Just wanted some input about a transmission swap for my racecar. I am running a 89 Civic with an SI tranny at a 1/3 mile circle track. We can't run tacks so I have no idea what im turning for RPM's, but I run third gear. Its not bad Car has three wins, seven top fives but I feel it could be faster with a lower third gear or a higher second gear. I have heard the Canadian HF tranny 89-91 Civic would bolt right in and I would be able to run second Gear. Any help would be awesome have a big 50 lap open race coming up and want to win.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CHRIS29 &raquo;</TD></TR><TR><TD CLASS="quote">I feel it could be faster with a lower third gear or a higher second gear.</TD></TR></TABLE>

well clarify this, which do you want taller gears (takes longer to wind up) or shorter gears(winds up quicker)?

An HF tranny will give you taller gears, and an SI will give you shorter gearing.

i believe the input shafts are different sizes between 88-89 and 90-91 so make sure to get the same type.

and I think you might need HF knuckles and axles for the HF but I'm not positive.


Modified by grog at 9:42 AM 8/31/2008

 

Third gear is to tall, second gear is to short. Second gear I'm up against the rev limit 3/4's down the front and back stretch. Like I said third gear isnt bad but if I could gain three to five hundred RPM's it would be tuff to beat this car. Engine is a b2 block, JE 10 1/2 to 1 pistons .030 over, lightweight crank, lightweight flywheel, A6 head, oversized valves 3 way angel port polished, Decked to minnimum block,SI tranny, 4.2.1 exhaust manny,Jet chipped PM6 box. If you need anymore info please let me know, or if anyone has a tranny for sale I would be very interested in buying it to try. Or if you have any other suggestions I could go with it would be awesome..Thanks

 

It really sounds to me like you need a cutom transmission made up using gears from a couple different trannies.

 

I can Custom build it I just need to know what gears to put in. I have taken the tranny apart because it was a Dx, swapped the main shaft and ring gear and installed Phantom Grim so I'm confortable doing it.

 

you could just do a final drive swap, not sure what ratio.

heres a tranny calculator
http://crx.honda-perf.org/math/index.html

 

from the sounds of it i would swap the 2nd and third gears from the hf into the si.I had a 89 hf and yes the 2nd gear is long

 

Thanks Ill order them through my local Honda dealer and try it out.

 

let us know how you do.Goodluck

 

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I have a DX five speed can I just pop in the four speed second gear?? I think it they have the same final. Up in here in Maine no junkyards carry parts for these things so its hard to get a used tranny.

 

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<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by grog &raquo;</TD></TR><TR><TD CLASS="quote">you could just do a final drive swap, not sure what ratio.

heres a tranny calculator
http://crx.honda-perf.org/math/index.html</TD></TR></TABLE>

not from what i read he can't.

he wants one gear to be longer and anoher to be shorter, thats unacheivable with only a final drive swap.

 

Do you use the Volkswagon jetta rims on your race car. If you don't its a little better than the stock Honda 14X5 and 14x5 1/2's, the Volks rims are 14x6 give a wider offset and more tread width and they bolt right on. Probably already new that but if not there you go..

 

Alright so I have two SI tranny's and a box of DX internals. I have a DX mainshaft and ring gear. I should be able to put that in the SI case and run the stock second gear from the DX four speed which is a 1.650 and it should be mint correct.