Hi, I'm in the process of building my own transaxle and have a choice of using a LSD or an Auto Locker (Detroit style). The reasson for the choice is I have both but if I use the LSD I have to custom make Drive flanges and get some CVs and half shafts. If I go the other path (Locker) the CVs and half shafts I already have will work, The only experience I have with Lockers is from off roading and I Know they tend to push the front and make it hard to steer. I imagine with a mid engine car with 18" wide slicks they would have the same effect. I know guys who have used lockers in rally cars and saloon circuit cars and say they work great but these are front engine cars, Does anybody have experience with this, your thoughs would be welcome. Cheers Leonmac.
LSD vs Detroit Lockers
- Thread starter leonmac
- Start date
In street use - the clatter of the DL while going around slow-speed corners is little distracting... Racing - obviously - you really don't care...
However -
When I ran a DL in the 9" Ford differential in my SCCA American Sedan Camaro, I found the high speed corners (150+ mph) to be just a bit hairier as the DL would switch driving wheels as one would release and the other catch - This would happen so fast that I just perceived the car as being aero loose.. But then we had a bearing problem and brought out the spare diff which had an Auburn limited slip and it was a lot more stabile in those corners..
Just my opinion..
However -
When I ran a DL in the 9" Ford differential in my SCCA American Sedan Camaro, I found the high speed corners (150+ mph) to be just a bit hairier as the DL would switch driving wheels as one would release and the other catch - This would happen so fast that I just perceived the car as being aero loose.. But then we had a bearing problem and brought out the spare diff which had an Auburn limited slip and it was a lot more stabile in those corners..
Just my opinion..
Ron Earp
Admin
I've SCCA road raced (wheel to wheel) I suppose four types of devices in rear wheel drive cars (260Z and Miata): a welded diff (essentially how your locker will behave on the track), a clutch pack LSD, a Quaife (ATB, Torsen) LSD, and a viscous coupled LSD. I have a differential with one of each except for the viscous coupled LSD.
Of these my favorite is a properly adjusted clutch pack. It has great traction under power, turns correctly on decel, and is robust. Adjustable, works well, and you'll find most folks using these on the race grids.
The welded I grew to like but it has a few things that must be dealt with. First, as you've noticed, it will push the car. You can adjust your suspension and driving to take care of that. If you do you'll find it has fantastic traction and power application. Better IMHO than the clutch pack. But, there are drawbacks. It saps power in turns since it is always causing one tire to slip since there is no differential. On/off power transistions can cause the car to slightly change directions. And they are hell in the rain. Plus a complete bitch to push around in the paddock. However, I like the welded on big long tracks without a lot of turning, when it is dry.
The Quaife ATB (Torsen, goes under other names) works pretty well and I think a lot of guys start off with these when they begin to race. They require no maintenance, work reasonably well as far as putting power down. But they have draw backs in situations where one wheel is unloaded heavily or not in contact with the pavement - they don't work. You can adjust your suspension to minimize this but you might not like the results. You don't find many of these in use on the pointy end of the grid.
Viscous coupled LSD - this thing is basically only for street cars and to help a tiny bit in snow and rain. On the race track they get hot quickly and stop working. Not that they worked much in the first place. Not recommended for track work.
Of these my favorite is a properly adjusted clutch pack. It has great traction under power, turns correctly on decel, and is robust. Adjustable, works well, and you'll find most folks using these on the race grids.
The welded I grew to like but it has a few things that must be dealt with. First, as you've noticed, it will push the car. You can adjust your suspension and driving to take care of that. If you do you'll find it has fantastic traction and power application. Better IMHO than the clutch pack. But, there are drawbacks. It saps power in turns since it is always causing one tire to slip since there is no differential. On/off power transistions can cause the car to slightly change directions. And they are hell in the rain. Plus a complete bitch to push around in the paddock. However, I like the welded on big long tracks without a lot of turning, when it is dry.
The Quaife ATB (Torsen, goes under other names) works pretty well and I think a lot of guys start off with these when they begin to race. They require no maintenance, work reasonably well as far as putting power down. But they have draw backs in situations where one wheel is unloaded heavily or not in contact with the pavement - they don't work. You can adjust your suspension to minimize this but you might not like the results. You don't find many of these in use on the pointy end of the grid.
Viscous coupled LSD - this thing is basically only for street cars and to help a tiny bit in snow and rain. On the race track they get hot quickly and stop working. Not that they worked much in the first place. Not recommended for track work.
I used to think lockers were the bees knees over an LSD with pre load, if nothing else it made the car easier to push around the shop/pits! But you will have Russ to do that anyway.
If it was mine I would sell both & get a tru-trac or other brand of TSD, they seem to be virtually bulletproof, predictable & consistent in action & dont require any friction modifiers or special lube ( You might want to consider that if you plan on same lube for both sections of your TA. While the ones for cars with high HP do have a small amount of preload to make them function with one wheel in the air, that is minimal compared to that in an LSD type.
If it was mine I would sell both & get a tru-trac or other brand of TSD, they seem to be virtually bulletproof, predictable & consistent in action & dont require any friction modifiers or special lube ( You might want to consider that if you plan on same lube for both sections of your TA. While the ones for cars with high HP do have a small amount of preload to make them function with one wheel in the air, that is minimal compared to that in an LSD type.I had a clutch pack LSD in a BMW I used to drive pretty hard and it was great - good traction, good manners in the turns (when set with moderate break away), kept power on the loaded wheel when the other is in the air and overall pretty driveable. The car wasn't driven for a while and the clutches in the LSD froze together (corrosion) - essentially, a locker with full lock. It was much less driveable and predictable. I haven't driven the torsen type diff on a track but it works great in the AWD audi in snow and wet!!
There's a lot of discussion in this thread:- http://www.gt40s.com/forum/gt40-tech-powertrain-transaxles/20961-spools-welded-diffs-track-cars.html.
You'll note the comment in there that Denny was reputed to have said they used Detroit Lockers in their Can Ams.... Since you've already got the locker and you're building a McLaren, and it saves you extra work, I'd say its a no brainer. If it was me I'd use the locker. :thumbsup: You can always do the extra work, spend the extra money, going to Plan B later if you don't like it!
You'll note the comment in there that Denny was reputed to have said they used Detroit Lockers in their Can Ams.... Since you've already got the locker and you're building a McLaren, and it saves you extra work, I'd say its a no brainer. If it was me I'd use the locker. :thumbsup: You can always do the extra work, spend the extra money, going to Plan B later if you don't like it!
With regard to the Can Am's, many of these used the 'Weissman' locker which has no gears or plates and different to the Detroit Locker in construction & operation, but achieves a similar objective in that it wont 'push' in deceleration or under 'no load conditions. It is also IIRC the 'only' type fitted/used in the original T44 as fitted to MKII/MKIV. Pic attached of the unit in pieces from an unknown trans type which I found on an old since revised Weissman website page, I thought at first it was from a T44, but dont believe it is as Ring Gear appears to be a part of assy. Carrol Smiths books also mention the use of this setup on several occasions.
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Thanks for the input. As some of you know I'm using Nissan Patrol Diff and they have undeniably the best LSD around, they are not preloaded and use a System of a Square shaft in a Split housing. As the load comes on the shaft starts to turn and spreads the housing which loads the Friction plates and the more load the tighter the LSD becomes, Very effective and very strong. The locker I have is a "LOCKRITE" Which is a unit that goes into the open diff centre. It operates in the "locked mode" except when there is "NO LOAD" and one or other of the wheels is being pushed faster than the other, ie: the out side wheel in a corner, but as soon as power is applied it locks. So after hearing what you have all said I'm Leaning very much to the locker, thanks for the input. Leonmac
