Rear End Talk

85rkyboby

Active Member
Mar 2, 2011
923
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South ATL
Talk to me about Rear Ends. I'm still trying to decide on a 9" Solid Axle or 8.8" with a Torque Arm, Panhard Bar. With the power I want I'm clueless as to if I will blow a 8.8" through the roof, do they make Torque Arm Setups for the 9"ers? I was looking at some Fab9 Rear Ends are they good? Am I going the right route with wanting a Torque Arm Setup? I'm looking for good cornering stability and the option to track the crap out of it. I however am shying away from the IRS Swap.
 
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no its a bolt on end like the 9" has. gets rid of the need for c clip elims. they dont leak and you can run a large 9" bearing end.
 
depends how serious of a track car it will be. if its going to see 1.0x 60's in a heavy car id prob go 9" with gun drilled 40's. but if you just want a street car id prob stay 8.8.

what is the combo that you expect 900-1300 out of?
 
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You're going to need a lot of chassis work if you're going to throw 1000+hp at it. Minimum 10pt cage,subframes,torque boxes,probably an ARB, and if going with a 8.8 you'll need to weld the tubes and add some bracing. I'd run a eaton trac loc if road racing. Spools do not like turning. I'm not sure how the panhard bar/torque arm will respond to that power level. If road course/track competion is in the plans that much power will be to much. Obviously you're going to need a very good brake system. If it's going to just see the street and Dragstrip id go with the 9"ends,35sp axles and either a spool or the Moser wave trac diff.
 
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Guys have run 8's (even quicker) for years on 8.8's.

Considering it will be a road race style setup you will probably never generate the traction to break an 8.8 that was built well.

Not going to give a full blown lecture on the goals here, but i'd suggest you give it some real thought about what you are building is going to be good at, if anything... Don't build something for bragging rights, build something useful.
 
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Don't build something for bragging rights, build something useful.

^^Agreed.

@85rkyboby
I just can't get my mind around the HP goal with road course racing.

If this is a road course only built car then how do you plan to accelerate out of corners with 900-1300hp? Most people on this site normally report that 450-500whp in a stang as pretty wicked and a beast to control when trying to just go straight.

If your competing in road course, aren't there rules as to what mods you can have? Limitations for class?

I believe @MFE92 is an autoX/road course racer and does very well with a mildly modified NA engine and he's posted some entertaining videos to prove it.

Where are you at with your build right now? Why not go IRS swap for road course?

Check out this video of some foxbody owners racing on a road course.

View: https://www.youtube.com/watch?v=J5_I_W31yKY
 
I don't have much to add, but If you're really intending a 1000 hp build, I hope you have all the following figured out before you start buying parts. How are you going to:

- Feed it
- Cool it
- Steer it
- Stop it

Getting all the components figured out to accomplish those things will likely dictate a lot of the parameters you need to think about with the rear end.
 
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what is the combo that you expect 900-1300 out of?

351 with a power adder, hopefully Vortech Blower.

You're going to need a lot of chassis work if you're going to throw 1000+hp at it. Minimum 10pt cage,subframes,torque boxes,probably an ARB, and if going with a 8.8 you'll need to weld the tubes and add some bracing. I'd run a eaton trac loc if road racing. Spools do not like turning. I'm not sure how the panhard bar/torque arm will respond to that power level. If road course/track competion is in the plans that much power will be to much. Obviously you're going to need a very good brake system. If it's going to just see the street and Dragstrip id go with the 9"ends,35sp axles and either a spool or the Moser wave trac diff.

Awesome. Yea, I've got a guy that's going to do a 10pt cage for me along with sfc and the torque arm setup. No on the competitions, for road course at least. However I would like to be able to go do track days on occasion. So would it be wiser to set this thing up for drag racing, would I still be able to track it at all?

Guys have run 8's (even quicker) for years on 8.8's.

Considering it will be a road race style setup you will probably never generate the traction to break an 8.8 that was built well.

Not going to give a full blown lecture on the goals here, but i'd suggest you give it some real thought about what you are building is going to be good at, if anything... Don't build something for bragging rights, build something useful.
So I need to build this thing as a dedicated track car?

^^Agreed.

@85rkyboby
I just can't get my mind around the HP goal with road course racing.

If this is a road course only built car then how do you plan to accelerate out of corners with 900-1300hp? Most people on this site normally report that 450-500whp in a stang as pretty wicked and a beast to control when trying to just go straight.

If your competing in road course, aren't there rules as to what mods you can have? Limitations for class?

I believe @MFE92 is an autoX/road course racer and does very well with a mildly modified NA engine and he's posted some entertaining videos to prove it.

Where are you at with your build right now? Why not go IRS swap for road course?

Not competing. As I have read the rules for SCCA & NASA whether it be AI, AIX, etc. As of right now I have the short block, some suspension parts (some installed, some not), & the car. I was just trying to avoid the IRS due to the wheel hop factor and how far it pushes the wheels out.

I don't have much to add, but If you're really intending a 1000 hp build, I hope you have all the following figured out before you start buying parts. How are you going to:

- Feed it
- Cool it
- Steer it
- Stop it

Getting all the components figured out to accomplish those things will likely dictate a lot of the parameters you need to think about with the rear end.

Yes, thank you. I have a few parts currently. This is why I'm trying to figure all this out now. Basically blueprinting, so to speak.

Thanks for all of the feedback and suggestions guys. Great responses, it's good to have people that will help and I can trust. Keep it coming.
 
It's way easier to drag race a car optimized for road race than to road race a car optimized for drags, but the requirements are so different, I'd build the drag car and then buy somebody else's finished corner carver for pennies on the dollar.
 
So I need to build this thing as a dedicated track car?

No, lol. I'm anti track only cars.
I'd tone the build back. What you are building isn't going to be good at road racing or drag racing. Probably suck on the street too. It's excessive. Which I know sounds great, trust me, I've been there, but it's just great in theory, in practice you will have something that is dangerous that you can't do anything with.

Build your 351, cut the power adder out for now. Probably save you 7-10 grand.
See how you like the car, then move forward if you really, really need more power.

1000hp is not good for road racing a street car (or maybe even any type of car), nor is it good on the drag strip on a road race suspension. In fact I bet at the drag strip you would run a massive mph and a 500hp ET losing to much less powerful machinery.

Building a good all around fox isn't easy, I know I've been working on it for 20 years. Ridiculous hp is NOT the way to get there.

I personally see the the max useful power on a non drag racing fox as about 600rwhp, even that may be a little generous.
 
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