To make an I-6 highway-able... Gears or tranny? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TwoFiftyShifter · 11-16-2009, 09:44 PM

I'm putting together a '64 shortbed this winter, and don't plan on spending a ton. With keeping the 230 and wanting to cruise at 65 on the highway, the current setup will not do it. I have the 3 on the tree and 3.73 gears. What's the better route, 3.08 gears or say..... a T5 tranny? I would be putting in a new clutch anyway, does anyone run an I-6 with a T5? Have a bench seat as well not sure about the shifter location....

Everytime I search for T5 I get people wanting to put it behind small blocks and other people saying it will break.... Thanks for the help.

terd ferguson · 11-16-2009, 09:51 PM

I know guys who run T5s with inlines. I think you want one from a truck to work with your bench. If I recall, the shifter is farther forward than on the car T5. You should be able to cruise all day with that. Or you can change the rear. Might be cheaper, adapters for the T5 can get pricey. If you're on the hamb, search there. There are a ton of these swaps with documentation and tons of info.

2manyprojects · 11-16-2009, 09:56 PM

I would go with a T5. I put 3:08's in a 66 with a 250 and it was a dog. The T5 cant handle the torque of a strong V8 but should be fine behind a 6 .

TwoFiftyShifter · 11-16-2009, 10:43 PM

Yeesh, I meant to put this in the 60-66 thread... Yeah I figured the 3.08 would be a dog but it would be way easier. I guess ill look into the T5 swap, thanks. Also, I have read that the S10 trannies were rated for 220lb torque, the little 230 isnt even near that, is it? And for calculating gear ratios, whats the top rpm for a six? 3800 or so?

okfine101 · 12-10-2009, 06:32 PM

There is another option. Replace your current Tranny with one that has overdrive (58-62 pass). The bolt up is the same an you can keep your three on the tree. You will need to add a little additional electrical (relay & kickdown switch).

playinsafe44 · 12-11-2009, 01:30 AM

I have a '73 longbed with a 250, 3 on the tree, and 3.73 gears. I can get it going 65 on the freeway but the hills usually slow me down a little. It does take a little longer to get up and going too. The only changes I have made is a holley/weber 2 bbl, and a stock style HEI. I think my set up would do 10X better if I put larger jets in the carb though. It's starving right now.

11-16-2009, 09:44 PM	#1
TwoFiftyShifter Registered User Join Date: Nov 2008 Location: Gwinnett GA Posts: 1,803	To make an I-6 highway-able... Gears or tranny? I'm putting together a '64 shortbed this winter, and don't plan on spending a ton. With keeping the 230 and wanting to cruise at 65 on the highway, the current setup will not do it. I have the 3 on the tree and 3.73 gears. What's the better route, 3.08 gears or say..... a T5 tranny? I would be putting in a new clutch anyway, does anyone run an I-6 with a T5? Have a bench seat as well not sure about the shifter location.... Everytime I search for T5 I get people wanting to put it behind small blocks and other people saying it will break.... Thanks for the help. __________________ 1982 K10 SWB 1987 V20 - Sold - Doh!

11-16-2009, 09:51 PM	#2
terd ferguson Registered User Join Date: Mar 2009 Location: Concord, NC Posts: 531	Re: To make an I-6 highway-able... Gears or tranny? I know guys who run T5s with inlines. I think you want one from a truck to work with your bench. If I recall, the shifter is farther forward than on the car T5. You should be able to cruise all day with that. Or you can change the rear. Might be cheaper, adapters for the T5 can get pricey. If you're on the hamb, search there. There are a ton of these swaps with documentation and tons of info. __________________ "I never apologize. I'm sorry, but that's just the way I am." - Homer J. Simpson 1955 2nd Series Chevy "King Of Trucks"

11-16-2009, 09:56 PM	#3
2manyprojects Registered User Join Date: Feb 2008 Location: Richmond VA Posts: 670	Re: To make an I-6 highway-able... Gears or tranny? I would go with a T5. I put 3:08's in a 66 with a 250 and it was a dog. The T5 cant handle the torque of a strong V8 but should be fine behind a 6 . Last edited by 2manyprojects; 11-16-2009 at 09:57 PM.

11-16-2009, 10:43 PM	#4
TwoFiftyShifter Registered User Join Date: Nov 2008 Location: Gwinnett GA Posts: 1,803	Re: To make an I-6 highway-able... Gears or tranny? Yeesh, I meant to put this in the 60-66 thread... Yeah I figured the 3.08 would be a dog but it would be way easier. I guess ill look into the T5 swap, thanks. Also, I have read that the S10 trannies were rated for 220lb torque, the little 230 isnt even near that, is it? And for calculating gear ratios, whats the top rpm for a six? 3800 or so? __________________ 1982 K10 SWB 1987 V20 - Sold - Doh!

12-10-2009, 06:32 PM	#5
okfine101 Registered User Join Date: Dec 2009 Location: Azusa, CA Posts: 3	Re: To make an I-6 highway-able... Gears or tranny? There is another option. Replace your current Tranny with one that has overdrive (58-62 pass). The bolt up is the same an you can keep your three on the tree. You will need to add a little additional electrical (relay & kickdown switch).

12-11-2009, 01:30 AM	#6
playinsafe44 Registered User Join Date: Feb 2007 Location: Portland OR Posts: 79	Re: To make an I-6 highway-able... Gears or tranny? I have a '73 longbed with a 250, 3 on the tree, and 3.73 gears. I can get it going 65 on the freeway but the hills usually slow me down a little. It does take a little longer to get up and going too. The only changes I have made is a holley/weber 2 bbl, and a stock style HEI. I think my set up would do 10X better if I put larger jets in the carb though. It's starving right now.



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