6 speed to 5 speed swap!

turbovan

Too many toys!!!
Mar 4, 2018
109
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Abbotsford, BC, Canada.
Long story short, I hurt 5th gear towing, so short on time, I can get a 6 speed with 100k, for a reasonable price. If I put my 5speed wiring and valve body in, will it work? If it will work, anything I should do while I am swapping it? TIA.
 

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
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Make sure it has the input speed sensor on the bell housing. LMM 6 spd doesn't have one there, it's on the engine.(Could still swap it over too if needed) You'll need to swap the NSBU switch over also
 
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Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Thanks so much.

Should I put a shit kit in the valve body?
shift kits are usually better lol. But it depends on how abuse that current 6 speed is. you can throw a transgo jr in there but if clutches are hurt or the converter is hurt, it wont hold much power for long. ideally, you will have it out so youd be better off just building it now.
 
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turbovan

Too many toys!!!
Mar 4, 2018
109
13
18
Abbotsford, BC, Canada.
shift kits are usually better lol. But it depends on how abuse that current 6 speed is. you can throw a transgo jr in there but if clutches are hurt or the converter is hurt, it wont hold much power for long. ideally, you will have it out so youd be better off just building it now.
They came out of wrecked vehicles, 100,000 km's, fluid cherry red. Pans were dropped, no metal etc in the pan.
Will be using my aftermarket converter.
Selling them for $550 complete. Has 2 left, blowing out stock.
My original went 450K, so this should get me a few years, and time to get the 5 speed gone thru and repaired/fixed up.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
They came out of wrecked vehicles, 100,000 km's, fluid cherry red. Pans were dropped, no metal etc in the pan.
Will be using my aftermarket converter.
Selling them for $550 complete. Has 2 left, blowing out stock.
My original went 450K, so this should get me a few years, and time to get the 5 speed gone thru and repaired/fixed up.
it wont hurt to put a transgo jr in then. also, make sure that converter is flushed/cleaned real well before you go putting it back in. same with the heat exchanger in the rad. would really suck to send old trash back through the new/used trans and then potentially kill it.
 

turbovan

Too many toys!!!
Mar 4, 2018
109
13
18
Abbotsford, BC, Canada.
You need a transgo JR. Nobody should ever use the full transgo kit on a 5spd regardless.
This kit can be installed in 2001 to 2005 vehicles with the Allison five-speed transmission, however, using this kit with these first design earlier five-speeds will not provide the 111% increase in torque capacity needed for 4th and 5th gear. Repeated failure of the C2 on these five-speed units is a common complaint, therefore we highly recommend installing part # ALLISON SK instead of this Allison-Jr for these early five speed units.
May I ask why? They only show one kit for the 5 speed and one for the 6 speed. It says you can use the 6 speed JR in the 5 speed but it won't get the benefits of higher clutch holding power.

Always open to learning. Thanks again.
 

Bdsankey

Vendor
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Feb 1, 2018
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May I ask why? They only show one kit for the 5 speed and one for the 6 speed. It says you can use the 6 speed JR in the 5 speed but it won't get the benefits of higher clutch holding power.

Always open to learning. Thanks again.
The issue is TransGo thought the issue was the C3 was overpowering the C2 and causing the issue when in fact it was the other way around. The 5spd kit causes harsh shifts as it removes the cushioning effect of the C2 piston.


Any decent builder will ignore the full transgo kit. If Mike were still around he'd be the first to tell you that the full transgo kit for a 5spd is a crock of shit and will cause more issues than help. The JR helps quite a bit but doesn't solve things like low line pressure, less aggressive clutch material, and reduced clutch counts.


As James said, you've got it out and would be a decent time to rebuild/overhaul it if you desired.
 

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
2,937
113
63
Central OH
If the new trans is a 6spd core and you're just swapping valve bodies, can't use the early "Full Transgo 5spd" kit anyway. Being that you're running an aftermarket converter, I'd pull the bell housing off so you can run a new regulator spring and mod the converter valve. If your 5spd has 400k miles on it now, I doubt you'll ever need to truly build the trans unless you plan on cranking the power up.
 
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turbovan

Too many toys!!!
Mar 4, 2018
109
13
18
Abbotsford, BC, Canada.
If the new trans is a 6spd core and you're just swapping valve bodies, can't use the early "Full Transgo 5spd" kit anyway. Being that you're running an aftermarket converter, I'd pull the bell housing off so you can run a new regulator spring and mod the converter valve. If your 5spd has 400k miles on it now, I doubt you'll ever need to truly build the trans unless you plan on cranking the power up.
Awesome. Yeah, the stocker went a long time.
Any link on modding the converter valve? New oem spring or aftermarket?
No plans on cranking, just a nice tow tune, that's all I need. :)
We all know that slippery slope, more power here equals more money over here, then over there and so on and so on, lol.
 

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
2,937
113
63
Central OH
You could shim the stock pressure spring, most people run the red ratiotek spring. The converter valve just needs a relief cut into the outer most part, there's a few threads on it floating around but I'd have to dig to find one with good pictures. Google will probably help more there. Or just get one already modified from Inglewood Transmission (I think they charge 40 or $50).
 
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Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
19,858
2,792
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Phoenix Az
Just run the Ratiotek spring. Stock springs are inconsistent and can go into coilbind pretty easy if you shim it too much. Don’t add shims to the Ratiotek spring, that pressure is plenty and more will shred the stock linings off. Iirc it’s 280-290psi