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B Series Trans for DD duties

Posted: Sat Jul 27, 2019 1:32 pm
by noahf
Another stupid post by me but this content isnt here so might as well have some of you educated people post responses for the future as well as my curiosity.

So daily driving the CTR with a s4c lsd trans has become a little annoying. its brutal. freeway cruising (which is 60 miles, at 70-80mph) is between 3.5k-5krpm. My mpg is between 27-29mpg. Ive done a lot to quite down the cab (2 layers of sound deadening) but its still brutal. My exhaust has been on order for like 5 months, but I still want to lower rpms.

What im looking for is the best "frankenstein" b series trans i can build, where i still have the good acceleration gears, but then great cruising speeds. I would really like 5th gear cruising at 70 mph in the lower 2k rpm's (not sure this is possible) i am running 16" rims with a 45x205. I would likely use a type r lsd. I just dont know what gearing i should try to go with? I would like to it be strong, and it may see one or two track days, but will mostly just be a street car with full interior and used to drive everywhere.

any thoughts?

(i will be keeping my b16b trans for when i retire it to a garage queen car and put it back in)

Re: B Series Trans for DD duties

Posted: Sat Jul 27, 2019 4:50 pm
by DC231
is the CTR trans 4.4 or 4.7? LS 5th gear is a really big gear drop. its like going from 4th to 7th great for mileage and not so loud because the gear drop however it will not accelerate at all especially if its 4.4 so i would steer away from that if you use 5th gear at the track. GSR 5th gear will be good for you it will still have some acceleration and will give you a good RPM drop like going 4th to 6th. if you have parts the 5th gear swap is relatively easy if you are a do it your selfer.

Re: B Series Trans for DD duties

Posted: Sat Jul 27, 2019 7:17 pm
by Stin1
Off topic , but you mentioned it. What exhaust are you waiting on?

Re: B Series Trans for DD duties

Posted: Sat Jul 27, 2019 10:50 pm
by jayhaire
Some people did the LS 5th in the past, but I'd suggest the GS-R 5th if you're going to modify a b-series trans. The 98-spec ITR used the GS-R / SiR-G 4th and 5th gears with the 4.75 final drive. It will bring it down slightly, but these cars tend to hang at higher RPMs on the highway.

The 6-speed K-series stuff is nice. Alternatively, the early NSX 5-speed had super long gears, and some complained about that too.

Re: B Series Trans for DD duties

Posted: Sun Jul 28, 2019 1:21 am
by I am the Liquor
I have a gs-r trans with ls 5th and at 80 im about 35-37 rpm

Re: B Series Trans for DD duties

Posted: Sun Jul 28, 2019 9:52 am
by RTW DC2R
What you described sounds pretty decent to me. Use a gear calculator to compare differences. http://www.teammfactory.com/calculator

I have an ITR trans with 4.9FD and GSR 5th. Its reasonable on the highway. 75-80mph is around 4k rpm. I thought about the LS 5th but the car just doesnt have enough torque for that long gear. Youd have to downshift just to accelerate and pass someone on the highway. Shifts from 4th to 5th would be like bwaaaaaaaaaaawwwwwwwwwww. Shifts from 5th to 4th would be like WAAAAAAAAHHHHHH!!! Too much of a gap between gear sizes.

On my old turbo setup I ran a 4.0FD with stock ITR gearing. The car had plenty of torque for the longer gearing.

I dont think any b series gearing will allow for 2k rpm at 70mph. Honda manual trans and motors arent designed for that type of driving. They need to rev unless they are boosted. If it is possible, 2k rpm at 70mph would be a horrible experience on a NA Bseries motor.

Re: B Series Trans for DD duties

Posted: Sun Jul 28, 2019 11:14 am
by Dave7CDMTYPER
I have usdm itr trans in my R with Jdm 4.7 fd. It's very nice, the shorter fd almost feels like a rally car/sti type of gearing. But sometimes I think about putting in a gsr 5th gear for better Hwy experience.

Re: B Series Trans for DD duties

Posted: Sun Jul 28, 2019 11:28 am
by DC231
RTW DC2R wrote: Sun Jul 28, 2019 9:52 am I dont think any b series gearing will allow for 2k rpm at 70mph. Honda manual trans and motors arent designed for that type of driving. They need to rev unless they are boosted. If it is possible, 2k rpm at 70mph WOULD BE A HORRIBLE EXPERIENCE ON A NA B SERIES MOTOR
what he said here^^ it would kill the engine fast

Re: B Series Trans for DD duties

Posted: Sun Jul 28, 2019 5:06 pm
by noahf
thanks for the feedback. its what i needed to hear about the LS 5th gear. looking for a jdm gsr lsd trans for now, as that meets most of requirements.

stin1: i am waiting on a hytech twin loop cat back.

Re: B Series Trans for DD duties

Posted: Sun Jul 28, 2019 7:24 pm
by RTW DC2R
One other note, do you have stiff trans mounts? That will significantly increase cabin noise and vibration.