Wondering what I need to do a 6 speed conversion to my 1991 NSX? I will retain the stock clutch for now. Thanks.
5 -6 Speed conversion in a 1991 NSX
- Thread starter jtrikakis
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- transmission swap
When you say that you will retain the stock clutch, you don't mean the stock clutch from your 5-speed, do you? The 6-speed uses a different clutch from the 5-speed.
Check here: http://www.scienceofspeed.com/produ...cienceofSpeed/transmissions/6-spd_conversion/
In short, you will need a single disc clutch, reverse lock-out solenoid, and obviously a 6-speed tranny which is $$$.
In short, you will need a single disc clutch, reverse lock-out solenoid, and obviously a 6-speed tranny which is $$$.
Or, you can buy the NSX-R mainshaft and re-use your 5-speed clutch.
A lot of money. :biggrin:
If your 5-speed is working fine, I recommend leaving it alone. Wait until you need a new clutch, or some other major transmission service. Or else trade for a '97-05 NSX. The cost of upgrading from a 5-speed to a 6-speed is huge, and the performance difference isn't worth it unless you're stuck shelling out for other transmission work anyway.
shawn110975
Suspended
What I did was buy the dual input shaft from SOS installed it into my 6-speed transmission. installed 6-speed into my 92
while I was in there put new dual clutch, never installed the lockout never once grinded even if I did it would not engage as if it spinning the chance the teeth engage are like winning the lotto.
I wired the lockout just never installed the relay.
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I disagree If I would have known installing the 6-speed would make my 92 stay in the powerband into 2nd gear and thru to 6 It would have been my first mod on my car.
now I agree with the price its pricey if you cant do it yourself
just my .02 obamma coins
while I was in there put new dual clutch, never installed the lockout never once grinded even if I did it would not engage as if it spinning the chance the teeth engage are like winning the lotto.
I wired the lockout just never installed the relay.
- - - Updated - - -
I disagree If I would have known installing the 6-speed would make my 92 stay in the powerband into 2nd gear and thru to 6 It would have been my first mod on my car.
now I agree with the price its pricey if you cant do it yourself
just my .02 obamma coins
Thanks for the encouragement. Besides the gear box and dual input shaft what else do I need to get to make this conversion work? What you do recommend for a new clutch? I do street / highway driving. Thanks.
Your factory 5-speed clutch will work with this setup. You can buy another one new from Acura, or you can buy the SoS Sport Clutch and skip the dual input shaft.
+1
I did 6 speed swap a few years ago, better off buying a supercharger for the money.
In case you're interested in numbers, changing a '91 from a 5-speed to a 6-speed without changing anything else will improve 0-60 times by 0.2 second and 1/4 mile times by 0.1 second. You'll get significantly more improvement than that by doing light mods that add 15 hp, such as a good set of headers/exhaust, and you won't spend anywhere near as much money doing it. I'm just using that as a point of comparison; adding a supercharger as Chris mentions will add way more horsepower, typically 60 hp or more, but it will cost thousands of dollars more than the light mods will. Either way, light mods or supercharger, will give you more bang for the buck than swapping transmissions.
Don't get me wrong, the 6-speed is a very nice setup, and preferable to the 5-speed in most ways (other than the cost of the factory clutch for the 6-speed, although see notes above regarding keeping the 5-speed clutch). It's just that you're getting relatively little bang for a relatively large buck. Again, the equation is different if you are having problems requiring some serious transmission work, when you're going to be spending a lot of money anyway. But if you don't need transmission work and you're spending all that money just to swap transmissions, I wouldn't recommend it.
Don't get me wrong, the 6-speed is a very nice setup, and preferable to the 5-speed in most ways (other than the cost of the factory clutch for the 6-speed, although see notes above regarding keeping the 5-speed clutch). It's just that you're getting relatively little bang for a relatively large buck. Again, the equation is different if you are having problems requiring some serious transmission work, when you're going to be spending a lot of money anyway. But if you don't need transmission work and you're spending all that money just to swap transmissions, I wouldn't recommend it.
Many thanks for everyone's advice. I am not looking for pure speed, but drive ability. I travel around 80+ miles round trip to work which are mostly highway. I normally can travel around 70 MPH. In 5th gear my RPM is around 3K, so my engine is being over worked. If I go the header/exhaust route would my engine work less? Also, anyone try the header / exhaust install on their own? many Thanks again.
Your engine is NOT over worked at 3k RPM. It's a honda...you could rev at 3k RPM all day everyday and be just fine. Even my 2006 Civic revs at 3k RPM's at that speed
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Absolutely correct! Turning 3000 RPM (or 4000 RPM or 5000 RPM) does not "overwork" the engine and is absolutely NOT a concern. This is NOT a reason to go spending thousands of dollars to swap from a five-speed to a six-speed.
You do realize that NSX engine failures are rare and when they occur are attributable to specific causes that don't include turning 3000 RPM, right?
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If you are close to San Diego, you're welcome to shake down my car and see for yourself. The only thing I don't like about the 6spd is the heavy OEM clutch assembly but that can be changed later.
Like others have said, you don't need a 6spd but when I do, I prefer to be in the NSX. Took me 4 yrs to find a 6spd in a NA1 and I did pay quite a $$ for it.
@80mph, I am just over 3k rpm w/ oem 4.06 diff and 265/35/18. with CA crapy 91 gas, I get 30mpg. With good TX 93, I get 33mpg.
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If you really want to lessen the 1-2 shift rpm drop (out of VTEC), then the JDM 5-speed gearset will do that for you.
It changes gears 2-3-4 inside the transmission, that's it.
Also, another consideration is that if you ever want to go forced induction in the future, the 5-speed trans is a bit stronger so should hold up better if you decide to go for big power!
Brian
It changes gears 2-3-4 inside the transmission, that's it.
Also, another consideration is that if you ever want to go forced induction in the future, the 5-speed trans is a bit stronger so should hold up better if you decide to go for big power!
Brian
FYI - at 70 mph with a six-speed, the engine is turning 2772 RPM. The tire size won't change the relation of the revs to the indicated speed on the speedometer, but the actual speed with 265/35-18 will be 1.8 percent higher than it will with the stock 225/50-16.
I hear what Ken is saying regarding the bang for the buck, but FWIW, after 225k miles I changed my 1992 5-speed to a 6 from SoS when it was clear that the synchro from 1-2 was worn. Looking back on it now, the 6 speed conversion and the muffler change to the B&B unit after I first bought the car (was sold by RM racing, but B&B serviced mine with a new can after 13 years for 300 bucks (wow!!!)) have added the most to driving satisfaction than anything I've done. The car should have been built this way. The fully synchro'd 6 speed box mated to the dual plate clutch is one of the sweetest transmissions you'll ever shift.
6 Speed conversion
Well, I took the plunge. I found a 6 speed that a fellow Prime member was selling. It came with a 4.55 and fairly new double clutch. The 4.55 does give out a whine, but the 6 speed sure shifts nice. I will have to give conversion a weeks or two before I can provide better feedback. More to come.:tongue:
Can someone(s!) confirm the RPM at say 85mph from a stock 5 speed and 6 speed?
Thx
Thx
Assuming you have the stock 4.062 R&P final drive gear, at 85 mph you'll be turning 3656 RPM in fifth with a five-speed, and 3366 RPM in sixth with a six-speed.
If you have any other R&P, you can multiply the ratios to figure out the RPM. For example, if you have a 4.55 R&P with the five-speed, at 85 mph you'll be turning 3656*4.55/4.062=4095 RPM.
Hey congrats! I am still on the fence about the conversion myself. Be careful with that 4.55, it is very aggressive and has done damage in the past. Must be a blast to drive though so eagerly awaiting your review impressions and if it was all worth it.
If you are worried about the 'high' 3k revs in your 5sp, you will be revving higher with the 4.55. I had a 5sp with short gears and a 4.23 and didn't like the high rpms at freeway speeds. I found a 6sp with stock 4.06 and put in a new SOS clutch and I really love this setup.
Thanks, that was helpful. BTW has anyone put in a taller 5th gear into a 5 speed, presumably during a tranny rebuild?
I've never heard of anyone doing this, or of a taller gear being available, either.
Since there is no taller gear available this would be a custom gear, with a custom price$$$$$$$$$$$$$$$$$$$$$$$
To the original poster, the 4.55 will make your original concern worse (higher revs at all speeds)
Regards,
LarryB
Regard,
LarryB
