shoulder bolts that are used as the anchor for the rear guy or tension 'wires' at the rear of the unit. I discuss the tension guy wire later. Just remember than since you have two bolts being threaded into the cross-tube very near each other that you must offset them from each other so they don't contact as you screw the bolts inward.
The bottom of the legs, since they are .25 higher than the floor (because they run through the tubes with a wall thickness of .25), needs to have some leveling pads. I create leveling pads by placing a captive nut inside the tube and using a bolt as the leveling pad. I grind down the head of the bolts so that when fully screwed in they are no more than 1/4" thick.
The cross leg has two leveling pads; the fore/aft leg has only one. Weld all the nuts in place.

The Slider

The slider is made up of round and square tubing, as seen here.

The slider itself is 2.5" tubing with two 1/2 holes in it at the end facing away from the car. Although the through bolt (mentioned above) holds up the slider, we do not want to let the slider move in relation to the post. Drill two 1/2" holes in the back of the tube for the weld-on nuts. On the opposite side of the tube at the 6" mark and centered on the tube, drill and tap a hole for 3/8x11" threaded rod. Weld the rod to the center post. Don't let the rod screw further than .25 inches in (you should not see it on the inside of the tube.)
Cut a length of small round pipe and drill a 1/2" hole through it half-way down its length. Place the hole so that its oriented with the lengthwise direction of the slider.
Weld the tube concentric to the threaded rod.
Weld all the nuts in place.

Rear frame bracket

At this point I found it useful to have at least post/slider unit completed. This way I could use it to hold up either one of the frame brackets as I built them.

Referring to Plan 4, cut the square tubing to length. At the center of the tubing's length, drill a 7/16 hole through both walls of the tube. The threaded rod on the slider goes through this hole. The round 1.875 gets welded concentric to this hole.
At the end of the square tube fit one of the drilled angle iron plates to the tube. Clamp in place and test fit on the car. Make sure you can get a bolt into the recess before welding the plate on.
Refer to the picture at left. After you have fitted one end tack in place and using one of your completed slider/post units hold in place and fit the other end.
Weld the angle plated to the tubing.

Front frame bracket

The front frame bracket is most difficult piece to weld. Plan 5 shows the parts. All parts must be square to each other (at 90 deg).
I would first cut the small horizontal tube, to which the round tube is welded. At the horizontal tubes mid-point, drill a 7/16 hole through both walls of the tube. Place and weld the round tube concentric to the hole. The slider's threaded rod goes through this hole.
I would next prepare the forks which bolt up to the car at the bumper brackets. Drill the holes to match those in the car and make sure the holes line up correctly. Drill the holes larger than the bolt holes.
Weld the side forks to lower horizontal tube.
Stand two of the small vertical posts up (center the posts to the lower horizontal tube). Magnetic holders work well here. Make sure you are square in all directions. Make sure the top horizontal tube also fits.
Weld the unit together.
It is better to be a little wide when placing the forks. You can always slide in a shim between the forks and the frame. If the distance is too narrow, then of course it won't fit. Measure your car's width to make sure it fits the drawing. Production tolerances vary greatly.

Ram fitment

Plan 6 outlines fitting the ram.
Because tolerences on the offshore units is bad (I had to return one because of misdrilled clevis hole) I suggest you assemble the entire unit first. Starting with the ram in its lowest postion assemble some pre-drilled side plates (.25 flat stock) for the bottom and top. My ram used 1/2 bolts for both the top and the bottom holes.
After you verified the unit goes up and down with hitting anything, tack weld the plates.
Finish welding off with rams removed.

Side Guy supports

Procure a 48 inch long 3/8 threaded rod. Using a rod coupler, attach an open hook to one end (See pics below). Weld the coupler in place. On the other end thread the rod into the turnbuckle.
The welded double nut is used to provide a wrench point when tightening down the guys.

Bring the assembly up to the tower, with at least the back leg inserted into the tower. Make sure the back leg is centered (use a tape measure). Insert bolts into the rearward facing guy support holes.
Put a 7/16 bolt into the eye end of the turnbuckle with the hook end toward the floor. Insert this bolt into the tower 6" under the 48" mark (you made this hole in a previous step -- it holds the slider in place).

Bring the hook end over and attempt to hook it onto the bolt. The turnbuckle should allow you enough adjustment to make it over the bolt and to make the guy tight. Adjust by removing some length off of the threaded rod.
You need to build two guy supports for each tower. The end result looks like this

Tips on welding nuts to the parts

For nuts welded inside of the tube, start by determining the position of the nuts.
Naturally, there needs to be holes in the tube prior to welding the nuts. First, I use a drill press to drill holes slightly larger than the bolt size. I then place the nut inside the tube and screw in a short, fully threaded bolt from the other side. Tighten the screw, which will hold the nut tightly to the inside. Weld as much of the nut to the tube as possible.
For the large 1/2 nuts, I simply thread in a bolt and drop the bolt into the hole. This centers the nut properly around the hole. Use a vice-grip on top of the bolt to hold the nut firmly in place when welding.

Using the Rotisserie

Dissassemble the car...sounds strange, but the rotisserie cannot handle the loads imposed by the weight of an assembled car. This unit is meant to support a totally stripped Mustang shell.
As you recall this site is for entertainment only and you will certainly not be entertained if the car crashes to the floor after you attempt to use this device on a fully assembled car.

Slide the through leg into the tower. Measure from each side to ensure the leg is center in the tower, left-to-right. Make sure the adjustment feet or bolts point down and that the guy support holes face away from the car. Slide the small leg such that it points to the car.
Tighten the 4 bolts in the tower to hold the legs in place.

Find suitable bolts for the front and rear brackets. I would use hardened bolts.
The front bolts should have large washers where they go through the forks.

At the rear use 1/2 bolts with large fender washers inside the trunk.

Once the brackets are attached to the car, simply pull the slider up to meet the bracket and push the rotisserie towers toward the bracket. Make sure the 3/8 rod goes through the brackets and attach a nut. Do NOT tighten the nut. It should be at least 1/2 inch from the bracket, as it is only a safety.

Tighten the two bolt keeps the car from rotating. If you do not it is possible for the car to tip over at an in-opportune time causing major damage.

Put both rams in place. If you are alone, pump up each ram no more than 10 strokes before moving to the other end.
Once the entire car is being held by the rotisserie, adjust the levelers so that all six points contact the concrete.
Continue lifting until the through bolt on the tower is visible under the slider.
Insert the 7/16 bolt through two of the turnbuckle eyes and splay the guys outward. Lower the ram so that slider now contacts the through-bolt.
This rotisserie is meant to be small and compact, therefore the side 'guy wires' are required.
Loop the bottom hook over the lower leg's guy support bolt. Screw in the turnbcukle until one side is taught. Do the other side, and tighten it down securely. Both guys should have a pronounced twang if hit with screwdriver (like a guitar string). After the bolt and guys are in place, the assembly should look like the picture under Side Guy Supports, above. Screw in the bolts on the end of the slider. This keeps the slider from moving on the tower.

Make sure there are no loose item in the car prior to rotating! A hammer on the floor will cause roof damage as the car rotates.
You can now unscrew the bolts that keep the car from rotating and move it into the desired position. Be sure to screw them back down prior to working on the car. Be careful! A rotating car still has a great deal of mass and inertia. Go slow and steady.

Do not remove the rams when working on the car. They are the fore/aft gussets and should remain in place (and pumped up against the 'stops') at all times.

To lower the car, make sure the car is level and the bolts that keep the car from rotating are secure.
Undo the bolts on the back of the slider. Release tension on the guy supports and remove the through-bolt. If alone, let the car down no more than a few inches, then do the same to the other end. Continue until it's down onto the jackstands.

A coat of paint will make your Rotisserie last longer and look better.

Other pictures


1) Rotisserie Up	2) Rotisserie Down	3) Clearance (12")