Has anyone had any experience with these 901 LSDs?

[KS]

https://www.3jdriveline.com/

Proper LSD as opposed to ATB type, look good, British made and a decent price...

Anyone had an experience?

Or how how about these? More expensive, though...

https://wavetrac.eu/products/wavetrac-a ... 14-1969-73

Or these?

https://gripperlsd.com/product/porsche-901/

[jwhillracer]

Hi Keith, I had a Gripper diff installed in my 915 gearbox for this season. I can’t fault it.
I asked them to set it up to the same spec as my old ZF, and if I hadn’t been there when it was installed, I would not have known that it was changed. The ZF was in a S/H competition 915 gearbox when we bought it in 1983, so I thought it was safer to retire it before we put 30% more power AND torque through it!
Cheers
JW

[jwhillracer]

PS, since my existing ZF will hopefully end up in our 914/6 gearbox, which should be an exact fit, then I guess it follows that the Gripper for the 901/914 box should be the same as the one I have as well.
JW

[Mike911scrs]

HI Keith/JW

the 914 box is a 911 box not a 901 box, the diff's are diffrent,

the 915 diff will fit the 911/914 box depending on whar CWP ratio you have and which LSD diff is fitted,

if you have a 7:31 CWP it will fit the 911/914 box , if you have a LSD from a 8:31 CWP box, then it is @2mm out on the fitting flange on the diff housing case if fitted to the 7:31 CWP into a early box,

the other thing to check is the drive-flange length into the diff, as the original/early ZF has longer shafts with corse splines, also NOTE; the STD diff out-put flanges are short and if fitted to this ZF diff will damage the diff actual LSD case/housing,

the later ZF (SC/3.2) with fine splines has short shafts

the LSD for the 911/914/915 box will NOT fit the 901 or the 1969 year change box.

the 3jdrive line diff is a good unit, had no isues with them, and is adjustable, in pre-load and ramp angles, also uses STD drive flanges, so strait swap

found the Wavetrack diff OK with no feed back on the ones fitted (so should be good??), only found there was no re-build parts available if needed when I asked (some time ago)

gripper, hummm (have not seen/fitted there latest diff so no feed back)

regards mike

[KS]

Hi Mike - my mistake! I keep saying ‘901’. Sorry about that!

Thanks for the feedback - once I’m back off hols (what promises to be a damp week in Brittany!), I’ll be in touch as I think I’m going to have to bite the bullet…

Cheers
Keith

[jwhillracer]

Hi Mike!
Thanks for your reply. My ZF is an original old one, we had to make a spacer years ago when we fitted the 8.31 diff. Will the standard 914 output flanges work with the ZF installed?
Cheers
JW

[Mike911scrs]

KS
you are thinking of changing to a plated diff, or wanting some adjustment in the take-off and cornering capability by adjusting the ramp angles and pre load, the suspension will need a tweek when fitting a plated diff to get the turn in, depending how tight a pre-load you have the diff set at

JW
if the ZF has corse splines in it, then the 914 shafts will FIT, BUT you will have to check the depth and may/will need a spacer under each shaft to get the runnimg/turning clearance on the shaft in the LSD, other wise when you fit the shaft and fit the retainer bolt it will just lock the shaft to the diff and on driving the diff will feel tight untill the LSD brakes the grip on the shaft and then the shaft come loose and damages the end/side of the diff,
a old STD Non lsd diff/crown wheel carrier will give you the parts needed, 1970 on

regards mike

[rhd racer]

I concur with the above Keith. I have a plated diff in the Boxster, and when originally fitted it was set up for circuits and it was impossible to manoeuvre in the paddock, onto the trailer etc and understeered into slow, tight corners. It was like running with a welded diff - the rear end of the car used to grown and hop, and make a god awful racket.

I had the ramp angles and pre load changed and it is like a different car, and there when you need it but not intrusive. Some found issues under hard braking with an LSD, but over lots of wet events I can’t say it has ever been an issue. I have a couple of competitor mates that speak highly of grippers but for different cars.


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[911hillclimber]

ATB in the Lola's 915 box, quiet, easy to paddock move etc and no wheel slip in/out of any hillclimb bend.

Came with the box Terry used when in the Nomad, but now n my 73T's mag case box which was donated to the Lola cause.

Mike Bainbridge passed no comments about them mind.

[Mike911scrs]

Mike Bainbridge passed no comments about them mind.

is it because he has a Quaife ATB in the box already???, I would think with the size of the rear tyres and grip you have on the back of the Lola, you may get away with a Std diff for hillclimbing, but compromise on reliability

also from the Wavetrac's site; Wavetrac - 40.309.140WK
Wavetrac ATB LSD for PORSCHE 915-18: 911, 930 1974-77

"Q" Is the Wavetrac differential a plate differential?
"A" No. It is an ‘automatic-torque-biassing’ or helical gear and pinion differential. So a ATB

Have you had a look at the Kaaz diff ? it is a plated diff, "911 (Coarse Spline 915MT) 1.5 Way Super Q- DBP3030" the diff will need re-jigging inside for the 914

regards mike

[rhd racer]

It’s a Kaaz I use in the Boxster


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[KS]

I’m familiar with the foibles of a plated diff compared to the ATB - my Carrera 2.7 had a factory- fitted ZF. It was very noisy at parking speeds…

As Mike says, I currently have a Quaife ATB which is fine in most situations but cannot stop the car spinning the inside wheel at both Sawbench and Martini at Wiscombe. As JW says, I must be losing a good half second or so struggling to get round Martini.

I’m impressed by what I see of the 3jdriveline unit and realise that this will mean some serious thought given to suspension geo. And learning to drive the car all over again, probably. But I’ve gone about as far as I can with the rest of the car, so maybe it’s time to get serious with the trans…

[camperco]

Probably the right time to to think about your CV joints sizes whilst you are at it Keith. The standard 914/VW Type 3 will be working very hard with 180BHP spinning the inside wheels. My 914 2.0 historic rally car used to go through them until I changed to 944/VW Type2 CV joints.