ZFQ new proposed GT40 transaxle

[Chris Melia]

Hi Guys

We require your constructive opinions on a brand new proposed GT40 transaxle to be known as the ZFQ. The new transaxle is dimensionally the same as a ZF and will be able to be directly bolted in place of a ZF unit in a GT40. It will bolt to the GT40 ZF bellhousing and have CV output shafts as standard in exactly the same dimensional position as the ZF. The transaxle will be fitted with a Quaife ATB differential and will be rated at 550 Ft lbs of torque with a maximum of 600BHP. at 7500 RPM.

This new 5 speed full synchromesh transaxle will have a H pattern gate and will have both solid and cable shift options.


The proposed gearing is shown in the chart below but however custom gear sets and final drive ratios will be made available.




Differential: 4.22
Tire Diam: 26.9 PERCENT DROP FROM
1st Gear: 2.30 DROP 6500 RPM
2nd Gear: 1.54 0.670 4352.2
3rd Gear: 1.14 0.740 4811.7
4th Gear: 0.90 0.789 5131.6
5th Gear: 0.73 0.811 5272.2

SPEED IN GEARS (MPH)
RPM 1st 2nd 3rd 4th 5th
1000 8.2 12.3 16.6 21.1 26.0
1500 12.4 18.5 24.9 31.6 39.0
2000 16.5 24.6 33.3 42.1 51.9
2500 20.6 30.8 41.6 52.7 64.9
3000 24.7 36.9 49.9 63.2 77.9
3500 28.9 43.1 58.2 73.7 90.9
4000 33.0 49.2 66.5 84.3 103.9
4500 37.1 55.4 74.8 94.8 116.9
5000 41.2 61.6 83.2 105.3 129.9
5500 45.3 67.7 91.5 115.9 142.9
6000 49.5 73.9 99.8 126.4 155.8
6500 53.6 80.0 108.1 136.9 168.8

[Chris Melia]

Transparent image

[Gregg]

Chris it looks nice. What are the dimensions from the center of the cv flange to the bottom of the bell housing and the center of the cv flange to the top of the main box not including the mounting ears?

[Rick Muck- Mark IV]

Sounds interesting.

With the popularity of the SPF GT and other GTs as well a multitude of mid-engined kits, there would be a market so long as the price is in line with a RBT ZF.

Better torque capacity and durability would be a real advantage and selling point. A really beefed case with modern computer designed reinforcements would be real plus.

Rick

[BruceB]

Looks interesting

What sort of time scale is on this and as everyone will want to know is the price range that is likely for this box. I was talking to Quaife at the Motorsport show at the NEC and they are in the process of updating their MK1 transaxle at the moment which is a H pattern syncro 6 speed and similar HP rating.

[Chris Melia]

Hi Bruce

We are working with Mike Quaife on this transaxle hence the name ZFQ, the intention is to have a modern clean quick shifting transaxle that will take the extra loading produced from modern day large capacity powerplants.

We are trying to keep the price for this new generation ZFQ transaxle in line with the RBT Pantera unit.

regards

Chris.

P.S. Greg I will get back to you on your dimension question.

[Brett James-McCall]

Chris,
That looks a nice piece of kit in the pipeline.

Brett

[Bill D]

Could it be setup from the begining with fittings for an external pump/cooler?

[Chris Melia]

Hi Bill
As we are still in the design stage an external pump and cooler fittings can and will be included, thanks for the input Bill.
One good thing about this transaxle is that it was designed to run in the GT40 configuration from the start i.e. no flipping of the crown wheel and pinion and no requirement for internal oil drainage modifications. The ATB differential (Automatic Torque Biasing) not only optimises traction irrespective of conditions but operates without generating the heat normally associated with limited slip differentials, therefore reducing the heat transferred to the gearbox oil.

Regards

Chris.

[Gregg]

Hey Chris, No rush on the dimensions. After taking another look at the pictures, having the dimensions really wouldn't affect what I was thinking this morning. How difficult would it be for you guys to build some type of quick change of the gears into the box. I think the box would be more appealing to the guys who track their cars and would also give you an edge over zf as that option is not available. Just a thought.

[Ron Earp]

I think that transaxle would have legs far beyond the GT40 community, and that is a good thing for production numbers. I'd use one for my GT40 if the transaxle were available, and I bet a lot of other folks would too. The external dimensions being ZF will appeal to those wanting to replicate that ZF look, while the beefed up internals and approach to shifting will appeal to those that have found the ZF to be lacking in those areas.

Sand racers, mid-engine replicas of many types, one-offs, even possible integration into a mass-produced production car are all possible for a well done product. Clearly the price point would be dependant on numbers built. I think you could easily achieve some large build quantities with exposure and get the price down to at or slightly above ZF levels. As Rick said, that price is where it'd have to be in order to be a sellable product.

Ron

[DBLDREW]

My personal feeling is that the gt40 is a true 200mph car so the transaxle should be geared as such. Not to mention with your current configuration if you are cruising on the highway at 75 mph you would be almost at 3000 rpm.

I would like to see something around this configuration…

Tire size 26”
Rpm 6500
Final drive ratio 3.55

Gear – gear ratio- speed @6500

1st- 2.70- 52.5mph
2nd- 1.80- 78.7
3rd- 1.22- 116mph
4th- .90 – 157.4 mph
5th- .70- 202.3 mph

RPM drop per gear
1st-2nd- 2167 rpm
2nd-3rd- 2094 rpm
3rd to 4th- 1705 rpm
4th- 5th- 1444 rpm

This will get you a cursing speed at 75mph at 2400 rpm.

Now obviously I could care less what the actual gear rations and final drive ratio is, as long as it is similar to the speed per gear in my example. Another option is to keep your existing gear ratios and go with a 3.44 final drive ratio. This will put it right at 200 in 5th. But then you are running at 63 mph in 1st, which would be tall for street use, but on the flip side for track use it makes 1st a bit more usable.

So anyway in conclusion a 200 mph car should not be crippled to only run in the 160s

[Rick Muck- Mark IV]

Just to give you a feeling for the potential market of this unit, yesterday I spoke with Jimmy Price of Hi-Tech Autos (Superformance manufacturer) and they have received orders for GT40s that have now surpassed the total production of FAV/JW Engineering.....all in one year!

That many high capacity transaxles are used in sand rails and other off road competitions only strengthens the potential market for a product of this sort. I am sure some will continue to by a RBT/ZF but the advantages of this unit would woo many buyers. The downside is that 100 to 300 units per year still does not allow the automated tooling and production that could cut the price in half.

Consider that Tremec gearboxes can be bought retail for $1200-1300 range, now they are not as expensive to manufacture as a transaxle but if the market for a unit such as this were in the thousands per annum, the cost could possibly be in the $2500-3500 range with a fair return on the investment.

Remember you can put your production costs in two places: labor and machine time or automated tooling. The latter only works if the volume allows amortization of the up-front (and considerable) costs. Materials are the smallest expense in a product such as this.

I wish you good luck and hope it works out.

Rick

[Rick Muck- Mark IV]

Originally Posted by DBLDREW

This will get you a cursing speed at 75mph at 2400 rpm.

Personally, I curse at 85MPH........

Rick

[Chris Melia]

Hi DBLDrew

and thanks for your comments this is exactly the type of discussion I hoped to promote. As I previously said the ZFQ can be supplied with different gear sets and final drive ratios, below is the table with a final drive of 3.77 giving a cruising speed of 87mph at 3000 rpm and 189 mph top speed at 6500.

In reality I acknowledge that the GT40 is a 200MPH car but it runs into an aerodynamic brick wall at around 165mph even Roy Smart with 500 Bhp on one of the longest airstrips in the UK had trouble going 170 Mph +. A professional driver driving an original GT40 at this years Le mans classic said that now the Mulsan straight had checains installed that his decision to run the 3.7 final drive was the wrong one! and that next time he would run the 4.2.

I doubt that there are many people on this forum that would ever get the opportunity to exceed 170 Mph.

The choice of which final drive and gear set is still up for discussion and I welcome further comments on this as we need to come to a decision in the next seven days on this for the first 25 transaxles to be manufactured.

regards

Chris.



Differential: 3.77
Tire Diam: 26.9 PERCENT DROP FROM
1st Gear: 2.30 DROP 6500 RPM
2nd Gear: 1.54 0.670 4352.2
3rd Gear: 1.14 0.740 4811.7
4th Gear: 0.90 0.789 5131.6
5th Gear: 0.73 0.811 5272.2
SPEED IN GEARS (MPH)
RPM 1st 2nd 3rd 4th 5th
1000 9.2 13.8 18.6 23.6 29.1
1500 13.8 20.7 27.9 35.4 43.6
2000 18.5 27.6 37.2 47.2 58.1
2500 23.1 34.5 46.5 59.0 72.7
3000 27.7 41.3 55.9 70.7 87.2
3500 32.3 48.2 65.2 82.5 101.8
4000 36.9 55.1 74.5 94.3 116.3
4500 41.5 62.0 83.8 106.1 130.8
5000 46.1 68.9 93.1 117.9 145.4
5500 50.8 75.8 102.4 129.7 159.9
6000 55.4 82.7 111.7 141.5 174.4
6500 60.0 89.6 121.0 153.3 189.0

[Mark Charlton]

Chris,

Great initiative here. I hope it goes well as the GT40 world could use more options.

Not being an engineer, I don't know if it is possible with your design, but the Pantera world would surely also be interested in an alternative to the ZF. If your design would work (flipped?), I'm sure it would broaden the market substantially, with almost 7000 Panteras built and thousands still on the road, there must be hundreds that require new or rebuilt boxes and/or would want alternate ratios.

[Chris Melia]

Hi Mark

as Ron pointed out earlier this box will have legs beyond the GT 40 community and we have already decided to incorporate the Pantera mountings and the ability to run inverted for that use.

The other good point is that bellhousing for chevy are available already so opening the market demand further.

Its kind of ironic that we may be supplying GT40 boxes for Pantera's

regards

Chris.

[Straight 8 Racing]

Where were you a year ago ? After a long and painfull research programme I ended up buying a VGC to fit into a car we are building for the track. The rule book we have to comply with precludes sequential gear boxes, the HP/Torque we have precludes ZF