Off road buggy ...

[rvndraju]

Roll cages

The next day started preparing templates for the roll cages & engine bay tube bending. We drew the actual sketch on the floor to the scale and bent TMT rods according to the same design and welded it with supporting rods so that the actual design doesn't get deformed or something. We thought that just printed CAD drawings with the dimensions will do but when we enquired with some local welders they told us drawings would be sufficient if we are going for CNC bending but for manual hand bending they told us to take full scale templates. Here CNC bending would cost more so we had to go for manual bending.

Later we loaded the templates and the tubes to be bent into our team mate "Willys jeep" and took it to a local tube bender.

THe bending guy almost did good bends like 90% accorging to the dimension & he charged $9 for all the bends its like $1 for each bend

 

[rvndraju]

For bending

 

[mckutzy]

Once again OP, I think you guys need to spend a little time on shop safety. Now Im not trying to be a downer on things, and would like to see this through. But put some glasses on when grinding and cutting with an angle grinder.
Also a big thing on safety is a Guard on that grinder.

Like I said not trying to nitpick, but Typically we have alot of the younger crowd present here quite a bit, and we have to make a mention whenever it arises when safety is a concern.

 

[OzFab]

I can attest to what happens if you get a hot spark in your eye; I've lost count of how many times it's happened to me, not to mention abrasion burns, radiation burns from not wearing the proper safety gear while welding, I even had a mild case of welders flash once & I can tell you, you don't want any of that to happen to you...

On a lighter note, the frame is coming along nicely

 

[DMCdesign]

hello Ravinder!

your project looks pretty promising there........

you should go to a car scrapyard (i have heard of many there...) to get suspension, disc brakes and other stuff

welcome to DIYGK!

regards
DMC design

 

[landuse]

You have come really far with the frame in such a short time. Hopefully you will be riding it real soon!

 

[rvndraju]

Well after we got the roll cage tubes bent we cut the extra edges and placed it on the chassis to see how it looks. But we thought of not welding the roll cages as of now because the entire steering system, brake, clutch, throttle pedals, master cylinder had to be mounted on to the front end so if we mount roll-cages accessibility will be reduced and it would be difficult to work between the cages so that part will be welded later i.e before test driving the vehicle and painting.

But we completed the engine bay because our plan was to start with engine and transmission mounting right after we complete the front suspension (most crucial part of any car)

That is one of my team mate sitting as a human dummy height 6ft and weighing around 80kg. i know his head is popping out of the roll cages which should not happen but it was a small miss calculation in the design which we could't make out before but only after placing the roll cage . Then we thought of reducing the seat height coz we cant modify the chassis after all the work we have done

 

[exenos]

You could get two more tubes bent up for form a sort of roof over where you head would stick out.

 

[firemanjim]

Just drop the seat down some. Your buddy's hips are to high. You need to be more in the cage. Drop the seat as low as you can go. You want a laid back posture, not like sitting on a school bus seat.....

 

[rvndraju]

It took us around 4 to 5 days to complete the chassis with out the roll cages being welded. Then we started of with the main task i.e the front suspension. Front suspension is a crucial part of any car because lot of parameters comes into play like, CASTER, CAMBER, STEERING GEOMETRY, ACKERMAN ANGLE, TOE ANGLE, BUMP STEER, TURN RADIUS, SUSPENSION TRAVEL and lot more. If any error occurs in any one of the above parameter it will effect the over all driving dynamics of the vehicle, Eg. if the vehicle goes on a bump the steering turns by itself and pulls the vehicle to diffrent direction (called bump steer) , and tires wearing out in an uneven manner, Oversteer or Understeer etc. this is why it is recommended to get the wheel alignment done periodically . So we thought of designing the front suspension in the best optimum way as possible. There are a lot of software's available to analyse & optimize front suspension geometry (even the rear end can be done ). We are using OPTIMUM KINEMATICS G & SUSPENSION ANALYZER v2.4 from performance trends. Both the software's are very good to work on for a person who knows the basics of suspension geometry, i felt SUSPENSION ANALYZER v2.4 is a bit user friendly when compared to other.

 

[rvndraju]

First thing was to get the front A-arm fabricated, for that again tube bending was required. And also bushing is important for smooth movement of the arms in the pivots. When i did some research about the bushing material in SAE BAJA forums and other sites it was recommended to use bronze, Polyurethane (PU rods ) or Nylon. Bronze was priced high so we decided to go for Polyurethane and nylon. Both the materials have very good damping & wear resistance property and can with stand high temperatures and heavy shocks. We headed to market and Purchased a PU rod (dia 30mm 1ft) for $3 (PU is costly) & Nylon rod ( dia 30mm 2ft) For $5.
Also purchased Nuts and bolts for mounting the a-arms to the chassis. shop guy charged me Rs. 23/- for one nut and bolt these are (heavy duty) longer ones made of steel & we wanted a dozen of those.

 

[rvndraju]

You could get two more tubes bent up for form a sort of roof over where you head would stick out.

yup even that idea flashed in my mind but we'll try bringing the seat down if its not working out then we gota make the roof kinda thing what you said

 

[rvndraju]

Just drop the seat down some. Your buddy's hips are to high. You need to be more in the cage. Drop the seat as low as you can go. You want a laid back posture, not like sitting on a school bus seat.....

.. yes you are right we want more laid back posture. And We'll be buying the seats soon may in another 10 days.

 

[rvndraju]

fabricating upper and lower arms ...

sorry seniors for not using the safety gears again but don't know why we always forget it . But for welding i never forget it after what happened to my skin.

 

[OzFab]

Re: Roll cage, are the bars even? ie: are they the same length from the bend on both ends? Is it possible to turn them around to gain a bit more height?

If not, here's another idea: Instead of mounting them where they are, create a hoop that goes over the seat back (as in above it) & heighten the angle of the roll cage bars to gain a few extra inches of height. Yes, you will lose a bit of length but, with the hoop positioned & reinfirced correctly, that shouldn't be a problem, in fact, it should put the hoop above the drivers head...

 

[mysteryboy28]

Goggles and gloves man, seriously! Have you seen Beavis and Butthead? Having flashbacks here... There is no good excuse for not using goggles and gloves when grinding (especially goggles).

 

[Poboy kartman]

Goggles and gloves man, seriously! Have you seen Beavis and Butthead? Having flashbacks here... There is no good excuse for not using goggles and gloves when grinding (especially goggles).

Goggles for sure. Gloves.... well... there is kinda a little bit of controversy here if you think about it. ... While gloves will protect you from getting a nasty rub.. (yes-I've done it)....that will take a little while to heal, a loose fitting glove could get caught between the disc and guard and break a finger.

There are no foolproof tools and no substitute for vigilance. ....

The most serious injuries I have incountered in my long career as a woodworker involving nail guns were those that had safeties, and were a direct result of the fact they did. So while saftey is always the priority concern- in practice- what is actually safer may not be that obvious. ...

 

[Desertduler]

You can not grow new eyes.

 

[Poboy kartman]

Yep- blind yourself just once and you'll never make that mistake again. ....

But even short of that.....the eyes are the most easily damaged and most painfully sensitive part of the body.....

 

[andrecht]

I am really impressed with the progress you made so far.

I do have to agree with the safety goggles, it only takes one little peace of steel, or a broken disc for that matter to ruin someones life!!

A recommendation on the roll cage construction, to weld in additional supports to cross brace the " diamond shape. Keep into consideration that if, and when the buggy rolls, the entire weight of the frame, engine, driver and additional momentum will be exerted on the frame...