Replace FWD tranny with AWD tranny

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mdelfunt
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Replace FWD tranny with AWD tranny

Post by mdelfunt » Wed May 17, 2017 9:01 am

Team, I have an 05 FS FWD with a bad tranny. I found a AWD tranny. What are the issues with putting the AWD tranny in it? (I don't care about having AWD - just trying to get my FWD working).
Thanks!!


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jas88
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Re: Replace FWD tranny with AWD tranny

Post by jas88 » Wed May 17, 2017 10:44 am

The 6-speed swap thread in this forum talks about folks who had AWD CVTs and replaced them with FWD 6-speeds successfully. I would think it would work, you just don't connect anything up to the PTO drive for the rear. Not sure what issues that might create WRT warning lights and such, tho.
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Scotty17
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Re: Replace FWD tranny with AWD tranny

Post by Scotty17 » Wed May 17, 2017 11:35 am

I bought my 2005 SEL off my mechanic back in Dec who did a conversion from a FWD to AWD he also swap out the instrument cluster as well running great.

mdelfunt
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Re: Replace FWD tranny with AWD tranny

Post by mdelfunt » Wed May 17, 2017 12:34 pm

Jas88 - to be clear, I'm not trying to install a 6-speed from a 500, I have a CVT from an AWD that I want to put into my 05 FWD with CVT.
Thanks!

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jas88
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Re: Replace FWD tranny with AWD tranny

Post by jas88 » Wed May 17, 2017 1:53 pm

Yes I know that I was just saying it's been done (in reverse) with the 6-speed so it may be doable with the CVT.
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Mike51Merc
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Re: Replace FWD tranny with AWD tranny

Post by Mike51Merc » Fri May 19, 2017 8:39 am

I believe there is no major difference between the AWD and the FWD transmission, both are known as the CFT30 transmission. The AWD transmission has a PTU (basically a 90 degree transfer case) bolted to it. The passenger side front axle shaft passes through the PTU on its way into the transmission.

Remove the PTU transfer case and you have a FWD transmission.

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Re: Replace FWD tranny with AWD tranny

Post by HHR » Sat May 20, 2017 10:11 pm

Mike51Merc wrote:I believe there is no major difference between the AWD and the FWD transmission, both are known as the CFT30 transmission. The AWD transmission has a PTU (basically a 90 degree transfer case) bolted to it. The passenger side front axle shaft passes through the PTU on its way into the transmission.

Remove the PTU transfer case and you have a FWD transmission.
I'm pretty sure the final drive gearing in the AWD transmission is deeper than the FWD.

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Re: Replace FWD tranny with AWD tranny

Post by Mike51Merc » Sun May 21, 2017 6:11 am

HHR wrote:I'm pretty sure the final drive gearing in the AWD transmission is deeper than the FWD.
Um, best as I know, CVTs don't have gearing, not to mention final drive gearing (which I always understood to mean differential gearing). Are you saying the sheaves are different? Do you have any reference to help answer the issue?

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Re: Replace FWD tranny with AWD tranny

Post by xvert » Mon May 22, 2017 8:42 am

Several years ago I had the idea of using FWD cvt in my bad AWD cvt, because FWD were cheaper and with less mileage. I was going to buy the FWD cvt and to moved from my AWD the following parts:
-"Bell Housing" with or whithout oil pump
- Mechatronic unit assembly with TCM or only TCM
- "Spur Gear"
- "Side Gear and Shaft Assembly"
- Differential shaft
Image
I could forget something but this is very easy to do. This is necessary because the gearratio the FWD cvt is 5.19 but the AWD is 5.54. Having been 20,000 km from the source of used spare parts, I did not dare to do such a job.
To all who want to change the cvt to the used one, I would advise to replace the O-ring between the torque converter and the input shaft. But it is better to disassemble the cvt and replace overhaul kit and bearings, inspect inputshaft and repair the torque converter. This work is inexpensive, but it will protect you from the new repairing of the cvt

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Re: Replace FWD tranny with AWD tranny

Post by Mike51Merc » Tue May 23, 2017 7:07 am

Xvert,
Interesting stuff I didn't know. Thanks for posting.
The OP wants to swap an AWD trans into a FWD car. Since the FWD car has no rear differential, then the gear ratio difference doesn't matter much at all.

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Re: Replace FWD tranny with AWD tranny

Post by Gator417 » Wed May 31, 2017 10:36 pm

I'm definitely not an expert on all this, so I'll just ask the question. Would the awd tranny be able to sense there is no resistance at the ptu? If the front tires slipped, would it then transfer power to the ptu and keep you from moving? To answer my own question, since the fwd tcm is being used, it won't try this at all. Is this right or am I way off?
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Mike51Merc
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Re: Replace FWD tranny with AWD tranny

Post by Mike51Merc » Thu Jun 01, 2017 5:45 am

The power transfer is not at the PTU, it's at the rear differential Haldex unit. The PTU and the driveshaft are "live" all the time. The Haldex unit "locks up" to transfer power to the differential.

If you have no Haldex unit, there is no transfer of power.

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Re: Replace FWD tranny with AWD tranny

Post by Gator417 » Fri Jun 02, 2017 1:05 am

OK, different question. Basically what I'm asking is will the difference in trannys "confuse" the tcm or cause any issues? Its pretty simple to put the tranny in place and hook it up, but I'm just wanting some experts here to confirm the swap will be good or not.
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Mike51Merc
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Re: Replace FWD tranny with AWD tranny

Post by Mike51Merc » Fri Jun 02, 2017 6:07 am

Sorry can't help with tcm question, I'm more old school mechanic than computer guru.

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