CR3171 Finally going back together!

[mate]

"I feel like I'm a bit of a joke sometimes."

No Mike, you are an immense inspiration and encouragement, even to those of us who don't and won't have the privilege of building one of these dreams. Thank you.

[Aussie Mike]

Originally Posted by DaveW

Hi Mike,
Chassis looks great, love the silver choice
Really looking forward to the finishing progress.
Hope to catch up some time.

Dave

Cheers Dave. I got thinking about silver after seeing the pics of your beautiful chassis.

Cheers

[deano59]

took me 3 yrs with my first cobra and I reckon the first 12 months was scrapping grease and crud of jag bits . the next 12 months totally recondition every part I had cleaned and another 12 months to put it together only too loose it in a divorce .

this time round there is no scrounging parts . the parts are all clean and new I don't think this mrs is going to drive off into the sunset like the old one did so lets put 18 months on this one to be on the road . oh difference between last time I also bought bits as I could afford them this time the budget for the cobra is already in the bank should make life a bit easier I hope .

how long mike was yours on the road before you stripped her down again ?

cheers dean

[Modena]

Yes it's true I'm embarrassed to say. It's probably one of the reasons I don't head along to club meetings so much any more. I feel like I'm a bit of a joke sometimes.

You have it all wrong Mike. Every meeting there are people looking for you as they want to chat. You need to come to more meetings! You missed a great talk from Jim Keogh last week.

[Aussie Mike]

A bit more tinkering this evening.

I test fitted the engine cross member. Originally the chassis had a piece of 2" x 1" RHS welded in between the engine mounts. I'm not sure it added much in the way of chassis stiffening but perhaps it helped support the engine mounts. The problem with it was that I couldn't easily pull the sump with the motor in place. Out came the angle grinder and I removed the cross member. I've fabed up some brackets and welded them in place and then machined a removable billet aluminium cross member. There's still some machining to do on it to remove a heap of weight but I just thought I'd try it for fit post powder coat. I had to machine a little off it to compensate for the thickness of the coating.



I put most of the power steering plumbing back in along with the front brake lines.



One thing I hadn't finished when making the rear arms was the pick up points for the sway bar. I'd thought to make some kind of sliding clamp arrangement to line things up with each of the adjustment holes but I reckon I'll weld in some threaded bosses instead. Got to do that before sending the arms off for powder coating.

Just trial fitting here to work out the right locations.



Another view of the rear sway bar setup.



Cheers

[Dimis]

Originally Posted by mate

"I feel like I'm a bit of a joke sometimes."

No Mike, you are an immense inspiration and encouragement, even to those of us who don't and won't have the privilege of building one of these dreams. Thank you.

Originally Posted by Modena

You have it all wrong Mike. Every meeting there are people looking for you as they want to chat. You need to come to more meetings! You missed a great talk from Jim Keogh last week.

Here! Here!

What they said ^

[DaveW]

What shocks are you using Mike ?

[Aussie Mike]

They are just single adjustable AVOs. Nothing special. I'd like to upgrade at some point. The Penske shocks that Ben has for his CR look nice.

Cheers

[Aussie Mike]

A little more progress on the weekend.

I worked out the sway bar connections. Machined up some threaded bosses then drilled the x bar on the arms and welded them in. The way they are set up gives 6 adjustment options with the rear bar. 3 hole positions and swapping the link from the inside to the outside changes the leverage the control arm has on the sway bar.

Next it's sand blast the control arms and the sway bar and powder coating.



Another job I'd been wanting to do was plumb the diff for an oil cooler. I figured it would be better to do it now rather than risking damaging the finish on the chassis by pulling the diff later. The fittings can be capped off for the moment till I can get the pump and cooler mounted.

This is the drain fitting to pull oil from the bottom of the diff housing.



This is the return. It's set up to pump the oil directly onto the LSD center.



So why a diff cooler? The center is from a HSV GTS Commodore. They were optioned with 3.9 gears and a hydratrak center. It's an unconventional and pretty innovative LSD in my opinion. Instead of clutch packs it hooks both axles together via a vane pump. The unit is sealed and filled with a silicone fluid. Difference in wheel speeds causes the vane pump to pump the silicone fluid around inside it's housing through small ports providing resistance. Like a torque converter it reaches a stall speed where it cant pump any faster. The result is it's a speed sensitive LSD with a smooth progressive engagement.

The downside of the hydratrak is that excessive heat makes them stop working so track days etc can give them a hard time. The diff cooler should in theory keep it working under hard use.

They are a sealed unit but I found a couple of pictures of one pulled apart.





So now the diff is all machined I can clean it and repaint it and then reinstall it in the chassis. Hopefully get that done this week.

Cheers

[spookypt]

Mike, with your diff how is it vented? Pin hole to the diff cover with an internal splash shield set up?

I found with mine, (M3) that I had some issues with it venting hard at full noise so I drilled and tapped a fitting in the existing vent hole and have it breathing to a drain back catch can.

May not be an issue but a thought anyways.

Spookypt

[Aussie Mike]

Diff venting is definitely an issue. The two track days at Winton blew diff oil all over the underside of the car with the stock vent setup. That's just a hose barb pressed into the back cover with a length of hose run up as high as possible.

The plan is to install a catch can breather setup.

Got any pics of yours? It'd good to get some ideas on how it fits in.

Cheers

[spookypt]

Cars all loaded up in the trailer Mike but will get some for you over the Nats weekend. I found for the diff most of the catch cans were overkill for a diff vent so I used one of these. I drilled a small vent hole in the lid.

Alloy Clutch Fluid Reservoir VT VX VY VZ VE Holden Commodore HSV T56 6 SP Manual | eBay

[Dimis]

Originally Posted by Aussie Mike

Diff venting is definitely an issue. The two track days at Winton blew diff oil all over the underside of the car with the stock vent setup. That's just a hose barb pressed into the back cover with a length of hose run up as high as possible.

The plan is to install a catch can breather setup.

Got any pics of yours? It'd good to get some ideas on how it fits in.

Cheers

FWIW: Mine is routed through and mounted in the boot/truck.

I have a spare little catch can with some venting, (an overkill billet job) that was mocked up by the boys in Provo, but its yours if you want it... I've no need for it, and its free to a good home...

[guye]

What will you paint the diff with, Mike?

[Aussie Mike]

Originally Posted by guye

What will you paint the diff with, Mike?

Probably some epoxy enamel or maybe POR15.

Cheers

[Aussie Mike]

Originally Posted by Dimis

FWIW: Mine is routed through and mounted in the boot/truck.

I have a spare little catch can with some venting, (an overkill billet job) that was mocked up by the boys in Provo, but its yours if you want it... I've no need for it, and its free to a good home...

Thanks Dimis. That's a very generous offer. I'll be in touch.

I'm thinking I'll route the breather up through the inner guard and mount it up next to the carbon canister.

Cheers

[Aussie Mike]

Got the diff cleaned up and painted and back in the chassis.

Added an AN#6 fitting for the vent to connect to.



Adapting the Commodore diff to the Ford sourced rear end wasn't that difficult. It turns out the BTR80 and BTR75 both have the same bolt pattern for the back cover. It was just a matter of swapping over the back covers to take care of the rear mounts. The front mount required some fabrication as its a completely different design to the ford.

Cheers

[Aussie Mike]

The rear suspension is starting to come together. I decided to sand blast and paint the arms rather than powder coat. It saves a bit of time and money plus I liked the paint finish I got on the diff. I used the same gunmetal hammered metal paint finish on the arms.



After some discussion with Peter Allen I decided to add some bracing to the cross bar on the lower arm where the sway bar attaches. There could be potentially quite a bit of load on that piece of 1" tube so I welded a spine along it to give it a helping hand.



The next job it to get the uprights and hubs cleaned up and painted. Hopefully should have the rear end all back together on the weekend.



Still having fun.

Cheers

[Aussie Mike]

Slow but steady progress.

The rear suspension is pretty much all back together now. Finished painting and reassembling the rear uprights on the weekend. The axles and track rod are in now. The design is a little different to how I first built it. I've added what I've learned building the CR bump steer kits and used the new clevises tied to the original chassis pickup points rather than tied to the point on the lower rear arm.



The axles are standard Commodore items so no need to make custom ones. I rifled through a bunch of different models at the wrecker and found a particular year that had the right length (VS I think).



Found I need to shorten up the sway bar links about 1/2" as there isn't enough clearance to the axles. Should be straight forward to do.



The next job is to sort out the rear brakes and then I can bolt the rear wheels on. Hooray!

[1985 CCX]

That is one heavy duty ride