EOI: Custom Gemini diff conversion R&D and manufacture
EOI: Custom Gemini diff conversion R&D and manufacture
In the build of my turbo conversion, finding a suitable rear end has caused me no end of headaches. It is my assumption that there are many others out there facing similar dilemmas (based on the numerous topics regarding diff conversions, yet a lack of a common consensus on a viable option).
It's is my intention to share what I am planning on having built with you, and in return I need genuine of expressions of interest that will convince the company I am working with that this is a feasible business opportunity for them.
Although seemingly simple, the criteria for my rear end conversion were as follows:
1. Ability to handle a large hp/torque figure (250-300rwkw range)
2. Ability to be easily bolted into the Gemini, with the least amount of floorpan/driveline modifications (if any).
3. Have a LSD/Locker arrangement, of some description.
4. Ability to be easily engineer certified whilst fulfilling points 1, 2 & 3
Based on the above and my reading/research both within these forums, within other forums, with other Gemini owners outside of these forums and with various differential workshops around Australia, the option that best fulfilled my criteria is:
1. Strengthed Gemini torque tube as supplied and used by CRZYFJ, Bugzy and any other reputable engineering shop willing to do the work. The principle is all the same, an alloy/chromoly tube welded over the standard Gemini one.
2. Strengthened Gemini torque tube rubber. As we know, this is a common point of failure even in standard HP Geminis. This unit has much more surface area and is made out of a stronger, denser rubber
3. Gemini Diesel housing with standard gears. This rear end has been used by a selection of Gemini drag cars with a locked (welded or spooled) center with great results, most notably Michael Sheringham's CrazyFJ which ran a sub 9 second pass. The diff housing is a straight bolt in swap (bar some small things I am yet to look at like brake lines/handbrake cable) for any Gemini Sedan/Coupe.
4. Custom 28 spline billet axles. Although the Gemini Diesel axles are larger and subsequently stronger, in order to consistently meet criteria point #1 I have opted for the custom billet items
5. A custom LSD unit suit the Gemini Diesel housing and center. Based on the current research done by the workshop I am dealing with, an R33 GTR rear LSD has many specs that would make it an option. This would be alongside a suite of custom machined parts.
Obviously points 1-4 have been done numerous times already and have been proven to work. It is point 5 where the most R&D and custom machine work will be done, and thus where the most cost will be. Point 5 is still being investigated, and it is the genuine expressions of interest in this thread that will help push this forward.
All R&D and machine work will be done through Bosnjak engineering, based in NSW. They are renowned for building many high quality racing components and are highly involved in many race team's ongoing parts development.
Price wise, we are looking at somewhere between $2500 and $3000 for point 5. Although seemingly expensive, bolt in LSDs for other cars (such as those from KAAZ) are not much less pricey than this. Additionally, parts 1-4 can be purchased relatively cheaply - approx $300 for a Gemini Diesel diff, $150 for the torque tube, $100 for the torque tube rubber and $800 for the axles. Running a total not far off your common 9 inch/Borg Warner 4 link conversion.
This thread is not an opportunity for you to suggest why your <insert favorite diff> conversion is better than what I am detailing. It is to gain genuine expressions of interest in the setup I am describing and to provide additional details on this specific conversion where possible.
I open the floor......
It's is my intention to share what I am planning on having built with you, and in return I need genuine of expressions of interest that will convince the company I am working with that this is a feasible business opportunity for them.
Although seemingly simple, the criteria for my rear end conversion were as follows:
1. Ability to handle a large hp/torque figure (250-300rwkw range)
2. Ability to be easily bolted into the Gemini, with the least amount of floorpan/driveline modifications (if any).
3. Have a LSD/Locker arrangement, of some description.
4. Ability to be easily engineer certified whilst fulfilling points 1, 2 & 3
Based on the above and my reading/research both within these forums, within other forums, with other Gemini owners outside of these forums and with various differential workshops around Australia, the option that best fulfilled my criteria is:
1. Strengthed Gemini torque tube as supplied and used by CRZYFJ, Bugzy and any other reputable engineering shop willing to do the work. The principle is all the same, an alloy/chromoly tube welded over the standard Gemini one.
2. Strengthened Gemini torque tube rubber. As we know, this is a common point of failure even in standard HP Geminis. This unit has much more surface area and is made out of a stronger, denser rubber
3. Gemini Diesel housing with standard gears. This rear end has been used by a selection of Gemini drag cars with a locked (welded or spooled) center with great results, most notably Michael Sheringham's CrazyFJ which ran a sub 9 second pass. The diff housing is a straight bolt in swap (bar some small things I am yet to look at like brake lines/handbrake cable) for any Gemini Sedan/Coupe.
4. Custom 28 spline billet axles. Although the Gemini Diesel axles are larger and subsequently stronger, in order to consistently meet criteria point #1 I have opted for the custom billet items
5. A custom LSD unit suit the Gemini Diesel housing and center. Based on the current research done by the workshop I am dealing with, an R33 GTR rear LSD has many specs that would make it an option. This would be alongside a suite of custom machined parts.
Obviously points 1-4 have been done numerous times already and have been proven to work. It is point 5 where the most R&D and custom machine work will be done, and thus where the most cost will be. Point 5 is still being investigated, and it is the genuine expressions of interest in this thread that will help push this forward.
All R&D and machine work will be done through Bosnjak engineering, based in NSW. They are renowned for building many high quality racing components and are highly involved in many race team's ongoing parts development.
Price wise, we are looking at somewhere between $2500 and $3000 for point 5. Although seemingly expensive, bolt in LSDs for other cars (such as those from KAAZ) are not much less pricey than this. Additionally, parts 1-4 can be purchased relatively cheaply - approx $300 for a Gemini Diesel diff, $150 for the torque tube, $100 for the torque tube rubber and $800 for the axles. Running a total not far off your common 9 inch/Borg Warner 4 link conversion.
This thread is not an opportunity for you to suggest why your <insert favorite diff> conversion is better than what I am detailing. It is to gain genuine expressions of interest in the setup I am describing and to provide additional details on this specific conversion where possible.
I open the floor......
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Very very feasible option this. As when we spoke is the only way to run big power without doing a diff conversion and having to run that 3rd arm.
BTW who did your strengthened torque tube? That tig weld is nuts
BTW who did your strengthened torque tube? That tig weld is nuts
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WH Caprice daily driver- Tune, Exhaust, auto, stall, diff gears, Valve springs, U/Dirve pulley, OTRCAI 12.7@ 108 MPH
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as per first post:gemzilla1 wrote:for that price you can get a hilux conversion done by a shop...
japanese 9"
Cuz wrote: ......This thread is not an opportunity for you to suggest why your <insert favorite diff> conversion is better than what I am detailing. It is to gain genuine expressions of interest in the setup I am describing and to provide additional details on this specific conversion where possible.....
Been down this path already - dead end.tobytj wrote:Have recently found that YB Piazza rear disc brake units are interchangable with gemini diesel diffs. Axles are I believe also much the same.
I am wondering if the interchangeability extends to the LSD components of the diff? Could be worth checking.
also as per first post:
Cuz wrote: ........This thread is not an opportunity for you to suggest why your <insert favorite diff> conversion is better than what I am detailing. It is to gain genuine expressions of interest in the setup I am describing and to provide additional details on this specific conversion where possible......
Cheers mate. Only problem now is, as per the first post, getting enough genuine interest to show Bosnjak this is a feasible business option.macca_loto wrote:Very very feasible option this. As when we spoke is the only way to run big power without doing a diff conversion and having to run that 3rd arm.
BTW who did your strengthened torque tube? That tig weld is nuts
Torque tube was organised through crzyfj.
- redzone (coxy)
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alot of the conversions for the 9 inch and and hilux ive seen are very ordinary, heavy components breaking mounting points need of an engineers certificate. this is a great idea.
i would base it around the standard housing.
as far as billet axles i wouldn't bother unless you are on the upper end of the power scale and in that case maybe switch to a 31 spline axle.
after months of research im getting standard 28 spline axles machined and heat treated. when mine get back and i test them out ill post picsa and details this will save approx $700.
i would base it around the standard housing.
as far as billet axles i wouldn't bother unless you are on the upper end of the power scale and in that case maybe switch to a 31 spline axle.
after months of research im getting standard 28 spline axles machined and heat treated. when mine get back and i test them out ill post picsa and details this will save approx $700.
The Diesel gearset/crownwheel/pinion all all larger and subsequently stronger than the petrol Gemini equivalent. There is also more room in the diesel housing to hold the LSD components.PSIGEM wrote:Why do you have to use a Diesel Gem housing if your going with a custom center???
Wouldnt it be better to make a custom center that will fit in the standard housing, Diesel diff's aint all that common
If it was for a petrol housing id be interested...
The petrol diff was ruled out in terms of both it's reduced strength and sizing compared to the Diesel.
EDIT - This may not be true, currently being looked into by Bosnjak. Please see this post:
http://www.ozgemini.com/forums/tech/vie ... 051#185051
Last edited by Cuz on Tue Sep 23, 2008 4:52 pm, edited 1 time in total.
The axles are one option you could could choose to change. They would, however, have to have the right spline for the sidegears that are used in the LSD unit. At this stage the LSD unit we are looking at would accommodate 28 spline axles - billet is obviously the more robust option.BAD 44u wrote:alot of the conversions for the 9 inch and and hilux ive seen are very ordinary, heavy components breaking mounting points need of an engineers certificate. this is a great idea.
i would base it around the standard housing.
as far as billet axles i wouldn't bother unless you are on the upper end of the power scale and in that case maybe switch to a 31 spline axle.
after months of research im getting standard 28 spline axles machined and heat treated. when mine get back and i test them out ill post picsa and details this will save approx $700.
Have you looked at this option? About $1300 and shipping could be reasonable with a group buy..
http://www.quaife.co.uk/Isuzu-Piazza-RW ... fferential
http://www.quaife.co.uk/Isuzu-Piazza-RW ... fferential