CR3171 Finally going back together!

[DaveW]

Hey Mike,
Spectacular.
I am amazed at the difference in chassis design between the square tube and round tube versions.
I didnt post a pic, cause its your thread, but maybe we should create a CR thread with pics from the the various CR versions from similar views. There is also differences between the round tubes, i.e. Greggs/Phils, vs Bens/Mine, vs Stuarts.

Love the look and your workmanship, fantastic.
Dave

[Aussie Mike]

Sounds like a good idea Dave. That would make for some interesting reading and be a useful resource for others.

I was actually thinking about the different generation frames last night after looking at the pic I'd taken of the rear frame structure. The new round tube chassis uses much more in the way of laser cut parts and I reckon it would be a lot easier to manufacture. It certainly looks more elegant and a bit less industrial.

The old square tube chassis also looks a lot heavier. It'd be interesting to compare the weights on the two.

Cheers

[Donunder]

Originally Posted by 1985 CCX

That is one heavy duty ride

You should have seen his drawings before he spoke with Colin Chapman!

[Aussie Mike]

The car is not a heavyweight though. It weighed in at 1050KG when I got it first registered Since then I've probably cut another 20KG or more out of the suspension components alone.

It'll be interesting to see it's final weight this time round.

Cheers

[gjkrv8]

Hey Mike. My round tube weighs in at 1100. Sounds like they would end up about the sane once you put on all the bits and pieces etc. I have underbody exhaust and fakesidepipes. Cheers Gregg.

[Aussie Mike]

That's what I was thinking. When I first got it registered it had no windscreen or carpet and an underbody exhaust. I've saved a bunch of weight on the suspension components since then but I've added a windscreen and wipers . The aluminum seats are lighter than the fiberglass ones I had but I'll be adding carpet. I'm expecting it to even out around the same weight.

Cheers

[Gav]

Mine weighed 1180kgs with the alloy motor and hard top.
It would be over 1200 easy with the cast iron block that is on the engine stand at the minute

[Aussie Mike]

There has been a lot of differences in the thickness of the fiberglass with the CR. That probably accounts for a lot of the weight differences. Mine is quite thin in sections. Across the rear deck it was only 2.5mm thick. I added another 3 layers of Kevlar mat to stiffen it up.

Fired up the lathe this evening and machined one of the 2 piece brake rotors. It looks as though the hat section was originally machined from a disc rotor as it's cast iron. Cast iron makes a mess when you machine it.

I'm just truing it up here prior to modifying the lip on the back of the hat so it fits into the ford backing plate.



The rear lip turned out fine and I've machined the outside of the flange to fit inside the rotor. With the rotor bolted up to the hat now the offsets are near perfect. Just got to re-drill the stud pattern so I can bolt it up and check the fit with the caliper.

Cheers

[Modena]

Mike is this just something that you didn't do back when fitting the bigger brakes? Not going to make some aluminium hats?

[Aussie Mike]

Hi Ben,

I had set the rear up with Ford territory rotors which are ventilated 328mx28mm. I bought these rotors from Albanycobra thinking they would be good for a future racecar project. Lord knows when that will happen. When I looked at them again the other day I realized the dimensions were close so why not use them now.

So the only real reason to do it is because I had the parts and 2 piece rotors look cooler than one piece

I thought of machining up aluminium hats but they still need a steel sleeve for the hand brake drum. These ones should work with the stock hand brake shoes once modified to fit.

Here's a rotor as I got them on the left and the modified one on the right.

Flipping the rotor to the other side of the flange resulted in near perfect offset.



Here's the back of the disc after machining the lugs down so the hat would fit in the back of the rotor. Also machined the lip on the back of the hat so it'll match the Ford backing plate.



Here's the modified 2 piece rotor next to the territory rotor. Weight is similar, the two piece may be a little lighter. Aluminum hats are an option for the future to reduce un-sprung weight some more.



I'll sand blast the surface rust off the rotors and probably sand blast the hats and paint them black to match the front.

Cheers

[Modena]

ah all good makes sense, for some reason I thought the previous post was about front rotors.

[Aussie Mike]

Hoping to start on the front end this coming weekend.

[Aussie Mike]

More machining fun tonight

I re-drilled the bolt circle to 4.5" to suit the Ford hubs. This meant setting up the rotary table and ensuring the rotor is centered.



I found the center point between the existing holes and drilled pilot holes then out to 1/2" and then to the final diameter of 5/8" for the shoulder on the wheel studs.



A trial fit found the center bore slightly too small. I had eyeballed it and thought it OK but the Ford center bore is actually 70.5 mm and the rotors were 70mm. Had to chuck the rotor up in the lathe again and take the center bore out by .5mm

I used the 4 jaw chuck and a dial indicator to get it exactly centered since everything is referenced off the center bore when the rotor is bolted to the hub.



Hooray! Perfect fit.



The caliper bolts up OK but I had to shim it out by about 2mm to compensate for the slightly larger disc diameter.



It was a really good feeling to be able to bolt a wheel on again.



Now to modify the other side rotor then sand blast and paint both of them.

Cheers

[deano59]

well done mike sounds like you just about on track to have it on the road for some nice warm days :-)

cheers dean

[DaveW]

Hi Mike,
Your rear brake setup now really resonates with me,
I spent a heap of time looking for combinations for my rear brakes and end up with territory rear discs due to the size and offset and the fact hat the handbrake drum is a common fit for the industry PBR handbrake setup.
I really wanted to find some hats and do a 2 piece, but couldnt find anything suitable and here you've ended up with exactly what i was looking for originally.
The rotors look like DBA5000, do you know what they actually are,
Do you think the hats were machined from discs originally ?

One of the issues i had with matching off the shelf parts was the different PCD of the disc to hat mounting holes.
cheers
Dave

[Aussie Mike]

Don't know what brand the rotors are. Haven't been able to find any identifying marks on them.

Changing the PCD is dead easy. A 10 minute job once the disc is set up and trued up on the rotary table.

I'm pretty confident the hats were made from cut down 1 piece rotors. Especially given they are made from cast iron. I'm thinking they may have been Holden going by the larger PCD they came with.

I'd be happy to help you machine a set up if you want to give it a crack.

[DaveW]

Mike,
going from the pics your rears look exactly like my fronts except for the size, (330x32).
I looked up DBA catalogue for DBA5000 rotors and found 328x28 version 5046.1SL or SR.
if the PCD of the rotor 12 bolt mounting is 182mm, then i expect they are DBA.

Would love to have a crack at some custom hats to suit, I already have stock VE rear rotors that came off the rear end assembly I bought to rip all the bits off.
This would be well outside my ability or equipment to machine up.
I'll measure the original discs, and then send you a PM.

Might be time for another video instruction series from you.

Dave

[Aussie Mike]

I'll check the measurements on them tonight.

[DaveW]

ahhh, dont know what i'm talking about, the hat for the VE is 190mm inner diameter, 204 external, wont be the DBA. would need a PCD of about 220mm

edit...found an ap racing rotor that is almost perfect cp3580-1092/3 with a 220.5 pcd, 330x25.4

[Aussie Mike]

Hi Dave,

I measured the rotor PCD. They are as close to 220.5mm as I can see on a steel rule. The ID for the lugs is 205mm so they fit over the hat just fine. The rotor is bang on 330mm diameter and the same thickness as the territory rotor.

Finished off the rear brakes tonight. Trial fitted the other hat and thought I'd snap a pic of how neat it fits into the Ford backing plate after machining. Very pleased with that.



Sand blasted the hats and the rotors to remove old paint and rust. The hats got a coat of high temp black paint to tie in with the black anodized hats on the front.



Love this view with 24" of rubber on the back.



Start on the front suspension tomorrow.

Cheers