Mitsi_Itsi
Probationary Member
- 15
- 6
- Mar 12, 2021
-
Amsterdam,
Europe
Hey guys, the time has come for me to switch to PPG gears on my 2G Manual AWD DSM, but I am faced with kind of a dilemma: What to do with my central diff? (This is not a "Spool vs 4-Spider" thread, please keep reading!)
As we all know PPG offers a Solid Spool Type and a Spider Type housing. The Solid Spool is extremely strong and gives a fixed torque distribution of 50/50, which is great for drag launches, but terrible for cornering and street applications. The Spider Type housing combined with a 4-Spider is also a very strong option, but a 4-spider is an open diff, so it will be up to the Viscous coupling unit to try to minimize the rotation difference between the front and rear wheels. That is great for street use and maintaining grip in corners, but not optimal for launches as the viscous coupling uses friction to eliminate rotational difference, once such a difference has occurred. Meaning that on the start line if your car doesn't have enough grip, it will still spin the front wheels and then try to bring the rear ones up to speed after you have already lost traction on the front.
Now because I'm the type of guy that wants the best of both worlds, I'm looking into options for using my Automatic Torque Biasing central differential from Quaife together with the straight cut PPG gears. Getting a straight cut housing for the Quaife diff will bring all the benefits of using a LSD and combining that with the strength and the shifting speed of the PPG gears. And as an added bonus, those differentials are known to strip the drive gear, which should not occur any more with the straight cut teeth.
I have already contacted Quaife and asked them if they will agree to produce a certain amount of straight cut housings for the QDH9B Quaife ATB Central LSD and waiting for their response. I will be posting any updates in this thread.
I have identified a few potential issues, so I would love to hear your opinion on those and any other concerns that you might have:
1. Purely political - Quaife may see PPG as a competitor company and may not want to support compatibility with a product coming from their competition. However Quaife does not offer straight cut gears for this platform, so there is no direct competition in this case.
2. Diff internals strength - The ATB Central LSD contains helical gears inside which are responsible for the torque distribution. Platforms using PPG gears usually make a lot more power than platforms with helical gears, it is possible that the internal helical gears of that diff cannot handle the big power and fail.
However I know a lot of other platforms, making big power and using Quaife differentials with the same internal design.
3. Housing strength - The different teeth profile can change the strength properties of the housing. Considering this is a custom request to Quaife, they most likely will not be able to properly test the strength of the new housing, so a warranty from their side might be out of the question.
4. Teeth profile - Quaife will need to match the teeth profile used by PPG on the Intermediate shaft. Not sure how difficult that is, but some reverse engineering of the PPG teeth profile will be needed here, so it might be up to our community to do so and passing the findings to Quaife.
I think the tooth count expected on the diff housing is a good start. Please correct me if I'm wrong, but I believe the PPG Spider Type housing has 28 teeth!
5. Minimum number of units produced - It might be the case that they only agree to produce a minimum of X number of units. If that is indeed the case I can organize a group buy and try to meet the minimum units requirement and reduce the production price.
6. Price - It simply might be to expensive for them to design the straight cut housing, which may result in very high price per unit. In my opinion as long as the housing price is not more than the price of the actual diff, it should be fine.
Considering the points above, there is a big chance that Quaife refuses to support our community with such a housing. If that is the case, but enough people show interest, perhaps we can find someone else to make the part for us. Any suggestions are welcome.
Or maybe someone here has the knowledge and access to machinery to manufacture such a part? Let me know!
In the meanwhile I would like to know how many people will show interest in a group buy, so I can let Quaife know what number range we are looking at. You can vote in the poll, or leave a comment
As we all know PPG offers a Solid Spool Type and a Spider Type housing. The Solid Spool is extremely strong and gives a fixed torque distribution of 50/50, which is great for drag launches, but terrible for cornering and street applications. The Spider Type housing combined with a 4-Spider is also a very strong option, but a 4-spider is an open diff, so it will be up to the Viscous coupling unit to try to minimize the rotation difference between the front and rear wheels. That is great for street use and maintaining grip in corners, but not optimal for launches as the viscous coupling uses friction to eliminate rotational difference, once such a difference has occurred. Meaning that on the start line if your car doesn't have enough grip, it will still spin the front wheels and then try to bring the rear ones up to speed after you have already lost traction on the front.
Now because I'm the type of guy that wants the best of both worlds, I'm looking into options for using my Automatic Torque Biasing central differential from Quaife together with the straight cut PPG gears. Getting a straight cut housing for the Quaife diff will bring all the benefits of using a LSD and combining that with the strength and the shifting speed of the PPG gears. And as an added bonus, those differentials are known to strip the drive gear, which should not occur any more with the straight cut teeth.
I have already contacted Quaife and asked them if they will agree to produce a certain amount of straight cut housings for the QDH9B Quaife ATB Central LSD and waiting for their response. I will be posting any updates in this thread.
I have identified a few potential issues, so I would love to hear your opinion on those and any other concerns that you might have:
1. Purely political - Quaife may see PPG as a competitor company and may not want to support compatibility with a product coming from their competition. However Quaife does not offer straight cut gears for this platform, so there is no direct competition in this case.
2. Diff internals strength - The ATB Central LSD contains helical gears inside which are responsible for the torque distribution. Platforms using PPG gears usually make a lot more power than platforms with helical gears, it is possible that the internal helical gears of that diff cannot handle the big power and fail.
However I know a lot of other platforms, making big power and using Quaife differentials with the same internal design.
3. Housing strength - The different teeth profile can change the strength properties of the housing. Considering this is a custom request to Quaife, they most likely will not be able to properly test the strength of the new housing, so a warranty from their side might be out of the question.
4. Teeth profile - Quaife will need to match the teeth profile used by PPG on the Intermediate shaft. Not sure how difficult that is, but some reverse engineering of the PPG teeth profile will be needed here, so it might be up to our community to do so and passing the findings to Quaife.
I think the tooth count expected on the diff housing is a good start. Please correct me if I'm wrong, but I believe the PPG Spider Type housing has 28 teeth!
5. Minimum number of units produced - It might be the case that they only agree to produce a minimum of X number of units. If that is indeed the case I can organize a group buy and try to meet the minimum units requirement and reduce the production price.
6. Price - It simply might be to expensive for them to design the straight cut housing, which may result in very high price per unit. In my opinion as long as the housing price is not more than the price of the actual diff, it should be fine.
Considering the points above, there is a big chance that Quaife refuses to support our community with such a housing. If that is the case, but enough people show interest, perhaps we can find someone else to make the part for us. Any suggestions are welcome.
Or maybe someone here has the knowledge and access to machinery to manufacture such a part? Let me know!
In the meanwhile I would like to know how many people will show interest in a group buy, so I can let Quaife know what number range we are looking at. You can vote in the poll, or leave a comment