IFS/IRS questions

[kstones63]

We are starting to decide what we are going to do with Nick's uni. We are contemplating IRS and IFS for this truck.
The choices would be Jag front and rear.
Mark VIII rear IRS with either Jag front end or Crown Vic front.
The third choice would be Corvette front and rear.
I have read plenty about the CV and the Jag front. Has anybody had any dealings with the Jag rear or Corvette front and rear?????
The Corvette suspension would probably handle the best. The Jag IRS is pretty cheap to buy. The Mark VIII IRS
is reasonable to buy and would probably be the easiest to install.
The engine will be a Mark VIII, mustang Gt or comparable.

Any thoughts or ideas????????

Kevin

[randyr]

We are starting to decide what we are going to do with Nick's uni. We are contemplating IRS and IFS for this truck.
The choices would be Jag front and rear.
Mark VIII rear IRS with either Jag front end or Crown Vic front.
The third choice would be Corvette front and rear.
I have read plenty about the CV and the Jag front. Has anybody had any dealings with the Jag rear or Corvette front and rear?????
The Corvette suspension would probably handle the best. The Jag IRS is pretty cheap to buy. The Mark VIII IRS
is reasonable to buy and would probably be the easiest to install.
The engine will be a Mark VIII, mustang Gt or comparable.

Any thoughts or ideas????????

Kevin

We are starting to decide what we are going to do with Nick's uni. We are contemplating IRS and IFS for this truck.
The choices would be Jag front and rear.
Mark VIII rear IRS with either Jag front end or Crown Vic front.
The third choice would be Corvette front and rear.
I have read plenty about the CV and the Jag front. Has anybody had any dealings with the Jag rear or Corvette front and rear?????
The Corvette suspension would probably handle the best. The Jag IRS is pretty cheap to buy. The Mark VIII IRS
is reasonable to buy and would probably be the easiest to install.
The engine will be a Mark VIII, mustang Gt or comparable.

Any thoughts or ideas????????

Kevin

Hey Kevin, Flatout Engineering http://www.flatout-engineering.com/ makes a really nice kit to mount the C4 Corvette front/rear suspension in these trucks. I won a kit at last years Western Nationals and got so excited I went out and snagged a deal on the complete suspension from an '84 Corvette. Then reality set in with my finances and I had to sell it all. But in the process, I learned a few things.
If you use the Corvette front, you may have crankshaft pulley clearance issues with the R&P, depending on your engine choice. As for the rear, you usually had a choice of 3:07 or 3:44 gears, I think but most of them had the 3:07.

The Jag has the same bolt pattern as the Corvette so you could use the Jag front and Corvette rear using the same wheels.

As you know, the Crown Vic front is pretty wide so you have to be prepared to use the proper offset on the wheels. I think on the Mark VIII IRS you have to have to swap the rear hubs to Mustang Cobra to get the 4.5" bolt pattern. You could also use the IRS from the '96/97 Tbird, which already has 4.5" bolt pattern.

There's also the Dodge Dakota kit for the front that looks pretty sweet.

Lots of options. Look forward to seeing some pics! Is it a short or long uni?

[Gritsngumbo]

Kevin: I also missed the post about the purchase and subsequent pictures. Knew you were looking for one for him. Can't give advice as I haven't done either yet, but are you sure you/he want/need IRS? It's exotic, yes, but much of what I've heard is that it's overkill in our trucks, sort of like most peoples opinions on rear disk brakes.

[Toyz]

Kevin,
Have you looked at the kit Factory Five uses for their Cobra replicas? It's based on MK VIII/ Thunderbird components "fancied" up a bit. It appears one of their width options would work well with the Slicks. It also can be set up with the Mustang Cobra's hubs to allow a much wider wheel selection than those of the Mark/MN12 fwd-style offset.
randyr, I don't know of a '97 Bird; pretty sure the '96 had the same Mark/Taurus/Bird pattern. Also, be aware not all Jags have the familiar 4.75 bolt pattern. I believe the common swap donor does, however. The XK's stayed with the 4.75 pattern, the XJ's and S-types did not.
I just got around to getting one of the MK VIII's up in the air today to remove both front and rear assemblies. I still want to do a "sidewinder" 32 valve mounted in the rear, but that will be well in the future, after the full-frame CV adaptation.
Paul

[randyr]

randyr, I don't know of a '97 Bird; pretty sure the '96 had the same Mark/Taurus/Bird pattern. Also, be aware not all Jags have the familiar 4.75 bolt pattern. I believe the common swap donor does, however. The XK's stayed with the 4.75 pattern, the XJ's and S-types did not.

Paul

You're right, Paul. My bad! I just looked it up and the '89-97 Tbirds all had 5x4.25, not 4.5. I thought I had read it differently somewhere. As for the Jags, here's a listing of the various bolt patterns http://www.discountedwheelwarehouse.com ... erence.cfm

[kstones63]

I agree that the IRS might be overkill for our trucks but we are looking to do something different.
I found an 86 C4 vette on craigslist without an engine for $1500 that has been there for a while so it will probably sell for less. I found an 86 Mark VIII with 104k on it for $1600 and again I might buy it for less. I am thinking that I can part out one of these vehicles and keep the parts that we need and be into them pretty cheap. I don't want to spend all of his money before we get very far. I would rather spend the time making something fit instead of spending a lot of his money. That's why I kind of ruled out the Flat out engineering mounts.
I had forgotten about the T-bird IRS. That could possibly come with a 4.6 engine that we could use.
Here is the link to his truck.
viewtopic.php?f=32&t=29805
He only paid $600 for this truck but I had to go to California to get it.

Kevin

[rickairmedic]

Kevin I cant remember if his uni is a long or short . I would say if its a short dont forget the full frame swap to a 89 or older crown vic chassis . That option is still fairly uncommon and yet quite cheap . I gave $900.00 for a complete one owner ( little old lady ) clean clean clean 88 crownvic with 108,000 on the clock and have the body sold to a demo dr=erby guy for $200.00 already and figure I will get another $200.00 out of the interior and other stuff I dont need leaving me with $500.00 invested in the chassis and drivetrain .


Rick

[kstones63]

His truck is a long bed.
I guess that the older Crown Vic frame could be stretched to fit a long bed. I will talk to him about that possibilty when I get a chance.
Nick is still working out of town and it is going to be hard to get some decisions made since he is gone most of the time. He is on his way to Dearborn right now for another almost 2 week project, then I have no idea where he is going after that.

Kevin

[Toyz]

Kevin,I believe the later Town Car extended wb is another option for the LB uni's. I'll re-confirm the wb, but I seem to remember it being right. The only thing I don't like about the full-frame conversions is the big rear hump in the bed. That is why I'm still considering the earlier Town Car front clip with a MK VIII rear. It should allow an "in the weeds" altitude while keeping the full bed floor. The Mk Viii "pumpkin" is aluminum while the T-bird is iron, if that matters. If you intend to remain with the stock donor components, also keep in mind that the Mark utilized air bag suspension, as you know. The Bird components will interchange; both will accept the common 8.8 internals, including 4.00 plus gearing if desired.
I have thought about using the Fatman front which is currently on one of my projects; utilizing Shockwaves in the front with a good compressor and the stock Mark cradle and bags at the rear to make a fairly inexpensive adjustable height suspension.
If Nick makes a trip to Houston, he's invited to come by my "orphanage". I currently have the Fatman MII '66 chassis, the mentioned early Town Car clip on a '64 frame, a late Crown Vic PI front, and three Mark VIII's, one currently being disassembled. My CFO casts a wary eye any time I approach the XK-R with a tape measure, but the limited resale value of same may make it, or a similar one,a donor candidate in the future! I've also got my eyes on a Lincoln Continental 32 valve fwd, and a crashed Marauder at the moment. The shop's neighbors include another Slick addicted family, as well as one who specializes in buying and rebuilding CVPI's, so there's a pretty good selection of components in the area.
There's also US's Paradise not too far away with it's ever-changing items (and people) of interest, so if he should end up down this way, he, and you, are more than welcome to stop by.
With your proven fabrication abilities, this should be another interesting project!
Paul

[Toyz]

I'm assuming the Mark VIII you mentioned is a '96. Keep in mind that was the only year of the Gen I Mark VIII's with OBD2, so those components are a potentially troublesome single-year situation. The secondary throttle system was changed for the Gen II's. Of course it can be replaced with a good 5.0 manifold and adapter, allowing the use of most of the multitude of 5.0 aftermarket and OEM manifolds.
Paul

[Gritsngumbo]

Boy Paul, I knew you had quite an "orphanage" but just reading your list of projects makes me tired.

[kstones63]

Paul, You are correct about it being a 96 Mark VIII. Typo error
Are there problems with the 96 that you know of. I haven't heard of any.

Kevin

[Toyz]

Kevin, no real problems other than those I mentioned. The secondary throttle valve controllers are failure-prone,not to mention expensive and poorly located; and of course, cause a MIL code to appear. They are, however, my favorite of the Gen I's, mostly for reasons beyond donor needs. OBD II makes for easier tuning; and compatibility with after-market gauges and controllers. IMO, the Gen II cars have a much better setup, if they can be found at the right price. You really can't go wrong with any of them for donor usage; the 4R70 and the 32 valve are a pretty dependable combination. If you get an early Gen I, be sure to inquire about the transmission "J-Mod"!
Paul

[Toyz]

Boy Paul, I knew you had quite an "orphanage" but just reading your list of projects makes me tired.

Yeah, I've told everyone I'm "cutting back", but another orphan showed up today, and hopefully, one more is on it's way!
Suffice to say, my son and I are going to renew my FE and Pinto-motor roots The FE came sans boat anchor, and with a new Demon on top of the boat anchor's replacement.
Paul

[PFM-64f100]

What about a dakota front end?

[bcook07]

I am doing the 03 up vic ifs. I would go with it again in a heartbeat (especially using a 4.6L). the install is extremely easy. Using a modular engine, the motor mounts are a bolt in task with a set of mounts for a 03-up crown vic. mustang headers/exhaust manifolds and x or h pipes bolt on and fit very nicely.

[kstones63]

What about a dakota front end?

The Dakota isn't ruled out. It is still a possibility. I am trying to keep his costs down as much as possible. I would rather put some time into it rather than his money. I want to get him as far along on this project so he doesn't get bored and tired of spending money on it.
We have plenty of time to decide what to do. It appears that he is scheduled to be on the road for work until some time in August, at least that is what the company has the rental car scheduled for.

bcook, I need to check the width on the Mark VIII IRS, if it is narrower than the CV IFS, I would need to use two different types of wheels. It is still a possibility because it would be easy to mount the engine.

Kevin

[Toyz]

What about a dakota front end?

The Dakota isn't ruled out. It is still a possibility. I am trying to keep his costs down as much as possible. I would rather put some time into it rather than his money. I want to get him as far along on this project so he doesn't get bored and tired of spending money on it.
We have plenty of time to decide what to do. It appears that he is scheduled to be on the road for work until some time in August, at least that is what the company has the rental car scheduled for.

bcook, I need to check the width on the Mark VIII IRS, if it is narrower than the CV IFS, I would need to use two different types of wheels. It is still a possibility because it would be easy to mount the engine.

Kevin

63.25" hub to hub on the Marks, so not really any narrower. 4.25" original wheel pattern, though. Easily re-drilled or swapped for 4.5", however.
Paul

[kstones63]

Paul, Do you know the hub to hub on the CV front end? If it is the same, that would make that combo a top choice. I don't think that getting the hubs converted over to 4.5 would be a problem.

Kevin

[Toyz]

Hub to hub is right at 67 inches, putting the high-positive offset wheel at 63.5" track width.
Scratching head as this all adds up. Thus, MK VIII IS narrower. I had ignored the fact the Factory Five wide kit is wider than the stock Mark width, making use of common wheels unacceptable. i'll have to go back and look at the T-Bird dimensions.
So, for the Mark rear, it's either adapter-spacers, or different wheels, as you stated. SN95 Bullits rear (or even some replicas with the Bullit design in 4.25" pattern), and SN 97 Bullits front might be a good example of combinations of offset with common appearance..
As I previously mentioned, one other inexpensive option would be the earlier Panther front; (doesn't unbolt, not aluminum); but "normal" wheel offset and pattern, with crossmember which will accept mod-motors if that is your choice of powertrain. Still pretty substantial suspension and brakes, especially on PI's, but would require splicing in to Slick frame. I'll have to measure to be sure, but I "think" it matches the MK VIII width. I also need to record all pertinent dimension info for the Fatman MII, the early Panther, and the CV fronts, as well as the Mark/ TC rears, and the FF and team 321 rear conversions!
Well, back to the dream drawing board; sorry for the mis-information!
Paul