Rear End Ratio?

C

custompony

New Member

Jul 7, 2011

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Jul 13, 2011

#1

• Jul 13, 2011

• #1

I have a 68 coupe that will have a 302 hooked up to a T-5 from a '90 mustang. I am planning on changing to an 8.8 rear end and am wondering what the ideal rear end ratio would be? I do a pretty even mix of freeway and city driving.

 

sdmustangrider

New Member

Sep 24, 2009

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San Diego

Jul 13, 2011

#2

• Jul 13, 2011

• #2

I've been interested in a T-5 lately, and from what I hear, 3.73 is pretty good for both if it comes for a 8.8. I'm running a C4 3.40 Ford 8 and it's not THAT bad.

 

blown65

Founding Member

Jul 7, 1999

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Queen Creek Arizona

Jul 13, 2011

#3

• Jul 13, 2011

• #3

At least 3.73's. Personally I'd probably run 4.10s cause even in 5th your going to have nice highway rpms and in the lower gears great performance. 1st is going to be kinda short though with the 4.10s depending on the gearing of your T5.

 

65fastbackresto

Active Member

Apr 13, 2007

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AR

Jul 13, 2011

#4

• Jul 13, 2011

• #4

I have T-5 and 355 rear

I can shift from 4th to 5th at 70 mph and it`ll drop to almost 2000rpm`s, which for my motor, is kinda lugging it. If I could do it over I`d prob go 411`s.

 

robbz28

Member

Sep 23, 2009

775

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Epps, LA

Jul 13, 2011

#5

• Jul 13, 2011

• #5

That will have a good bit to do with your camshaft and your engines "happy spot", also the ratio of your T5, since they vary some. If you have a fairly bone stock 302 then 3.55-3.73's will probably do wonderful, but if your engine is modded and likes higher RPM's then 3.73-4.11's. Lots of guys on here with that swap.

 

65fastbackresto

Active Member

Apr 13, 2007

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Jul 13, 2011

#6

• Jul 13, 2011

• #6

Thats my problem,, motor is built for top end

I can either run 55mph or 80mph in its happy spot. It gets pretty scary over 100mph though, its like too much motor not enough car.

 

Fstbk

Member

Sep 7, 2010

215

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Jul 13, 2011

#7

• Jul 13, 2011

• #7

Here is a handy calculator that may help?

 

jlangholzj

Mustang Master

Oct 23, 2006

248

31

93

MI

Jul 13, 2011

#8

• Jul 13, 2011

• #8

robbz28 said:

That will have a good bit to do with your camshaft and your engines "happy spot", also the ratio of your T5, since they vary some. If you have a fairly bone stock 302 then 3.55-3.73's will probably do wonderful, but if your engine is modded and likes higher RPM's then 3.73-4.11's. Lots of guys on here with that swap.

Click to expand...

this. I've got a fairly standard HCI 289 and with the o/d ratio of an AOD and 3.00 gears it was at about 1200 rpm. I'm planning on putting 3.73's in as I've ridden in other mustangs with a similar setup and it seems to be well. with the .76/1 of the AOD and 3.73 gears we were seeing about 1800-2k at speeds of 60mph or so. But it climbs out of the hole mighty fast

 

C

custompony

New Member

Jul 7, 2011

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Jul 13, 2011

#9

• Jul 13, 2011

• #9

Fstbk said:

Here is a handy calculator that may help?

Click to expand...

That thing is awesome. Right now at 80mph in 5th I'm at 2k. Definitely looks like 3.73 or thereabouts is gonna be great for me. Thanks for the responses.

 

blown65

Founding Member

Jul 7, 1999

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Queen Creek Arizona

Jul 14, 2011

#10

• Jul 14, 2011

• #10

jlangholzj said:

this. I've got a fairly standard HCI 289 and with the o/d ratio of an AOD and 3.00 gears it was at about 1200 rpm. I'm planning on putting 3.73's in as I've ridden in other mustangs with a similar setup and it seems to be well. with the .76/1 of the AOD and 3.73 gears we were seeing about 1800-2k at speeds of 60mph or so. But it climbs out of the hole mighty fast

Click to expand...

We run 4.56's with our AOD car and its still 2500-2600 at 60-65mph. Not too bad IMO for a classic. However its set up for the rpms that motor sees.

 

jcode68

Active Member

Jul 15, 2003

892

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Massachussetts

Jul 14, 2011

#11

• Jul 14, 2011

• #11

I'm running 3.73's with my T5 and think it is the perfect ratio. If you plan to spend time on the strip, you might want to go steeper, but for street driven, I have no regrets.