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Discussion Starter #1
So I need a longer final drive and I cannot afford nor want to deal with the difficulties of swapping the Supra/GS430 rear end into my IS300. I've read the thread about swapping the MKIII ring & pinion and it doesn't seem too hard at all.

Has anyone been able to fit a 3.54 ring & pinion into the stock IS300 rear end? It is the tallest one available for the Toyota 8" rear end so I'm guessing it would fit. Anything bigger and it probably wouldn't physically fit in the pumpkin.

So does anyone know if this ring & pinion would work?

Application Guide for Toyota Truck Ring/Pinion Sets and Positractions - Drivetrain.com

If I can get confirmation I'm going to order it ASAP. Any input would be greatly appreciated.
 

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If you're already boosted just leave what you have in there IMO... What trim waas your car originally? 5spd or auto?
Because having to shift into 5th in the 1/4 mile is a waste of time.

It was originally a 5-speed, the v161 + stock 3.72 rear end = annoyingly short gears for boost...
 

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You can always build your head and raise the rpms up so that you don't have to shift...? If I had a v161 I'd run my 3.9 rearend and have my top end built for high rev...
 

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You can always build your head and raise the rpms up so that you don't have to shift...? If I had a v161 I'd run my 3.9 rearend and have my top end built for high rev...
It would still be too short with a 3.9 rear end. In 6th at 80mph with a v161 and 3.9 rear end you will be at like 3600-3800 rpm haha.

I'm trying to get my rev limit issue sorted out, I think with a 7400 rpm rev limit with the 3.54 ring and pinion the car will be perfect.
 

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Lemme help with a visual aid.

A 3.54 might be ideal. But outside of that, you could also try running a larger diameter tire size in combination with that 7400 rpm rev limitor.

This should put you right at ~124 mph when you run out of gear. What are you trapping currently?
 

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Discussion Starter #8
Lemme help with a visual aid.

A 3.54 might be ideal. But outside of that, you could also try running a larger diameter tire size in combination with that 7400 rpm rev limitor.

This should put you right at ~124 mph when you run out of gear. What are you trapping currently?
I'm trapping at 122ish right now, give or take 2mph, so I'm right at the top of 5th gear...

I think the 3.54 + 7400rpm rev limit will be perfect! But I need to know if the 3.54 gear will work from the site I posted. Or where I could get one that will work. Jawsgear no longer makes them.

Also did you get my PM TeckIS about the rev limit issue? Your help would be greatly appreciated!
 

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Hey did you get this to work buddy?
 

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I feel like this is possible. Also look at what I found:

41201-29547 --> EXPENSIVE but its 3.42!

41201-39795 - 3.583:1
41201-29547 - 3.42:1
 

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I did it. It's a pain in the ass. I'm running a 3.58 gear set now. I had to build special jigs and get a torsion type inch/lb torque wrench to measure pre-load.

It's worth paying someone else to do it. As long as they do it correctly.

https://www.driftmotion.com/DM-MK3-29-Spline-Ring-and-Pinion-Diff-Kit-p/dm3462.htm

Is the kit I used. I got a solid pinion spacer too.
Give us some real-world data on the 3.58 swap, when you have time. I am toying with doing it to mine. Single turbo gte and AR5. Mileage improvement/longer gearing like it love it etc. what should we expect. I’m on 3.9 gears currently.

Thanks in advance!
 

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Sadly I probably won't be driving it again till spring. I was already at 3.73 so, you change would be bigger than mine.
 

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Well, is it worth the outlay of money?

250$ r&p
$250ish bearings, seals, etc
250$? Labor to assemble and set backlash

Will I notice much difference in your opinion?
 

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Well, is it worth the outlay of money?

250$ r&p
$250ish bearings, seals, etc
250$? Labor to assemble and set backlash

Will I notice much difference in your opinion?
It's a huge difference, completely changed the driving experience. With the CD009 and 3.90 rear the shifts were so short that it took the fun right out of driving. I think it added around 8 mph in sixth gear at 3000 rpm cruising. Money well spent IMO.
 

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Funny you posted this. I just took my Diff and new R&P to get the 3.58 swap done. I waited a month for new pinion bearings from Amayama Trading, but they finally did come through. I have an AR5, so I don’t think it is as short as a CD009 but doing the math, I’m looking at an 8-10mph difference in 5th between the 3.9 and 3.5. That is huge.

Hope to change out to poly bushings and get it stabbed back in next week. I’ll go easy on it before I flog it, but will update the thread when I do.
 
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