Homegrown race car

[Tomi]

I decided to share my project and as this is my first race car project and I'm sure I need all the info and comments from you guys. This will be a long project as I'm building most of the things myself and I still don't know all the specs of the fin(n)ished product. I try to update this thread from time to time, at least when there is something to update.

The project started a year ago as I wanted to change my current street car's cage to 8.5 second leagal 8pt cage. So I bought RLR 8pt chromemoly cage which Jyrki had imported few years ago and no one has used. After a while I bought more tubes in order to build a full tube chassic as I figered that would be the easiest way after all. I also bought RLR back half for the car. I already had another fairly good 1952 split window waiting for better times so I decided to use that and not cut the UB-52. I also sourced a salvageable set of original fenders so the body and all that is in order. I just need to get the chassis on wheels before getting into that.







We started from floor up and each tube was bent by various race car builders based on our cardboard or plywood models. As the chassis was 250km's form my home it took us at least 7 or 8 monts to get to this point and some frustrating moments when I could only fit one or two tubes during whole weekend. I wanted to save all the original sheet metal under the bonnet so the front end is a bit different from normal chassis. I'm sure it works like this  as well. We ended up using only four prebent tubes form RLR sets, for example main loop and whole back half were bent locally to better follow the body lines inside the car. So thinking backwards it would have been better just to buy quality bender and whole lot of tubes.







About a month ago the chassis was taken to local "chassis shop" be welded and get the rest of the tubes fitted. It only took them 40 hrs and the chassis was done. Welds are very nice and tube fitting just perfect. I couldn't have been happier with them.





So now the chassis is like this. The floor meets new(?) sfi25.4 specs and if I add funny car cage this could get tagged to 7.5 seconds. I will not add the extra cage at least not at this stage. The weight is 64,5 kg's but I still have to add a few tubes and tabs for the body and components. Even if it matters very little I hope it stays under 70kg's.





Basically this is where the project just begins for me as I'm getting the chassis to my own garage. I have no schedule for this but I hope it will not take too many years. The plan is to get the car on wheels during this winter and then fit and weld the body.
 
I have no idea what kind of engine I will use. I will most probably use 091 transmission and irs setup at rear but I can think those things later when everything else is in order.

[smurf67]

Looks a great project best of luck. Alex

[autohausdolby]

Looks cool

[BossHogg76]

Looks great as does the Cossie sat in the back ground...I do have a soft spot for Cossies

[Jyrki]

Believe me, this is one of the nicest projects & concepts in VW scene ever!!!
Jyrki

[Basti]

Very cool Project! Please keep on posting pictures...

[Ragtop]

Very nice build. I think for 7.50 you need some more bars under the feet and sides so the tires can't get in the car.

[Tomi]

Yes, I will add crossbars to the floor as well as diagonal bars to the sides. I need the pedals first so I can use the same bars to support them. Also rear end will get some more supporting bars.The plan is to keep everything as simple as possible in order to finish this at all. The only more complex thing is rear suspension but I hope it is so well designed I won't get into troubles with it.

[Neil Davies]

Interesting rear end, it looks a little like Keith Seume's No Mercy suspension with a 4 bar IRS. Cool car!

[johandryselius]

Very nice car and exiting project - keep us posted!

Johan

[BeetleBug]

Thank you for posting this project thread Tomi!

So... I guess this one will be a turbo car?

-BB-

[Tomi]

Turbo is not at all out of the question. But first I have to finish the chassis and body. And if still at that point my street car engine is in one piece I will be tempted to dial in the car with that. If the new car is lets say 200kg's lighter it will be possible to run high 9's, but like Jyrki said, it will be boring as hell.

[Ragtop]

Turbo is not at all out of the question. But first I have to finish the chassis and body. And if still at that point my street car engine is in one piece I will be tempted to dial in the car with that. If the new car is lets say 200kg's lighter it will be possible to run high 9's, but like Jyrki said, it will be boring as hell.

Haha, I agree with Jyrki 

[Mathias B Röschmann]

Awesome!

Looking forward to follow the progress!

[Elnef]

Yes very nice project  

[Jyrki]

Turbo is not at all out of the question. But first I have to finish the chassis and body. And if still at that point my street car engine is in one piece I will be tempted to dial in the car with that. If the new car is lets say 200kg's lighter it will be possible to run high 9's, but like Jyrki said, it will be boring as hell.

Haha, I agree with Jyrki 

Yap, a properly set up heavy chassis car, or even a pan car with ladder bars, runs 9s without any drama = boring as hell. For adrenaline rush you need some boost!
Jyrki

[dielinde]

Very nice Projekt  i love these fast old racecars 

[Tomi]

No progress at all but some new ideas I would like to try and get opinions of. I wanted to maximize shock movement as the wheel only travels about 40mm upwards so I wanted to see if cantilevers would do the trick. With 1.5:1 rocker ratio I get 60mm and more precise control. Ride height will be adjusted with the link bar and not spring height so the rate remains constant. This is getting a bit away of the simple theme but if it works I don't mind. What do you think, should I give this a try or does anyone see some design flaws?

[Erlend / bug66]

Dang..

I was rendering a push rod rear suspension with my uncle last night.
It was not that sweet

You could get more travel if you traverse the pushrod and coilover to the other side. One over the other.

Or check out this Mustsng: http://m.youtube.com/watch?feature=plpp&list=PL933202463D47A1C2&v=42GTMDhLG2Y

[Tomi]

Running the shocks across was the initial idea but in that case only 14" shock could have been used due to limited space between the back end tubes. Having them longitudinally there is basically no limitation for shock length. The rocker ratio here is 1:1.5 and range of movement is just about perfect with 17" shock which I will be using. For swing axle car it would probably be better to use 1:2 ratio as the pushrod movement is far less than with IRS. So swing axle cars would benefit this kind of suspension even more than IRS cars.

I can't use any cad programs so I'm just giving my ideas to ones who really can. I also get the needed parts with the same effort. I'm slowly beginning to think that this is getting a bit too complicated but I just want to try something different than the usual swing axle with ladder bars. I know this is not making the car any faster but I like the idea of no camber or any other alignment changes.

[nicolas]

you should talk to Peter Shattock to see how he did the suspension setup. it doesn't have this shock setup, but what i saw on his car (pictures of it) looks really good.

[Tomi]

Yes, I have seen some pictures of Peter's suspension and it looks great. I was thinking about having similar made while I was still going to build a pan car. But with a tube chassis I had the possibility to use four links which I hope to add stability at launches. I also like the Mopar wheel bearing hubs, similar to Empi, etc. which allows me to use longer drive shafts for better CV joint angle. My transmission will be moved forward at least 90mm so with short shafts the angle would be quite big.

[Neil Davies]

There are more photos of Peter's build on the Andy Robinson Race Cars site, but check this advert on the samba http://www.thesamba.com/vw/classifieds/detail.php?id=1570472 it has a ladder bar with IRS set up.

[max2919]

The Red Baron has a rear suspension that seems to work...
Swing axel with push rod suspension?

[Berger]

No progress at all but some new ideas I would like to try and get opinions of. I wanted to maximize shock movement as the wheel only travels about 40mm upwards so I wanted to see if cantilevers would do the trick. With 1.5:1 rocker ratio I get 60mm and more precise control. Ride height will be adjusted with the link bar and not spring height so the rate remains constant. This is getting a bit away of the simple theme but if it works I don't mind. What do you think, should I give this a try or does anyone see some design flaws?

Tomi, have you done a 3D simulation of the movements in this suspension setup? From what I see, it looks like the link bars going from the hubs to the coilover rocker have to much angle to give the rockers the necessary movement. As the hubs are going straight up and down, I think most of the movements will bee in the uni-balls, and not creating any force to the springs. Just my thoughts.   

[Tomi]

Yes, this has been simulated and also some stress testing made. Without simulation I doubt this could even have been possible as all the mounting points do have effect on the alignment changes etc. In this picture the suspension is at it's highest and lowest point and no change in toe in or camber and as you can see the shock is fully compressed. Suspension idea itself is copied from Alan Fore's car with the exception of four links and shock placement. When I asked from the manufacturer with the intention of buying the setup I got no clear answer on anything except the price. I still would have had to do the simulation to find the mounting tab positions so I decided to spend my money locally. And I'm really glad I did.


This is an early model with 14" shock and 1:1 rocker ratio but it shows the pushrod and rocker movement.

[Tomi]

I finally got all the needed parts for rear suspension and some of them are now tacked into place. I also added some more tubes to the floor and backhalf.



I will add a bracket on top of the rocker as well as I don't want it to twist the tubes.



This transmission is just for mock up and I'm having hard time figuring how to mount upper arm as starter motor and drive shaft is in the way. Easiest fix would be Mendeola, but I would still like to use 091 as I already have it and also plates for it.

[leec]

Hi there,
Great project. Have you built the floor section to sfi spec? If so do you have any more pics and tubing specs to share please. Need to update my lummus chassis.
Thanks
Lee

[Tomi]

Yes, the floor should be sfi 25.4 spec. I don't have the spec book with me right now but will try to find it.

[morkrieger]

Hi Tomi,

I'm interested in your Stress test simulation, what amount of force did you apply and what safety factor did you reach on the construction?
Have you also tried a 'Dynamic' test on the construction?