Escort Sigma 1600 Race Car

[Roadsport]

Re: Escort Sigma 1600 Race Car

I need to know the actual nose down angle of the axle while it is on the car before I can start alerting the toe and camber. Thats done on the axle stands and if the axle is at a wrong angle on the stands the toe and camber won't add up when installed back in to the car.

Am I making any sence?

[FOSSIE]

Re: Escort Sigma 1600 Race Car

You're making sense, yes, and I agree that the pinion will "wind up" a little under torque... But, you should be aiming for the pinion to be equal and opposite to the engine/driveline angle. For example, if your engine is angles 2 degrees down towards the rear, then the pinion should be angled 2 degrees UP - this way the combined UJ angle is zero degrees. If you take the wind-up into account (half a degree at the most with 4-links, especially as your's are solid at both ends) then maybe 1.5 degrees nose up with the car at rest.

I just guessed at the 2 degrees by the way... If your engine is flat then modify the numbers to suit...

There is lots of literature on the internet about pinion angles (the Americans, and in particular the drag racers are the experts) - just google pinion angle, driveline angle etc.

[Roadsport]

Re: Escort Sigma 1600 Race Car

The car is too low / the axle too high to achieve zero angle to both prop joints. The best I can get is a slight angle at the engine end and zero on rear end. To make the agle smaller I've allready lifted the the tailhousing up. Ideally the angles would be equal like you suggested. Say two degrees facing down at the engine side and two on the axle side facing up. But lifting the pinion angle up would put the prop in weird steep angles. The pinion would be higher than the gearbox output shaft.

[Tristan]

Re: Escort Sigma 1600 Race Car

Clever bloke Marcus... Better and better.

[Roadsport]

Re: Escort Sigma 1600 Race Car

I measured the pinion angle movement during squat. It was just like FOSSIE said. The change in the angle is minimal. The pinion rises one degree as the rear squats. I'll set the pinion angle to 1 degree down or level at stand still.

[RWD fords rule]

Re: Escort Sigma 1600 Race Car

Top work Markus

[Roadsport]

Re: Escort Sigma 1600 Race Car

Thank you Jason. I'm hoping to make a trip up north thisweekend to bend the axle to achieve the wanted camber and toe. Once thats sorted I can tack / weld on the axle braces. Then its only a matter of brake caliper brackets and paint.

Speaking of brakes I intend to save more unsprung weight there. My Wilwoods take only 22mm disc hence the focus 252 mm dia discs. Sierra vented disc is 24mm's tdick and 240 in dia. Does anyone know could one shave one mm off both sides of the disc? Going down on disc diameter would help save weight whilst still easily deliver the deenend braking for the rear axle. Plus I could really use some deeper discs. Having caliper too far out makes the bracketry a bitch and causes some offset issues with the wheels. I also intend to shave some meat off the wheel mounting face of the disc. Theres plenty there to shave off. Maybe Milling some holes too.
My other option is to seek out thinner pads or widen the caliper.

Oh and weighted the axle yesterday. 40kgs dry, less the caliper brackets that,s 18kg's of saved unsprung weight. The mustang axle was 60kg's with oil.

[Roadsport]

Re: Escort Sigma 1600 Race Car

A weekend well spent. I took a trip up north to do the trackin. I also needed to weld the axle braces on while on the jig to see how mutch would the axle bend while welding and correct it.

The axle was very straight to start with so only tiny adjustments was needed. It allready had some toe in and negative camber we just needed to add a little. At the end of the day (at 2 am) we got a healthy one degree of negative camber and 1,5 mm's of toe in per side. Double the camber I have with the mustang axle.

Tee axle needed a fairly large ammount of heat to start moving so I was confident the welding would not distort the axle. I was wrong.
Welding proved to bend the axle more efficiently than the blow torch. So after welding we were left with toe out. I was a bit worried at this point as I had just welded the axle to be stiffer and tougher. And it may not bend back enough. But heating multiple small spots along the axles front side made it twist back eventually.

All this took a good while. And as we got to it late in the afternoon it was way past midnight when we welded the gussets on. The necessary refreshments made the welding a bit challengin so some tidying up will need to be done.

Next: brake caliper mounts and painting.

Speaking of brakes it turned out my calipers will not take 240mm discs. So I'll use Sierra/ Escort RS turbo 260mm discs. According to federal mogul the 260mm discs will be 600g's lighter than my current discs. But I'll need to skim the disc down from 24mm to 22mm's thick so that will provide more weight savings. I intend to drill and shave here and there so will be interresting to see how much weight can be shed from the discs.

[Roadsport]

Re: Escort Sigma 1600 Race Car

Did some tidying up today. Ground down the welds and wire brushed the surface rust off.
I finished up the breather and finally thought of a way to wire lock the drain plug. I'm not a firm believer on wire locking but since this plug does not seem to leak untill completely removed the wire will work fine.
Also while in the workshop I drilled some holes to the bottom of the axle braces to drain the possible water out. These holes will come in handy when applying the waxoyl too.

[exboyracer]

Re: Escort Sigma 1600 Race Car

Looking good

[Tristan]

Re: Escort Sigma 1600 Race Car

It's a fairly huge unsprung weight saving!

[Roadsport]

Re: Escort Sigma 1600 Race Car

Yes it is. I hope it translates to laptimes too. I'll need to put the saved weight back to the car though but this time it will be where its needed, instead of dragging it in the rear axle. And I benefit from the closer ratio too. So hopefully another step to the right direction.

If this concept proves itself theres still weight to be shed. Perhaps an alloy diff carrier saves another 4.75kgs and bell rear brakes worth a another 5 kgs maybe. That would pretty much be as light as a live axle could ever be and still be able to finish races.

I was very surprised to see some preload in the Quaife LSD. Something that I never had with the Eaton.

[mario r h santos]

Re: Escort Sigma 1600 Race Car

It's a very nice rear axle build you have there.

Congratulations on your fab quality.

Cheers,

Mário Santos.

[Roadsport]

Re: Escort Sigma 1600 Race Car

Thank you for the compliment Mario.

Hopefully I'll get the brakes sorted next week. Then I'll need to find some place warm enough to do some spraying... After that I've ran out of excuses to tackle the bloody Tran - X

[RWD fords rule]

Re: Escort Sigma 1600 Race Car

Good work, post plenty of pics of the tran-x problems sure we can come up with some decent solutions, fix it for good!