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| SJ80 front diff gear conversion https://www.auszookers.com/forum/viewtopic.php?f=37&t=56715 |
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| Author: | Renzy [ Sun Oct 25, 2020 3:00 pm ] |
| Post subject: | SJ80 front diff gear conversion |
Hello, I have purchased a set of 457 diff gears from LROR and putting them into my Sj80. Rear went in ok, but on the front the new ring gear bolt holes do not align with my original carrier (8 holes in original & 10 in new ring gear) Am sure someone else has put these diff gears in before and wondering how they got around it. Can anyone confirm if the SJ70 & Sj80 front diff centre & axle arrangement identical - LROR says all Samaris run smaller front axles and I am guessing this will also translate to a 8 bolt hole carrier for ring gear mount. Am thinking an option is to find a rear centre carrier and use but bit hard to find Cheers |
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| Author: | greenzook89 [ Tue Oct 27, 2020 10:31 am ] |
| Post subject: | Re: SJ80 front diff gear conversion |
Coilys run a unique front centre. It's physically smaller than an SJ70 and nothing else fits. Even if a rear centre fitted in the housing(it won't) you'll find the tie rod is now in the way. Coilys are a pain |
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| Author: | Gwagensteve [ Tue Oct 27, 2020 11:39 am ] |
| Post subject: | Re: SJ80 front diff gear conversion |
Best option to change from the 3.9 ratios would be to swap in a complete Jimny front axle assembly which would get you 4.1 or 4.3. What are you trying to achieve? Swapping in a 1.3 leaf spring transfer case will raise gearing on road by almost exactly the same amount as swapping the diffs to 4.57, with the added benefit of better low range. Obviously you also have options of 1.0litre ratios or reduction gearing which is lower again. |
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| Author: | ZUZUKI [ Tue Oct 27, 2020 8:44 pm ] |
| Post subject: | Re: SJ80 front diff gear conversion |
Hi Renzy, There's a trap for noobies right there - the good ol' USA didn't get the SJ80 Coily, so when a US based co. like LROR says "all Samari's (our Sierra)...." that excludes the SJ80, as it was never sold in their market - therefore does not exist. The front diff is a high pinion design & is not compatible with anything else. Rgs, Michael |
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| Author: | Renzy [ Thu Oct 29, 2020 9:42 am ] |
| Post subject: | Re: SJ80 front diff gear conversion |
Cheers for the info fellas - this confirms what I was fearing I think pretty well my only option now is to drill out my carrier to suit the PCD of new crown gear - not ideal but have come this far. Two bolt holes align so I will assemble and check to see if it will actually turn in there with out clashing first before drilling. Cheers Simon |
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| Author: | Gwagensteve [ Sat Oct 31, 2020 1:49 pm ] |
| Post subject: | Re: SJ80 front diff gear conversion |
Don't do this, the diff gears in your car are literally cut the opposite way, they will not mesh at all if you try and get them into your housing. The front diff of an SJ80 and Jimny is what's known as "high pinion" or "reverse rotation" - the pinion sits above the centreline of the differential. On an SJ40/50/70 the front and rear diff gears are "low pinion" and are interchangeable front to rear. They are not in your car. There is literally no solution for you that would let you use those gears, unless you swap in an SJ70 front axlehousing, which is quite challenging as the suspension configuration is different, leaving no room for the panhard rod. I don't think this is a viable solution for you unless you want to highly develop the car for off road capability. (and in reality, swapping in a Jimny front axle is preferable) Please take this the right way, but it sounds like you don't have a lot of experience with setting up diffs if it wasn't apparent the helical cut of the gears is opposite. I'd leave your existing front diff well alone. They are rare, pulling it apart and trying to drill a different pattern will wreck it and you'll be searching for another. Please take some time to read the second part of my last response. Transfer gearing will deliver exactly what you're looking for from a gearing perspective without any custom work. You can easily resell the 4.57 gears, they're reasonably sought after and have a good reputation for strength. |
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| Author: | Renzy [ Tue Nov 03, 2020 5:36 pm ] |
| Post subject: | Re: SJ80 front diff gear conversion |
Hi Gwagensteve, Yeah, I found out that the gear teeth were running opposite directions on weekend and so made sense when zuzuki above advised the front is a high pinion design. I understand now why the tie rod would be in the way and SJ80s are a pain - I had already stripped the diff ready for re-assembly when I ran into issue. I replaced the bearings and put back together on weekend, still have to finish rest of axle refurb, then pull rear back out - bit disappointed though as the car pulled so much better with the gear reduction. I had read what you said about swapping transfer cases and will look into this now once car back in 4wd. I would not have thought the transfer case would effect 2wd though Cheers Simon |
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| Author: | Gwagensteve [ Wed Nov 04, 2020 12:03 pm ] |
| Post subject: | Re: SJ80 front diff gear conversion |
High range is indirect in a Sierra. In your case (SJ80) it’s 1.22 or something. A 1.3 leaf Sierra is 1.409, a 1.0litre Sierra is 1.58 and transfer reduction gears are 1.58 to 1.7 depending on low range ratio. |
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| Author: | Renzy [ Thu Nov 05, 2020 5:18 pm ] |
| Post subject: | Re: SJ80 front diff gear conversion |
Thanks for info, will keep an eye out for transfer case and give it a go Cheers |
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