Swapping out 8-in for 9-in Diff
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- Mustang Star
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Swapping out 8-in for 9-in Diff
I am about to swap out the old 8-in 28 spline rear end from a 70 Fastback, and replace it with 9-in 31 spline with 3.25:1 Lsd centre. Housing is from a 67-70 Mustang. Staying with drum brakes and a standard yoke.
Are there any issues that may be involved with this upgrade?
Are there any issues that may be involved with this upgrade?
Living the dream.
1969 Mach 1 351c
1970 Fastback 302w
1971 Fastback 351c
1969 Mach 1 351c
1970 Fastback 302w
1971 Fastback 351c
Re: Swapping out 8-in for 9-in Diff
Whats the ratio in the 8"?
A change on ratio will put your speedo out..
Just a matter of changing the driven gear in the trans though.
A change on ratio will put your speedo out..
Just a matter of changing the driven gear in the trans though.
Cheers,
Birchy...
Dodgy Bros. Customs
Suspect 67 - http://www.mustangtech.com.au/Forums/vi ... /t=52.html
Birchy...
Dodgy Bros. Customs
Suspect 67 - http://www.mustangtech.com.au/Forums/vi ... /t=52.html
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- Mustang Star
- Posts: 320
- Joined: Tue Jul 26, 2011 5:36 pm
Re: Swapping out 8-in for 9-in Diff
Unsure of current ratio. I am going to get the C4 tranny reconditioned at a later date, I assume a change of driven gear can be made then.
Note: What I know about the greasy bits of cars wouldn't cover the bottom of a vegemite jar, hence some of my questions may seem a bit lame.
Note: What I know about the greasy bits of cars wouldn't cover the bottom of a vegemite jar, hence some of my questions may seem a bit lame.
Living the dream.
1969 Mach 1 351c
1970 Fastback 302w
1971 Fastback 351c
1969 Mach 1 351c
1970 Fastback 302w
1971 Fastback 351c
Re: Swapping out 8-in for 9-in Diff
Pretty sure it requires longer U bolts over the tubes...
A little less clearance,nothing really concerning when mine was done.
A little less clearance,nothing really concerning when mine was done.
Re: Swapping out 8-in for 9-in Diff
Yes, awesome donuts & extreme tyre wear - at least they wear evenly.Faststangfan wrote: Are there any issues that may be involved with this upgrade?
See avatar.........
(PRAYER) Oh thank you Wild Turkey American Honey & Cola in those small thin bottles, for giving me the strength to act like a half wit, and say stupid things at inappropriate times, semi-anonymously, on a public forum.
Amen.
Amen.
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- Mustang Star
- Posts: 320
- Joined: Tue Jul 26, 2011 5:36 pm
Re: Swapping out 8-in for 9-in Diff
Righto, thanks.
I will use the opportunity while the rear end is out to clean up and respray the underbody. No rotisserie will use engine crane to lift rear of body high enough to work under.
I will use the opportunity while the rear end is out to clean up and respray the underbody. No rotisserie will use engine crane to lift rear of body high enough to work under.
Living the dream.
1969 Mach 1 351c
1970 Fastback 302w
1971 Fastback 351c
1969 Mach 1 351c
1970 Fastback 302w
1971 Fastback 351c
Re: Swapping out 8-in for 9-in Diff
And adding stands I hope....Faststangfan wrote:Righto, thanks.
I will use the opportunity while the rear end is out to clean up and respray the underbody. No rotisserie will use engine crane to lift rear of body high enough to work under.
Kerry
To our wives and sweethearts. May they never meet
To our wives and sweethearts. May they never meet
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- Mustang Star
- Posts: 320
- Joined: Tue Jul 26, 2011 5:36 pm
Re: Swapping out 8-in for 9-in Diff
Yep, one to hold the beer and one to hold the phone in case the car falls on me and I need to call an ambulance.
Living the dream.
1969 Mach 1 351c
1970 Fastback 302w
1971 Fastback 351c
1969 Mach 1 351c
1970 Fastback 302w
1971 Fastback 351c
Re: Swapping out 8-in for 9-in Diff
As Muzzy66 said, the U bolts are a different width and a little longer. Hopefully the donar diff comes with the U bolts other wise you will need a set that suits a 9"
Matt
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Matt
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Re: Swapping out 8-in for 9-in Diff
Make sure your beer has a stubbie holder incase your pinned under there for longer than 5 minutesFaststangfan wrote:Yep, one to hold the beer and one to hold the phone in case the car falls on me and I need to call an ambulance.
Dont want ya beer to go warm during the wait!!
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