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The mkiv Supra Owners Club

R154 power limitations


Noz
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I've been doing some research on this. Other peoples opinions would be great.

 

Has anyone got some real advice from personal experience. I'm a fellow Google warrior so first hand advice would be great.

 

Searching only brings up peoples `opinions`. Very little experience.

 

Though that said, I found this post on Supra forums and was surprised:

 

"One thing is for sure....The R154 is the most durable/animal 5 speed japanese

transmission.A low milage/healthy one can hold up to 700 rwhp as stock,and

rebuilt with 2-3 performance parts from Marlin Crawler (like 1st gear thrust washer,

bearing retainer,etc.,) can take you up to 1000 whp.

People running 600 whp motors on high milage R154s trans (never serviced or changed

it's oil) and they blew it away...saying the R transmission sucks.

Also the choise of a good clutch kit will be quite important for the trans life..."

 

http://www.supraforums.com/forum/showthread.php?554078-r154-into-mk4

 

This had led me to want to ask people their thoughts as I wanted to consider the upgrades currently on the market and get the box rebuild.

 

I don't really know where to aim for power wise, so I'm just looking into what my options would be if I upgrade my box.

 

All advice appreciated.

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what clutch are you looking at?

 

I'll worry about the clutch when I've finally decided what power I'm aiming for.

 

At the moment, I'm just weighing up the limitation factors. Once I fully understand the transmission limitations, I'll plan out the remaining components.

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FWIW, I bought the Marlin Crawler uprated thrust washer for first gear when I bought a slave cylinder & some other bits from Driftmotion.

 

The idea was to strip the box myself and rebuild it with the new part before I fitted it to the car but eventually I decided to run the box for a while to begin with, to see if anything else might be amiss with it, no point in tearing a box apart (and I do literally mean completely apart to fit that thrust washer) then rebuilding it if the rest of the box was on its last legs.

 

I still intend to upgrade the box at some stage, possibly with a few more components as well, the reason being that my particular box would be the very best it could be in terms of usability, but also saleability. It would have everything going for it, cradle, bell-housing, proper sensors and then all the upgraded internals as well.

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FWIW, I bought the Marlin Crawler uprated thrust washer for first gear when I bought a slave cylinder & some other bits from Driftmotion.

 

So how hard has your boxes life been since ownership. And what sort of power levels are you running?

 

Wilkorangerover had a nice Mkiii running a big singe 1JZ with the R154 and that was over 600hp, box was fine and i gave it some hammer when i drove it and i know he did...

 

My original thought on the box was 600hp would be safe, but now from the US guys it seems a rebuilt box with a decent clutch that doesn't create any harmonic stress on the transmission makes them good for 600whp.

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So how hard has your boxes life been since ownership. And what sort of power levels are you running?

 

Oh I'm only BPU on the 1JZ, 400FWHP would be an extremely optimistic guess & probably closer to a blatant lie.:)

 

I wouldn't say I'm particularly hard on the box either, being used in the track car there is no need to light the tyres in first and I've managed to temper my down changes somewhat as they can be as hard on gearbox internals as being bolted to a monster-power engine.

 

No, I plan to get my money's worth out of this particular set-up.

 

My reason for getting the upgrades was on the off chance I ever travelled North or over to the UK for some drag racing events, AFAIK hard launches are the Achilles hell of the R154 and even then it appears to only be in conjunction with 600+ bhp & the related torque figures.

Edited by pedrosixfour (see edit history)
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Oh I'm only BPU on the 1JZ, 400FWHP would be an extremely optimistic guess & probably closer to a blatant lie.:)

 

My reason for getting the upgrades was on the off chance I ever travelled North or over to the UK for some drag racing events, AFAIK hard launches are the Achilles hell of the R154 and even then it appears to only be in conjunction with 600+ bhp & the related torque figures.

 

I'd love to think I wouldn't drive it like that again. But I know I would.

 

Did you find much information on installing other components into the box. i.e. justification for such actions.

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I ran the W58 on about 400-420 with a new stock clutch and it was fine. Just need more power :)

 

Well mine was 417 and threw it's toys out.

 

Ha!

 

My W58 minced the third gear retainer while still bolted to an NA.

 

It handled stock 1JZ-GTE power and torque just fine after I rebuilt it with a bit of a modification though, it was sold as a working lump and I haven't heard anything to the contrary since.

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Did you find much information on installing other components into the box. i.e. justification for such actions.

 

Probably no more than you've discovered yourself at this stage mate, all I knew is I needed a five speed gearbox I could rely on to handle a relatively tough life, the stock R154 is probably the answer, an uprated R154 definitely is.

 

Plus I like pulling things apart.

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AjazYazin was running one attached to his 1.5JZ lump. IIRC he had around the 700hp mark out of it. Hopefully he will see this and come on. He said he had uprated the washer and had some other work done, bits cryo treated. I ended up buying it and the engine and it is in the process of getting fitted as we type.

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I'd of thought any low temp processes would of made it brittle.

 

I'd have to look into more to feel it would have a benefit.

 

Problem with carrying out experimental processes on gearbox internals is it's a lot of work for me to then blow it up due to getting the hardness or treatment incorrect :(

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I put 578lbs-ft though one and it seem to survive. I ran ATF in it if that makes any difference. You could buy 3 boxes for £100 back then. Funny how they are £600 a piece now.

 

Front thrust washer is weak, lay shaft has issues, These a truck boxes so they don't shift nicely. Second can be a real pig to select when cold.

 

If you want a box that is mega tough then a Tremec TKO 600 should be on your shopping list. I mapped a Corba with a Twin Turbo 7.0 LS6 on the Dyno pack when I worked at Thor with one of these boxes fitted and the dyno and clutch gave up before the box did (it was 630bhp with 750lbs/ft) :D

 

I think these are about £1700.

 

http://www.roadcraftuk.co.uk/index.php?route=product/product&product_id=620 i think these used to be RoverCraft back in the day.

 

I was right :D

 

I know someone who does a nice conversion of this box onto the 1uz ;)

 

Lyndon.

Edited by Nodalmighty (see edit history)
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