Towing the ZR1

[Dynomite]

Towing the ZR-1.

Emergency Kit.....15 ft tow rope (5,000 lb vehicle rating), Jumper Cables, Tow Adapter, Lug Wrench
https://cimg4.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/900x900-1/80-b2528f90_9e7e_4b76_9340_cdeadcd1e960_99c412d74b4e5 ab1734766a00a85d72920b39d74.jpg

Daniel_Mc provided a concept/photo of a Tow Adapter for a ZR-1 that in its simplicity I just could not pass up :thumbs:
So......I designed one after the photo provided by Daniel_Mc and had a local steel shop fabricate the Tow Adapter.
I did some towing tests to see if there are any issues or limitations. One limitation will be towing at an angle in a turn which this adapter without being bolted on the back side of the cross member will not function (that did not seem to be an issue during the tow tests). The Tow Adapter is made from 1/8 inch steel plate which is substantial and flexible enough to tow the ZR-1 with Nylon Tow Ropes having a steel hook on one end.

https://cimg5.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/350x400-1/80-da9e6436_f183_4b3a_bff6_9f997d908d58_795ed0e07894d fb5b72843fcc89f64b846f7353a.jpghttps://cimg6.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/350x400-1/80-7eb15f73_53c4_414c_a342_736b38857678_cb9248a7a36c0 bf76dd79a178b4018b8d4853830.jpg

The Tow Adapter is made to engage the 1-1/4 inch square tubing of the frame support under the front of the ZR-1.
https://cimg7.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/900x900-1/80-90f6e3a5_15f7_4070_baf7_ae6b081337aa_ba93afd0fa285 89b9353f59fe7200db7a73484cb.jpghttps://cimg8.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/350x400-1/80-7973a366_cc53_49aa_b12c_2ef395aa62dd_1417d30ba1415 2479c3aa87bb703395b99fea9b8.jpg

A. Tow Adapter Description.

When needed for towing, the Tow Adapter is slipped through a 4 inch x 1/8 inch slot in the front Air Spoiler. There are two 1/2 inch holes (not shown in photos) in the Tow Adapter plate (one for 90' and one for 91') depending on which model year you use the Tow Adapter. 1/4 inch Allen Head Bolts are inserted into one hole or other with large Pan Head Washers on each side (and adjusted snug against the Air Spoiler. The 1/4 inch Allen Head bolt keeps the Tow Adapter in place if you want to keep it installed as you drive.
https://cimg9.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/350x400-1/80-c821de2e_f70d_44e2_ad47_671922bb8040_cfa261e3e0180 7b2365d65b13be5c1ffdf8e2840.jpghttps://cimg0.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/350x400-1/80-e47b5e12_a27b_4028_a33f_947aed7baba3_17cb143f1a49c c584ac1e1da67d0d35559ec9e12.jpg

The best tool to make the 4 inch x 1/8 inch slot in the front Air Spoiler is an Angle Grinder (with Cut Off wheel).
The Tow Adapter sticks out beyond the skirt about 4 inches on a 91' and about 6 inches on a 90'.

https://cimg1.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/350x400-1/80-8ddc4dc6_297b_40b9_a1a9_12d5ca7baf00_c229f2b1e4578 739ff75c649bef3a9fb2cb67502.jpghttps://cimg2.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/350x400-1/80-fbc895f3_f33b_4cd0_90cd_00eece184c88_b1577fe18f38c 17196c205f711fb418a7ecc9d8c.jpg

A nylon tow rope (a steel hook on the end is required) can be attached to the receiver in the Tow Adapter (2 inch x 2-1/2 inch hole).

B. Installing the Tow Adapter.

The Tow Adapter is simply installed by reaching under the Air Spoiler and inserting the front tip of the Tow Adapter into the slot in the Air Spoiler. Push forward and then lightly tap the rear of the Tow Adapter onto the cross member with a small hammer. The Tow Adapter is removed by lightly tapping on the front tip of the Tow Adapter with a small hammer.

[Dynomite]

C. Testing Tow Adapter.

The Tow Adapter was tested towing the 91' ZR-1 with a lawn tractor on gravel. A small nylon sling was used for towing. The Tow Adapter was NOT bolted to the frame in any way.

https://cimg4.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/350x400-1/80-49089722_2f9e_43b5_85fa_946a8ef1e888_45823cc6ff8af 1e0e7f9445206d30fa87d313265.jpghttps://cimg6.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/350x400-1/80-1c6c7f9c_d3b7_44e7_8a03_c938c69b61ff_0399fedaf15e8 9c9290b5b65342ff96d13d3eca8.jpg

When towing at an angle of 45 degrees the front wheels were turned in the direction of towing. With a lawn tractor and the use of this Tow Adapter, the ZR-1 could be backed into the street and with a lawn tractor pulled and then releasing the clutch in second gear starting the engine if your battery is dead. There was no deformation of the Tow Adapter during these tests :thumbs:

Towing in a straight line............................................To wing at an angle of 45 degrees.
https://cimg9.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/350x400-1/80-4cf73557_f6df_4af1_8a4b_8f63200720ee_04733d9a62948 694a15cf9d4ca047608c5e90ae1.jpghttps://cimg0.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/350x400-1/80-22bda23a_d691_46a4_88d5_9d73a7494648_eccf9a69d45af c22f94681f1eb0dcd5119712cba.jpg

D. Storing Tow Adapter.

I have elected to carry the tow adapter on the right side of the passenger seat where it fits perfectly with my Gorilla Lug Wrench. I have found with the tow adapter installed it is easy to hit it with a curb when parking. It is very easy to slip in place if needed without jacking the vehicle.

Tow Adapter Stored next to Passenger Seat......................Gorilla Lug Wrench
https://cimg1.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/350x400-1/80-9ae87dfa_2dae_42e4_9b5e_a50a983afdc1_de393a2632476 c3c09d2b77adb28d30c84862568.jpghttps://cimg2.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/350x400-1/80-b3b240d1_9a9a_4c0c_ae03_26d3ecfc7857_826f9d4f28ed2 12459ff6f2ec58c98625a82bb07.jpg

[garyhugo]

Is the tow adapter available to purchase? Is the cross member it attaches to strong enough to be pulled onto a flatbed? I've often worried about what I would do if my ZR-1 had to be put on a flatbed.

[Dynomite]

Is the tow adapter available to purchase? Is the cross member it attaches to strong enough to be pulled onto a flatbed? I've often worried about what I would do if my ZR-1 had to be put on a flatbed.

The weak link is probably the eye of the tow adapter with .25 square inches of steel (the area of the two 1" x 1/8" sides). A36 steel would have a yield of 36,000 lbs and if we assume 50% for safety the yield would be 4,500 lbs or 1.5 times the total weight of the ZR1 The tow adapter is designed to spread the load over a 6' width of the two 1-1/4" box section cross members creating a tensile load on the box section longitudinal stiffeners (1-1/4" x maybe 1/16" thick steel) or and area of .625 square inches of steel or at 50% of 36,000 psi would be a load of 11,000 lbs. But....we do not know the condition of the butt welds.....

I will look at the structure a bit today but the real truth would be a tensile test with the hook used applying a load on the ZR-1 equivelant to the weight of the ZR1 on the slope ramp (I would need to assume a ramp slope angle).
For example if the ramp was vertical or 100% slope the load would be 3,500 lbs or the approximate weight of the ZR1 :thumbsup:

But again......I would want to test the Tow Adapter with a proof load which I did in the pictures above pulling the ZR1 on a level gravel road with my Craftsman :thumbsup:

The other failure mode of the adapter would be the bending of the 6" wide flange which in fact might be the ultimate failure mode.

I coiuld do the test you are looking for by pulling the ZR1 onto my trailer using my truck but the issue would be undercarriage clearance of the ZR1 which would prevent pulling the ZR1 onto a trailer without backing the trailer up to a area of higher ground limiting the need for a steep angle of the ramps. Or....just use longer ramps.

Having said all this.......some guys and gals call a tow truck when their starter fails to energize because of bad contacts in the starter. When in fact all you have to do is push the clutch in and in second gear with key on have two guys push the Z by hand and you pop the clutch :cheers::cheers:

[garyhugo]

Thank you for all your thought on this subject. It does seem iffy to use the tow adapter to load the ZR-1 onto a flatbed truck. So, do you have any good ideas on how this could be done in an emergency? Maybe someone on the forum has some experience doing this. Thanks again Cliff.

[garyhugo]

I have had the car push started successfully. Would like a plan for a really bad day.

[Dynomite]

Thank you for all your thought on this subject. It does seem iffy to use the tow adapter to load the ZR-1 onto a flatbed truck. So, do you have any good ideas on how this could be done in an emergency? Maybe someone on the forum has some experience doing this. Thanks again Cliff.

You cannot push against the rear of the ZR1 or pull on the front without the tow adapter. You can then use a winch or long cable over the front of the trailer pulling with a vehicle along side the vehicle attached to the trailer. That would be easier if you parked the trsiler in a sharp turn so you vould pull straight ahead with the tow vehicle.

I know there have been some guys and gals that have called a service to move their ZR1......It would be interesting how the service hooked up to the ZR1......:cheers:

[Dynomite]

I have had the car push started successfully. Would like a plan for a really bad day.



Push started manually by hand pushing or with a vehicle....If vehicle, what did they push against?


Sent from my iPhone using ZR-1 Net Registry (http://r.tapatalk.com/byo?rid=90383)

[Mikey]

I don?t understand this. Why not just use the tow hole provision in the frame rail on either side of the car? That?s where I hook my winch into when pulling onto a trailer.

[Dynomite]

I don?t understand this. Why not just use the tow hole provision in the frame rail on either side of the car? That?s where I hook my winch into when pulling onto a trailer.

Never heard of two tow hole provisions on the C4 ZR1 before.....;)

[garyhugo]

Pushed by hand in a parking lot.
My concern is tow truck driver showing up and neither of us know how to get it on the truck without damage.

[conesare2seconds]

There are factory tie down points on all four corners of the C4. A little hard to reach when the car is on the ground but doable once you know where they are.