Olitho

I need to service my differential on my T1 car.

I was out running Horse thief Mile at Willow Springs this past weekend. It is an extremely tight track, the tightest I have ever run. The average speed for the fastest cars and drivers is only 60 MPH.

The problem I experienced was pulling out of the point and shoot corners on this track. I would get a lot of wheel spin primarily from my inside right rear tire. I just could not get good drive up the hills out of the corners, especially if it is a right hand turn.

Do any of you know if there is a special diff set-up that works best for the T1 configured cars. Should the diff be looser... tighter?

I don't think I am allowed to use any parts other than the stock parts when it is serviced/rebuilt. I am going to go take a peek at the rule book now.

Your words of wisdom are appreciated.


Oli

BuckeyeZ06

Rear diff is "open" in T1; so you are not restrcited to stock replacement parts.

Do a simple diagnostic test: jack one side of the read up. With the car in neutral turn the wheel in air with a torque wrench. That wheel should take 80-85 lbs to spin if the diff is working properly.

There is a recent thread on this site about a vendor who is offering Quaiffe diffs. Nice units, consider that as an alternative.

DMP

Olitho

Hey thanks Buckeye, you are the best. I had heard about the Quaiffe's, but I was assuming they are not allowed. I hear the Quaiffe is very durable and performs well on the track. I guess the Viper guys are using them and Porsches have used them for a long time.

I am going to do some searches and educate myself on this diff product.

gkmccready

Wow. So the top T1 teams carry a bunch of aftermarket rear gear ratios around to pick the best gearing for any particular track?

AU N EGL

and trans too. The MN6 was used more the the MN12.

BuckeyeZ06

Let me be clear: the rear gear ratio must stay stock in T1. With the C5 it is a 3.42:1, with the Viper it is a 3.07:1. These cannot change.

Olitho

Thanks Buckeye, I was not going to change ratios at all so I should be good to go. I am just hoping Orange County Corvette can get my baby fixed before WSIR this weekend.

I Googled around for Quaife information. I found there site for North America and the online brochure makes some compelling promises. I tried to poke around and find more information about review on the use of a Quaife and how that might change the performance/handling of the car, but all I could find are dealers advertising them for sale and a few other not-to-descriptive posts. Does anyone have some reviews or detailed reviews about what I should expect performance wise?

Thanks,

Oli

Z11409

http://www.thunderracing.com/catalog...&vid=7&pcid=66

XPC5R

Quaiffes and Torsens generally reduce corner entry and corner exit understeer, as they remain relativley unlocked under deceleration, and distribute torque on acceleration better. Here is the link to the earlier thread on C5 units available now: http://forums.corvetteforum.com/show....php?t=1623506

Only downside is typically a lifted inside wheel will cause the diff to function like an open diff, as the system needs to sense some torque/traction from the inside wheel to work right.

Zip Corvettes

Oli,
I sell the Quaife unit and build the diffs. We can do what ever you like. I have one in stock if someone else is building the unit. As far as the breakaway torque on your diff, most stock C5's will be in the 40lb range once they are broken in, you will never see a used diff with 80lbs on it. We used to build a custom clutch setup that would have an initial 125-150 lbs until it was broken in and then it would stay at 70-75 until it was time to be rebuilt. We stopped building those once the Quaife was finished. That is the way to go. I can ship it tommorrow if you need it.
Thanks
Justin Abbott
Zip Products

wtknght1

Uh, not sure where you're getting that info Dave. Diff must be stock. There's nothing in the GCR that says you can use aftermarket parts...that I've ever seen. If you know where that is, please let me know.

davidfarmer

While ZIP builds great diffs, I think it is overkill for T1. You really don't have the torque (relative to grip) to need more than the OEM torque bias.

Just my opinion

BuckeyeZ06

Chris, the diff can be changed. Not the gears.

GCR 9.1.10 page 542:


b. Final Drive

1. Unless otherwise so noted on the Vehicle’s Specification Line, the differential ratio shall be as delivered as standard equipment by the manufacturer.

2. All legitimately classified cars in Touring Class are permitted a limited-slip differential (Quaiffe, Torsen, etc.). Locked differentials are not allowed.


Justin, I used a torque wrench and I think I got 80 lbs. I learned thi trick from Lance Knupp, and he learned from Kurt Omensetter. Maybe my memory is bad, but I don't think so. Yes, I will have to admit you have more credibility on this than I do.

emf

'07 GCR page 542 for Touring

At first blush, I'd agree that the OE diff could be replaced by an aftermarket LSD, assuming that the ratio is the same. Agreed, it may be an uphill battle if it's contested . . . . but since there's nothing in the C5's TCS and since the intent of an aftermarket LSD does not "additionally perform a prohibited function" . . . . .


Oli -- Sean's been working with Unitrax for his diff rebuilds + Quaife -- so far, looks like results have been good.

jlucas

Alternate diffs are definitely legal for Touring, just see the wording that was posted previously. I ran a clutch type (instead of the stock gear type) in the T2 S2000 car that I ran in 2005. The aftermarket clutch type for the S2000 had stronger & quicker bite in the dry or when lifting a rear due to having to use stock springs, but it was down right nasty in the wet.

Just because Spec Z06 (aka T1) hasn't seen to many of them, just about every car in T2 has a non stock unit.

Zip Corvettes

Buckeye, was that what it took to initially break it or constant. Not interested in what it took to initially break, we are looking at once it is broken loose. Really what we need to be saying in the correct terms are rotating torque.

Bimota Guy

Technically, a differential is the "thing" the ring gear bolts to. Sometimes the term is incorrectly used to mean the entire rear center section (housing, ring and pinion, and the, um, differential) and sometimes even the entire rear axle housing and "guts" in a live axle arrangement.

Hope that helps...

DTE Powertrain

Oli-
We produce a specific road racing differential assembly that uses a unique internal differential that allows for a 4-way adjustment of the units traits during entry braking, apex braking, exit acceleration and straightline performance. We have the only unit in the USA at the moment and we've been doing testing for the original manufacturer, for which they will be producing a specific internal differential for DTE only, based on the real-world data we've gathered from the track. It allows for nearly full wheel lock on entry braking for decreased braking distance for the same speed, it begins to unlock during apex braking to keep the tires planted at the apex of the turn, switches to almost full-open during exit acceleration so the car won't get loose while under power exiting a turn and as the car straightens out, it reverts to a pre-determined locking state for max. straightline performance

We feel this unit is better suited for road racing than the Quaiffe unit, as we have track data from that one as well. That unit does better on apex braking and exit acceleration than the stock parts, but it goes fully open on heavy decel braking due to it being unloaded and the rear of the car becomes very loose. The wheels alternate back-forth from a locked/unlocked state, causing the rear of the car to "wiggle" where braking distances are increased because of it.

We sponsor all three of LG Motorsports SCCA World Challenge C6-R Corvette's and these cars are the quickest they've ever been using our products in tandem with other mod improvements LGM has done to the chassis, braking, suspension and aero. The differential is quite innovative to say the least and it's really Indy-Car type technology...

Give me a call and we'll discuss it further if you wish.


Phil

Zip Corvettes

Interesting, Phil I also am familiar with that test. If you are going to use the negatives though share all the information. One it was a roll center problem in the chassis that could have been fixed, Two the car was a second faster. So the F1 technology are you using hydraulic actuated clutches? If so I am very interested in this and would be interested in purchasing for our race diffs.
Thanks
Justin
Zip

DTE Powertrain

First, I'm not going to disclose the chassis set-up of LG's race cars here publically online, nor in in private; as that is his proprietary information. If you want that information, ask him directly, but I seriously doubt that he will divulge anything.

Additionally, once the change to our differential was made, the rear end "wiggle" under heavy entry braking was corrected that Lou directly attributed to the function of the differential...... In fact, Lou disliked that unit so much, he switched back to the O.E. differential for the time being until our differential was used/tested, because the stockers were more predictable on decel to his preference, where the Quaiffe was not.

Secondly, I didn't state it was F1 technology, I stated it was Indy car technology. Those two types of cars are two completely different animals, despite them both being open wheeled chassis designs....

Lastly, I'm not ready to divulge this differential design entirely just yet, as it's still going through some testing phases. However, we've got it dialed in quite accutely at the moment and everything has progressed along better than anticipated.

I never stated that the Quaiffe differential wasn't a good design, only pointed out the unit we're testing/using operates a bit better for the intended purpose due to it's nearly infinitely adjustable combinations of 4 different facets of the differential. In fact, I think the Quaiffe differential would be suited quite well for drag racing, since it has no clutches to wear out. The sun-gear/planetary differential concept that Quaiffe, True Trac, Eaton and a couple of others have used over many years in their differential design (including our new model coming up) has been proven durable, but it does have it's limitations in a road racing application, as one can't easily be adjusted (if at all) to alter it's operating traits in 4 different ways as the unit we have.

The original thread poster requested information on what differential types are out these days and that's what we provided him, based on our extensive experience in this field with both types of these differentials. No matter what type he chooses, at least he has information that he can use to make an informed decision one way or the other.

Once we get these things some track time under our belt and it functions as we expect it to, than I'd be more than happy to speak with you regading their use in your products. Just give me a call.



Phil