ZFQ Transaxle failure

[EGLITOM]

I would say it very much depends on the torque and RPM as well. TIrechoice is also a factor to think about ( width compound)

I´m currently on the search for a gearbox for BMW M1 with a turbocharged engine
750 HP at 8000 RPM, 650 Nm at 7000 RPM and it should be vintage (max make1985) too. Up to now the only options are Hewland LG500/600 or VGC.

Ricardos are told to hold that power up, but they are very big and ugly as hell, nor are they vintage.

A well built and improved 930 box could PROBABLY make it as well.

tom

 

[Jim Rosenthal]

The Pantera guys in the US run engines that robust, and their ZFs hold up. Maybe a ZF that is built properly is the way to go- it would fit from the beginning, unlike the others, and the linkage is already set up. You might talk to Dennis Quella at Pantera Performance in Colorado, I think his Pantera has that much power at least.

 

[Mike Drew]

The Pantera guys in the US run engines that robust, and their ZFs hold up. Maybe a ZF that is built properly is the way to go- it would fit from the beginning, unlike the others, and the linkage is already set up. You might talk to Dennis Quella at Pantera Performance in Colorado, I think his Pantera has that much power at least.

800 HP is pushing it a bit, but the ZF will withstand it IF it isn't abused. By that, I mean that it isn't speed-shifted, or you don't sidestep off the clutch in first gear, etc.

The Byars Brothers have been putting stroker 460s into Panteras, which is a big job as it moves the gearbox back far enough to require CV joints, because U-joint driveshaft angles are too acute. Engines as much as 572 inches (I believe) have been used, well up in the 700-800 hp range.

The guinea pig car for this conversion was seriously abused. Don Byars used it to show how much faster a Pantera could be, vice 'only' a 550 hp stroker Windsor or Cleveland. He would do burnouts and full-throttle launches from stoplights, again and again. Eventually the ZF cried "enough" and dismantled itself in the street. But Don freely admitted that he caused the failure, rather than attributing it to some defect or inadequacy of the gearbox itself.

Dennis Quella has a tube-framed Pantera replica track car, and he runs it really hard. But he's respectful, and doesn't seem to have any gearbox problems.

Gregg Esakoff drives his 750 hp race Pantera like "Animal" from The Muppet Show plays drums. He's REALLY fast and REALLY abusive, and he manages to break his gearbox in ways that nobody has ever seen before. He never uses the clutch, so it's no surprise when the thing only lasts a half-dozen events or so.

But the bottom line is, whether in a Pantera or a GT40, as long as it's subjected to no more abuse than the Ford teams dished out racing at Le Mans, they should be fine. And the reality is, if you're just driving on the street and/or the track, and not deliberately doing something stupid, the ZF will almost assuredly outlast YOU! :laugh:

 

[Tom]

I realize that this thread is only a month or so old, but have Quaife said anything about the ZFQ, or done a post-failure analysis of the broken box?

 

[Mark]

I'm with Tom.

 

[EGLITOM]

I'm with Tom.

with which TOm ?

TOM

 

[Mark]

BOTH as it happens. LOL

 

[Erik Johnson]

Hey there everyone,

I was curious if anyone knew how many of the ZFQ gearboxes are currently out there? Have there been enough sold to warrant making a billet replacement piece to address this weakness? Have there been discussions on modifying this piece in future generations of this gearbox to ensure that this does happen again, or is this thought to be an isolated event?

Thanks for any thoughts on this.

Erik Johnson
(928) 855-5755

 

[Keith]

Why don't you contact the makers/agents directly?

GT Transmissions - Quaife Engineering

 

[czan]

Maximum recommended 500bhp

QBE62G - Quaife Engineering
Check it out
Obviously NO MORE than 500bhp :furious:

 

Guys

the chap that owns this transaxle has not been in touch with either me or Quaife so we have not seen the unit or inspected it, as it is still in the US.
I know that he has a GT40r Superformance car with 10,000 miles on it, and the car has had a considerable amount of track time with several drivers including Jernalists. I understand that this failure happened after fitting large racing slicks and dropping the clutch, previously his road tires would give some compliance by spinning.
Its interesting that the Le Mans winning Audi cars of the last few years, had up to 10 transaxle changes in the course of one 24 hour race a distance of around 3500 miles or so.

From the photographs you can see in the top photo the sheared hexagon head of the main shaft bolt and the sheared thread in the back of the main shaft in the photo below. Quaife originally used machined main shaft bolts from their Porsche transaxles but these were upgraded with forged bolts with rolled threads and these can be obtained direct from Quaife for retrofitting.
Machined thread bolts have a drive slot milled into the head of the bolt and are located at the rear of the unit in the main shaft (lower shaft).

Most GT40s these days don't have any compliance built into the drive train, if you recall original cars had rubber doughnuts between the drive shafts and the gearbox output flanges. The clutch plate hubs were sprung loaded etc to remove snatch and to overcome the initial inertia from the drive train.
After one days testing with the prototype ZFQ we had to replace the drive shaft CV joints on a new Superformance GT40. Superformance have now fitted GKN drive joints as an upgrade.

75, ZFQ have been sold to date and they are specifyed in our Component Sign off agreement with R T Quaife Ltd as rated at 600Bhp and 550Ftlbs of Torque, the Quaife litterateur is misprinted.

It is true that the later units have the pinion shaft thrust bearing mounted in the front bulk head, this upgrade can be done on the early units if you require it; but the unit would have to be machined by Quaife or one of their service agents.

I would also like to say that I have herd of several ZF failures this last year including two in the same car, so its not so unusual for racing transaxles when handling high HP and torque loads to break,


regards

Chris.

 

[Gord Zonailo]

Hi Chris, thanks for your information and update re the Quaife component design spec.

You note that the later units have the pinion shaft thrust bearing mounted in the front bulkhead. My unit is identified as E62G 064 V9 and was purchased in March 2010. Does this unit have the revised design or not? What serial number was the design change made at? I'm sure that many others will also want to know.

Thanks,

Gord

 

[Keith]

Welcome back Chris, wondered where you'd got to..

 

[David Morton]

Chris - The only transaxle failure with an Audi at Le Mans was 2001 during the heavy rain. I have been part of that team every year including Bentley since the year 2000.
AND it did not fail - it was running with reduced shift time and loss of pressure about 3 hours into the race so we looked for a period of safety car running (heavy rain) and the job was done in 5minutes 15 seconds of which 4 minutes 30 seconds was in the garage. It was the leading car in the race and rejoined the race on the same lap as the safety car
after the transmission was changed. Incidentally the practice of having a "Dressed Transmission" is now against the rules because Peugeot appealed against it. And they are French. And so is the race. So each transmisson is marked and recorded and the car has to finish with the same unit as it started with 24 hours previously and that unit is the only one allowed in the car. It would normally be a fresh unit for the start of the race.

 

Hi guys

I have had a response from Quaife saying that they will be looking into a upgraded tail housing during the next couple of months for the older units. This would need fitment by an Authorized dealer.

regards

Chris

Audi @ Le mans http://speedhunters.com/archive/2009/05/01/retrospective-gt-gt-audi-at-le-mans-1999.aspx

 

[Tom]

Chris,

please read the 8th posting on this thread.

Tom

 

[wanni]

Chris - The only transaxle failure with an Audi at Le Mans was 2001 during the heavy rain. I have been part of that team every year including Bentley since the year 2000.
AND it did not fail - it was running with reduced shift time and loss of pressure about 3 hours into the race so we looked for a period of safety car running (heavy rain) and the job was done in 5minutes 15 seconds of which 4 minutes 30 seconds was in the garage. It was the leading car in the race and rejoined the race on the same lap as the safety car
after the transmission was changed. Incidentally the practice of having a "Dressed Transmission" is now against the rules because Peugeot appealed against it. And they are French. And so is the race. So each transmisson is marked and recorded and the car has to finish with the same unit as it started with 24 hours previously and that unit is the only one allowed in the car. It would normally be a fresh unit for the start of the race.

Anyway,
anyone of you Sirs, has the budjet and the rear of the car of Audi.
They replace the complete rear of the car ( GBOX + suspensions and accessories ) in less then 5 minutes because they knew they have to pay a non perfect reliability for the lighteness extremisation.
The comparison is out of questions.
Regards

 

[wanni]

QBE62G - Quaife Engineering
Check it out
Obviously NO MORE than 500bhp :furious:

500 bhp means nearly nothing.
The torque and the tire grip are influencing the reliability.
Engines with 500 bhp may have between 400 and 900 Nm.
Old style tires have 0.9 of friction vs the 1.4 of modern stret tires and 2.5 -3.0 of slick tires.
Regards

 

[Randy V]

Hi Wanni,

It's interesting... I've had this conversation before with other people that claimed to know what they were talking about (these people worked for Borg Warner).. My question was in regard to how they came upon a specific torque rating for a transmission.
The transmission was the Tremec TR3550. I believe it was "rated" for 450 Lb Ft of Torque.

My question was - how did they rate it? In what gear? Against a full stalled or locked output shaft? I asked 3 people and got 3 answers - none of them sounded fully plausible.

The way I see it - You can have 1,000 Pd-Ft TQ and if you don't have a tire that will convert that maintain traction, your actual loading on the gearbox is substantially less than the rated torque of the engine.

So - is there a secret? If it was a secret, you'd surely not tell me - but what I'd like to know is how transmissions attain their rated Torque Spec.

Thanks!

 

[wanni]

Hi Wanni,

It's interesting... I've had this conversation before with other people that claimed to know what they were talking about (these people worked for Borg Warner).. My question was in regard to how they came upon a specific torque rating for a transmission.
The transmission was the Tremec TR3550. I believe it was "rated" for 450 Lb Ft of Torque.

My question was - how did they rate it? In what gear? Against a full stalled or locked output shaft? I asked 3 people and got 3 answers - none of them sounded fully plausible.

The way I see it - You can have 1,000 Pd-Ft TQ and if you don't have a tire that will convert that maintain traction, your actual loading on the gearbox is substantially less than the rated torque of the engine.

So - is there a secret? If it was a secret, you'd surely not tell me - but what I'd like to know is how transmissions attain their rated Torque Spec.

Thanks!

It starts by calculating a suitable vehicle for the transmission in subject.
The important values are:
Power and torque data
Rear tires size and grip
Mass of the vehicle fully laden
Static weight distribution on the axles
Height of the centre of gravity
Aerodynamic drag
Frontal section area
The bevel set and the differential are calculated @ wheel spinning as well as the lower gears ( if sized @ nominal torque the GBOX becomes too heavy ) + 50 % for impact torque.
This result produces the maximum continious output torque value and the 50 % safety factor tells the maximum peak of output torque.
Generally the life for a transaxle for extreme supercars is settled up to 50.000 kms made by a 50 % driver. Track use is forbidden as well as the use with tires having a greater grip then the street legal tires. It is as well forbidden to use the transmission on conditions simulators ( roll test benches and high speed tracks with continious bankings ).
Out of this sizing we will have, for example:
Max input torque: 1.000 Nm
Max output torque: 7.500 Nm
Assuming ratios as follows:

1ST 3.133 – 2ND 2.100 – 3RD 1.520 – 4TH 1.172 – 5TH 0.941 – 6TH 0.784 – 7TH 0.675 - FD 3.454

the continious output torque in 1st gear would be 1.000 Nm x 3.133 x 3.454 = 10.820 Nm. But the rear wheels are spinning with 7.500 Nm. This means that in 1st gear it is not possible to transfer more then 690 Nm if the conditions are perfect. The 1st gear will then be sized for about 700 Nm.
Without boring you with further calculations, the gears from 3rd to 7th are sized for 1.000 Nm getting stronger and stronger increasing the gear ratio. In fact, the transitory time under load of the gears is short in lower gears, getting longer and longer by shifting up ( in 3rd gear, the time necessary to the engine to accelerate from 4.000 to 7.000 rpm is much much shorter then the time necessary in 7th gear to achieve the same work.
This is just the base of the theory. In facts, under load, the shafts are defletting with the consequence of changing the work conditions theoretically expected. That's why some profile corrections shall be made for assuring a correct mode of work between the gears.
Thermal extension is doing its negative job. The alluminum cases are extending exactly the double of the steel gearing. That's why the oil temperature shall be controlled to be always in the area of 70-90°C. Considering that the oil protective film becomes thinner by encreasing the temperature, it is clear that the oil shall not warm up too much, just enough to garranty confortable shiftings ( at the contrary synchro rings do not like fat oil.
Big ammount of input torque means that an appropriate clutch is trasferring it. As much as the clutch gets bigger, as much its inertia gets higher. This inertia shall be synchronized by the synchromesh system in order to keep acceptable the shifting time. This is the reason for multicones synchronizers. Obviously the clutch must be drag free.
What else ? Ask me.
Ciao