What can I do that the zf can handle 850nm ?
Quife also not fit in a pantera.
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You need to speak with Butfoy. I'm not sure that you can increase power handling of the unit.
He's the one that said it isn't the HP but the torque handling is the limiting factor.
He was saying he used 550 ft-lbs as the guideline.
There are others here that have not blown the things up with a lot more power documented on dynos then that.
I suppose you just run it until you hear and feel the gaboom? Then you just dial down the power?
He's the one that said it isn't the HP but the torque handling is the limiting factor.
He was saying he used 550 ft-lbs as the guideline.
There are others here that have not blown the things up with a lot more power documented on dynos then that.
I suppose you just run it until you hear and feel the gaboom? Then you just dial down the power?
From what I know the ZF's are very strong , the German's have always a high security level from 100%.
Only see them destroyed when you jump on full trottle , the wheels comes lose from the road are spinning and when you come back on the road
give's a lot of stress for the gearbox.
Simon
Only see them destroyed when you jump on full trottle , the wheels comes lose from the road are spinning and when you come back on the road
give's a lot of stress for the gearbox.
Simon
Les Gray has a great story about Jim Click's GT-40 ZF getting destroyed with that exact maneuver. The rear wheels came up under full throttle, and when they came back down - BANG!
There's a lot more to the story that I will leave for someone else to tell....
Rocky
There's a lot more to the story that I will leave for someone else to tell....
Rocky
The ZF and stock half shafts are pretty darn tough as long as you don't abuse them.
Racing is hard on any gearbox I have 250HP and destroyed 3 gear sets my last race weekend, fortunately mine can be replaced in 45 minutes!
Julian
Racing is hard on any gearbox I have 250HP and destroyed 3 gear sets my last race weekend, fortunately mine can be replaced in 45 minutes!
Julian
The limits are around 500 rear wheel horse power, the instillation of big blocks is not being done anymore by aftermarket vendors, due to high TORQUE that was twisting off the Z.F output shaft among other problems. 600 H.P. at the flywheel.
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Question; what can done to improve reliability under racing conditions?
quote:Originally posted by pantera chris:
The limits are around 500 rear wheel horse power, the instillation of big blocks is not being done anymore by aftermarket vendors, due to high TORQUE that was twisting off the Z.F output shaft among other problems. 600 H.P. at the flywheel.
That's my understanding as well but there are a bunch of people running big cubes here. If they are breaking the ZF then they are keeping it secret?
This isn't a new concept though since 427 Fords were being installed in the Pantera since way back in the '70s.
The answer is no one knows for sure but if you break it, then there is a big "I told you so" that goes with it.
quote:Originally posted by Push1267:
Question; what can done to improve reliability under racing conditions?
I recall an article years ago in PI. There was a guy racing one with over 800 hp. He stated that he was going through ZF's until he put a cooler in. With being careful on launches and using a cooler he had not damaged the ZF since.
Cryogenic treating the components ( GT-40 program), the "Candy" racer runs a oil cooler driven off the right output with a pulley ahead of the half shaft turning the pump.
The cars prepared for the 1966 Le Mans win were the American developed MK11’s which were fitted with the 427 cu ins FE motor and Ford built T44 transaxle. Holman / Moody are making the original GT-40 from the original parts NOS or re fabricated the transaxle, Kar Kraft T-44 style 4 speed with magnesium case castings, ratios are changeable. This is the correct and original transmission for these cars.
The cars prepared for the 1966 Le Mans win were the American developed MK11’s which were fitted with the 427 cu ins FE motor and Ford built T44 transaxle. Holman / Moody are making the original GT-40 from the original parts NOS or re fabricated the transaxle, Kar Kraft T-44 style 4 speed with magnesium case castings, ratios are changeable. This is the correct and original transmission for these cars.
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quote:Originally posted by pantera chris:
Cryogenic treating the components ( GT-40 program), the "Candy" racer runs a oil cooler driven off the right output with a pulley ahead of the half shaft turning the pump.
The cars prepared for the 1966 Le Mans win were the American developed MK11’s which were fitted with the 427 cu ins FE motor and Ford built T44 transaxle. Holman / Moody are making the original GT-40 from the original parts NOS or re fabricated the transaxle, Kar Kraft T-44 style 4 speed with magnesium case castings, ratios are changeable. This is the correct and original transmission for these cars.
I wouldn't count too much on the t44 as being an alternative to most of us.
They wanted $995,000, for a "continuation" MarkIV, two years ago when I was at SAAC 39 at VIR.
How much is a transmission for it? Don't bother.
The only way you can get one is to buy the car and take it out. They wouldn't even talk to me about selling me parts.
Of course if your name is Shelby, Foyt, Andretti or Penske I'm sure something could be arranged?
The only discussion they would have about parts was that there were 7,000 pop rivets in a MarkII
"continuation" car.
Easy, precise shifting and no ham-handed abuse or showy 'getting-air' allows higher torque without breakage. Jr Wilson shifted slow & easy in his SS racer and had quite a run of successes with a 900-bhp big-block racer. In the past, Lloyd has made up critical ZF gears of even higher-grade steels than Ford specified back in 1970, for racers who routinely abuse their cars. Note that these upgraded parts are still 'real ZF gears' as supplied from RBT. And a ZF cooler may be of some value in real 1-hr-or-more races.
Bwahahahahaha. . . .
The real answer?
When I had my ring & pinion changed I asked Lloyd what power level the ZF could handle. Lloyd's answer? "I know people that can break an anvil in a sand box . . . " Basically he said if you drive like you want to break it, you will. Smokey burnouts and donuts are a no-no at any power level.
Drive it like you stole it, but carry a spare ZF!
The real answer?
When I had my ring & pinion changed I asked Lloyd what power level the ZF could handle. Lloyd's answer? "I know people that can break an anvil in a sand box . . . " Basically he said if you drive like you want to break it, you will. Smokey burnouts and donuts are a no-no at any power level.
Drive it like you stole it, but carry a spare ZF!
this got me thinking!
Given the ZF is the weak link, is there a way to limit possible damage. my first thought was torque limiting slip clutches, BUT then I though with modern engine controls, why not stutter the motor when torque exceeds the ZF's capability.
the most obvious condition would be a situtation where at full throttle the tires loose contact, then regain grip. a similair situaton was a very big concern to electrical generators, as the power produced by the driver far exceeds the iniertia of the generator when the electrical load is suddenly lost. their engine managent controls had a circuit called Power/Load unbalance, that would sense the sudden loss and stutter the engine immediately.
Surprisingly a google search came back with the necessary components to make such protection for axle drives is available from "automotive" speciilty companies. So I wonder if some auto my already have such control. Maybe it is an advance feature in traction control that is being offered now
Given the ZF is the weak link, is there a way to limit possible damage. my first thought was torque limiting slip clutches, BUT then I though with modern engine controls, why not stutter the motor when torque exceeds the ZF's capability.
the most obvious condition would be a situtation where at full throttle the tires loose contact, then regain grip. a similair situaton was a very big concern to electrical generators, as the power produced by the driver far exceeds the iniertia of the generator when the electrical load is suddenly lost. their engine managent controls had a circuit called Power/Load unbalance, that would sense the sudden loss and stutter the engine immediately.
Surprisingly a google search came back with the necessary components to make such protection for axle drives is available from "automotive" speciilty companies. So I wonder if some auto my already have such control. Maybe it is an advance feature in traction control that is being offered now
The zf was tailored to the 1970-ish version of the 351c.
Ford tinkered with the ratios such as the 2.41 vs. the 2.20:1 first gears, in order to reduce the likeliness of waranty replacements of the ZF.
There is documentation somewhere that Ford thought it likely that 1 out of 4 ZF's would fail under waranty and as a result recommended that Pantera dealers consider stocking them in the replacement parts department.
I saw quite a few NOS still in crates being "wholesaled out" in the late '70s.
I do not think that the waranty "concern" ever quite developed as Ford expected it to?
Having said all of that, the unit is designed for an engine that produces a max of around 550ft-lbs and horsepower of about the same.
I think that obviously they can and are run with much larger capacities but I think the key with that is you need to "pussy-foot" them.
If you stay with a 5.7 liter naturally aspirated engine and somewhere around 500 hp, you are in the ball park of GOOD longevity of the unit.
Things like safety wiring and messing around with better lubes are just going to help you out.
In fact, the cable shifter adds durability to it and certainly will help with the chronic second gear synchro issue.
Other then that probably go with a T44 if you can afford one and figure out how to put it into the Pantera chassis?
I would take a guess on the cost of one at around $35,000, considering you would HAVE to get one through Holman.
The only current users that can accurately comment on the longevity would be current racers. I haven't seen any bitchin' about breaking them but they may just break so much in race situations they don't even mention the ZF's breaking.
I'll bet they all have at least one spare.
Ford tinkered with the ratios such as the 2.41 vs. the 2.20:1 first gears, in order to reduce the likeliness of waranty replacements of the ZF.
There is documentation somewhere that Ford thought it likely that 1 out of 4 ZF's would fail under waranty and as a result recommended that Pantera dealers consider stocking them in the replacement parts department.
I saw quite a few NOS still in crates being "wholesaled out" in the late '70s.
I do not think that the waranty "concern" ever quite developed as Ford expected it to?
Having said all of that, the unit is designed for an engine that produces a max of around 550ft-lbs and horsepower of about the same.
I think that obviously they can and are run with much larger capacities but I think the key with that is you need to "pussy-foot" them.
If you stay with a 5.7 liter naturally aspirated engine and somewhere around 500 hp, you are in the ball park of GOOD longevity of the unit.
Things like safety wiring and messing around with better lubes are just going to help you out.
In fact, the cable shifter adds durability to it and certainly will help with the chronic second gear synchro issue.
Other then that probably go with a T44 if you can afford one and figure out how to put it into the Pantera chassis?
I would take a guess on the cost of one at around $35,000, considering you would HAVE to get one through Holman.
The only current users that can accurately comment on the longevity would be current racers. I haven't seen any bitchin' about breaking them but they may just break so much in race situations they don't even mention the ZF's breaking.
I'll bet they all have at least one spare.
Hi Peter -
There are a couple of the POCA Newsletters you might want to check out.
The Sept. 2015 issue has an article titled "Little Known ZF Facts", and has lots of good information. This article has some pictures of the BMW M-1 setup, with an oil cooler.
The Oct. 2015 issue has an article titled "How Many ZFs Were Made". This discusses the ZF generally, but has some interesting information on some other options that were tried , such as a Hall Pantera 3-Speed automatic transaxle, using Ford C-6 innards.
There is a bit of discussion of the rare Ford T-44 2 Speed crash box built for GT-40s by KarKraft. There is also a box from a Renault integrated into a Pantera at Steve Wilkenson's shop pictured in the magazine.
Unfortunately, none of the automatic options attempted, and discussed in this issue, provided robust performance with powerful engines, but it is interesting to see some of the design solutions.
Note that in this issue, you will find out own Simon joined the club in Oct. 2015.
There are a couple of the POCA Newsletters you might want to check out.
The Sept. 2015 issue has an article titled "Little Known ZF Facts", and has lots of good information. This article has some pictures of the BMW M-1 setup, with an oil cooler.
The Oct. 2015 issue has an article titled "How Many ZFs Were Made". This discusses the ZF generally, but has some interesting information on some other options that were tried , such as a Hall Pantera 3-Speed automatic transaxle, using Ford C-6 innards.
There is a bit of discussion of the rare Ford T-44 2 Speed crash box built for GT-40s by KarKraft. There is also a box from a Renault integrated into a Pantera at Steve Wilkenson's shop pictured in the magazine.
Unfortunately, none of the automatic options attempted, and discussed in this issue, provided robust performance with powerful engines, but it is interesting to see some of the design solutions.
Note that in this issue, you will find out own Simon joined the club in Oct. 2015.
Peter,
Having followed many of your requests for parts etc. what is your intended use of the car? Will you be racing it and if so what series? Many of the vintage racing outfits particularly in Europe are very strict in using original as raced in the day parts and configuration.
If it's not racing and you are just building a high HP street machine, how often will you use it in real anger? Yes there are other transaxle options available; Albins, Mendeola, Ricardo etc. but all cost $$ and will require some modifications to fit.
Julian
Having followed many of your requests for parts etc. what is your intended use of the car? Will you be racing it and if so what series? Many of the vintage racing outfits particularly in Europe are very strict in using original as raced in the day parts and configuration.
If it's not racing and you are just building a high HP street machine, how often will you use it in real anger? Yes there are other transaxle options available; Albins, Mendeola, Ricardo etc. but all cost $$ and will require some modifications to fit.
Julian
Hi GT4, can you translate you 880nm's to lbs of torque?
650 ft-lb.
Not to beat a dying horse, that is going to stress the Z.F. that has not had special treatment and is driven with those considerations. Greg Isokoff (sp) has or had a full racer with those numbers and he told me he had to go through many hardening of parts to make his trany survive, those that are familiar with his car know it is very fast....................!
ZF's from the "Ford Dealer" parts department were ONLY about $800 new across the counter then.
I know a few people that bought a few of them.
They weren't even worth fixing then.
I know a few people that bought a few of them.
They weren't even worth fixing then.
About 950 hp will do this with a standart zf .
Only 1 time full throttle
What about the mendeola transaxle ?
Renault is rated lower than the zf.
The zf is rated 500 nm torque max.
The Renault about 250nm.
Only 1 time full throttle
What about the mendeola transaxle ?
Renault is rated lower than the zf.
The zf is rated 500 nm torque max.
The Renault about 250nm.
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Peter,
You're assuming this damage was due to too much torque for the ZF to handle. Perhaps the person who rebuilt this particular ZF didn't know what they were doing. Perhaps the R&P should have been replaced when this ZF was rebuilt. There are too many variables involved to simply blame the design of the ZF.
It's my understanding that most ZF failures occur in racing situations and involve broken input shafts on cars with slick tires. On a street driven Pantera, the tires limit how much torque can be transmitted through the transaxle. A 950 Hp motor will simply spin the tires under full throttle.
The best transaxle option for you, without spending $$$$$, is probably a brand new RBT ZF.
You're assuming this damage was due to too much torque for the ZF to handle. Perhaps the person who rebuilt this particular ZF didn't know what they were doing. Perhaps the R&P should have been replaced when this ZF was rebuilt. There are too many variables involved to simply blame the design of the ZF.
It's my understanding that most ZF failures occur in racing situations and involve broken input shafts on cars with slick tires. On a street driven Pantera, the tires limit how much torque can be transmitted through the transaxle. A 950 Hp motor will simply spin the tires under full throttle.
The best transaxle option for you, without spending $$$$$, is probably a brand new RBT ZF.
Racing tires . The zf was rebuilt direct from zf.
I am looking to change my stock 4.22 ring and pinion to a 3.56 or 3.78 anyone got one? will swap or sell after change. Note it is a 25-1
Larry 772-284-0331
Larry 772-284-0331
It would be worth checking interchange between -1 and -2 on the ring & pinion with someone like Lloyd at RBT. Is it the -1 that has a shorter input shaft and uses an extension?
GT4, that picture is a mind blowing example of the ZF limits. I would contact Loyd as he sells many different racing transmissions, his father was the trans guru on the Shelby GT-40 program.
Chris,
I think GT4Peter's unfortunate experience is more of a lesson in how to service your transaxle than it is in the limitations of the ZF trans.
You'll recall when Peter bought this ZF it was essentially a box of parts. The pinion gear was pitted but he decided to save a few $ and see how long it would last. The first time he used it, he got his answer.
This is also a reminder to use a known expert when rebuilding your ZF. This means using the manufacturer (RBT) or one of a known handful of Pantera shops. Sure, there are lots of people that are perfectly capable of servicing a ZF trans but it's an expensive gamble if you aren't 100% sure of their ability. Don't just send it to a transmission shop. If I'm not mistaken, GT4Peter used an ex-ZF company mechanic for his rebuild.
ZF "washed their hands" of our transaxles about 25 years ago. At that time they sold the rights, tooling and entire inventory of parts to Lloyd Butfoy's father, Roy. RBT has been the manufacturer ever since.
I think GT4Peter's unfortunate experience is more of a lesson in how to service your transaxle than it is in the limitations of the ZF trans.
You'll recall when Peter bought this ZF it was essentially a box of parts. The pinion gear was pitted but he decided to save a few $ and see how long it would last. The first time he used it, he got his answer.
This is also a reminder to use a known expert when rebuilding your ZF. This means using the manufacturer (RBT) or one of a known handful of Pantera shops. Sure, there are lots of people that are perfectly capable of servicing a ZF trans but it's an expensive gamble if you aren't 100% sure of their ability. Don't just send it to a transmission shop. If I'm not mistaken, GT4Peter used an ex-ZF company mechanic for his rebuild.
ZF "washed their hands" of our transaxles about 25 years ago. At that time they sold the rights, tooling and entire inventory of parts to Lloyd Butfoy's father, Roy. RBT has been the manufacturer ever since.
I agree, David. FWIW, with a very high torque engine, it's well known that the aluminum ZF cases 'spread' under load, moving the ring and pinion apart a bit and unloading the differential side gears- which usually fail. Originally, the GT-40 ZFs had cast aluminum side covers, no crossbolts in the access cover and no bellhousing brace-bolts. Those parts and more were upgraded to steel or cast iron in an attempt to stiffen up the ZF cases for LeMans, at the strong suggestion of Ford engineering. Ford went with a Collotti transaxle for the 427 GT-40s and had even more trouble with that POS.
IMHO, if you're going to go pro racing, use a pro racing transmission and put up with the fitment adaptions, shifting ills etc. The unsynchronized Hewland DG 300 (& others) was a popular replacement back in the day for F-5000, Can-Am etc, and the boxes wore out very fast but worked. Hewland is still in business in England and a quick Google search shows a few Hewlands for sale at ZF prices. There's no synchronizers because the gears are wider- which makes them stronger but requires even more care in gear-speed-matching than with the ZF.
IMHO, if you're going to go pro racing, use a pro racing transmission and put up with the fitment adaptions, shifting ills etc. The unsynchronized Hewland DG 300 (& others) was a popular replacement back in the day for F-5000, Can-Am etc, and the boxes wore out very fast but worked. Hewland is still in business in England and a quick Google search shows a few Hewlands for sale at ZF prices. There's no synchronizers because the gears are wider- which makes them stronger but requires even more care in gear-speed-matching than with the ZF.
All good points Jack, plus the added benefit of easily changing out gear ratios to match the various tracks.
My last race weekend in Sonoma I had the Hewland apart 3 times and back together ready for the next session. Try that with a ZF!
I seem to recall reading the later ADA Si Pantera ran a Hewland transmission?
My last race weekend in Sonoma I had the Hewland apart 3 times and back together ready for the next session. Try that with a ZF!
I seem to recall reading the later ADA Si Pantera ran a Hewland transmission?
This was not mine zf , youst one from a friend. I bought a new ring and pinion for mine. At this time, we are closer to make more than 800 nm hapen in a zf.
We tried to call rtb and zf direct , we also bought a quife and we did a lot of basic groundwork with the zf now. I am happy to say : we are able to do it better now !
Friends from a big austrian aircraft company redesign ring and pinion to a modern "klingenberg" theeth with a bigger area and some other oil skills , so that the peassure between the teeth is not to high. All the new parts we develop now are at minimum factor 1.5 better than stock. We also do a new aluminium housing in cooperation with zf . Also the ratio is changed to about 4.0 , I think its a nice ratio for the engines with more power than stock.
And yes , this all is done by us. One had worked at zf and have done maybe more than 100 25-2 ,
So he know everything about the zf. Also he have better sinter plates for the diferential. The man who develop the new ring and pinion works for more than 20 years in the car and aircraftindusteoe and develops several gears for turbopropengines or mercedes.
I am happy to initiate this all, If somebody like a new ring and pinion please pm me.
We tried to call rtb and zf direct , we also bought a quife and we did a lot of basic groundwork with the zf now. I am happy to say : we are able to do it better now !
Friends from a big austrian aircraft company redesign ring and pinion to a modern "klingenberg" theeth with a bigger area and some other oil skills , so that the peassure between the teeth is not to high. All the new parts we develop now are at minimum factor 1.5 better than stock. We also do a new aluminium housing in cooperation with zf . Also the ratio is changed to about 4.0 , I think its a nice ratio for the engines with more power than stock.
And yes , this all is done by us. One had worked at zf and have done maybe more than 100 25-2 ,
So he know everything about the zf. Also he have better sinter plates for the diferential. The man who develop the new ring and pinion works for more than 20 years in the car and aircraftindusteoe and develops several gears for turbopropengines or mercedes.
I am happy to initiate this all, If somebody like a new ring and pinion please pm me.
Ps : not only the zf housing is the problem.
The teeth are to hard. Ring and pinion is about 1.2 mm hardened. Sorry for my english.
This means that the teeth is hardened complete at the small side.
Here starts the damage. Small parts break out. The next damage is on the bearing from the pinion. The "play" between those parts getting bigger. Now its the time and its only a matter of time and it chrash. The housing problem have only rtb. Theire mould is not hot enough and the quality from the aluminium is ok but the have some problems . Old zfs or the new zfs for the gt5s should not have those problems.
The teeth are to hard. Ring and pinion is about 1.2 mm hardened. Sorry for my english.
This means that the teeth is hardened complete at the small side.
Here starts the damage. Small parts break out. The next damage is on the bearing from the pinion. The "play" between those parts getting bigger. Now its the time and its only a matter of time and it chrash. The housing problem have only rtb. Theire mould is not hot enough and the quality from the aluminium is ok but the have some problems . Old zfs or the new zfs for the gt5s should not have those problems.
some intersting comments about improvments to the ZF.
You mentioned harding depth...I would assume with new manufacturing techniques this depth is better controlled thus given the wear surface but keeping a ductile core.
I am not familiar with the klingenberg profile.
Do you know if the work (with explainations) being done will be made public. and the improved ZFs be marketed
You mentioned harding depth...I would assume with new manufacturing techniques this depth is better controlled thus given the wear surface but keeping a ductile core.
I am not familiar with the klingenberg profile.
Do you know if the work (with explainations) being done will be made public. and the improved ZFs be marketed
Yes, the harding depth is the major problem. Back in the days, they can not control the "hardening" so good, so its getting to deep. This lets the bearing failure. I hate this bearing , because the size is terrible: 83 x 46 x 25 mm and they are hard to find .
Peter, that's very interesting.
Please continue to keep us updated on your work on the transmission, including parts availability and prices.
Sounds like a brutal Pantera you guys are working on - any pictures and details?
Please continue to keep us updated on your work on the transmission, including parts availability and prices.
Sounds like a brutal Pantera you guys are working on - any pictures and details?
hi Push, yes we have some crazy people here in Austria :-) But in fact, the last zf , I have rebuild here was from 1972! The ring and pinion, states the date also and it was from 1972!
I think in the near future the ZF "problem " will grow up ! The engines are stronger than in the past and the zf´s are getting older and older.
We have worked out that our new Ring and Pinion have a live time from 32 000 hours @ 141 nm and 4500 rpm. But with 9000 RPM and 700 nm it is dead after only one hour! The function is not linerar - its like a e-function. But our new Ring and Pinion is minimum 1.5 factor better than the stock one!
So you can imagine how long a old ring and pinion set works, when you drive hard with a 700 nm Engine! Maybe a couple of weeks! Friends with racing BMW M1 change every year the ring and pinion sets, because they do not want to have a big zf failure during the race! When you increase the power from the Engine, the zf is realy a weak point. Right now we collect orders for the new ring and pinion sets. The ratio is about 4.0 . price something arround 2500.- and 3000.- euros it depends on the quantity. please pm me, when you are interessed.
I think in the near future the ZF "problem " will grow up ! The engines are stronger than in the past and the zf´s are getting older and older.
We have worked out that our new Ring and Pinion have a live time from 32 000 hours @ 141 nm and 4500 rpm. But with 9000 RPM and 700 nm it is dead after only one hour! The function is not linerar - its like a e-function. But our new Ring and Pinion is minimum 1.5 factor better than the stock one!
So you can imagine how long a old ring and pinion set works, when you drive hard with a 700 nm Engine! Maybe a couple of weeks! Friends with racing BMW M1 change every year the ring and pinion sets, because they do not want to have a big zf failure during the race! When you increase the power from the Engine, the zf is realy a weak point. Right now we collect orders for the new ring and pinion sets. The ratio is about 4.0 . price something arround 2500.- and 3000.- euros it depends on the quantity. please pm me, when you are interessed.