ZF RBT vs. ZFQ
- Thread starter Alan R
- Start date
Thank you for the Pictures -Mac
My .02¢
I don't believe that the pinions trying to leave through the back-end of the gearbox.
If this was the case then the pinion support and bearings would not be doing there job.(under engineered for power.)
No matter Hypoid or Spiral bevel the Ring Gear is doing the deflection under hard acceleration.
From the little I know of the ZF box but do know of drivers using my transaxles and Porsche units.
I would say this is due to missing the shift to 2nd gear and hitting reverse.
If I understand the shift pattern of this and other gearboxes of this era.
I would love to inspect the carnage of a unit that has this dilemma to get a real feel for it.
Thanks :thumbsup:
Got any more?
Maybe of the rear cover and reverse gear.
The stuff near the rear cover.
Thanks mate.:thumbsup:
Well done DeLynn, correct. So it looks like the guy who did the drawings was thinking along Pantera lines at least!!
Two more Jay, they are all from another thread titled ZFQ Failure I think, there is more to this though , will post my thoughts later tonite if I get time, involves a bit of internet trickery..and posters editing posts
Two more Jay, they are all from another thread titled ZFQ Failure I think, there is more to this though , will post my thoughts later tonite if I get time, involves a bit of internet trickery..and posters editing posts
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Just a question,
Don't all transaxles fail at some point? Have we any evidence of this aprticular failure happening to any other ZFQ's or just this one alone? And as Alan stated before, this failure was addressed and a modified billet end became the norm on the last production run.
Why such torrid attacks against the ZFQ? From reading these posts and the words people use, someone like me would think they all blew apart as soon as you ran slicks. Is that infact the case?
Don't all transaxles fail at some point? Have we any evidence of this aprticular failure happening to any other ZFQ's or just this one alone? And as Alan stated before, this failure was addressed and a modified billet end became the norm on the last production run.
Why such torrid attacks against the ZFQ? From reading these posts and the words people use, someone like me would think they all blew apart as soon as you ran slicks. Is that infact the case?
"
Any transmission or Diff can be blown apart by application of power in the wrong circumstances, Ive seen standard cast iron [ not the Nodular Iron race versions ] Ford 9" diffs with the pinion carrier blown out the front with bolt thread boss's still attached in a similar fashion, one on a Chevette with SBC & 15" wide slicks in a standing start on uphill gradient, the other on a similar Trans Am car when the driver kept his foot on the throttle when forced over the ripple strip by another car, both cases I would say the incidents were the straw that broke the camels back as cars had many prior competition outings.
Jay, the attached dwg with comparisons between spiral bevel & hypoid pinions with the difference in tooth profile, helix angle & resultant thrust vectors should demonstrate why the hypoid setup would require a more substantial pinion load retention system. Yes there is a degree of Ring Gear deflection, but the pinion is wanting to get out as well! On deceleration the opposite happens & the ring gear trys to pull the pinion in to mesh, again in different amounts due to the tooth profile, hypoid distance & helix angle.
When DT930 posted his parts for sale [p6 Garage Sale-Parting out Quaife GT40 Transaxle] he was unable to post his pics, so Tom Leonard did this for him on a thread on this forum [ ZFQ Failure ], I read the posts on the for sale thread, then was making reply post #4 on the ZFQ failure thread, went back to the F.S. thread to check it & found it had been edited, lets just say that had I actually quoted the unedited F.S. post in my reply, things might be a bit clearer to everyone...
For my part, after 45 years in 'the trade' I find tracking down the root cause of a failure quite interesting and often its not the obvious.... in the pics of the ZFQ above for example the head of the bolt on the lower [ input] shaft has detached & left the bolt remains in the shaft... now did that happen if/when the pinion went out the back door, or was it the result of a massive overload to whatever of the five forward gears was engaged at the time or even in a prior situation- the helix angle of those forward gears helps to offset some of the load on the pinion thrust bearing [ assuming the artist who did the drawing got that bit right]
Any transmission or Diff can be blown apart by application of power in the wrong circumstances, Ive seen standard cast iron [ not the Nodular Iron race versions ] Ford 9" diffs with the pinion carrier blown out the front with bolt thread boss's still attached in a similar fashion, one on a Chevette with SBC & 15" wide slicks in a standing start on uphill gradient, the other on a similar Trans Am car when the driver kept his foot on the throttle when forced over the ripple strip by another car, both cases I would say the incidents were the straw that broke the camels back as cars had many prior competition outings.
Jay, the attached dwg with comparisons between spiral bevel & hypoid pinions with the difference in tooth profile, helix angle & resultant thrust vectors should demonstrate why the hypoid setup would require a more substantial pinion load retention system. Yes there is a degree of Ring Gear deflection, but the pinion is wanting to get out as well! On deceleration the opposite happens & the ring gear trys to pull the pinion in to mesh, again in different amounts due to the tooth profile, hypoid distance & helix angle.
When DT930 posted his parts for sale [p6 Garage Sale-Parting out Quaife GT40 Transaxle] he was unable to post his pics, so Tom Leonard did this for him on a thread on this forum [ ZFQ Failure ], I read the posts on the for sale thread, then was making reply post #4 on the ZFQ failure thread, went back to the F.S. thread to check it & found it had been edited, lets just say that had I actually quoted the unedited F.S. post in my reply, things might be a bit clearer to everyone...
For my part, after 45 years in 'the trade' I find tracking down the root cause of a failure quite interesting and often its not the obvious.... in the pics of the ZFQ above for example the head of the bolt on the lower [ input] shaft has detached & left the bolt remains in the shaft... now did that happen if/when the pinion went out the back door, or was it the result of a massive overload to whatever of the five forward gears was engaged at the time or even in a prior situation- the helix angle of those forward gears helps to offset some of the load on the pinion thrust bearing [ assuming the artist who did the drawing got that bit right
]
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Seymour Snerd
Lifetime Supporter
Given that the Quaife web site says "Standard GT40 or inverted De Tomaso fitment" is this really surprising?
Also, by the way, one photo shows the head of the main shaft bolt and the other shows the threaded portion still in the back of the main shaft. Quite early in production Quaife started to fit a forged main shaft bolt rather than a machined main shaft bolt. As this was an early unit perhaps that is the root cause of the failure.
For anyone with an early unit interested in fixing this the part is "E-42G3-135 SHAFT CLAMP SCREW" item 71 in the QBE62G exploded drawing. It's relatively easily accessible from the rear of the transaxle after removing the bearing clamp tailpiece (eight M8 socket head cap screws).
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The billet replacement end cover should address those issues, remember the trans in pics above is/was an early production item, its worth noting that none of the studs appear to have pulled out of the main housing or is there any sign of distress to the main housing around those studs, only the cast end cover in the machined fillet areas you mention.
With regard to speculation about multiple failures or only this one, since the owner of this trans apparently never contacted Chris or Quaife logic suggests that there must have been at least an indication of imminent failure on at least one other T/A somewhere in the world with an owner who raised his concerns for the two fix's/upgrades to have been implemented, hopefully one would have been enough....
Alan, the info re the Pantera application on the site 'could' be interpreted two ways:
1. That there was going to be a R&P set to suit the Pantera Application with input shaft over pinion shaft ..
2. That Pantera owners would need to relocate the engine lower in the engine bay and use the GT40 type application .....
All depends on which way was/is up...
Seymour Snerd
Lifetime Supporter
Alan, the info re the Pantera application on the site 'could' be interpreted two ways:
1. That there was going to be a R&P set to suit the Pantera Application with input shaft over pinion shaft ..
2. That Pantera owners would need to relocate the engine lower in the engine bay and use the GT40 type application .....
All depends on which way was/is up...
Sure, although it seems to me their use of the word "inverted" excludes the second interpretation. But if not it wouldn't be the first time someone has said "yes our product can be used the other way as long as you can juggle standing on your head."
I purchased my ZFQ 2nd hand. Is the exploded parts diagram available as a download, or did you recieve it with the unit? Any other paperwork I should try to get?
Thanks, Cy
Yes, I would like to see an exploded parts view diagram of the ZFQ.
So to compare the ZF 5DS25/2 with the QBE62G.
If some one could point us in the right direction-Thank you
