Salisbury or Quaife ATB?

[Brian S.]

My name is Brian and I am the powertrain captain for Drexel Racing. After a disappointing season, the team is considering a complete redesign for Drexel's next car. One of the decisions on the table is the differential. We currently run an ICP Variloc Salisbury-style differential. We had purchased a Taylor Race MK2 which features a Quaife ATB for our hybrid/electric team recently, but only two senior design teams worked on it and only did theoretical work. Consequently, we now have the option to use either diff, but I am not sure which one suites our needs better.

Since the Variloc is adjustable, it gives us many more options for chassis setup. However, we have not touched the diff since I joined the team three years ago and not much is known about it between all of the team members (including myself). I have no idea when the last time the clutch plates were replaced or the preload was checked. From our records we are running 80/80 ramps, so it is essentially set up as an open diff. We also do not have wheel speed readings (working on that) so the only way we can tune it is through driver feedback. Unfortunately, we currently don't have any experienced drivers that are capable of this.

This leads me to the Taylor Race MK2. For starters, it weighs 4 lbs. less than the Variloc. However, to my knowledge, it is not adjustable. This would require us to set up the suspension to work with the Quaife ATB, which I feel we are much more capable of doing. It also requires much less maintenance, which should save us time and money in the long run.

With these arguments, I feel the Taylor Race MK2 is the better choice. However, I am not sure if giving up the adjustability is worth it. Does my argument for the Taylor Race MK2 sound valid? Any feedback from teams running a Quaife ATB diff would be greatly appreciated as well.

Brian

[SNasello]

Your arguments all sound valid. It sounds like you have already made a decision.

It also sounds like no one in your team understands the pros of the salisbury diff, or how to maintain it properly. The question I have is, how adjustable is the Variloc? Do you have a bunch of different ramp combinations that you can build in? Different shims to adjust preload? Can you adjust preload externally? If the answer is no then you might as well be running an open diff, or anything else for that matter.

I would suggest doing some more reading on how the various options work, what the pros and cons are, and then think about what the best option is for your team.

[Brian S.]

Thanks for the response.

They have many different combinations of ramps available on ICP's website, and they will make custom ramps as well. However, I do not think we have any of them around at the shop. The pre-load is only internally adjustable using shims. It is a fairly out-dated design (I think we've had it since 2005, not sure though) and was designed for larger cars like Formula 1000. From the few times I've driven last year's car, I can tell that it could use a lot more locking on corner exit as it loves to oversteer.

Since our team has been one of those teams that is finishing their car at competition, having an adjustable diff doesn't really help. However, that is not a good enough reason for me because I'm going to do everything I can to make sure that doesn't happen this year.

I guess a better question is would maintaining and tuning our current diff be better use of our time than re-designing our rear shear-plate, diff hangers, sprocket, and half-shafts for the Taylor Race MK2?

[Jay Lawrence]

If you're one of the teams that finishes their car at comp, why not remove the complexity/mass/time/etc by running a spool. We ran a Torsen for several years (similar in properties I think to the Taylor) and only had issues with it when our setup was off (lifting inside) but then switched to a KAAZ Salisbury diff. It was lighter and more adjustable, but even with a month of tuning we didn't have time to tune it (there are many more aspects of the car that take up your time), plus it leaked. Since then the team has gone to a spool and it is working very well.

Can't comment really on the Taylor diff, but personally I'd remove adjustability from your criteria; it just creates more variability to try to tackle in a very limited time frame.

[Brian S.]

Thank you for your input.

The Quaife is similar to a Torsen but is better, according to Quaife's website. I really can't find much documentation on it other than general information on Taylor Race's and Quaife's websites. I understand the Salisbury better, but as you said, it may be above our heads to be able to tune it effectively in conjunction with suspension tuning. According to Taylor Race’s website, the Quaife works well with stiff springs and soft ARB’s, which is how our car is currently set up. I don’t feel we will be able to get our car working well with a spool, but we may consider it for our 2015 car. We are trying to not change too many things this year, but a change to the Taylor Race MK2 might be worth it for the sake of simplicity.

Does anyone have any more info on or experience with the Taylor Race diff/Quaife ATB? I’m going to contact Taylor Race to see if they can give me some more info on it.

[dmacke]

Our team has run a Torsen for the past couple of years and it has worked well for us. We were able to get it a bit lighter than the Drexler without issues and have been happy with our performance. Granted our team isn't quite to the point where we have the time to tune our differential so we haven't tried a Salisbury type. The Taylor Race is a good differential if you have deep enough pockets. Our team does not.

[jlangholzj]

Originally posted by dmacke:
Our team has run a Torsen for the past couple of years and it has worked well for us. We were able to get it a bit lighter than the Drexler without issues and have been happy with our performance. Granted our team isn't quite to the point where we have the time to tune our differential so we haven't tried a Salisbury type. The Taylor Race is a good differential if you have deep enough pockets. Our team does not.

I don't view our team as having "deep pockets" necessarily and we've got several. 2 of the original diffs with the aluminum center section as well as one of the new MKII's.

As a disclaimer, I've never worked with any of the other diff companies....HOWEVER...Taylor ALWAYS is around comps and will usually get back to you pretty quick on questions and parts ordering.

We chose the Taylor because I'm not entirely sure if we'll ever reach the point of needing to tune the diff. Hopefully this summer I'll get around to actually seeing what the slip% is around corners just to have it.

One last thing, wouldn't more lock on corner exit make oversteer worse? (just a question I have personally...Never really looked at diff tuning)

[dmacke]

Originally posted by jlangholzj:

I don't view our team as having "deep pockets" necessarily and we've got several. 2 of the original diffs with the aluminum center section as well as one of the new MKII's.

As a disclaimer, I've never worked with any of the other diff companies....HOWEVER...Taylor ALWAYS is around comps and will usually get back to you pretty quick on questions and parts ordering.

We chose the Taylor because I'm not entirely sure if we'll ever reach the point of needing to tune the diff. Hopefully this summer I'll get around to actually seeing what the slip% is around corners just to have it.

One last thing, wouldn't more lock on corner exit make oversteer worse? (just a question I have personally...Never really looked at diff tuning)

I guess you could classify our team as poor then. We would rather use the money saved from buying a $500 diff and some aluminum vs a $3000 diff on other areas of the car. Agreed on the part of tuning the diff. I don't see that as a point our team will reach anytime in the near future.

[Brian S.]

Originally posted by jlangholzj:
One last thing, wouldn't more lock on corner exit make oversteer worse? (just a question I have personally...Never really looked at diff tuning)

My understanding of it is that when both wheels are accelerating at the same speed (locked), they make the car want to go straight, thus reducing oversteer at corner exit.

[jlangholzj]

Originally posted by dmacke:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by jlangholzj:

I don't view our team as having "deep pockets" necessarily and we've got several. 2 of the original diffs with the aluminum center section as well as one of the new MKII's.

As a disclaimer, I've never worked with any of the other diff companies....HOWEVER...Taylor ALWAYS is around comps and will usually get back to you pretty quick on questions and parts ordering.

We chose the Taylor because I'm not entirely sure if we'll ever reach the point of needing to tune the diff. Hopefully this summer I'll get around to actually seeing what the slip% is around corners just to have it.

One last thing, wouldn't more lock on corner exit make oversteer worse? (just a question I have personally...Never really looked at diff tuning)

I guess you could classify our team as poor then. We would rather use the money saved from buying a $500 diff and some aluminum vs a $3000 diff on other areas of the car. Agreed on the part of tuning the diff. I don't see that as a point our team will reach anytime in the near future. </div></BLOCKQUOTE>

Geese now you have to go and make me feel bad macke! I understand how it is. I took us about 8 years of picking and choosing to get those three diffs!

Back on the subject of Diff tuning, thinking about it again it does make sens Brian. I was thinking more about when you lose traction how it tends to oversteer more. But relating back to driving hotrods with a spool....they don't want to corner that great!