Trailer build: Race car.

[MOSSIE.JHB]

Hi Guys

I am in the planning stages of a Trailer build to transport my race car to and from the Track.

so I got a bit stuck at the Axle placement part.....

I have read up and seen that the rule of thumb is to put the axel 40% of length of the deck from the back.

but this is where my problem comes in. The 40% rule is for Trailers that has the load spread out as even as possible over the whole Deck of the trailer to make sure you don’t end up with a trailer that has more weight behind the axel than in front of it and then this will promote a tail fishing trailer [IMG]file:///C:%5CUsers%5Cjmostert%5CAppData%5CLocal%5CTemp%5Cm sohtmlclip1%5C01%5Cclip_image001.gif[/IMG]

now the race car is stripped out and I am guessing that about 65%-70% of the weight of the car is in the noise.

Now the Datsun weighs in at about 720KG and if 70% of the weight is in the front of the car we sitting with +- 400KG of weight.

so if 60% of that is in front of the Axel we have +- 240KG on the Tow ball.

I hope my Maths have not gone all bonkers on me [IMG]file:///C:%5CUsers%5Cjmostert%5CAppData%5CLocal%5CTemp%5Cm sohtmlclip1%5C01%5Cclip_image002.gif[/IMG]

The ideal weight for the Tow ball is roughly 150KG so I don’t want to end up with a tow car that has it's back pushed on to the ground.

I also load 2 toolboxes, 4x rims and slicks and about 60L of race fuel on the back of the tow car.

This trailer will only be used for the race car so I want it optimized for the towing of that not a general setup.

so what do I do with the Axel?

Do I move it forward?

If I do move it forward how does one work out by how much?

the sizes I am working on is a 4M long trailer (the car is 3.8M bumper to bumper) and 1.8M wide.

thanks for the help, I will post some pics as soon as I start the building process.

mossie

[Chris Viljee]

I got this off the Internet a while ago. Hope it helps.

[Apocalypse]

the best thing to do is to load the trailer and measure the nose weight.

I used to just put some adjustment holes forward and backward of the central position so I could move the axle if needed. In addition, if it's dedicated for that car you can set the cars position with chocks and put it where needed on the trailer.

quite often you load the car with engine to the back and all the tool boxes etc at the front to keep some balance...

believe me, you do not want a nose heavy or light race car trailer.

start in the middle of the bed - the A frame will keep the nose weight on. don't forget that even something like a Porsche 911 only has 60% weight distribution, if your motor is between the axles you'll probably be on 55/45 at the worst for weight distribution. I can't think of any LMV that would have 70% of weight to the front.

build it, bolt in the axle, load it, the nose needs to weigh 50 to 100kg. If you can't lift it (with effort depending on your strength) it's too heavy - move the axle forward on the holes or move the car position. if it's light - move the axle back...

[Chris Viljee]

This is a spreadsheet to do all the calculations.
Sorry, the spreadsheet will not load

[Apocalypse]

Chris, the system will only load xls spread sheets, not 2010 sxls...

[MOSSIE.JHB]

the best thing to do is to load the trailer and measure the nose weight.

I used to just put some adjustment holes forward and backward of the central position so I could move the axle if needed. In addition, if it's dedicated for that car you can set the cars position with chocks and put it where needed on the trailer.

quite often you load the car with engine to the back and all the tool boxes etc at the front to keep some balance...

believe me, you do not want a nose heavy or light race car trailer.

start in the middle of the bed - the A frame will keep the nose weight on. don't forget that even something like a Porsche 911 only has 60% weight distribution, if your motor is between the axles you'll probably be on 55/45 at the worst for weight distribution. I can't think of any LMV that would have 70% of weight to the front.

build it, bolt in the axle, load it, the nose needs to weigh 50 to 100kg. If you can't lift it (with effort depending on your strength) it's too heavy - move the axle forward on the holes or move the car position. if it's light - move the axle back...

Hi Alex

agreed, but I am building the trailer so it is just the right lenght for the Datsun so I will not really be abel to move the car back or forth.

this is a Datsun GX coupe completely stripped out only a seat, stearing wheel and pedals the back is so light that me and my dad can pick it up with a bit of effort.

most of the weight is in front as the engine weighs the most.

I am just going to have to build it and then as you say move the axel forward till we have the correct towball weight.....

mossie

[Apocalypse]

Mossie - I've built well over 1000 purpose built racing and stunt vehicles in my time, from modified to total scratch builds.

believe me, unless you've hung the motor a VERY LONG WAY out front or back (like well beyond what Porsche or Audi consider normal) there is NO WAY you have 70/30 weight distribution

another tip is to hold the axle in place with g clamps or a tack weld to load it then adjust afterwards.

save drilling a lot of holes...

be careful that you fit a braked axle, and depending what you are towing with you might need a service brake.

and check your licence is the right one

[ozosborne]

I would put the axle in the centre of the load bed. Its not too much work to move it anyways, if it is a problem.

With all the car trailers we have built over the years all the axles were centred, the only times we moved them was for your Bats and so on, as their motors sit right at the back, so we shifted the axles slightly back.

[MOSSIE.JHB]

I would put the axle in the centre of the load bed. Its not too much work to move it anyways, if it is a problem.

With all the car trailers we have built over the years all the axles were centred, the only times we moved them was for your Bats and so on, as their motors sit right at the back, so we shifted the axles slightly back.

thanks Ozosborne will start off in the center and then move back as needed

[MOSSIE.JHB]

Mossie - I've built well over 1000 purpose built racing and stunt vehicles in my time, from modified to total scratch builds.

believe me, unless you've hung the motor a VERY LONG WAY out front or back (like well beyond what Porsche or Audi consider normal) there is NO WAY you have 70/30 weight distribution

another tip is to hold the axle in place with g clamps or a tack weld to load it then adjust afterwards.

save drilling a lot of holes...

be careful that you fit a braked axle, and depending what you are towing with you might need a service brake.

and check your licence is the right one

Hi Alex

yes I might be wromg with the 70% weight but even at 60/40 weight you still end up with a lot more weight than 100-150KG on the ball...

will just start in the center holding the axel on with u-bolts and them move it as needed....

I am thinking of going solid trailer (no Leaves) as this will help keep the trailer nice and low...

Am using a braked axel, using Isuzu Double cab as tow car so should all be legal

mossie

[Apocalypse]

no springs?

where's the bloody holy squirrel butt smiley?

no springs - the frame will take such a hammering - it will fall to bits in no time - the car being sprung will help but the impact on the load points will be immense!!!

I'd be a bit careful about that...

[MOSSIE.JHB]

no springs?

where's the bloody holy squirrel butt smiley?

no springs - the frame will take such a hammering - it will fall to bits in no time - the car being sprung will help but the impact on the load points will be immense!!!

I'd be a bit careful about that...

interesting statement.....

okay so you say go with springs......

even if I only put straps around the tires and not strap the cars body to the trailer..

[Apocalypse]

interesting statement.....

okay so you say go with springs......

even if I only put straps around the tires and not strap the cars body to the trailer..

well, your bed is going to be 4m long and weigh, say 150kg. plus other unsprung kit.

so, the car itself is nicely damped but don't forget it's still loading the trailer about 1.5m each side of your unsprung axle. lets say 500kg each side.

one pothole at 100km/h and something is going to have to give....

just another thought - if your weight balance is really bad, try turning the car around and packing your tools etc onto the Aframe. should even things out...

[MOSSIE.JHB]

good point....

I would prefer only the car on the trailer, as we leave the cars at the track on Fridays and only take home our kit and the tools.

Then on Saterday night after racing we tow the cars back home. So I leave all the kit on the back of the Doublecab and only want the car on the Trailer.

[Sneaky Pete]

Where do you race Mossie? Which track?

[Wetkit]

Mossie, had a similar problem when I had a trailer built for my pipecar.
Eventually we did the deck and put the car onto the deck and lifted the whole thing up and moved the axle forwards and backwards untill we got the correct weight on the tow hook. Use a bathroom scale to check.

You can also look at the Burquip axles, the one with the rubber bushings. With these you can also lower the bed of the trailer. This way it will be much more stable at speed and offer less wind resistance, to help the Izuzu along....

[Chris Viljee]

Ok, Here goes with the spreadsheet. Thanks Apoc

[Oppers]

no springs?

where's the bloody holy squirrel butt smiley?

no springs - the frame will take such a hammering - it will fall to bits in no time - the car being sprung will help but the impact on the load points will be immense!!!

I'd be a bit careful about that...

Alex, far be it from me to differ with obviously well experienced okes like yourself... BUT...

I used a trailer from one of our local service stations to fetch a friend's fully loaded 4x4 doble cab from Rooi Duin on the other side of Lamberts Bay over this past Easter weekend. This trailer is regularly used to bring in broken down vehicles and it's been going for a number of years... and yes, it's got no leafs at all. It's a double axle trailer 'cause they load heavy vehicles.

To top that, stock car racing is big here, and I don't think I've seen one of their trailers with leaf springs.

What am I missing?

[Apocalypse]

I guess it depends how strong you make it.

but you have to put so much steel in to take the hammering that suspension would absorb, even a tiny bit of movement helps.

farm trailers don't have suspension, but they only do 30 and have big soft tyres.

for road use and any kind of distance, you must have springs...

[MOSSIE.JHB]

Where do you race Mossie? Which track?

Hi Sneaky Pete

We race in the Midas Historic Challange and we race at Kaylami, Midvaal and Zwartkops.

There is one race a year at Phakisa and one in East-London (these are to far so I dont race in them )

mossie