rear tow points

[.]

I am hoping to add two rear tow points to my 240z in preparation for Bathurst in Easter.

 

The only point which I can see it is practical to attach the tow point is to remove the rear bumper and bolt the bumper over the top.

 

I am thinking of some rather thick flat steel plate with some reinforcing to stop it bending. Extending the plate about 50 - 75 mm below the bumper and then bolting a thick U shaped shackel on to the plate at right angles to the plate (pointing back away from the car). I am also planning to weld another U on the bottom of the plate pointing to the ground for securing the car while being towed.

 

1. How thick should the plate be (7.5 mm?)

2. Are there any better suggestions? (Photos would be great) 

[stevo_gj]

Greg is it something like the picture I posted? I can't speak from experience but I can calculate the effectiveness of certain sizes if you want.

 

Could you give me approximate dimensions for the red circled bits? I'm assuming its welded on the top.

 

In terms of working out the maximum forces. What would be the fastest the towing vehicle would accelerate?

[stevo_gj]

Could you draw it in paint for me? Having trouble getting my head around what you're saying.

 

Also, regarding the sharp braking, I need to know what speeds we're talking for a worst case scenario, so I can work out deceleration/acceleration and therefore a force. (I'll use a safety factor of 3) If you could give me a speed in km/h and a distance to come to a stop this would work as well.

[Zedman240®]

I've been thinking about installing some tow points because I have to (MSCA Sprints) but have been told to avoid using the bumper mounts. If the car is stuck say in deep soft ground, the force needed to pull the car out would pull the rear panel away from the rest of the body. It's only spot welded so it can't take too much force from there. I've been toying with the idea of installing some u-bolts or similar on the suspension which is the safest place especialy on a soft body like the zed. I've noticed alot of older open wheel race cars have towing points on the suspension arms. Better bending suspension parts than pulling apart a unibody shell. Theres a youtube video of a 4WD pulling out a small car stuck on snow and ripping off the whole rear section!

[PZG302]

Greg, have a look at what others have done re the rear tow hooks. What you propose is pretty good but I wouldn't worry about the horizontal piece, just bend the bar out to about 45 degrees.

 

I can't really help as I don't run a rear bar, but I use a flat bar that has two holes lining up with the original bar mounts and then bent outwards to about 30-45 degrees with a 40mm hole. This has successfully pulled me out of many sand traps and other situations, including pulling the car on three wheels about 100m at Oran Park when the right rear corner was ripped off the car.

 

As for towing the car on a trailer, my preference is to attach the car to the trailer through the wheels, ie use a ratchet strap, mine are rated at 2000 and 4000kg and fed through the wheels so the car can move about on it's suspension. Seems to put a lot less strain on the trailer and the car. Even better is if you can get a hold of the straps towies use where they just go over the wheels and tie onto the deck, less strain all round. Also remember to keep the car in neutral, and if you have a handbrake it's up to you if you put it on or not. My car is towed out of gear, no handbrake, because it doesn't have one, and tied down at each corner using the wheels.

[garvice]

My 2+2 has stock rear tow points exactly where you are talking about Greg.

If I had my car here I would take a photo for you. Will try and find a picture in my files for you.

 

Brad

 

EDIT:

You can see them a bit in these photos.

You can just see the profile in these pictures

 

Let me know if you need better photos and I will get my mate to take a photo of mine.

[ZED660]

Maybe something like this which seems to bolt to the rear tow points.

 

http://www.zccjdm.com/catalog.php/azcarbum/ct/pd1761636/240Z_SCCA_LEGAL_2__FRONT__REAR_TOW_BRACKET_KIT_

[garvice]

Maybe I can run a rod (in addition to everything already discussed) from the plate down under the fuel tank onto some solid structure.

 

That might end up like a spear into what or whoever runs into the back of you (not that you want someone running into the back of you).

 

Not sure how different the rear bumpers are from a 240z to a 260z 2+2, but mine has been towed quite a few times from them. Generally they hook onto both mounts to get it onto a flatbed. Never been pulled out of sand though like PZG302.

[garvice]

Fair enough. Would it still work under tension then? or would it try and push the tank into the car? I guess that all depends how strong you make it.

 

I still think if the tow mounts are good enough for the factory then they would have to be good enough for what you need. If you do get stuck in something that you think will put strain on the bumper mount, then just tow it from the diff. Then use your new mounts for general towing/lifting onto trailer.

[sco_aus]

Just a thought, but maybe see what CAMS recommends too, they are anal, so it may pay to make sure it complies.  Not at all saying none of the above does, just a suggestion. 

 

[twosixty]

If you have seen a tow bar for a 240z or 260z what I am describing is like the bar that runs under the tank. I am not sure what it bolts onto though. Can anyone answer that?

Because it would have a bend following the contour of the tank it would fold in if hit from behind.

 

From memory (and this was a few years ago), when I removed the towbar on mine the single bar that run under the fuel tank made a close to 90 degree bend, with two bars in a v shape attatched with bolted plates (maybe 75mm square) to the an area near the spare wheel well. Less than ideal design as far as the 90 degree bend, but pretty beefy bar to accomodate.

 

[NZeder]

Have you thought about using 3" seat belt webbing? A number of zed here in NZ are using this type of setup. The good thing is that you bolt it to the front bump iron and tuck it behind the bumper (not seen) when needed it is just a matter of lifting the loop from behind the bumper to in front of the bumper. Simple neat and strong. We get the from a local race belt manufacture/supplier in Wellington. I can get a pic for you guys in the weekend when I am at the track with the BRE car (that is a BRE tribute car).

 

I know this is for the front setup but the same could be done on the rear (the BRE does not run a rear bumper so it just has an exhaust loop bracket on one of the factory bumper mounts)

[sco_aus]

CAMS has been considering making front tow points be only soft material, getting rid of anything sharp and solid, ie most peoples current tow points.  It would be replaced with basically as NZeder has mentioned above.  The problem being, any custom seat belt/snatch strap type material would have to be re sewn to fit and then wouldnt be compliant.

[PZG302]

Greg,

 

Don't need to over complicate things. A simple piece of flat 3-5mm thick sheet cut to shape will do fine. As I said my tow hooks are bolted to the original bumper mount for the rear and bolted to the forward rail where it joins the radiator support for the front.

 

As NZedder also put up a piece of 3" seat belt webbing will also work.

 

Come out to Lakeside on March 1 for the MX5 club track day and have a look at what the 2B and 2F prod sports cars are running for tow hooks.

 

At this stage I will be running the Z if I can get the bottom end rebuild done in time, so you can see how basic my tow hooks are and they have been used to pull me out of plenty of sand traps no worries.

 

In fact the only time a tow hook has been damaged was by a tow truck driver when the car was moved from one workshop to another without my knowledge and I wasn't there to supervise to tell him where to put the straps to keep the car on the tilt tray.

[Scando]

You can sort of see mine in this photo:

http://www.viczcar.com/gallery/displayimage.php?album=random&cat=10399&pos=-2620

 

It's similar to what you have in mind.  Just a flat piece of metal bent at 90 degrees with a loop welded to it.

[NZeder]

If you look close on the left bumper iron you will see some red - that is the 3" towing loop I was talking about

 

Here are some example of these type of towing eyes/loops

http://www.tracksidetim.com/dspitem.asp?CatID=37&SubCatID=63#TOW-TLA

[Zedman240®]

This thread has given me a few good ideas.. seatbelt webbing attatched to the suspension and just tied to the rear out of the way till you need it.. sounds good to me. Same for the front.

[BenZed]

I just got some generic tow loops from Revolution racegear. The rear one I bent and fitted to the bumper bolt, with a piece of plate to stop it bending and hitting the bumper when towed. At the front I just extended it with a bit of plate steel so it could move around a bit, but if I get towed out of a sand-trap from the front my spoiler will probably get ripped off anyway  :-\

[PZG302]

Greg, don't forget to paint the tow hooks red so they can found when you're stuck in the sand from going to fast....