LSD for 016

Does anyone have any experience with the Phantom Grip LSD for the Audi 016? I did a search and found a thread that was a couple of years old. It sounds like back then a couple of guys bought them but hadn't tried them yet. Any updates? I'm planning a strictly street car with about 350 hp. I see the Quaife unit for about $1500 and I was hoping to find a lower cost alternative.

Thanks,
Charlie
 

Neal

Lifetime Supporter
I have about 30 miles on mine. Once the weather clears I plan to give it a more thorough workout on the road and track. I'll keep you posted. I don't think it will match a torque biased diff such as the Quaife but for road driving and lapping days the FG looks adequate.
 

Ron Earp

Admin
There is quite a bit of real world experience over on www.improvedtouring.com, a site I go to a lot. It is made up of SCCA racers racing in Improved Touring and more than a few have tried the FG. No good news on it though, everyone complained about the performance and a few blamed their diff failures on it, both front wheel drive and rear wheel drive users. In fact, there were two users here that had tried them and had failures, I think one Audo and one Renault box - search for them. Neither posted a lot, just I remember a brief update.

I've seen nothing good on serious use, but you can read over there and draw your own conclusions. In IT, if no LSD is available people just weld the diff instead of using PG, as the Phanton Grip seems to be not up to serious track use.

R
 
Since I am having one installed as we speak I'll chip in my two cents. If I was going to track my car on a regular basis I would not go with the PG. You can find much better units that are stronger and better suited for that purpose. But along with those units you need to add dollars. Lets face it, you can get an 016 for $275US, do you now want to drop 800 to 1500 on a LS. In my case the answer was no. The PG ran 350US plus anuther 200 having it put in, total investment $825.

As for how it performs, the people I spoke to who were using it in street applications with the occasional autoX for the most part had no problems and were happy with the way the PG performed.

One last point, the 016 is not known to be the strongest box around, if I was going to track my car it would not be my choice. I would get a Porsche box with LS and know that I had the correct combination.But since my car is for the street with the occasional track day, I feel that the PG will meet my needs.

Peter
 

Russ Noble

GT40s Supporter
Lifetime Supporter
So, does anyone with a GT40 have any experience with a welded diff as mentioned by Ron or a spool. Obviously not a realistic option for the road but how do they go on the track in something like a GT40? I'm thinking more about a hairpin corner, with the engine in the back and 10" and 14" rims is it possible to get the back out under braking into the corner and then hold the required attitude with power on or will it just go into massive understeer when the power goes on and the weight transfer takes effect? I suppose you could counter that by going in deep under brakes and cutting a late apex on the way out? What about turnin in the wet, can you get enough weight transfer to the front bearing in mind you are going to be running more brakes on the rear in the wet which will help anyway? Anyone with any practical experience?
 

Ron Earp

Admin
I was wondering about a welded diff in a 40 as well. I doubt it would work well.

The welded diff will want to cause the car to push. Add in some really sticky R compound tires and very wide rears and I would think this would put too much understeer into the chassis because the wide tires with weight on them will not want to allow the outside tire to slip as much as it ought to.

I've got two cars with welded diffs, but both are front engine/rear wheel drive. It works well on the track but I just don't know about a 40 or track or street. Pushing it around the paddock would be an absolute nightmare. It is hard to push these light 2200lb cars with weld diffs but they have much narrower tires and the outside tire will slip. Driving a 40 on the track with really wide and sticky tires it might not slip as it needs to but instead break something.

I agree with Peter's statements on the PG and cheap boxes, makes sense and might do well for less severe duty. I'll let you know how the 016 does on the track in about a year, I plan to bash it pretty hard. If it doesn't work, well, I can always go ZF.
 
I checked out the link to Improved Touring (thanks Ron) and they REALLY don't like the PG over there. Are there any other alternatives in between that and the Quaiffe? I have nothing against the clutch type, It seems to me that this type would be less costly to produce than the torque biased type.

Charlie
 

Russ Noble

GT40s Supporter
Lifetime Supporter
Ron,
On the track it is the unloaded inside tyre which slips, I don't think sticky wide rubber would make a lot of difference as it would allow greater forces to be generated, weight transfer forward under braking combined with transfer to the outside during turn in lightening up the inside wheel even more. I'm pretty sure you could tune it to suit by altering the brake balance ie Too much understeer during turn in could be tuned out by running more rear brake. Since everything is a compromise brake balance would then be adjusted to give optimum lap times which I bet would be faster than with a LSD This is slow corners, fast corners wouldn't be a problem.Out of interest I run a TR7V8 with a Powertrax No Slip, it is a locker that is either in or out, this works on a trailing throttle by allowing the outside wheel to speed up to negotiate a corner however when the power goes on and the inside wheel starts to spin it cannot be driven faster than the outside wheel because the diff locks. The best of both worlds really, being excellent on the track in wet and dry conditions and good on the road. At a recent local race meeting I was 9th on the grid after dry practice, during the wet race I came through to 2nd and set fastest lap so it's very drivable under all conditions.Pretty durable too so far. Unfotunately last time I looked they didn't have a listing for a Porsche.Probably because the preferred Porsche setup is 100% lock up on trailing throttle and 20-80% power on. The No Slip is obviously zero under trailing throttle, 100% with power on. I don't know whether they list an Audi application. Price was good too about US$400 I think from memory. It would be good if someone on the forum could find some No Slips that could be made to fit our transaxles. It can't be too difficult but being half a world away from where stocks are kept that's in the too hard basket for me.
Regards
 

Ron Earp

Admin
Hi Russ,

Sorry, that is suppose to be inside tire.

Regardless of the racing dynamics the welded diff has some issues in a turn no matter what the speed. What I am referring to is the problem that a welded differential has - if the car is turning left the inside tire, the left one, has to travel a short distance. The outside tire, the right one, has to travel a greater distance. They are both on the same axle and since it is welded they must turn at the same rate. The inside tire has to slip to accomidate this and I don't know if it will with a goodly amount of weight on the rear and wide sticky tires.

All I know is pushing a welded diff car around is REALLY hard and it makes awful noises as the tires slip. One can't help to think "this can't be good for the rear end...."

Of the welded diffs in place in SCCA IT racing I know of a few guys who break axles and other bits precisely because of this problem. Some rear ends can take it, others can not. We've got a welded diff in the Jensen and a LSD and welded for the Z car but both of these have pretty good rear ends. My guess is that a Audi 016 would not like a welded differential.

My business partner, Jeff Young, runs a TR8 in SCCA IT, 3.5L Rover V8, is yours the same? He'd be interested in hearing about this PowerTrax thing, I've never heard of it but it seems intersting.

Ron
 

Russ Noble

GT40s Supporter
Lifetime Supporter
Ron,
You're right it will load up the axles until you break traction.The problem is when you're on the limit and the inside wheel is very lightly loaded , the majority of the torque goes through the outside axle, this is worse than a full bore standing start because in a standing start the torque is split equally between the two axles.
My TR7 runs in classic racing here with a 4.9 Rover. I'm running an 8" Ford diff with the Powertrax.
For details on the Powertrax.Try

www.richmondgear.com

Also for a good overview of most of the locking diffs written by the designer of several of them.Try

www.darksiderz.co.uk/technical/lockers/

Regards
 

Russ Noble

GT40s Supporter
Lifetime Supporter
Hi Mark,
Many people have said exactly that to me. So far so good, nothings broken. When it does and I write the car off I'll let you know and you can say "I told you so!" However in the case of failure I am putting 100% faith in my reaction times and ability. If I'm wrong I will pay heavily!
Regards
 

Ron Earp

Admin
I think the welded diffs are good in race cars with a rear differential - that is, no transaxles. Don't know how they would work as far as reliablility goes in a GT40. That said, there are plently of FWD rabbits etc. that run welded diffs in SCCA IT racing and do really well. BUT - these cars are in ITC etc and only make about 100hp - a lot less than a GT40!!!!!

Russ, your car sounds cool but in IT we can't change the motor, transmission, etc. as we've got to run what comes in the car. Bummer!!! I'd like to have a drive in a TR8/7 with a 5L V8.

Good references, a locker seems to be a nice thing to have or use and I'd rather have it than a welded differential, that is for sure.
 
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