Subframe differences... Scratch that... K-Member Koncerns

996stang · Jan 29, 2024

Hello guys, ive done alot of research and heard the same answer 100 times but im wondering what the difference is between a 99 3.8 subframe and a 94-95 v8 subframe. Im doing the swap and i have a fox subframe that from my understanding with a few modifications should work, but im genuinely not understanding what the difference is, if the 94-95 5.0 and 3.8 subframe were identical, and the 3.8 is basically identical as far as mounting location goes, why will the stock subframe not work? has anyone tried? can anyone tell me what the differences were exactly? i feel that the difference wouldnt be huge, but ive been wrong before.
my reason for even caring is suspension wise i dont have much for the fox subframe and i dont know what will swap over, car will basically be a track car that will eventually get a tubular k, i just want it in and running. any info is greatly appreciated!

Noobz347 · Jan 29, 2024

I'm getting the impression that there is not a clear definition of terms.

The 99 and 94/95 are different platforms.

The [subframe] is not a removable component of either platform and what I think you are taking about is the [K-member] and not the subframe. is this correct?

996stang · Jan 29, 2024

Noobz347 said:
I'm getting the impression that there is not a clear definition of terms.

The 99 and 94/95 are different platforms.

The [subframe] is not a removable component of either platform and what I think you are taking about is the [K-member] and not the subframe. is this correct?

yes correct sorry

Noobz347 · Jan 29, 2024

996stang said:
yes correct sorry

In that case, if I am understanding the rest of your question correctly is, Yes... A Fox V8 K-Member should work just fine in a 94/95 Windsor engine V8 conversion.

I am [not] so certain that the Fox K-Member will fit in the 99, if that is what you mean.

996stang · Jan 29, 2024

Noobz347 said:
In that case, if I am understanding the rest of your question correctly is, Yes... A Fox V8 K-Member should work just fine in a 94/95 Windsor engine V8 conversion.

I am [not] so certain that the Fox K-Member will fit in the 99, if that is what you mean.

No, my question is what is the reason the stock k frame will not work, sorry if theres a misunderstanding.

Noobz347 · Jan 29, 2024

The engine mount locations between the 3.8 and the V8 are different.

So, if you have a Mustang that came with a 3.8, you need to swap to a V8 K member if you want to drop in a V8. Each engine has a different backset.

996stang · Jan 29, 2024

so basically a v8 would sit either to far forward or backwards? ive seen forums where guys say a 94-95 3.8 and a 94-95 5.0 subframe are the same. so i can safely assume ive been mislead by that information?

996stang · Jan 29, 2024

Noobz347 said:
The engine mount locations between the 3.8 and the V8 are different.

So, if you have a Mustang that came with a 3.8, you need to swap to a V8 K member if you want to drop in a V8. Each engine has a different backset.

sorry k frame.

Noobz347 · Jan 29, 2024

996stang said:
so basically a v8 would sit either to far forward or backwards? ive seen forums where guys say a 94-95 3.8 and a 94-95 5.0 subframe are the same. so i can safely assume ive been mislead by that information?

Let's double check that theory. What I know is that the Fox K-Member fits just fine in an SN95. My expertise ends there.

So, lemme move this thread to another forum where there's dudes that have swapped pretty much everything into everything and we'll find out for sure.

996stang · Jan 29, 2024

Noobz347 said:
Let's double check that theory. What I know is that the Fox K-Member fits just fine in an SN95. My expertise ends there.

So, lemme move this thread to another forum where there's dudes that have swapped pretty much everything into everything and we'll find out for sure.

Thank you!

AeroCoupe · Jan 29, 2024

Need some clarity here.:

1) What year car do you have, what motor came in it, and does it still have the factory k-member in it?
2) What k-member(s) do you have?
3) What motor are you wanting to put in it?

For your information (and I think you know this but just making sure) these are k-members, top is the stock one and bottom and an aftermarket tubular:

996stang · Jan 29, 2024

AeroCoupe said:
Need some clarity here.:

1) What year car do you have, what motor came in it, and does it still have the factory k-member in it?
2) What k-member(s) do you have?
3) What motor are you wanting to put in it?

For your information (and I think you know this but just making sure) these are k-members, top is the stock one and bottom and an aftermarket tubular:

Yes, im a tech we call almost anything thats a frame bolted in the car a subframe around the shop so i apologize if i use the term,
i have a 99, 3.8 t5. im looking to swap a little built 351 i have into the car. i have a k member out of a fox if i cannot use the factory one.

996stang · Jan 29, 2024

AeroCoupe said:
Need some clarity here.:

1) What year car do you have, what motor came in it, and does it still have the factory k-member in it?
2) What k-member(s) do you have?
3) What motor are you wanting to put in it?

For your information (and I think you know this but just making sure) these are k-members, top is the stock one and bottom and an aftermarket tubular:

Fox k member is a 5.0 k member

996stang · Jan 29, 2024

996stang said:
Fox k member is a 5.0 k member

factory K Member is still in the car, everything is in the car.

AeroCoupe · Jan 29, 2024

So a stock Fox k-member will not just drop into the 99 or at least that is what I have read on multiple forums. There is an issue with the rear mounting point on the lower control arm but it is solved by slotting the hole. Not sure what direction or how much bit that sounds sketchy to me anyhow. Most agree that a 94/95 kmember will work with some massaging of the kmember to frame mounting locations. Easiest way is a tubular kmember made for a Windsor motor swap.

996stang · Jan 29, 2024

AeroCoupe said:
So a stock Fox k-member will not just drop into the 99 or at least that is what I have read on multiple forums. There is an issue with the rear mounting point on the lower control arm but it is solved by slotting the hole. Not sure what direction or how much bit that sounds sketchy to me anyhow. Most agree that a 94/95 kmember will work with some massaging of the kmember to frame mounting locations. Easiest way is a tubular kmember made for a Windsor motor swap.

Where did you find that info? This car will mainly be driven on our local drag strip and with this subframe will never see more then 350-400 whp (on a good day). im not too worried about slotting the hole a little bit as it is what i have available, i think it should be fine until a tubular k member is an option.

AeroCoupe · Jan 30, 2024

Google.

Mustang5L5 · Jan 30, 2024

Like said, the main differences between the 87-95 K-member and 96-04 K-member (aside from engine mounts) is the location of the 4 rear bolts on the small pad. You'll have to do some grinding/modification to get those to work.

Also, steering rack is about 1" higher on the 79-95 K-member. This may create a bumpsteer issue with 96+ spindles because the tie rod location should be 1" higher to compensate. Bumpsteer kits don't work in this situation because the tie rod end needs to move UP into the area where the tie rod spindle mount currently occupies.

996stang · Jan 30, 2024

Mustang5L5 said:
Like said, the main differences between the 87-95 K-member and 96-04 K-member (aside from engine mounts) is the location of the 4 rear bolts on the small pad. You'll have to do some grinding/modification to get those to work.

Also, steering rack is about 1" higher on the 79-95 K-member. This may create a bumpsteer issue with 96+ spindles because the tie rod location should be 1" higher to compensate. Bumpsteer kits don't work in this situation because the tie rod end needs to move UP into the area where the tie rod spindle mount currently occupies.

Good to know, that is something i will have to keep an eye on. I have heard of bump-steer either being terrible or no big deal depending on severity so thats something guess ill just have to see myself. for anyone else ever wondering ive also found the suspension stuff is all useable as well, the control arms are 3/4 inch longer on the SN chassis, and the shock mounting side on the spindle side is a touch different but everything will bolt up especially if using the stock sn shock and a arms.

Mustang5L5 · Jan 30, 2024

There are differences in the 88-93 4cyl k-members vs the V8. The 4cyl are narrower.

You can tell by the spring perch cups which one you have. Do you have a pic? It’s hard to describe but visually easy to tell.

More info here

Fox - k member differences

Ok! I have a 1989 4 cyl. donor car. Is it true that the control arm mounting points are narrower? I would like to run longer control arms from the sn95 chassis on my fox and this I think would help me. My fox already has sn95 spindles paired with 2000 cobra r brakes. I am attempting a...

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Subframe differences... Scratch that... K-Member Koncerns

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