V1 Quaife Limited Slip Differential differences

[Cnixon160]

Does anyone happen to know the actual differences between the QDF17B and the QDF17B/23DG, their website is unhelpful and I have had an email in with their support for two weeks now with no response, the QDF17B is listed for the FWD Vauxhall Vectra and the QDF17B/23DG is listed for the Mid/rear Vauxhall VX220/ Opel Speedster both of which use the F23.

 

[Ross]

The QDF17B/23DG has 23 degree helix cut gears, and I'm guessing the other one you listed does not. Probably the usual 31 degree helix cut gears, but I couldn't find the specification anywhere.

Basically the two differentials have different Torque Bias Ratios.

Quaife said:
We do not use or quote TBR figures as they don't really mean much to anyone. The TBR is a very difficult thing to measure (we know this from our work with OEM diffs) and actually not very useful.

Essentially the TBR is a complicated way of comparing the helix angle of the internals (sun gears and pinions) and the vast majority of our diffs have the same angle internals although some of the very large and very small diffs have different angles. A few diffs have options (eg QDF9U) as they are used in different applications, i.e. QDF9U (31dg) in a Honda Civic Type R or QDF9U/23dg in an Ariel Atom. If you put a standard QDF9U (31dg) in an Atom (very light mid engined car) the diff would push too hard for the amount of grip at the front.

... Good luck

I have noticed with the Quaife in my F35 goblin, I can push the front end when under full throttle. In order to steer, I need to get off the throttle. Just like a motorcycle under hard throttle. I believe my goblin has the 31 degree helix cut gears, as Quaife doesn't offer a choice for the F35.

 

[Cnixon160]

The QDF17B/23DG has 23 degree helix cut gears, and I'm guessing the other one you listed does not. Probably the usual 31 degree helix cut gears, but I couldn't find the specification anywhere.

Basically the two differentials have different Torque Bias Ratios.



I have noticed with the Quaife in my F35 goblin, I can push the front end when under full throttle. In order to steer, I need to get off the throttle. Just like a motorcycle under hard throttle. I believe my goblin has the 31 degree helix cut gears, as Quaife doesn't offer a choice for the F35.

So in short for donuts and other non-sense the 31° is going to "lock harder" as opposed to the 23° having more gradual lock properties and be more ideal for actual track usage? Also where did you find the helix info for either? My Google subscription hasn't been particularly helpful in this instance.

 

[Ross]

Yes, I think you have the TBR infomation right. Google found the specifications for me...here.
Also, I knew Quaife made a special helix angle for the Ariel Atom... so this discussion made sense to me.

 

[Cnixon160]

Yes, I think you have the TBR infomation right. Google found the specifications for me...here.
Also, I knew Quaife made a special helix angle for the Ariel Atom... so this discussion made sense to me.

Both good reads, I'll just risk it and get the QDF17B/23DG as it's intended for a rear drive setup, I'm only doing mid level AutoX stuff and maybe a track day 1-2 times a year so it's not critical, I'll message a vendor that carries both and see if they have a recommendation as well