Build Thread '83 T-top Coupe - Welding Holes in My Rear

[Mustang5L5]

I'm lost. Now we are doing Zonda exhaust?

Just toss the IRS in and stick to nice sticky 295s. Is 20mm of tire worth the extra work? How much power you plan on running that you really need 315s?

 

[95BlueStallion]

There's always this.

 

[droopie85gt]

With a fuel line and a spark plug to get rid of those unwanted pedestrians or motorcycles at the stop light!

 

[95BlueStallion]

 

[95BlueStallion]

In reality Dave, I was thinking something like this on my car, because Ive never seen it done on a fox.

 

[90sickfox]

It could be done... with enough work...

If you lay the shock inboard it might contact the sway bar. That attachment point ( rear ) could be moved to inside the rear frame. Gas tank would have to move. The next challenge would be the spring seat location on the lower control arm.???

The front mounting location could be easily moved.

Looks like a different lower arm would need to be fabricated. ( way beyond my skill level )

 

[90sickfox]

In reality Dave, I was thinking something like this on my car, because Ive never seen it done on a fox.

This reminds me of a gt with lx pipes coming through the rear bumper.

 

[Davedacarpainter]

It could be done... with enough work...

If you lay the shock inboard it might contact the sway bar. That attachment point ( rear ) could be moved to inside the rear frame. Gas tank would have to move. The next challenge would be the spring seat location on the lower control arm.???

The front mounting location could be easily moved.

Looks like a different lower arm would need to be fabricated. ( way beyond my skill level )

Would the front mounts need to be changed at all?

Aren't the main contact points for larger wheels/tires the rear mount and shock? Would there be contact with the lower front connection?

I would use coilovers if I did this, so spring mount wouldn't be an issue. Might even consider new lower control arms from KB or MM that has the lower spring mount removed.

As for the shocks, I would think moving the upper mount in and back would still allow clearance from the sway bar. In my mind, that would be the challenge. I'm not sure because I don't have an irs to do any measuring at the moment.

Why the need to move the gas tank? I'm asking this because I really don't know the problems I might have with it.

I was thinking a hard tail mount that would bracket the frame and the handlebar be mounted to the bracket directly below the frame.

 

[Davedacarpainter]

I'm lost. Is 20mm of tire worth the extra work?

Yes

 

[CarMichael Angelo]

Yes

If I died tomorrow, I can die peacefully knowing that you said that.

 

[Hoytster]

Would the front mounts need to be changed at all?

Aren't the main contact points for larger wheels/tires the rear mount and shock? Would there be contact with the lower front connection?

You shouldn't have to modify the front mounts at all, there is plenty of room there. I'm seriously considering making my front mounts a hard mount also, just don't know what that would do to NVH. Not that I should probably care about that.

 

[CarMichael Angelo]

I would be doing the same thing Dave. If I was considering an IRS, I'd be looking for the same solutions to NOT cut my quarters and put a fender flare on it to allow a real tire to fit the car. If the cradle can be narrowed, I'd narrow it. I'd tip in the shock, or look at reconfiguring the whole mount to relocate the shock if that is the limiting factor.

 

[CarMichael Angelo]

It could be done... with enough work...

If you lay the shock inboard it might contact the sway bar. That attachment point ( rear ) could be moved to inside the rear frame. Gas tank would have to move. The next challenge would be the spring seat location on the lower control arm.???

The front mounting location could be easily moved.

Looks like a different lower arm would need to be fabricated. ( way beyond my skill level )

How much does this thing weigh as a complete unit anyway?

Where does the fact that this thing looks to be at least 200 pounds heavier than a SRA come into play?

How much ground clearance do we sacrifice to accommodate 3" tail pipes that run under the rear end?

I'd make two individual 1" tall X 5" wide rectangular tunnels under the rear seat that would solve the "where do I run my exhaust?" Possibly even running them far enough back through the trunk under a false raised floor, and the redirect the exhaust down and out after that.

Factory shock/ spring would be so gone,....and replaced with a C/O....why sacrifice even more room, and carry around the weight of the factory lunkers?

But all this is crazy talk anyway, I wouldn't be considering an irs...

 

[Davedacarpainter]

You shouldn't have to modify the front mounts at all, there is plenty of room there. I'm seriously considering making my front mounts a hard mount also, just don't know what that would do to NVH. Not that I should probably care about that.

I kind of see it as a rear k-member. Those are solidly attached with a control arm with bushings.

Oh well, I guess I have enough to think about at the moment though.

BTW, anyone within 600ish miles of me, if you find a deal on an IRS and you don’t want it, send me a note about it please. I have a new truck just waiting for a decent cruise.

 

[Hoytster]

How much does this thing weigh as a complete unit anyway?

Where does the fact that this thing looks to be at least 200 pounds heavier than a SRA come into play?

General consensus is the IRS weights about 145 pounds more than a SRA, and reduces unsprung weight by about 125 pounds.

 

[Hoytster]

I kind of see it as a rear k-member. Those are solidly attached with a control arm with bushings.

I'm really starting to lean toward doing it. It seems to me the factory used bushings so it could re-use mounting locations and allow for some flex in the design since the fox chassis is not always consistent from chassis to chassis.

 

[95BlueStallion]

This reminds me of a gt with lx pipes coming through the rear bumper.

I know what you mean, as I saw examples of that in the very search that netted me that classic through the valance style. I cut my rear GT bumper, so it shouldnt look as tacky. Its all still up in the air.

 

[Davedacarpainter]

Ok, just thinking here. Since I’ll remove the upper control arm bracket, wouldn’t there be a little extra room to run exhaust up there?

How much room is there above the mounted irs? @90sickfox ?

 

[90sickfox]

The issue with running exhaust above IRS is that there's no room between the sway bar and rear of cradle. The fuel tank sits right at the back of the cradle. If the fuel tank want there the mounting points could change to inside the rear frame rails and the exhaust could easily run over it.

That old tank is probably full off crud and holes. Could put a nice low profile baffled fuel cell right in the trunk.

 

[bird_dog0347]

Maybe I'm strange in that I LIKE the look of the IRS tailpipes. It's certainly the lowest hanging thing on my car and mine sits pretty low, but there's enough clearance that it hasn't been a problem. Things like speedbumps aren't an issue as the lowest point of the exhaust is in between the rear tires so it goes up when they do.

You won't need to do anything with the front mounts on the cradle as you'll be able to fit whatever tire you could fit with an SRA. Up and over the IRS for the exhaust is not an option without cutting out the floor pan and going inside, plus you'd have to come back out the trunk around the gas tank... sounds like a PITA to me.

The IRS is heavier as mentioned but reducing the unsprung weight is key here. Also having the weight in the rear helps to better balance it front to back. And also as mentioned already, you'd certainly want to use a coil over for it. But if you were to cant the shock inboard you'd have to move the shock mounts in the trunk as well and make sure they can carry the load now going through them. I'll keep an eye out for an IRS down here in DFW... if you're going to do it you really should only look for an 03/04 as it's stronger/better than the 99/01.