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Topic: 1998 sn95 Spindles on 87 tbird 5.0 (Read 204 times) previous topic - next topic

1998 sn95 Spindles on 87 tbird 5.0

I have sn95 mustang gt i bought for parts, i am rebuilding the axle and replacing the ring pinion with 3.27 ford trac lock, taking the 4r70w and putting the wide ratio gears in my AOD in the tbird.   my concern is fitment of the 98 SN95 spindles, is there anything i need to modify, do i need to put the control arms from the sn95 in the tbird, should i replace the steering rack with the sn95.   im not sure if there is going to be significant changes in angles that require more than just replacing the spindles.  Your help is most appreciated!!

engine still thinking what to do, i am thinking going cheap streetable, gt40p heads with gt40/explorer intake and a 270 grind roller cam, looking for a good torque curve between 1800rpm to 5800rpm

Re: 1998 sn95 Spindles on 87 tbird 5.0

Reply #1
i noticed the inner tie rods on a 98 mustang are 1.75 inches longer than 87 thunderbird.  do i need to swap the inner tie rods and purchase a bumpsteer tie rod kit that works for a 98 mustang, or do i keep the old inner tie rods and get a bump steer kit that fits the 87 thunderbird inners?
 i know i need to get maximum motorsports camber caster plates

Re: 1998 sn95 Spindles on 87 tbird 5.0

Reply #2
Okay, I would say do a search but here it goes being I've done this swap a few times and on my Coupe and Bird both with Cobra brakes.

1) What you really want is '94-'95 spindles if you are running a stock k-member as most aftermarket tubular k-members are designed around the geometry of the '96 and up spindles.  I will say that I ran '96-'04 spindles on my Coupe prior to installing the Maximum Motorsports k-member and all was well but I did run a bump steer kit to help offset the geometry issue.  The bump steer kit I used was the one with the tapered ends and I used all the spacers between the spindle and outer tie rod.  The other think you might want to do is install MM's solid rack bushings which will also help with rack deflection which causes issues on bumps.  If you already have a tubular k-member you need to check with the manufacturer as to which spindle design (Fox, 94-95, or 96-'04) they designed the k-member around.

2) So the 87-88 Birds and Cougars have '94-'04 SN95 front LCA geometry LCA's in them already so swapping over to the SN95's front LCA's is perfectly fine to do.  Just make sure the bushings and ball joints are good to go.  If you use the SN95 LCA's everything just bolts up.  If you elect to use the existing '87 Bird LCA's you will need a washer stack to go between the top of the spindle and the castle nut as the Fox spindle is thicker here.  Simply measure both spindles and you can come up with the difference but I believe it is 0.330" stack of washers or a spacer.  I know the spacers used to be available online which makes sense if you are reusing your existing LCA's and the ball joints are new or low miles.  If not then just buy SN95 ball joints and press them into your existing LCA's.

3) My recommendation on brakes would be to run the '99 and up PBR twin piston calipers from either a V6 or V8 car (non-Cobra) on the '94-'04 spindles as they work with the '94-'04 V6/GT front rotors.  The '94-'98 calieprs are single piston and the braking is vastly improved with the dual piston units off the '99-'04 cars.  This requires just a touch of metal removal right at the caliper mounting "ears" on the '94-'98 spindles so the PBR's will fit but should be a bolt on with the '99-'04 spindles.  You will also need new brake lines so get the SS braided ones that are for a Fox car converted to SN95 calipers and yes the SS braided lines make a difference.

4) To do the SN95 rack and pinion swap I used the Maximum Motorsports hybrid steering shaft.  The Fox rack is splined at the steering shaft connection where the SN95 has a funky triangular shape to it.  The hybrid shaft has the correct connection and is telescoping which makes the install a lot easier.  They did away with the rag joint and the knuckles do not have any set screws so the unit is pretty compact and will not interfere with exhaust like the Flaming River units have a tendency to do.  This is not cheap so you may want to visit other options.  Reuse your existing low and high pressure lines but you will need new Teflon seals which typically can be found in the help section at any local parts store.  The benefit of the SN95 rack over the Fox rack is the Fox rack is way over boosted where the SN95 rack is not and this is due to the torsion bar and the way the rack transitions to power assist.  Both of these mods require a more effort from the driver but to me it feels more like a German car like a BMW or Mercedes which I like in that I get a better feel of the car.

5)  The '79-'93 Mustangs tie rods (power and manual) have 9/16"-18 SAE threads.  The '94-'04 Mustang power steering rack tie-rods have metric M14x1.5 threads.  So if you convert over to the SN95 rack there are two ways to fix the problem of the mismatched threads.  Remove the inner tie rods off the Fox rack and install them on the SN95 rack and use your existing outer tie rods.  The other option which I believe works is to use the SN95 inner and outer tie rods but you will have to cut down the threaded part of the inner tie rods as the whole assembly is just too long.  Since you have both you can verify this with some measuring.

6) The bump steer kit will depend on which way you go.  There is a tapered kit and what they call a straight through kit.  I have the straight through kit on both of my cars due to how low they are (full coil over cars).  To do this you have to buy a reamer and ream out the outer tie rod connection point on the SN95 spindles.  Go to Maximum Motorsports website and you will see what I am talking about.

7) Good choice on the CC plates.
 

83 351W TKO'd T-Bird on the bottle


93 331 Mustang coupe that beat your mom's LTD

Re: 1998 sn95 Spindles on 87 tbird 5.0

Reply #3
I really appreciate the info, the forum has been acting funky on me lately, i got most of my info in searches in pieces.  You verifying and summing it all up helps.  It is 400 dollars on ebay for 94 95 spindles, if i was to use a combination of both offset bushings and tappered bumpsteer tie rods, would i position the rack lower or raise the rack?  Since i already have 98 spindles might as well use them

Re: 1998 sn95 Spindles on 87 tbird 5.0

Reply #4
would i use the bump steer kit for 79-93 mustangs with sn95 control arms, or just the regular 79-93 bumpsteer from maximum motorsports?

Re: 1998 sn95 Spindles on 87 tbird 5.0

Reply #5
A '93 5.0 Mustang and an '87 5.0 Bird have the same inner and outer tie rods and the same rack an pinion so with that I would say that you would order the regular bump steer kit for a '79-'93 Mustang.

Typically you will raise the rack as most cars are lowered.  What I did in lieu of using a bump steer gauge was try and make the inner/outer tie rod combo as parallel to the LCA's as I could with the suspension of the car loaded.  If a person does not have a drive on lift you can put jack stands under the rear end and then put them under the "hat" of the rotor with the rotor secured to the wheel bearing/hub assembly with lug nuts.  I will say that this is dangerous but I have done this when working on the car without being under it.  I do have a second set of jack stands under the rear of the front subframes as close to touching as I can so that in case there is is a failure there is a backup.  All I do is get them set up and then remove the jack stands out from under the rotor "hats" and let the secondary set then do the job while I am torquing things up.

83 351W TKO'd T-Bird on the bottle


93 331 Mustang coupe that beat your mom's LTD

 

Re: 1998 sn95 Spindles on 87 tbird 5.0

Reply #6
It is impossible to fix the bumpsteer issue created by using 1996-2004 spindles on a car with a 1979-93 k-member, with a bumpsteer kit. A bumpsteer kit can only lower the outer tie rod. With this combination of parts, the outer tie rod needs to be inside the end of the steering arm (raised 1"). See the links below for more information.

https://forums.corral.net/forums/8565296-post36.html

https://www.maximummotorsports.com/Good-Handling-Is-Fun-Facts-Fiction-and-the-Myth-of-the-Mustang-Bumpsteer-Problem.aspx