Home » Public Forums » GMCnet » Limited Slip
| Limited Slip [message #75007] |
Fri, 26 February 2010 10:54  |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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You want to see the limited slip that Jim K. is building? Go to Jim Bounds Daily Pose. This is a slick unit. I watched Miguel install Neil's. Of course, it looks like a normal unit so I had to rely on what Neil said about his. If I had a gravel drive to climb I think this would be the ticket. I want to ride in a coach with this unit, going up Manny's driveway.
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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| Re: Limited Slip [message #75008 is a reply to message #75007] |
Fri, 26 February 2010 11:11  |
voodoolng
Messages: 40
Registered: February 2004
Location: Colo
Karma: 0
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Just had a question. Putting the limited slip in a front wheel drive. Is it safe to do something like this. Here in Colorado in the mountains on a curve after a sheet of ice from a rain or snow (black ice).
Will the inside wheel slide enough to make the curve OR do you tend to go straight and off a cliff. All icy roads and curves.
Has anyone considered this?
73 Glacier Voodoo lounge
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| Re: [GMCnet] Limited Slip [message #75014 is a reply to message #75008] |
Fri, 26 February 2010 13:01 |
GMC_LES
Messages: 569
Registered: October 2009
Location: Montreal
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With a GMC, one should approach icy road conditions the same way with or
without an LSD. Dead slow and cautious! Having an LSD would help you get
through difficult traction conditions, but should not be a reason for
driving beyond what the road conditions justify. An LSD would not cause any
more loss of control than a regular diff. Loss of control is more often the
result of driving beyond your (or your vehicle's) ability.
After driving a few VWs with an aftermarket LSD front diff, I found that
there were no differences when driving the cars normally. The LSD action
only kicks in when the driving gets aggressive, or when one wheel looses
traction under light throttle. I wasn't lucky enough to drive those cars on
ice though.
I used to own a 4x4 Ford Ranger in which I installed LSDs in both front and
rear axles. It was difficult to get stuck off road or in the snow. On ice it
required some careful driving when in 4WD as the truck would do a 4 wheel
slide if using too much engine braking or brake application. Inexperienced
drivers could easily loose it in an icy curve with that truck. Knowing the
truck's limits & abilities, I was able to out drive most other vehicles
during bad road conditions, often while still in 2WD.
IMHO Proper tire selection will provide better traction & safety on ice than
an LSD.
Thanks,
Les Burt
Montreal
1975 Eleganza II 26ft
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Les Burt
Montreal
1975 Eleganza 26ft
A work in Progress
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| Re: [GMCnet] Limited Slip [message #75028 is a reply to message #75008] |
Fri, 26 February 2010 16:40 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Tim,
I might be an Ornamental, but these issues have been disused and
tested to a point where it will be safe.
If the surface is so slick that the coefficient of friction at both
wheels are that low, your going to go over the ledge anyway.
This one is designed for front wheel drive unit and will defiantly help.
On Fri, Feb 26, 2010 at 9:11 AM, Tim Petras <voodoolng@msn.com> wrote:
>
>
> Just had a question. Putting the limited slip in a front wheel drive. Is it safe to do something like this. Here in Colorado in the mountains on a curve after a sheet of ice from a rain or snow (black ice).
> Will the inside wheel slide enough to make the curve OR do you tend to go straight and off a cliff. All icy roads and curves.
> Has anyone considered this?
>
> --
> 73 Glacier Voodoo lounge
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Limited Slip [message #75030 is a reply to message #75007] |
Fri, 26 February 2010 17:41 |
Firefly
Messages: 98
Registered: May 2008
Location: Augusta, Maine
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JimK:
Is this a torque sensitive (geared or clutch-based) or speed sensitive (clutch pack)?
Thanks,
Mark
Mark Scoble, Lunenburg, MA - 1973 23' Palm Beach Stretched to 32' and in residence at the GMC Co-Op in Orlando, FL
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| Re: Limited Slip [message #75035 is a reply to message #75007] |
Fri, 26 February 2010 18:43 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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I think that with light steady power applied, both wheels will pull you in the direction of the steer. Beyond that with heavy wheel spin you will loose steering. I would think it would be like a 4 x 4 in heavy snow where adding a little throttle pulls you through straight. It's like very light drifting but controlable and predictable. I think FWD on the GMC is great due to all the benefits long list we all know about and it worked out for the TZE package to be what it is. However I think that FWD overall was just a cheaper way to make smaller cars and save money by eliminating expensive parts and is basicly "wrong". If you believe that form follows function and Darwin's survival of the fittest and design emmulates nature---- name me one land animal that has evolved and survived that is not either rear wheel drive or all wheel drive. Waiting........... there are none. Also is NASCAR front wheel drive even on the body styles that are in real life? how about Indy, F1, dirt track etc. In Chicago this week big news is a cop died in a pursuit on Lake Shore Drive wrapping his FWD Impalla (not a RWD Crown Vic) in half on a tree. In my mind he would still be here in the more predictable RWD vehicle. Not good at the edge of the envelope with FWD.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Limited Slip [message #75042 is a reply to message #75007] |
Fri, 26 February 2010 20:19 |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
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John writes
>In my mind he would still be here in the more predictable RWD vehicle. Not good at the edge of the envelope with FWD
John, you have to remember that auto manufacturer's business is built on volume, and also not unlike race cars, conformance to a set of "rules". Race cars, the rules are about performance, but in passenger vehicles, the rules, set by our government are all about fuel economy and crash safety. Starting in the late 70's most mass-market vehicles went to fwd because by getting rid of driveshafts, packaging room for a "live" rear axle, transmission intrusion into the footwells, and improvements in other dimensional issues, the outside of the vehicle and the mass could shrink while preserving interior room. With transverse fwd, there's an additional fuel economy improvement of around 3% by not having to "bend" the power 90 degrees in the differential. The fwd package also does well in crash, as the transverse powertrain (which is essentially incompressible) can be easily designed to go under the floor pan in a crash, allowing the front end sheet metal to compress. And, freeing up driveshaft and rear axle space, allows for more favorable fuel tank location with regards to crash impact. So, it's considerations other than driving dynamics (or cost for that matter) that drove the big push to fwd.
As far as predictable handling, fwd is about as boring and predictable as you can get, with both the driving wheels and the center of mass well forward, under a wide range of vehicle loading or driving conditions it's always understeer. More or less throttle means a little more or less understeer, but not the huge state changes you get in a rear wheel drive vehicle with wheel spin. There are some forms of racing like professional rallying where a rwd vehicle doesn't stand a chance against a fwd one. That doesn't mean they are right for everyone, but for the "avearage" customer who tends to worry more about hearing their cell phone than driving fun, getting good mileage, and carrying a lot of grocery bags, especially in season climates, fwd is a very good choice.
Craig Lechowicz
'77 Kingsley, Waterford, MI
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| Re: Limited Slip [message #75046 is a reply to message #75007] |
Fri, 26 February 2010 21:58 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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I understand all the reasons you listed, I just gave it the short form answer which is for all practical purposes related to money. (IE to get the same crash results with RWD would be more expensive). Personally I just don't like driving FWD cars. When you were a kid did you build a go-kart from salvaged lawn mower parts? Was it FWD? I doubt it. (Sadly, in the TZE we don't benefit on the 3% rule and are probably at neg 3% with the chain and the diff.) With weight transfer working against you, you can only apply so much torque to FWD. I'm supprized my Darwin theory didn't get a Harrumph out of ya. You can't fool Mother Nature. She's always right in the long run. In the case of our FWD, it really all worked out with the high front office and the low main floor, despite it's sometimes quirky behavior. To me learning to drive in RWD it is a lot more predictable especially in snow. I'd rather be able to modulate my rear swing with a throttle than have the front end learching, jerking the wheel and moving sideways into the next lane. Not for me.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Limited Slip [message #75047 is a reply to message #75007] |
Fri, 26 February 2010 22:32 |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
Karma: 0
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John,
Didn't mean the comment as a slam. What it amounts to is you actually know how to drive, and unfortunately, a lot of mainstream consumers don't. (or at least not very well). I was thinking about the cost trade-offs, and it's not a simple answer. FWD requires complicated constant velocity joints (and that transmission chain) and that's probably close to a wash with the cost of the rear axle parts (that don't make it into the fwd transaxle) and driveshaft of a rwd car. I'm not smart enough about body structure to know what the differences there amount to. Get to dump the trans crossmember on fwd, so that might help. If you are looking at unibody vehicles, the way they load the front cradles with all the powertrain is very efficient from an assembly standpoint, and doing the engine drop on rwd is messy. But, on a framed vehicle, it's simple to do without the body on, so there's some it depends there as well. Especially as I get older, I love that low step-in height on the GMC though.
Craig Lechowicz
'77 Kingsley, Waterford, MI
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| Re: [GMCnet] Limited Slip [message #75049 is a reply to message #75030] |
Fri, 26 February 2010 22:55 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Mark, it is not speed sensitive. It is dependent on input and out put torque.
I have yet to fully understand this unit enough to convey the way it works.
On Fri, Feb 26, 2010 at 3:41 PM, Mark Scoble <worldnet@aol.com> wrote:
>
>
> JimK:
>
> Is this a torque sensitive (geared or clutch-based) or speed sensitive (clutch pack)?
>
> Thanks,
> Mark
> --
> Mark Scoble, Augusta, Maine - 1973 23' Palm Beach Stretched to 32' and undergoing complete renovation at the GMC Co-Op
>
> _______________________________________________
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Limited Slip [message #75067 is a reply to message #75007] |
Sat, 27 February 2010 08:32 |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
Karma: 0
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Matt wrote:
>In student pilot days is was taught by an instructor that I very much respected that a
>truly superior pilot (goes for most pilots - air, land or water) uses his truly superior
>judgment to preclude the likelihood having to demonstrate his superior piloting
>skills. It is a thought that has been with me at many good times.
I've never been a pilot, but was in a ski club with a bunch of really neat older pilots for some time. (Most of them were late 60's or better) and they often said, "There are old pilots, and there are bold pilots, but there are no old, bold pilots."
Craig Lechowicz
'77 Kingsley, Waterford, MI
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| Re: [GMCnet] Limited Slip [message #75134 is a reply to message #75116] |
Sun, 28 February 2010 07:31 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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| jimk wrote on Sat, 27 February 2010 21:46 |
I guess I must.
On Sat, Feb 27, 2010 at 7:10 PM, Larry <weidnerl@wwt.net> wrote:
>
>
> jimk wrote on Sat, 27 February 2010 19:39
>> We went for a ride in the rain today and pushed it hard.
>> I think we have around 10-12 units with LSD (limited slip
>> differential) out there.
>> I'm installing one in our 540 Cad GMC.
>
> And.......your ride in the rain.....????
> --
> Larry  :)
> 78 Royale w/500 Caddy
> Menomonie, WI.
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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ARRRGGGG!!!
What did the ride in the rain tell you???....Geeeesssee!
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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