Factory Five Racing Forum banner

1 - 12 of 12 Posts

·
Senior Charter Member
Joined
·
1,230 Posts
Discussion Starter #1
I have a MkII with pindrive width front control arms. I would like to change to the MkIV spindles for for improved handling.

I have several questions though:
1) Is there a significant handling improvement by going to the MkIV spindle (my understanding is improved SAI with the MKIV spindle)?

2) I thought that FFR had an upper control arm mount adapter kit for converting MKI-III cars to the MKIV spindle, but I dont see it on the FFR site. Maybe I am wrong about this and ALL generation of chassis use the same upper control arm mounts. Hopefully someone more knowledgeable than me can clarify this.

3) I believe that the pindrive length lower control arms do not work with the MKIV spindle, so I will likely need standard length lower control arms. If that is true, then I will need longer sleeves for the upper control arms, and different front wheels with the correct offset. Hopefully someone can clarify this for me.

4) Anything else I am missing here? Longer ends on the steering rack (Flaming River manual rack)? Should the rack position remain in the factory MKII position, or should the "ackerman" mod be done (I have already done it with offset rack bushings, but I could move it back if needed)?

All advice is appreciated.
-Trevor
 

·
Official OLD GUY
Joined
·
3,869 Posts
OK, I'll see if I can give this a shot:

(1) IF you are suffering from drastic changes in your toe-in/toe-out during normal driving (what's referred to as "bump-steer"), then yes, the newer spindles will help get rid of that. That being said, I'm not sure just how it will effect your setup of pin drive widths. Bump Steer can be almost completely eliminated with a few parts (BS kit and the Breeze bushings) and some time spent adjusting your front suspension.

(2) The FOX and SN-95 spindles use an adapter to mount the spindle to the upper ball joint, that adapter is not needed with the newer style spindles as they are longer and made to replace both the spindle AND adapter of earlier year designs. The mount adapter you are asking about is the SAI bracket that is now integral with MK-IV frames and allows the UCA to be mounted on a vertical plane as opposed to the earlier horizontal plane, moving the UCA outward and down to help with the SAI issue of past models.

(3) Not sure on this one as I've never worked on a car with the pin-drive LCA's / UCA's. Just changing the spindles shouldn't effect where you mount your UCA's or LCA's so you shouldn't need new wheels and tires. Remember that the uppers are NOT going to be mounted on a SAI type bracket on your MK-II unless you change everything suspension related.

(4) Your tie rod ends should stay the same and have a considerable amount of "adjustment" in them. Unless you have cut them shorter, you should be fine.
The Ackerman mod isn't accomplished with the Breeze bushings, those are used to center the rack housing to the frame horizontally or "lift / drop" it a bit to help with tie rod alignment to the LCA. Ackerman adjustments are made by moving the rack back toward the rear end shortening the distance from rear end center to front end center to help with steering angle during turns.

Hope I've helped a bit, hopefully others will chime in if my answers are off base. I have a MK-II with out any of the mods (SAI or Ackerman) and have pretty much eliminated Bump Steer with adjustments and the Breeze bushings to lift the rack and a Bump Steer kit that allows incremental adjustments up and down.

I run 275-17's up front . . . I run 3-1/2° of positive caster and -.5 camber with 1/16" Toe-In with a Flaming River manual rack (18:1 ratio) . . .

Doc
 

·
Charter Member
Joined
·
1,060 Posts
I'd call FFR and ask them about the spindle adapter and what other parts you may need to change. They don't always have everything on the website.
I found that changing up some of the parts of the MKII front suspension left me with a very noticeable bump steer condition. I spent most of this past winter trying to resolve it, mainly because there are many options based on the approach decided on (each having their own trade-offs). Just be knowledgeable about what you need and what you have to re-evaluate after changing these parts. After changing the spindle, at a minimum you will need an alignment and check to see if bump steer is manageable.
 

·
FFCobra Craftsman
Joined
·
24,197 Posts
If you install the FFR spindles the UCA ball joint fits right into the top of the spindle w/o an adapter. But, you need to make a new mount for the frame end of the UCA. This is how FFR does it on the current frames.
FFR Fr Susp 3 by craig stuard, on Flickr
But you can make it from some 1/4 x 2" angle iron like it was done in the SAI kits.
20210401_080409 by craig stuard, on Flickr
This is a description of where the holes need to end up from Jim Schenk, FFR Engineer.
IMG_20161114_074719136 by craig stuard, on Flickr
Backround. The point of the SAI kit was to move the UCA ball joint outward. Fox spindles are too tall to do that as they would be the same place the inner rim of the wheel is. But SN95/FFR spindles are shorter which allows room inside the wheels for the BJ as long as they are 17" or larger. Since the spindles are shorter, the BJ moves down as well as out. So, to keep geometry the same, the frame mount point needs to move down as well as out also. Another benefit of the new frame mount is that you can usually re-use the UCA w/ no need to make it longer.
 
  • Like
Reactions: Robert D

·
Too Cheap to paint!
Joined
·
6,346 Posts
Great info so far, I am following.

I have a MKII, standard width, now with SN95 spindles. I have done considerable work to make the front suspension better, including the Breeze Rack bushing kit and rack position, Alignment specs, re-positioned upper shock mounts, changed springs, and have the front end set up quite well, no bump steer. I have been recommended to get the MkIV spindles, but with my car, not sure how much it will improve.
 

·
Charter Member
Joined
·
1,060 Posts
I'm guessing, but I suspect, the MkIV 2 piece spindles are the same geometry, yet easier to install, version of the SN95 spindles with the SAI kit. Craig, do know if this is true, close to it?
 

·
FFCobra Craftsman
Joined
·
24,197 Posts
I'm guessing, but I suspect, the MkIV 2 piece spindles are the same geometry, yet easier to install, version of the SN95 spindles with the SAI kit. Craig, do know if this is true, close to it?
That is my understanding yes.
 

·
FFCobra Fanatic
Joined
·
5,522 Posts
They do sell the bracket to weld to the frame. I got one for my MK2. Its for the challenge car, I will look up the info for you. I also relocated my rack further back for better ackerman. Breeze used to sell rack bushings specifically for this. I will post some pics later on when I get home.
 

·
FFCobra Craftsman
Joined
·
24,197 Posts
"They do sell the bracket to weld to the frame. I got one for my MK2. Its for the challenge car,.." Thanks for posting this. I wasn't aware they did this.
 

·
FFCobra Fanatic
Joined
·
5,522 Posts
Found it, took me a while! Here is a thread about it and a link to the pdf, just cut and paste the link in google and it will open up!


http://www.factoryfiveparts.com/content/instructions/15414-mk4-front-upper-arm-retrofit.pdf

Hope this helps!

Mike
 

·
Senior Charter Member
Joined
·
1,230 Posts
Discussion Starter #11
You guys are great. Thank you.

I received an email from Jon Whittall of FFR and he said that all I need is different length sleeves for the UCA. I guess I will call him again, but the retrofit instructions clearly require an UCA relocation bracket (which I thought required standard length LCAs, standard length UCA sleeves, and front wheels with a compatible offset).
 

·
FFCobra Fanatic
Joined
·
5,522 Posts
I cut my upper sleeves down a bit, I have 2nd or 3rd gen arms, the ones with the aluminum pivot ends. I am pretty sure they need to be shorter, I am running power steering as well so I can get more caster for better high speed stability. I may have only cut one of the sleeves on each side, cant remember. I have standard length lower arms. Normal Fox offset on the wheels 17X9 with 6" bs.
 
1 - 12 of 12 Posts
Top