HF Trans. in a wagon
DDCWAGON
Banned
Sup guys, I was wondering if anyone knows if a Hf trans will swap into my 90 wagon 2wd? Right now it has a JDM ZC L3 5sp. in it. I had to have hybrid axles made to avoid changing knuckles. Anyway the axles have integra inners and civic outer spline count. My trans is grindin & I would like to replace it with something with less rpm on the highway,since gas is the way it is. Now it turns 3500 to 4000 @70-80mph. My buddy has a crx hf & i love the gearing. It seems like it would compliment boost also, but I dont know how durable they are. I'm just shopping for options now but I will have to do some thing soon. Any help is appreciated!
Comments
yeah the HF was only used in the CRX.
axles, i dont think there is a half shaft with the HF trans, also i dont know if you can keep the half shaft if you swap trannies... someone else will have to chime in about that.
in the long run though, it will bolt up
btw, hows that ECU treating you?
''Integra inners'' won't fit the HF diff 'cuz it's a Civic inner.
To make it work u need to take the HF innards & put them in ur ZC case with the ZC diff.The ZC diff won't fit into the HF case.You didn't mention if ur ZC has a LSD :?:Just make sure you can turn the input shaft once the tranny case is all bolted back up.
HF's trannies weak point are it's smaller bearings.
It will bolt up, but you'll have to run regular civic axles.
A much better solution would be to find a nice 88-91 Si tranny and swap in just the HF 5th gear to keep the 1-4 nice and tight, but still have a nice, low cruising rpm for the freeway.
does your shop, or another local one do that kind of work? I have an Si, EX, HF, and DX trannies. Is the gear swap atraightforward? (I've built a mess of truck boxes)
my daily average is 37 +/- a few, mainy town driving.
highway cruising was ~42 when i roadtripped from Michigan to Georgia.
-peace
Actually the ZC tranny, if it came from a DOHC ZC has completely different gearing and final drive than the 88-91 Si tranny.
The DOHC ZC tranny has the closest 1-5 gearing than any other SOHC tranny. The "problem" with them is that they also have the DX spec taller 3.88 final drive in them.
The 88-91 Si tranny has longer, more spaced out gearing, but a much better 4.25 final drive in them, so OVERALL after multiplying gears against the final drives the Si tranny is actually SHORTER/BETTER geared than the ZC tranny.
What I have done, and it works out amazingly well, is I took ZC 1-4 gears and stacked them into an Si tranny case with the better Si final drive - but I left the stock Si 5th gear!!! What this gave me was a ultra close, awesome accelerating 1-4 gear ratio, but a stock 88-91 Si 5th gear for highway cruising rpm.
Let me ask you this:
Currently do you have the DOHC ZC tranny complete with the midshaft, or have I gone off on a tangent for nothing? The reason I ask is that the DOHC ZC L3 tranny is 100% different inside than the SOHC L3 ZC tranny.
JDM DOHC ZC L3:
1st - 3.250
2nd - 1.944
3rd - 1.346
4th - 1.033
5th - 0.878
Final drive - 3.888
I bolded 5th because that's shorter than a USDM Type R 5th gear ratio!!! Now when you do the math against the 3.88FD it's not too crazy though - you get 3.40.
Now for USDM Si or JDM SOHC ZC L3 ratios:
1st - 3.250
2nd - 1.894
3rd - 1.259
4th - 0.937
5th - 0.771
Final drive - 4.250
I bolded the final drive because it's the best one we got here in a regular 5-speed L3 tranny here. When you multiply the 4.25Fd against the .771 lower 5th gear you get 3.27 - still lower than the DOHC ZC overall 5th gear ratio. This means the USDM 88-91 Si tranny has a slightly lower cruising highway rpm in 5th gear.
So basically acceleration would be in direct correlation with how close each gear is to each other, because the less of a number difference between the gears, the less rpm drops, and the higher each overall gear number ratio is (gear ratio x final drive ratio) the quicker you get to rip through that gear.
I'm going to try and do the math of my custom Zc/Si hybrid tranny where i used ZC 1-4 closer gearing coupled with the Si 5th and 4.25 FD to sow you what I mean. I will simply take each gear ratio and multiply it against the 4.25 FD to get my overall gear ratios per gear.
1st - 13.81 (same as 88-91 Si tranny either way)
2nd - 8.26
3rd - 5.72
4th - 4.39
5th - same 3.27 since I kept the Si 5th gear, but if I had kept the ZC 5th it'd be a ridiculous 3.73!!! That's a huge difference!
Anyways see how close each number is? Like I said the closer the numbers stay together, the quicker you rip through each gear, and thus, the quicker you accelerate.
For comparison's sake I'll do the same math with a regular 88-91 Si tranny that most of us try to get when we do a SOHC build here in the US:
1st - 13.81
2nd - 8.04
3rd - 5.35
4th - 3.98
5th - 3.27
And finally the DOHC Zc with it's shorter gearing, but shitty 3.88 DX-spec FD:
1st - 12.61 (YIKES! Would take longer to go through!)
2nd - 7.54
3rd - 5.22
4th - 4.00
5th - 3.40
So compare the numbers and see the difference? You'll note that the custom Zc/Si tranny has higher numbers, and closer to each other numbers too. This means quicker ripping through gears.
You'll also note that even our regular 88-91 Si tranny has a clear advantage over the JDM DOHC ZC tranny too, because of the taller 3.88 FD they have. The taller FD negates the closer gears.
Does that make sense?
You like a tranny with more pull,but it'll be OK for DDCWAGON as stated:
I drove a DX with a HF 5th & that's geared weaker than the Si you're talkin about..You're right about a weaker pull,but it works for highway cruising with a 10%+ boost in MPG.The only time she complained was when she had 5 people in it & going up a hill.She ran it down to 4th.