Rear end.....

**secondgearscratch** · 04-22-2007, 10:07 PM

i was on tech a little this week and came across a thread about rear ends. it was said that a manual is better mated with a 9 inch and an auto should have a 12 bolt. i was wondering what the reasoning is behind this. i would have asked, but i didnt feel like getting ridiculed for having a low post count and not owning a mustang (on an ls1 website btw).

i just figured i would go with what was cheaper, and since a ford 9 inch housing can be had for 200 bucks, i was going to take my chances. but i still would like to know the difference between the two rears and the trannies that spin them. help is much appreciated.

**secondgearscratch** · 04-23-2007, 11:11 AM

bump for pathetic little me.....

**Ws6 Love** · 04-23-2007, 11:38 AM

ppl say with a manual it puts a lot more stress on the 12, and the 9 holds up a lot stronger. the only reason IMO to get a 9 is if ur gonna get above 700whp, i know ppl with a 12 bolt with 700 and its still holding up, just get a 33 spline, plus i think the 9 robs more hp out of u too

**Bobby97SS** · 04-26-2007, 03:50 AM

9' ford rears are the strongest out there and gears are cheaper and easy to change. On my short track car we kept a couple of center sections ready to go and could swap in less than an hour.

**INMY01TA** · 05-20-2007, 04:17 PM

I know like 10 guys with six speed/12 bolts that broke em.

**slims00ls1z28** · 05-24-2007, 12:32 PM

I'm an auto and I have a 9. Planned ahead. Decided I wasn't going to be one of the guys who dumped 5k in motor mods and breaks the rear. I would guess the reasoning stands that the strange 12 bolts TA mounting design can warp easier in high HP launches and seeing that m6's are harder than A4's it would just add to that. I got the 9 because for now I have a 3500 stall and will be launching plenty hard on it when its all done so I went 9 for strength. And changing from a 2.73 to 4.10 ger I didn't notice ANY hp losses

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