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Discussion Starter #1 (Edited)
Big thanks to Sigma Projects for this idea! https://www.insightcentral.net/forums/modifications-technical-issues/120307-my-transmission-swap.html

Last weekend, I put in a Honda Civic Hybrid 1st gen(HCH1) manual transmission into my 1st gen IMAess Insight. Why? Because the HCH1 have a shorter differential ratio (3.6 vs 3.21) and 1st to 2nd gear ratio is much closer. Revving to 4k in first gear to just to get to 2k in second gear is a drag. See the below for more info.

I used the Insight's EXEDY KHC11 clutch kit from Rockauto, the pilot bearing is the correct size. I planned to do the rear main seal as well, but I can't get the stator off without the special puller so I left the old rear main seal in. The old clutch looks to have another 100k miles of life left, and the new clutch and pressure plate surprisingly is lighter than the old ones. I used 180 grit sand paper to re-surface the flywheel.

Minor things to take notes:
Couple of brackets for the starter wire can't be re-use on top of the transmission
Reverse light wiring needed to be extended
Needed to use a different hole for chassis to transmission grounding wire and bolt, I used an hole on the transmission mount
Air box will now support by two bolts instead of three

Major things to take notes:
ONE: The input shaft on the HCH1 needed to be machined a little, you don't touch the bearing surface, but the area between the bearing surface and the splines need to be reduce from 18mm diameter to 15mm diameter or less. I used my grinder and Dremel tool.



Two, Buy two 12x1.25 fine thread nut and washers because the two studs on top of the HCH1 transmission is bigger than the Insight transmission's 10mm studs. The motor mounts will accept the bigger studs fine, you'll just need the bigger washers and nuts.


Old clutch


New clutch
 

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Discussion Starter #3 (Edited)
Insight transmission with 3.21 FD



HCH1 transmission with 3.6 FD




Driving experience? I love the HCH1 transmission! I used to have to rev out to 4k in first gear so I can get to 2k in second gear to keep the engine in its power band. That's changed now, only a little over 3k in first to get to 2k in second. I can use second gear bewteen 10-18mph without lagging the engine. Acceleration is improved in all gear and feel way more than 12% as the FD ratio suggest. The car can climb small incline in 5th gear now on highway! It requires way less downshift just to maintain speed. The IMAless Insight actually feel FUN to drive!

Sigma Projects, thanks again!!!

What about MPG? Constant 45mph with 6 stops got me.
 

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Great write up and pics, thanks!

Is it a plug and play with speedometer too?

This would be even cooler if the speedo works correctly with the new final drive ratio.
 

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Awesome! Btw the studs on the stock transmission can be transferred over to the HCH1 trans. I swapped them over because I liked how the Insight studs were made just long enough to bolt on the bracket.

Also the speedo gear is ran off a gear on the differential and are the same teeth count and since our diff is the same size it shouldn't have any trouble even if you put the original in. My speedo seems fine even with the fit speed sensor, but at some point I will hook up my friend's Honda diagnostic computer to see if the computer is noticing any speed discrepancies.
 

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That’s really amazing information! Great work. It certainly increases the pool of parts, doesn’t it?
Now... my curiosity is peaked about the possibilities on the CVT side!
 

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So the full transmission works with factory axles? It looks like Sigma did a gear swap and you did a full transmission swap.
They do, I did a gear swap (including the differential) of Honda Fit gears into the HCH1 case, but the differential itself between the GD3 Fit and HCH1 are the same.
 

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Discussion Starter #11
So the full transmission works with factory axles? It looks like Sigma did a gear swap and you did a full transmission swap.
You got it.


That’s really amazing information! Great work. It certainly increases the pool of parts, doesn’t it?
Now... my curiosity is peaked about the possibilities on the CVT side!
I'm afraid of CVT, when I see a car has CVT, I turn around running!
 

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Nice work.

Is the input shaft bearing different on the G1 V HCH1 gearbox?

Are they different parts? Sizes?

As we know the G1 can have ISB problems, I have never heard of an hch1 with ISB issues...

Any difference? Wonder if a part swap is possible etc..
 

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Nice work.

Is the input shaft bearing different on the G1 V HCH1 gearbox?

Are they different parts? Sizes?

As we know the G1 can have ISB problems, I have never heard of an hch1 with ISB issues...

Any difference? Wonder if a part swap is possible etc..
I posted about this a while ago. ISB between the two are different. They have the same ID and bearing height, but the OD of the HCH1 is larger, you would have to machine out the bearing location on the bell housing.
 

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Nice work.

Is the input shaft bearing different on the G1 V HCH1 gearbox?

Are they different parts? Sizes?

As we know the G1 can have ISB problems, I have never heard of an hch1 with ISB issues...

Any difference? Wonder if a part swap is possible etc..
My MT HCH1 was developing good old Honda ISB whine when I dumped it. ~145k miles.

Sent from my ZTE A2017U using Tapatalk
 

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Epic! My trans has a bad grind in 2nd, would love to fix it but after reading this I'd rather just replace it with an HCH trans.
 

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Discussion Starter #17 (Edited)
Do I need to change out the clutch and all that to the HCH or is all that compatible?
Insight clutch fits HCH1 transmission input shaft but you need to read post 1 again to get all the details.
 

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Insight clutch fits HCH1 transmission input shaft but you need to read post 1 again to get all the details.
This is where I wish I grabbed a HCH1 flywheel for comparison. Since I'm 95% sure if a person needed a new clutch and got a flywheel/clutch for a HCH1 they'd be golden and wouldn't need to modify the main shaft.
 

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Discussion Starter #19
This is where I wish I grabbed a HCH1 flywheel for comparison. Since I'm 95% sure if a person needed a new clutch and got a flywheel/clutch for a HCH1 they'd be golden and wouldn't need to modify the main shaft.
HCH1 clutch disc is bigger at 8.687 in diameter vs Insight's 7.5, which mean the flywheel, pressure plate, clutch disc will be heavier. Unless someone is adding turbocharger/supercharger/nitrous the Insight clutch will be plenty to hold the torque, my 175k clutch disc looks to have another 100k of life left! Machining the input shaft takes maybe 5-10 minutes of time, it's a good way to save the extra weight on the rotational parts.
 

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HCH1 clutch disc is bigger at 8.687 in diameter vs Insight's 7.5, which mean the flywheel, pressure plate, clutch disc will be heavier. Unless someone is adding turbocharger/supercharger/nitrous the Insight clutch will be plenty to hold the torque, my 175k clutch disc looks to have another 100k of life left! Machining the input shaft takes maybe 5-10 minutes of time, it's a good way to save the extra weight on the rotational parts.
That's with the assumption that the flywheel is the same weight. The CRZ flywheel uses a slightly larger clutch, but the flywheel itself is 1.2lbs lighter. I'm betting it would be a wash. I'm suggesting though for someone who needs a new clutch. Otherwise it would be cheaper to just modify the main shaft to reuse the stock items. And the increase in size of the clutch is actually pretty small, but the nice benefit is that the clutch radius is larger which allows to grab better, probably making it easier to have the clutch catch.
 
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