Roll Cage design question

glswanson

glswanson

New member
So, since my ITC Fiesta is simply not competitive any longer (can't be the 60+ driver, could it?) and I'm too old to run at the back of the pack with no hope of being competitive, I've decided to take the spare shell I've collected and start an HP build. Here's the question - on the Fiesta the rear shock mount is separate from the spring perch. Where should the rear braces weld in? At the shock mount, or the spring perch? Not sure where the real dynamics occur.
 
Page 113 of the GCR, only states:

Cars must have 2 braces extending to the rear from the main hoop and attaching to the frame or chassis. Braces
must be attached as near as possible to the top of the main hoop (not more than 6 inches below the top), and at
an included angle of at least 30 degrees.

I would attach it to where the largest "structure" you can find. Got any photo's of the rear of the Fiesta that shows the rear shock towers, etc?
 
I would tie the cage to the spring perches and if possible, then to the shock tops. I don't think there is a restriction in Production on the number of feet in a cage. IT and maybe Touring have that restriction.

If I was only to pick one point to tie in, I would pick the spring perches.
 
I think more info is needed for those of us who are not very Fiesta-savvy.

(I actually had one as a daily driver in the 80s but never really modified it)

What is the rear suspension type? I assume the shocks are not struts and thus the load at the body is vertical not sideways like a strut would work. Where is the side load fed in? As Tim said "show us pics".

I was also going to write "Why not go to an adjustable coilover?" but a quick look at the PCS tells me (I think) that you can't use those on the rear since (as you state) the original spring/shock were not coaxial. Am I reading that right?

Welcome to HP, it's a good place to play! And even seems to be growing, at least regionally.

Al Seim
HP VW Scirocco 1.6
 
I think you want a horizontal bar between the shock mounts and other bars can then tie into that.

Other questions... What are you doing for front hubs, and a transmission?

The rear springs can be made adjustable fairly easily, using some circle track parts. They use a large plate for a nut and a large threaded rod that will adjust the upper spring plate.
 
Here is how I did my Fiesta. I would have rather had the rear main hoop braces tied in, but they were there when I got the car.
 
Thanks for the input. Ted, the pictures are very helpful, thanks. My "gut" had been telling me the spring perch was the way to go, but I really like the idea of tieing (sp?) the shock towers together. As for the front axles/bearings, I know about the Tempo upgrade in general - don't know the details. I had found a couple of BAT hubs for the ITC car, but didn't think they'd be enough for Production. Transmission - stock w/quaiffe to begin. Ted - are you going to be at the ProdFest? Thinking about going to watch.
 
Prod Fest, well if I get the car up and running then yes I will make that event.

The Tempo hubs and bearings are much stronger. You might not want to put anything right above the rear springs, if you want to make those adjustable, since the big threaded rod will go up thru the center.

I can take some pictures of my car so you can see. I think all the pictures so far are from Larry Banners car, he has the green one, mine is yellow. There are so few they are all different colors, ha ha....


Once you modify the spindles for the new bearings, to make the conversion, you will then need custom axles, fiesta inner spline and tempo outer, to connect the CV joints. Tempo left and right axles have different outer CV joint splines.... SO if you want to keep it a little simpler when having axles made, buy 2 left or 2 right tempo axles to get the outer CV's.

The problem with the transmission, you will only have 2 gears third and fourth and the two ratios are too far apart. One option is the ford escort 5 speed gearbox, we are only allowed 4 gears so you just block out first. It will bolt to the engine, but nothing else fits..... But it can be made to work, then you will have 3 on track gears, 3rd and 4th are a little closer together and on a longer straight you have 5th. Nothing else fits, you will need the escort gear linkage, and that will have to be made shorter, the escort has a hydraulic clutch release, you will need a custom clutch disc. Also if you made custom axles for the tempo / fiesta set-up, you will have to make another set for the tempo / escort set-up. Some body work will also have to be trimmed.... Then there is the starter....
 
Or you can use the Escort box and put Quaife gear set in and have 4 useable gears with 1st or 5th blocked out.
Chris
 
Yes you could possibly upgrade the escort gearbox.

Fiesta gearboxes are getting hard to find, while the escort ones are still available, which was the primary reason I did the conversion.

With limited prep 3 gears might be OK, better than just two, and better to be able to replace the gearbox if needed.
 
Thanks for the info. Couple of questions. Is there a particular model year for the escort gearbox? My plan had been to get the car built at a "year 1" level over the winter and then upgrade as time permits. Limited time & $. The Escort gearbox seems like its a major time & $ project.

Ted do you know a shop with experience on the axle conversion?

Also, what do you think about rear disc brakes?
 
Transmission conversion is not much cost, but it will take some time and tinkering to get all the little stuff set-up. The only real cost is the custom axles, and if you do the tempo hub conversion you will need custom axles to do that, if you also do the transmission conversion, then you just do one set of axles.

Since I did the tempo hub conversion then later did the transnission, I had to do 2 sets of axles.

To get custom axles made, first you need a sample. You will already have fiesta axles and inner cv joints. So if you are only doing the tempo conversion, you will need tempo axles to get the outer CV's. So after you have all the axle assemblies. Cut a fiesta axle and a tempo axle, assemble everything on the car, and weld the two axles together. You can even weld a piece of angle metal to one of them first and have the axels cut too short and slide along the angle piece until you get the length just right. Then take every thing apart and ship the sample to get the axle shaft made. Moser made mine. They do not want to get the axle with the CV's snapped on, as some are difficult to remove, so you have to remove those.

After you get them back make sure they are not a little to long or to short..... I think my last transmission broke from the vibration that was casued by the axles being a little to long and they bottomed out on the inner CV, some how I never noticed this before. But after putting a replacement gearbox in I ran it with the car up on jack stands, out of gear, no vibration, put in gear and bad vibration.... Took a little while to figure out what was wrong.... I managed to shorten them a little, not easy...

If you see me at the Prod Fest, you can see all the little things needed to make the trans conversion, or I can send some pictures.
 
Rear disc brakes, I have almost done that conversion....

What I did so far, took extra set of brake drums and had those turned into hubs, a set of front disc's fit over those. Then a small wilwood caliper or other caliper can be used, bracket will bolt to the 4 studs that used to hold the drum brake assembly.

At this point I just need to make the brackets and assemble everything.

I have also converted to twin brake master set-up.
 
Since all race cars are for sale, why don't you dish your Fiesta stuff and buy my Volkswagon stuff. Then you can get a car ready to go without the hastle and costs of building one.
 
Custom axles? Not with inner and outer CV joints. On my Honda I just bought new axle and old axle then took apart the CVs and mated them back up with new to the inside and old to the outside. I don't call that custom.

James -r
 
I had to have custom axles made, since the Tempo outer CV's will not fit on the Fiesta axle shaft.

The after converting to a alternate gearbox, the Escort inner CV's would not fit onto the axle shaft, so another set of axle shafts had to be made.

This is not actually very difficult, just make up a sample for the axle shop to copy. Moser made mine both times.

If a different CV joint will fit on the axle shaft, then you might be able to use the original axle shaft for your conversion.

I have heard of using welded together axles, for the cost of having a set made, it didn't make sense to attempt to run welded axles.
 
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