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Straight cut synchronized gear box!

Posted by keltalon, Jun 22, 2018

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  1. keltalon

    keltalon Supporting VIP

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    Nice. What center are you running?
     

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  2. DSMReviver

    DSMReviver Proven Member

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    The same one that you are running. Oh, and PAR can adapt that housing to Quaife internals to make it a full Torsen center diff. Already talked to them about it. I was going to have it done but it wasn't on my priority list. I needed the 5th gear first.
     
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  3. DSMReviver

    DSMReviver Proven Member

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    PAR can convert their center diff to adapt Quaife internals. This in effect will make it a Torsen center diff. All they need is Quaife outer housing so they can machine theirs. I talk to them about it when I got their dog gears.
     
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  4. Canadian_CD9A

    Canadian_CD9A Proven Member

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    I could possibly live with a helical dogbox on the street, but I would be concerned about wearing out any dogbox from shifting it too much, and strength is a concern with any helical gear in our transmissions. Albins made a helical dog-box gear kit, but the ratios are stuuuupid short. On Evo final drive, it tops out around 118 MPH at 8,000 RPM. On a DSM, 130 MPH. Their 6 speed has a taller 1st than the 5 speed, and 6th gear is shorter than the 5th in the 5 speed. Weird stuff.
     
  5. donk

    donk Proven Member

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    Isnt THE Quaife center weaker then a 4 Spider diff ? /A
     
  6. Archer Fabrications

    Archer Fabrications Proven Member

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    Yesss!!!! 5 speed for life!!
     

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  7. Canadian_CD9A

    Canadian_CD9A Proven Member

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    Only because the gear on it was machined with too much backlash, it will eventually break teeth off. Change the gear, no more problems. I made a thread about this a couple years ago, I was considering getting Matthias Boldt to do it, but Quaife stopped selling the housings.
     
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  8. DSMReviver

    DSMReviver Proven Member

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    PPG advised their dog box will last 80k miles on the street with oil change and direct shifting. I don't see why PAR can't last just as long. Case in point most sports bikes are all dog straight cut transmissions. They outlast their high revving motors. These are oem dog gears directly from the manufactures. These bikes see at least 10k rpm shifts. Small motors but the principal/useage is all the same. Dog gear is fine for street use. I'm sure It will even outlast my motor.
     
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  9. DSMReviver

    DSMReviver Proven Member

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    With straight cut PAR center this will not be an issue. They said they can cut the internals to accept Quaife parts.
     
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  10. bastarddsm

    bastarddsm Proven Member

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    Go on queef UK's site and look at the print for the cd. Then notice how close the pocket for the lower planet gears are to the drive gear's root diameter. Now I'm not sure what they did, but there is a chance that the PAR's courser teeth has a smaller root diameter. See the issue there? Don't matter how big and gnarly the tooth is if it's attached to a piece of tin foil.
     

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  11. DSMReviver

    DSMReviver Proven Member

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    Quaife housing itself has not been a known issue. Some of the failures have been backlash teeth issue. Converting it to straight cut teeth with stronger case material from PAR will eliminate the durability concerns. PAR does use a stronger "CN" base material with extensive massaging to the alloy so it would be as strong as their gears.
     
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  12. bastarddsm

    bastarddsm Proven Member

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    The backlash doesn't. Matter when you attach a tooth to a piece of tinfoil
     

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  13. DSMReviver

    DSMReviver Proven Member

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    With all do respect, neither you and I have seen PAR Quafie center so assuming it is a tinfoil is not a fair assessment. We are talking about entirely new PAR outer housing and the design may very well be different from Quaife -the thickness-wise.

    I also have not seen Quaife housing fail. it is always the teeth that has a problem.

    Again it is my opinion.
     
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  14. bastarddsm

    bastarddsm Proven Member

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    Look at the drawing. That's all you have to do. The queef for a dsm is thin near the planet gears. It's not a backlash issue. That was a 15yr old theory. I even regurgitated that bad theory years ago. Then new info came about, I learned, and moved forward. I've seen the housings there is no meat under the teeth near the planet gears.

    It's like a dsm 4th gear they are way undercut, and loose whole teeth below the root circle. Normally a tooth breaks off above the root circle.

    Now unless par massively changed the center diff ratio, it's still a problem. We're talking huge like changing the CD ratio from 1.275 to somewhere in the 1.8 range. Which based on the gear ratios posted is impossible. There is no easy fix. You can't just move the planets due to space constraints.
     

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  15. bastarddsm

    bastarddsm Proven Member

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    Since you can go look yourself, I grabbed the drawing from. Queef. If you can't see the problem I can't help you.
    Screenshot_20180625-113420.png
     

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  16. bastarddsm

    bastarddsm Proven Member

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    The root diameter is 3.658, and the OD of the planet gear pockets is 3.440. How thick is the material at the root? . 050"? Might as well be tinfoil. It needs to be 0.250"+
     

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  17. ThunderChild

    ThunderChild Supporting VIP

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    Wow that is super thin, under .095 if I'm looking at the right spot, though it does look to be that thin only in certain areas. Still, seems like that could be disastrous.
     

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  18. 95REGF150

    95REGF150 Proven Member

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    Ya from the drawing it doesnt look like it is that thin all the way around. Just where the pockets for the gears are drilled. However it usually only takes 1 or 2 teeth to fail to cause the entire gear to get wiped out. General rule of thumb I have used when designing parts that get gears or splines cut on them is to keep the tooth height of the gear worth of material underneath it.
     

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  19. DSMReviver

    DSMReviver Proven Member

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    I'm not asking for anyone's help. It is my pure opinion and you have yours.

    Like others have said below your post. It's in certain areas where the worm gears are -that are thin. Not all the way around. This is exactly like the DSM center housing where cross shaft sits. Those areas are thin due to the space constraint of the DSM cross shaft. The material removed from these four posts can weaken even a stock housing (not to mention helical gear sideload). I count 2 maybe 3 warm gears inside the Quaife housing that may "weaken" the housing. We are talking about a better material PAR housing with straight cut teeth on the housing. DSM stock housing has 4 areas were it can jeopardize the strength of the teeth. People have gone 9's on 4 spider gear set up.

    My opinion is this PAR center Torsen is just as strong as stock if not stronger. I'm sticking to it.

    http://i62.photobucket.com/albums/h116/FastJetta97/CBR900/Galant VR4/P8251017.jpg
     
    Last edited: Jun 25, 2018
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  20. DSMReviver

    DSMReviver Proven Member

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    I agree with you. It is only thin in certain areas much like the dsm cross shaft sits in the stock housing.

    Yes only thin in certain areas.
     
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  21. bastarddsm

    bastarddsm Proven Member

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    I don't want to be a dick, but you clearly don't have a clue whats going on here, and your opinion is very very wrong. It's only as strong as it's weakest point. Neither the PAR nor the stock dsm housing has any area where the the gear is thin when machined for a 4 spider. They would fail very quickly.
     

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  22. DSMReviver

    DSMReviver Proven Member

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    I think you are wrong too and I am not a dick either. Unless you have broken a PAR center diff version I would slightly believe you.

    Lets agree to disagree. We are making an assumption on a PAR own design Torsen diff with better tooth profile and stronger material that does not even exist yet. When we just have theories on why Quaife fail.

    I am going to leave it here.
     
    Last edited: Jun 25, 2018
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  23. Mello

    Mello Proven Member

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    Why not send the Quaife drawing to PAR & let them determine the feasibility.
     
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  24. bastarddsm

    bastarddsm Proven Member

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    The problem is queef doesn't think that this is an issue, but it clearly is. I suspect PAR hasn't made one yet, which is why they still say they can do it.
     

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  25. mavericktsi83

    mavericktsi83 Proven Member

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    I know a couple ppl have talked to PAR and Matthias in regards to adapting the Quaife and Cusco CDs respectively and both manufacturers will not offer an answer by providing a drawing. A member on 4g sent a Cusco tarmac diff to Matthias to investigate the feasibility of adapting his straight cut gear and the inner radius and housing thickness was “risky”, essentially what Kurt is alluding to regarding the Quaife in this scenario. I have not seen a drawing for the Cusco but I assume the housing must be thicker than the Quaife in this respect because there are a few on Evo123 and 4g putting good power through them w/o widespread housing failure. Both housings are built from a superior high strength, case hardened material (as does PAR) and it is simply not enough to overcome failure with regard to the Quaife design/size constraints. Of course Quaife acknowledges no weakness in their product and shifts the blame to the Mitsu 3rd gear being the culprit as opposed to housing material thickness. There are other issues with the Quaife design too from a durability standpoint but the housing failure shows up first and resulted in a bunch of claims, and Quaifes not so compelling response and then warranty denial. The drawing suggests this is not necessary but there are some interesting papers on the subject of detail analysis on housing/housing foot requirements for planetary assemblies but the measurements required to calculate are extensive—similar modeling to what Kurt did when looking at the CD cross shaft.

    @keltalon which 3/4 hub/slider are you running? I see that the EvoIII hub/slider is obsolete…it’s my understanding that it is the one to have as it is forged. Does TRE have any left overs? The OEM DSM ones are cast and it’s my understanding that machining them down to accept dbbl synchros diminishes strength further. This would imply the still available unmodified/single synchro DSM small hub slider is superior in strength barring getting a hold of some new EvoIII ones or good used ones. I suppose this is just another common weak link but I raise this because it would suck to explode the 3/4 H&S and subsequently trash the PAR gearset and I am curious as to what TRE recommended and set you up with and what torque limit? I hope that the revised PAR gears are indeed stronger than the previous version too and you get some considerable miles/passes out of this setup. Subscribed.
     
    Last edited: Jun 25, 2018
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