Gripper Diff

[boldy205 75]

Hi, i have a gripper diff set to 30/60, and find the traction to be great, however, when applying the power mid corner (on track and road) the diff seems to wind up and pull into the corner, shooting the back end out in a

very aggresive manor indeed. If this happened every corner/in a predictive manor, then i need to learn the car, but this loads up and snatches so much so, that i dont have confidence driving it on track.

I am using 75/80 fully synthetic (std pug 205 box oil), the chap from Gripper Diffs, recommends 80/140fully synthetic LSD oil, would running the LSD oil reduce the snatching?

 

Many thanks

 

Matt

[Cameron 16]

What makes you think it's the diff that's at fault? Seems like there could be something else at work here, and the diff is just making it a lot more obvious, worn bushes / wishbones / ovalled hubs would be the first thing I'd check.

[oli-pug 6 2 Cars]

Wouldn't have thought the oil would make too much difference, it's always recommended to run the standard grade of oil in these gearboxes as well, no matter what diff you're using, so tread carefully.

 

I'd say that you need to look at your suspension setup further and check for play in balljoints, bearings and bushes as these could exaggerate the snatchiness if worn.

[boldy205 75]

previous to fitting the LSD the car was very tight/ precise to drive. All the bushes were very new and uprated, however, the wishbone bushes were a few years old and since fitting the diff i can feel very slight torque steer when playing the throttle in a straight line, maybe try new wishbone bushes then. Who on here has run specific LSD oil and found it better than std pug box oil?

 

Thanks

 

Matt

[oilman 7]

It might be worth considering a compromise with the oil, a 75w-90 LSD suitable oil like the Fuchs Syn 5 could be worth a go.

 

http://www.opieoils.co.uk/p-68901-fuchs-titan-race-syn-5-75w-90-fully-synthetic-gear-oil-was-silkolene-syn-5-75w-90.aspx

 

Cheers

 

Tim

[feb 47]

Isn't 140 going to be too viscous for the gearbox?

The oil will never get warm enough to justify its use IMHO.

I was using what oilman suggested above in my Quaife and never had any problems.

As already mentioned above I don't believe a change in oil would really change the way the car behaves though, what Cameron and oli-oug suggest could more probably be the reason.

Edited March 30, 2011 by feb

[tri_longer 25]

I'd concur with others on checking your suspension set up as I have had similar symptoms which turned out to be a combination of worn ball joint and an ovalled hub.

[boldy205 75]

Ok thanks for advice I will try new wish bone bushes and go from there. Has anyone here tried adjusting a gripper diff? I spoke to the chap, mr gripper, who was very helpfull, and described the procedure of swapping the wedges round? Any experiance of this ?

Many thanks,

Matt

[Anthony 1,003]

Two points further to the above:

 

Have you you driven a FWD car with a plate diff before? They are *much* more agressive than a Quaife ATB or standard open-diff, and stomping on the power mid-bend will pull the nose in and drag the car round the corner. As such, I find that you do need to adapt your driving to get the most out of it, and certainly need to concentrate and hold the wheel when pressing on.

 

A plate diff seems to highlight worn suspension / drivetrain parts and incorrect tracking compared to a normal open-diff, so it is possible that the car felt reasonable before but doesn't now.

 

As for oil, I just run Total BV 75W80 to suit the box/synchros and don't have any issues, other than changing it on a more frequent basis as a precaution.

[Cameron 16]

Yeah as Anthony says power oversteer with a plate diff is a common thing, made much more so if you have a stiff rear end (thick TB's / ARB or both). So it could well feel strange because you aren't used to it.

 

Before you go buying new parts, I'd get the car in the air and actually check whether you need them first. If you go through the faff of fitting new bushes it's pretty likely that that won't be the problem, then you'll be right back at square 1 blaming the diff.

[feb 47]

Anthony and Cameron, is there really power oversteer with a plated diff?!

Pulling the nose in, I don't mind but I don't want to get (unpredictable?) power oversteer.

 

In an AWD car power oversteer is easily controlled by staying on the throttle and opposite lock but I have never experienced such a thing in a FWD car (or knew that it existed TBH) so I am wondering if it is something that can catch you out.

 

The Quaife I had fitted in my previous car with the phase II SBC made the car fantastically balanced and predictable, yet still playful, you could still achieve long drifts if turning in early and braking simultaneouly, then powering on would drift you around a corner and pull you out in such a way I could not believe it.

 

I wouldn't mind a slightly more agressive diff but I don't want to spoil the balance of the new car that will have the same suspension hence the question.

Edited March 30, 2011 by feb

[Anthony 1,003]

"Power oversteer" is stretching the truth somewhat - it's still a FWD car at the end of the day after all.

 

It's more that the diff is vigorously pulling the front round the corner and dragging the tail round behind, which can slide out a degree or two (and stay there) when pressing on. Doesn't (to me) feel nervous or like it wants to spin though, and is still very much FWD rather than RWD/AWD in behaviour.

 

If I've got my car finished and on the road when you're next over, you can take it for a spin and see what you make of it

[feb 47]

Your description sounds good Anthony. I will take up on your offer, that will help me decide I guess!

Thanks

Edited March 30, 2011 by feb

[Cameron 16]

Yeah there is such a thing, not in a POWERSLIDE POWERSLIDE POWERSLIDE Jeremy Clarkson kinda way, but in a way that the car lightly oversteers when you get on the throttle mid-corner. It's really great once you get used to it, as you can completely direct the car on the throttle and little adjustments at the wheel, and he fact that the back end comes out a few degrees really helps you get on the power early when exiting the corner.

 

There's nothing unpredictable about it, as it happens when you apply the throttle you should be expecting it.

[boldy205 75]

Has anyone adjusted a gripper diff? I spoke to a guy at gripper and he said it's easy by changing the wedges when taking of the top plate? I have searched but no real info.

Thanks

Matt

[Cameron 16]

You need to buy new ramp plates (not sure if that's the proper name) first, they aren't something you can just adjust by taking the diff apart. It's nothing difficult really, you just need to either note down the order the bits came out in, or have a good memory, and make sure your work space and all your tools are VERY clean - same as any other engine or gearbox work really!

 

Typically you don't get much choice in ramp angles off the shelf, it's either 30/60 or 45/45. I'm sure Gripper would make you custom ramps if you requested them but you need a lot of experience before you can start to specify this, I'd just follow their advice.

[markw 1]

Boldy,

 

I have had three grippers now in various spec track cars, my latest is not yet finished but my previous had a 180hp 8v,

on gp A billies allround, 21mm TB and 23mmARB, and that certainly didnt oversteer, even when sprinting.

 

You may just have to get used to the way they drive when fitted with a plate diff.

[boldy205 75]

Thanks for the ideas, i have a set of new W/bone bushes to try, and will check everything over before the diff comes out/change oil.

 

Many thanks

 

Matt

[Cameron 16]

Check the hub carrier balljoint hole for oval while you're at it.

[markw 1]

Cam,

 

thats a good call, my car used to pull right under power and then turn left again when you lift off,

caused me a right ar*e twiching moment going down the m6 south/m1 slip road at cathorpe interchange

and thats before the diff was fitted

 

mark

 

ps a while later the lower pinch bolt area of the hub carrier broke off, on the 1st uphill corner at curbrough and

put me into the ditch