Hybrid Transmission: Anything missing? (D-series)
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Joined: Jan 2004
Posts: 46
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From: North Carolina
Hybrid Transmission: Anything missing? (D-series)
I currently have a 1989 Honda CRX HF (1839 lbs) with a JDM D15B Vtec (128 hp). At the time of the swap (a few months ago) I was unable to obtain a Si tranny. Just last week I started to hear the whirring and chattering of bearings going out (Input Shaft bearing and probably a few others) Time for a new transmission as the HF tranny isn't worth the $200-$300 worth of new bearings and seals.
This weekend I purchased a ZC tranny (20 spline = 1989-91) which has the closest gearing of any D-Series transmission. I personally don't wish to use the equal-length axles that are required by the ZC transmission... So I'll be swapping in my HF's differential so that I may continue to use the stock axles. (the HF, DX and Si Differential are all the same right? Minus the Ring Gear and bearing sizes)
While I have the new tranny broken down, I'll install the HF 5th gear (including the corrosponding counter gear) so that I may keep my highway speed RPM's down (making my long drives much more pleasant)
Just thought I'd share my plans with everyone and see if I'm missing anything that needs to be done in order to carry my plans out.
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Running 185/60/14 (22.74 Inch) Tire/Wheel Combo
My Hybrid Transmission
ZC 1-4 (1st: 3.250; 2nd: 1.944; 3rd: 1.346; 4th: 1.033)
HF 5 (5th: 0.694)
ZC Final Drive(Final: 3.88 )
Data shown with redlining @ 7200rpm
GEAR MPH RANGE (RPM SHIFT RANGE)
1st: 0 - 38.64 (idle - 7200)
2nd: 38.64 - 64.60 (4306 - 7200)
3rd: 64.60 - 93.31 (4985 - 7200)
4th: 93.31 - 121.58 (5526 - 7200)
5th: 121.58 - 180.96 (4837 - 7200)
5th @ 80mph: 3183 rpm
ZC 5th Gear @ 80mph would be 4027 rpm!
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----------------------------------------
Things to do:
--Replace all bearings and seals
-There's a difference in the bearing sizes
Countershaft bearing (30x47x21 = HF; 30x55x21 = Si)
Mainshaft bearing (6205UC/26 = HF; 6305SPL = Si)
Differential Oil Seal (35x56x8 = HF; 40x56x8 = Si)
Speedometer Drive Gears have different part numbers between HF and Si
The transmission cases are of course different part numbers because the bearings are different sizes.
Since the only sizing that is different is one dimension, can I use either size bearings on the HF differential?
If I can use eithe size bearing on the HF Differential and ZC Main/Countershafts then I can use either case (ZC or HF) I want right? Just pick the bearings that match the casing?
--Swap in HF 5th gear and counter gear
--Swap in the HF Differential
-I am required to re-shim the differential upon bearing replacement right?
-Since I'm using the ZC Countershaft (part of Final Drive) I need to swap on the ZC ring gear onto the HF Differential correct? Is that all that the "final gear" consists of?
I've been searching every Honda/Acura website I can find as well as Google etc to gather as much info as I can. The above questions still remained somewhat unanswered to me from what I've found.
Thanks you for any help you may give.
John (BlueCrxNC)
bluecrxnc@hotmail.com
This weekend I purchased a ZC tranny (20 spline = 1989-91) which has the closest gearing of any D-Series transmission. I personally don't wish to use the equal-length axles that are required by the ZC transmission... So I'll be swapping in my HF's differential so that I may continue to use the stock axles. (the HF, DX and Si Differential are all the same right? Minus the Ring Gear and bearing sizes)
While I have the new tranny broken down, I'll install the HF 5th gear (including the corrosponding counter gear) so that I may keep my highway speed RPM's down (making my long drives much more pleasant)
Just thought I'd share my plans with everyone and see if I'm missing anything that needs to be done in order to carry my plans out.
--------------------------------------------------------------
--------------------------------------------------------------
Running 185/60/14 (22.74 Inch) Tire/Wheel Combo
My Hybrid Transmission
ZC 1-4 (1st: 3.250; 2nd: 1.944; 3rd: 1.346; 4th: 1.033)
HF 5 (5th: 0.694)
ZC Final Drive(Final: 3.88 )
Data shown with redlining @ 7200rpm
GEAR MPH RANGE (RPM SHIFT RANGE)
1st: 0 - 38.64 (idle - 7200)
2nd: 38.64 - 64.60 (4306 - 7200)
3rd: 64.60 - 93.31 (4985 - 7200)
4th: 93.31 - 121.58 (5526 - 7200)
5th: 121.58 - 180.96 (4837 - 7200)
5th @ 80mph: 3183 rpm
ZC 5th Gear @ 80mph would be 4027 rpm!
----------------------------------------
----------------------------------------
Things to do:
--Replace all bearings and seals
-There's a difference in the bearing sizes
Countershaft bearing (30x47x21 = HF; 30x55x21 = Si)
Mainshaft bearing (6205UC/26 = HF; 6305SPL = Si)
Differential Oil Seal (35x56x8 = HF; 40x56x8 = Si)
Speedometer Drive Gears have different part numbers between HF and Si
The transmission cases are of course different part numbers because the bearings are different sizes.
Since the only sizing that is different is one dimension, can I use either size bearings on the HF differential?
If I can use eithe size bearing on the HF Differential and ZC Main/Countershafts then I can use either case (ZC or HF) I want right? Just pick the bearings that match the casing?
--Swap in HF 5th gear and counter gear
--Swap in the HF Differential
-I am required to re-shim the differential upon bearing replacement right?
-Since I'm using the ZC Countershaft (part of Final Drive) I need to swap on the ZC ring gear onto the HF Differential correct? Is that all that the "final gear" consists of?
I've been searching every Honda/Acura website I can find as well as Google etc to gather as much info as I can. The above questions still remained somewhat unanswered to me from what I've found.
Thanks you for any help you may give.
John (BlueCrxNC)
bluecrxnc@hotmail.com
Thread Starter
Member
Joined: Jan 2004
Posts: 46
Likes: 0
From: North Carolina
From Jerry Isner:
John,
Sounds to me like you have a good grasp on the basics. The bearings that are on each side of the differential where they fit into the case are smaller outside diameter on the HF than on the Si. If you want to use your HF case with the HF axles, yes, you can just use the Si countershaft and swap the Si ring gear onto the HF differential (ring gear bolts are left hand thread). Or conversely, you could swap the HF bearings onto the Si differential. Use the ZC input shaft with ZC gears on it and swap the HF 5th onto it. You need to use the ZC input shaft as 2nd gear is part of the shaft and is not removeable. (Luckily you don't have 21 spline 88 transmission or you would also need to change the clutch.) Swap the ZC 2 thru 4 gears onto the Si countershaft and the HF 5th. All of this would give you a ZC/Si hybrid.
If you want to use all ZC gears, just swap the ZC ring gear onto the HF differential (with the HF bearings to use the HF case or the ZC bearings to
use the ZC case), use both ZC main and counter shafts with ZC gears and swap on the HF 5th. There are lots of possibilities, depending on what parts you have and what you want to end up with. If you need more help, just let me know.
Jerry
John,
Sounds to me like you have a good grasp on the basics. The bearings that are on each side of the differential where they fit into the case are smaller outside diameter on the HF than on the Si. If you want to use your HF case with the HF axles, yes, you can just use the Si countershaft and swap the Si ring gear onto the HF differential (ring gear bolts are left hand thread). Or conversely, you could swap the HF bearings onto the Si differential. Use the ZC input shaft with ZC gears on it and swap the HF 5th onto it. You need to use the ZC input shaft as 2nd gear is part of the shaft and is not removeable. (Luckily you don't have 21 spline 88 transmission or you would also need to change the clutch.) Swap the ZC 2 thru 4 gears onto the Si countershaft and the HF 5th. All of this would give you a ZC/Si hybrid.
If you want to use all ZC gears, just swap the ZC ring gear onto the HF differential (with the HF bearings to use the HF case or the ZC bearings to
use the ZC case), use both ZC main and counter shafts with ZC gears and swap on the HF 5th. There are lots of possibilities, depending on what parts you have and what you want to end up with. If you need more help, just let me know.
Jerry
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