What ramp angles?

[Shortshift]

I posted about this in Geoff Brown's excellent Titan LSD thread, but I suspect my request for advice got mostly overlooked amongst the outpourings of expensive anguish over there.  So I'm asking again, here.

Car is a 2012 R500D with Quaife 6-speed sequential and I'm about to replace the Titan LSD with one of Steve Perks' much praised Tracsport units.  All good except I'm not sure what ramp angles to go for. 

The Titan unit that I am replacing was 30/90 but the Tracsport can be built to either 30/30 or 45/45 configurations, so not an apples-for-apples swap. 

Which of the two Tracsport options should I go for?  I'd be interested to hear of experience and recommendations, based on the car being used around 30% on road and 70% on trackdays.

James

 

[ECR]

What does Steve say?....

[Shortshift]

Quite a bit, actually!!

James

[ECR]

 

[Geoff Brown]

Both myself (R400D) & a local area member (R300D) opted for 45/45 which Steve deemed to be the best for the cars - road use & occasionally track work.

Initial road testing of both cars of up to 40 miles on some arduous Wiltshire B roads (with good high speed bends) has proven that Steve's LSD with 45/45 produces good stability. And no crisis !

 

[7 wonders of the world]

James you need to look at this in the manner the unit works, 

Initially you could be forgiven for thinking that running 30/30 would make for a car that wont turn in, (tight on overrun)  - compared to a 30/90 set up, however the amount of torque generated on overrun compared to drive is minimal and the resulting difference will be negligible, 

There is sufficient force generated to reduce the chance of the inner rear locking under braking though, which makes the car feel more stable.

I've run 30/90 30/60 30/45 45/45 in previous set up's, the 30 on drive gives a nice positive action assuming you used to driving the car properly (which you are) this wont pose any problems to you.

My new Tracsport is 30/30 - and when the Gritters finally feck off   I will be able to give some real world feedback, bear in mind the Tracsport in Caterham spec is set to 20lb/ft preload but spread over 4 larger plates not 2 tiny ones, (i have got the actual surface areas to hand) which gives a very smooth operation.

Hope this helps   

[Shortshift]

"Initially you could be forgiven for thinking that running 30/30 would make for a car that wont turn in, (tight on overrun)  - compared to a 30/90 set up"

That is exactly my concern!

"My new Tracsport is 30/30 - and when the Gritters finally feck off   I will be able to give some real world feedback"

Neil, just stop faffing about and get out there so as to give me some real-world feedback!!

James

[7 wonders of the world]

  

In numeric terms I will throw some 'generic' figures into the pot

Engine peak torque 180 ft/lbs

1st gear ratio  2.7

Final drive ratio 3.6

Compound ratio  9.72

Max theoretical drive torque seen by LSD   1750 ft/ibs   (in higher gears or with wheel spin this will be lower)

 

 

The amount of torque generated in overrun is limited by tyre adhesion and wheel radius, even working against a very high compression engine its a minimal number, compared to the drive figure

Preload has a much greater effect on turn in feel in light cars, or using the wrong oil and you can feel the plates chatter on tight low speed corners.

 

 

[Simon.Rogers]

James you will not have any issues with turn in using the 30/30

I would not hesitate for your use to select the 30/30

[heptagon]

Sorry thread drift, what's the approx cost of a Tracsport vs a Titan unit?

[7 wonders of the world]

in terms of outright purchase fitted to a final drive ...

..... or factoring the high rebuild costs that many members have suffered on one of them....?

Tracsport is slighlty more expensive, but there are significant differences in the units.

 

https://www.tracsport.com/lsds