What do you guys prefer:

GS-R with 4.928:1 FD or USDM Type R with 4.928:1????

I have both tranies and I have the Mfactory final drive!!

Thanks

 

I'd go with the Type R. Short gears FTW

 

Thats what I would think but at Mosport with a CTR trany with ats 3-4-5th short gears I was low 1.40min and with a USDM Type R with 4.785 FD I was mid 1.38min....sometime short isn't good cause you shift more!

I'm trying to find out what the road race guys are using??

Cheers

 

What engine do you have, and at what RPM do you typically shift? What tracks are you normally running on?

 

I race in the Castrol Canadian Touring Car Championship:
- Mosport
- Toronto Honda Indy Car Grand Prix
- Trois Riviere Grand Prix
- Calabogie Motorsport Park
- Shannonville Motorsport Park
- I-Car Mirabel
Series tires are Toyo R888 in a 205-15-50
Motor is B18C5 209whp@8500rpm and 138ft-lbs (shifting 8700ish)

 

I would guess that unless any of those tracks have super long straights the ITR with 4.9 FD would be better, especially revving that high. Hard to say without knowing the tracks though. You'd have to find a balance really, where on some tracks you might suffer because of it, but at others it'd be better.

 

The GS-R with 4.928 would work better at Mosport because I would be shifting less and riding the 4th alot...What I will do is assemble the gsr for my race at shannonville next weekend (a Short track) and see how it behaves, if good I will keep it, if not then I will go the type R route and suffer a little at Mosport (All the Track except for Mosport and Calabogie are short)

I would still like races that have tried both's imput????

 

Sounds like you need atleast 2 gearboxes like most road racers have, probably 3.

 

If budget wasn't an issue, I would lol

I have 1 Housing, 1 Kaaz Diff, a 98+ Type r full gearing, USDM Type R Gearing and the GSR gearing with a Mfactory 4.928:1 FD.....If I had more cash all the gearings would be in housing with kaaz diffs hahahaha

Cheers

 

The 4.9 in the ITR is waaaaayyyy too short for Mosport but could work well at SMP and possibly Calabogie.

 

i set the T class lap records last year at mosport and calabogie with a 4.4 itr tranny and only 170hp .. i miss my splitter .. this year is gonna be tougher
i was slow at shannon and 3riv though .. shorter ratios at 3riv would be nice

the 4.7 itr that you already have is probably best

don't forget, we're switching to the long track at calabogie this year ..

 

Hey Mr.Heron,

I agree on the front splitter, I had one on Friday's test day and got arround in 1.38s and took it off for the dry race and couldn't get lower then a 1.44...keeping in mind that I didn't have VTEC for Sunday's dry race because I had major blow by and lost over 2L of oil hahaha (I probably blew some blue smoke in your front windshield whne you lapped me at the end lol)

I will see you at SMP this weekend and let me know if you want my 4.785:1 FD

Cheers

 

What times do you run at shannonville? What is a fast time?

 

Pat, didn't get a chance to talk at shannon .. i'll come see you at mosport next week.. did you put in the 4.9 finally?

i had a best of 2:01.5 on the full track .. best in our T class was 1:59.7 .. best in ST class was 1:55.

with the 4.4 i never used 5th .. 2nd at start of front and back straights .. 3-4 everywhere else.

 

I'd go with the Type R tranny. Limited slip FTW!

 

ummm
OEM LSD FTL on the RR

 

any updates? im in the same boat.. except i just have a 97 spec itr trans.. but i am trying to decide between 4.7 and 4.9 final drives

 

What tracks do you run on with what size tires and rev limit?

 

For Road racing, use the GSR Gearing with the 4.9 and the Kaaz.
I have never liked the '98+ Type R gearing on any road course. Believe me I've tried them all! Incuding some very unusual combinations...

Kiwi

 

You don't get to the east coast tracks much do you?

 

No, but after 35 years of professional Touring car racing in Australia, New Zealand, UK, and having raced in South America and most of the US West Coast circuits up to and including Road America and Mid Ohio, I think I know what I'm talking about...
Are you going to be standing up talking, when you should be sitting down listening... again?
How many of you East Coasters are coming to the NASA Nationals this year for your yearly *** Whupping!


Kiwi

 

Should be sitting down... good one.

I've built enough B trannys for road racing to know what does and does not work, and I've run almost every possible D series gearing setup on track (only setup I haven't run is my MFactory gear set with a final drive, as I know from running a ZC gearset with FD's that it would be too short even on the shortest track I run on).

 

I'm finishing up a GSR right now with a MFactory 4.928 final and a CTR LSD. Because I haven't run the car yet I can't comment much, but looking at the numbers alone I'd stick with the GSR transmission for 2 reasons.

1. Most drivers that I have talked to like a lower 2nd gear ratio, this makes 2nd more "useful". But that doesn't count the remaining gear ratios.
2. You'll get about 10 or so extra MPH on the top end with a GSR tranny. Depending upon what tracks you run that MIGHT come in useful for that one key strait.

Most people I know prefer an ITR transmission because of the 4.785 final and shorter gear ratios. Once you change the final to a 4.928, the GSR transmission might be better. As mentioned previously, your gears can get too short.

No race experience yet on either of these. So just an opinion.

EDIT: I forgot the USDM ITR has a 4.4 final. It's 2nd through 5th are different than a USDM GSR though. GSR has a 1.9 2nd while the ITR has a 2.105 (USDM). That's about 6 MPH difference.

 

JDM/EDM ITR trans with 4.786 has GSR 4/5. If you have a 4.7 or 4.9, it doesn't matter much what 2nd you have unless you're on tall tires or have a very high rev limit.

 

i've been looking at the ratios .. and it looks like gsr4.9 2nd is almost the same as itr4.4 2nd .. so 2nd could still be used where needed

using the shorter us-itr 5th with 1-4 gsr and a 4.9 looks interesting .. hummm

trying them all in lapsim doesn't seem to change lap times much though .. there's alot of give and take at different sections of the track .. without trying it for real, it's hard to decide if the cost/advantage is worth building a new tranny.