Edited by Lee200, Dec 20 2018 - 08:46 PM.


Gpl Salisbury Limited Slip Differential
#21
Posted Dec 20 2018 - 08:34 PM
#22
Posted Dec 22 2018 - 07:03 AM
Lee200, on Dec 20 2018 - 01:55 PM, said:
I wonder if differentials would be changed during race weekends back in the day (70s), would there be an engineer changing the ramp angles (cage halfs) and amount of clutches (clutch disks)!? (ofcourse as you mentioned before, in 1967 they wouldn't use this type of differential)
My guess is they wouldn't, also since you speak about a differential designer...
Edited by Robert Fleurke, Dec 22 2018 - 07:24 AM.
#23
Posted Dec 22 2018 - 07:23 AM
Back in the shop, the mechanics could change the plungers (pawls) on the Cam and Pawl and the ramps and disks on the Salisbury.
Someone else may have different info.
#24
Posted Dec 22 2018 - 07:31 AM
I've learnt within nowadays F1, they can adjust the diff settings (locking) on the wheel. That's really handy with changing griplevels and changing balance, to compensate or to change tire temps for certain tires. I gathered this hearing onboard communications.
#25
Posted Dec 22 2018 - 04:01 PM
#26
Posted Dec 24 2018 - 06:56 PM
Did somebody test it?
Cheers, Marcos.
#27
Posted Dec 25 2018 - 01:33 AM

So Marcos, there's a slight difference, and I'm impressed you feel the difference. Both settings cause a lot of rotation on the thottle, with 60/60/6 slightly more.

Edited by Robert Fleurke, Dec 25 2018 - 02:01 AM.
#28
Posted Dec 25 2018 - 10:01 AM
Robert Fleurke, on Dec 25 2018 - 01:33 AM, said:

So Marcos, there's a slight difference, and I'm impressed you feel the difference. Both settings cause a lot of rotation on the thottle, with 60/60/6 slightly more.

Yes... my point is that 30/30:3 and 60/60:60 should behave almost the same. I'll do further tests with the original gpl cars. My tests were with the 67x and don't know if somebody went that deep in the code to modify some of that calculations...
Thanks and Merry Christmas!!
Marcos
#29
Posted Jan 03 2019 - 08:41 AM
However as explained before, GPL uses the cosine of the ramp angle in calculating its locking percent. I now believe this is a minor bug in the code and Papy should have used the cotangent of the ramp angle instead.
The attached graph displays GPL's locking percent if the cotangent is used instead of the cosine in the calculation. It shows that the same locking percent can be achieved with lower ramp angles. This may explain why real world power on ramp angles are typically lower than what we need for GPL.
I could easily make a patch that fixes this bug, but it's not worth doing as essentially it's a cosmetic fix. As stated before, locking percent is what is important for handling regardless of the ramp angle, number of clutches, or trigonometric function used to determine it.
Just FYI.
Attached Files
#30
Posted Jan 03 2019 - 09:08 AM
I do allways use the locking percent in my head for my setups

As far as I understand, we must not change anything
I do vary my setups from 8 to 10 % on curvy tracks 12-13% for eg Monza...
#31
Posted Jan 04 2019 - 08:04 AM

So, if I do understand this well, 30/30/3 (cosine ramp angles calculation) should have shown as 30/30/1 (cotangent calculation) in GPL (about same locking percentage). Indeed it would be a cosmetic fix, as long we understand it's about locking percentages, it's no problem

Edited by Robert Fleurke, Jan 04 2019 - 08:05 AM.
#32
Posted Jan 04 2019 - 08:14 AM
Robert Fleurke, on Jan 04 2019 - 08:04 AM, said:

Yes.

I wonder if whoever was writing this piece of code simply made a typo and typed in cos instead of cot.
#33
Posted Jan 04 2019 - 09:41 AM
Still I am an idiot.
What is the GPL drive-ability difference between 45/xx/1 and 75/xx/6 when both are 10 percent +/-.
Is it time?
Rotation/time, time/rotation?
Or what if any difference is there?

#34
Posted Jan 04 2019 - 10:00 AM
#35
Posted Jan 04 2019 - 06:11 PM
On a more serious note, I still think in terms of the ramp angles and clutches rather than the locking percentages as shown in GPLSM, which I should probably try and migrate towards in future.
Great thread Lee; it's interesting to still find there are bugs in the code after 20 years!
Rob - that really is one of the areas that could be explained in more detail about modern F1, but there is increasingly less of a focus on the actual driving in the media coverage of it and moreso on the social/storyline side..
#36
Posted Jan 04 2019 - 06:39 PM
John Woods, on Jan 04 2019 - 09:41 AM, said:
Still I am an idiot.
What is the GPL drive-ability difference between 45/xx/1 and 75/xx/6 when both are 10 percent +/-.
Is it time?
Rotation/time, time/rotation?
Or what if any difference is there?

I still would like some talented drivers if they really feel the same comparing those different schemes producing the same lock. I don't feel them the same...
Cheers. Marcos
#37
Posted Jan 05 2019 - 04:09 AM
The diff settings were all equal.
Edited by Remco Hitman, Jan 05 2019 - 04:10 AM.
#38
Posted Jan 05 2019 - 04:12 AM
#39
Posted Jan 05 2019 - 06:37 AM
#40
Posted Jan 05 2019 - 08:47 AM
TvO, on Jan 05 2019 - 06:37 AM, said:
Robert Michael James Gascoyne-Cecil according to this:

https://en.wikipedia...ss_of_Salisbury
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