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As I wrote you in response to the PM you sent me:

"Yes, changing the final drive affect all gears. However, I'm not sure where you are planning on getting a 3.88 final drive. If you are driving IMA-less I would consider an HCH Swap, which will get you a 12.2% lower 3.6 Final drive."

Are you looking at the 3.842 final drive that was used in the 7th gen Civic HX? If that's the case, it's important to understand that the 7th gen Civic HX came equip with a "D" series engine. Honda's D series engine spins in the opposite direction as compared to the Insight's engine as well as the "L" series engines used in the HCH and Fit.

While it's more than likely that the ring and pinion would physically fit, the helical gears are cut in the opposite direction and that is going to alter the thrust loads on the bearings inside the transmission in a way Honda never intended. Without further analysis, it's hard to say what the repercussions of that would be.

Non-sequitur: I need to update my HCH Transmission Swap Anthology thread with a nice comparison graph like the one I did in this thread.

Oh of course that's right, some Hondas have the engine on the left instead of the right like the Insight, and so of course the gears would be different with an engine turning the other direction! Oops!
 

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Oh of course that's right, some Hondas have the engine on the left instead of the right like the Insight, and so of course the gears would be different with an engine turning the other direction! Oops!
Oh of course that's right, some Hondas have the engine on the left instead of the right like the Insight, and so of course the gears would be different with an engine turning the other direction! Oops!

So what is different about the trans in the Civic Hybrid, why can you can use those gears? Isn't the Hybrid like the other Civic transmissions, mounted on the right side of the car and so set up to rotate the opposite direction from the Insight? What other Honda cars have the trans on the left and so rotate the same way as the Insight? Is it just the Fit? What final drive ratios do they have, and would it be possible to use a Fit final drive gear in an Insight?
 

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Discussion Starter #23 (Edited)
I literally already answered this question.

Are you looking at the 3.842 final drive that was used in the 7th gen Civic HX? If that's the case, it's important to understand that the 7th gen Civic HX came equip with a "D" series engine. Honda's D [and B] series engine spins in the opposite direction as compared to the Insight's engine as well as the "L" series engines used in the HCH and Fit.
You can definitely put a Fit final drive into an HCH trans. Forum member Sigma Projects has already done this. It's probable that a Fit final drive would also (physically) fit into an Insight transmission case, but I haven't tested this.

There are other many other Hondas with the same layout, but the transmissions are not the same inside.
 

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I literally already answered this question.



You can definitely put a Fit final drive intro an HCH trans. Forum member Sigma Projects has already done this. It's probable that a Fit final drive would also (physically) fit into an Insight transmission case, but I haven't tested this.

There are other many other Hondas with the same layout, but the transmissions are not the same inside.
Thanks! I am trying to absorb all the info in your article about installing the HCH trans in an Insight. Looks like a Honda Fit manual trans had 4.1 or 4.294 final drive. That would be a BIG change in gearing, it would drop the mph/1000 rpm down to about 22 or 23, so lean burn would be from about 45 to 60 mph. Which just might work for the way I drive the car. Stay tuned, some day I might just try a Fit final drive in an Insight trans, and if I do I will of course post my results.
 

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...Continued.

First Impressions
... “This is how Honda should have geared the transmission.” In my humble opinion, I have put together the best combination of off the shelf parts that both maintains the fuel-efficient spirit of the Insight and improves drivability.
Great work, and write-up!
 

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Wowser. This dedicated and generous thread is a perfect example of Enthusiasm, Comraderie, and the Beauty of 'Open Source' data. Citizen (In)S(ight)cience ~without~ Special Interest; Profit Driven goal structure. I'm off to weep now. Thanks Guys! (Spoiler Alert: Bull Dog = 🎅)!

Happy 2020!,
 

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Thanks! I am trying to absorb all the info in your article about installing the HCH trans in an Insight. Looks like a Honda Fit manual trans had 4.1 or 4.294 final drive. That would be a BIG change in gearing, it would drop the mph/1000 rpm down to about 22 or 23, so lean burn would be from about 45 to 60 mph. Which just might work for the way I drive the car. Stay tuned, some day I might just try a Fit final drive in an Insight trans, and if I do I will of course post my results.
...Continued.

Modification Time

Having done all the research I could, I worked out a time with Scott (KLR3CYL) to once again travel 1,100 miles down to Jue Motors, in Covina, CA so that we could accomplish the re-gearing.

Scott and I are good friends. Scott works for and is long-time friends with Jimmy Jue, the owner of Jue Motors. Jimmy is a terrific guy and I am incredibly grateful to him for allowing Scott and I to work together on projects like this one in his shop. Jue Motors is an excellent independent automotive repair shop with a sterling reputation.

View attachment 83661
This is an HCH differential with an Insight ring gear bolted to it.

View attachment 83662
My HCH Transmission Frankentrans is back together and ready for reinstallation.


Over the course of a few days in late July 2019, Scott and I performed the aforementioned modifications to the transmission. After reassembling everything and reinstalling the transmission into my 2006 Insight, it was finally time drive the car and see if it was worth all the effort.


First Impressions

The Frankentrans doesn’t immediately feel radically different compared a regular Insight transmission. And that is by design. What I’ve done is to smooth out some of the rough edges and improve drivability while sacrificing a minimal amount on the fuel economy front.

And that is where the Frankentrans shines. The 6.4% lower second gear means accelerating from 10-11 MPH in second is easier and less likely to necessitate a downshift into first. Third gear is 11.6% lower which makes accelerating in third easier. Fifth gear is 6.1% lower, dramatically improving drivability in lean burn.

After the first 80 miles driving with my Frankentrans, the thought occurred to me, “This is how Honda should have geared the transmission.” In my humble opinion, I have put together the best combination of off the shelf parts that both maintains the fuel-efficient spirit of the Insight and improves drivability.



MBD 137 here, from the Phila area. I have decided to try a 3.6 final drive from a Civic Hybrid in my 2000 Insight trans. But the gears are unavailable, on back order from Honda. Am looking into used parts, do you or anyone you know have a HCH ring gear, countershaft and speedo drive gear for sale?
 

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I might still have what you are looking for. I'll check tomorrow. You won't need a speed sensor if you keep the Insight case.
Thanks, that would be great, yes please look. So you are saying the stock Insight VSS will work, but do I need the HCH speedo drive gear in my Insight trans? I have ordered a speedometer correction module from Jay Car, so I can dial in the correct speedo reading if I can get the parts to physically match up. So can I re-use my stock Insight speedo drive gear and VSS and then use the correction module to get an accurate reading?
 

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Discussion Starter #30
The VSS measures the speed at which the axles are turning. Changes you make upstream of that won't affect it's accuracy. You will not need a correction module if you keep the Insight transmission case.

Just checked, yes, I still have the HCH Ring and Pinion left over from this Franken-trans project. I am sending you a PM so we can discuss details.
 

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mbd137, please include your Location in your Profile, as ALL G1 Insighters have done.
 

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The VSS measures the speed at which the axles are turning. Changes you make upstream of that won't affect it's accuracy. You will not need a correction module if you keep the Insight transmission case.

Just checked, yes, I still have the HCH Ring and Pinion left over from this Franken-trans project. I am sending you a PM so we can discuss details.
Great! Oh, I see how the VSS works now. Thank you very much!
 

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Discussion Starter #35
Time for a somewhat overdue update.

In late January, my Frankentrans suffered an unexpected failure. I started hearing a speed dependent and infrequent howling noise. Over the course of a couple of weeks, the noise became more frequent, and eventually, I was able to confirm that the howling sound was indeed coming from the transmission. Bugger!

Thankfully, my Frankentrans waited to fail until I was back down in SoCal working with Scott at Jue Motors. So up on the lift my car went and out came the transmission.

After opening up the transmission and removing the shafts, the root cause of the issue was readily apparent…
P1000110.jpg

The countershaft’s bellhousing-side, roller bearing had come out of its bore and started rubbing against the bottom of the pinion gear on the countershaft. (To get a rough idea of how this bearing should look, please see the next picture.)

So why did this happen?

Before I answer that, a little history is in order. As far as I can tell, the Honda Insight was the first vehicle in which Honda used this specific roller bearing, Honda part number 91101-PHR-003.

P1000112.jpg

As seen in the above photo, model year 2000 Insights used a “bearing set plate” to retain the countershaft bearing. By 2001 or 2002 Honda stopped installing this bearing set plate in the Insight transmission. I even made note of this back in 2015 when I was rebuilding the transmission on my 2006 Insight.

Bull Dog said:
I was thrown for a bit of a loop because the service manual calls for installing a bearing set plate. I checked through all my parts thinking I must have removed it and forgotten. But after looking through the pictures I took during disassembly, I realized that my transmission never had one installed from the factory.
So, what did Honda change to make it so that the set plate was no longer needed? In the case of the Insight, they made an unspecified engineering change to the countershaft.

P1000125.jpg

The shaft on the left is from a 2000 Insight transmission and the one on the right is from a 2002 Insight transmission. Please note how the countershaft on the right has a shoulder that extends down part way from the pinion gear.

This is what Honda changed. It is also why they no longer needed the bearing set plate with the revised countershaft in the Insight transmission.

This difference also illuminates why Honda's other transmissions that also use the same bearing don’t have a provision for a bearing set plate. With the revision to the design of the countershaft, the plate isn’t needed.

In short, the problem with my Frankentrans arose because,
  1. The Honda Civic Hybrid transmission case has no provision for a countershaft bearing retention plate because the HCH countershaft doesn’t require the use of one.
  2. I used a model year 2000 Insight countershaft which requires the use of a countershaft bearing retention plate.
An unfortunate mistake, but on the upside, now I know.
 

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Very interesting - thanks for sharing that.

If one wants to make a Frankentrans, the takeaways appear to be:
1) When combining a HCH housing and Insight countershaft, make sure to use a 2001 or later Insight countershaft with the shoulder at the pinion gear.
2) If one cannot find a 2001 or later Insight countershaft, the HCH case is going to have to be modified (if possible by drilling, tapping, and possibly sealing) to accommodate the bearing set plate.
 

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If there is sufficient material and strength in the later gearbox casings then drill and tap to accept a retention plate.

I suppose you could simply bond the bearing into the case?

How tight a fit is it?
 

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If there is sufficient material and strength in the later gearbox casings then drill and tap to accept a retention plate.

I suppose you could simply bond the bearing into the case?

How tight a fit is it?
If it's anything like the K series I've worked on, it's snug enough that you might think it would stay on its own.

Can't believe I missed this thread! Thank you so much for sharing this. I personally would keep 5th the same, so probably using an Insight ring and pinion in an HCH trans to get the improved 2-3-4 spacing. Can you link to the thread where you discussed modifications necessary to put the HCH box in?

I have a Frankentrans in my K swap and ran into several unforseen issues as well. It's funny how poorly documented some engineering changes are.
 

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Discussion Starter #40
Here is my HCH Swap thread.
 
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