J-car rack and pinion

bnickel · Jul 13, 2004

hey lino, would that rack happen to be randalls rack or speed direct's rack, i personally like the the randalls rack setup, look pretty impressive for a basically off the shelf rack with a few small modifications, what do you think of it?

Psydwaze · Jul 13, 2004

Well here are the racks and you can see the difference in the centerlink mounting points. Not that they are bad designs but these are simply some of the workarounds and comprimises when working with an OEM rack from another vehicle.

Note the broader mounting points.

End take-off racks don't have this issue but unfortunately don't work very well in classic Mustangs.

Has anyone installed one of the Randalls Rack yet? I'll admit I'm being lazy and didn't use the search button.

tweet66 · Jul 13, 2004

Streetmod I have one of the Sacremento Mustang racks on my 66. It's an old TCP design, non-power unit that had the flex shaft, but TCP later sent me a shaft and 2 universals to replace it with. Its been on there for about 8 years now without a problem . Strangely enough when I trashed my Nissan 200SX I pulled the power rack because it had the same dimensions as the TCP unit. I've made the crossmember and bolted it into my 64 Falcon but the universals bind in it current location. Back to the drawing board .

streetmod · Jul 13, 2004

Psydwaze, there is definately some confidence and knowledge of fabrication and suspension geometry needed with this kind of project, including proper welding practices. You are right that the ends of the centerlink act as levers against the links mounting point, in this case, two bolts on the rack. Just for comparison, the guys over at Corner Carvers Forum could probably come up with the fraction of the forces that the steering components absorb compared to the rest of the suspension.

This reminds me of all the deflection points that the stock system inherited: pitman arm, power steering control valve, idler arm. All of these induce forces on the center link as well, maybe more so than what we are doing here?

The rack needs to be securely mounted to the car and the center link, either modified/stock or custom made needs to be attached to the rack so that (deflection) can be kept to a minimum. This puts most of the forces in the rack itself and a new/rebuild unit should be used.

71vert-pga · Jul 13, 2004

How about taking the j-car (or intrepid) rack to a shop and having it machined to move the centerlink mounting points outward? If both points were moved out about 2 inches and switched to the opposite side it would be roughly comparable to the TCP rack in that all forces would be distributed across a much greater area. It would also accept the tierods on the rear like Randall or TCP in order to allow header clearance.

The rest is just elbow grease.

streetmod · Jul 13, 2004

Just crawled under the car with a tape, roughly 16" between inner tie rod mounting points(69 coupe).

The J-rack bolts are approximately 2" apart. So, lets just say the center link will be mounted centered on the rack, that turns out to be roughly 7" from each rack mount bolt out to the inner tie rod point.
Whats the big deal with that? Especially if the set-up is done right, meaning the tie rod linkage is level/parallel with the center link at ride height, all of the force will be in a straight line across the link and into the rack, with little deflection.

The only thing I might do is make a custom centerlink. Maybe using threaded ends, kinda like the newer taurus design with the inner tie rod with threaded cups that screw onto the end of the link. I think that is what is in one of those pictures that psydwazw posted.

71vert-pga · Jul 13, 2004

That's correct!

There would be no twisting force against the rack structure. Only pushing and pulling with the tierods. Randallsrack offers a couple of different options on his setup.

http://www.randallsrack.com/AdjustableCenterlink.html

Most of these guys don't want to part-out a kit (cuts into the profit margins I guess) but since he said he has no plans no develop a kit for the 71-73 so maybe he would be willing to sell just a centerlink.

Guess I should take some more measurements and write him again.

** Randall ** - Are you monitoring this?

Psydwaze · Jul 14, 2004

I would say that fabbing in a rack would be a great improvement over the factory components as long as it is done safely, the geometry isn't too far off and you don't end up with an intolerable turing radius.

It is very easy to increase the amount of bump steer when only moving the inner tie-rods a half-inch in the wrong direction. If you can't keep the centerlink in the exact same position I wouldn't even try moving it without running a simulation to see what effects the new position will have.

The tie-rod linkage is only parallel with the center link at one point. A stock suspension has over 7" of travel. Don't take these for completely accurate numbers but just to give us an idea. Assuming a 16" tie-rod (?) and 3.5" of travel in each direction (compression/rebound) you can have over 12* mis-alignment.

mdjay · Jul 14, 2004

We started selling the Randall's Rack recently and they are moving well. I have a local customer installing one on his 65 and I'll keep you informed on how it goes. We were forced to find an alternative to TCP and Randall's seems to be the best power rack alternative to the late great TCP unit. Can't seem to get a phone call from Chassis works? Hmm...

71vert-pga · Jul 14, 2004

Takin the rack to the machine shop this afternoon to have it modified to attach the centerlink on the backside.

I'll see what other "cheap" stuff they can help me with while I'm there.

streetmod · Jul 14, 2004

Here is my idea for a custom center link.

Find a newer taurus rack and cut off the ends of the rack (about 5" each side) where the threaded inner rods attach. I like the taurus' ball and socket style inner tie rod. Next find a piece of steel tubing that the ends of the taurus rack slide snuggly into. Cut the tubing shorter than the original mustang center link so that about three inches of the rack ends sticking out each side equal the original center link length. Before sliding the rack ends into the tubing, drill and tap a 3/8" hole about an inch from each end of the tubing. This is for some temporary set screws to hold the rack ends in place during bump steer adjustment. Now the tubing can be fabricated to mount to the GM rack.

Now the steering and suspension can be assembled and cycled through its travel and the bump steer can be easily adjusted by loosening the set screws and sliding the taurus rack ends in or out of the tubing. After getting the correct setting, the taurus rack ends are ring welded to the ends of the tubing.

This would be even better if the stock taurus inner and outer tie rods could be used, but I'm not sure yet if they are the right length or if the outer rod has the correct taper.

71vert-pga · Jul 14, 2004

J rack modification

Streetmod, will this increase the total travel of the Taurus rack?
-------------------------------
I spent about 2 1/2 hours at the local machine shop this evening and this what we came up with. The travel of the stock j-car rack is 6 1/8 inches. The internal mechanism travels farther but is currently limited by the opening in the front of the aluminum housing that the centerlink attaches to and moves within. This opening can be milled out ¼ inch farther on each side to allow for a full 6 1/2 inches of movement (same as original).

His offer…

- Mill the opening 1/4 inch farther on each side.
- Reverse the housing.
- Fab the new centerlink and the spacer/mounting bracket to attach it to the rack.

Total cost = $250.00

He can also throw in a remanufactured rack from ARI for about $95.00 if I don’t want to go to all this effort on a JY rack. Or I can order a new one from “carsteering.com” for $129.00.

This seems practical to me, but being the cheap bastard that I am I told him I needed to give it some thought before I spend that much money.

What do you guys think?

71vert-pga · Jul 14, 2004

Can't upload attachment!!!

I have a photo with the details on it but I can't seem to get it posted for some reason.

The machine shop owner is also going to bring in an Intrepid rack tomorrow for me to look at. Says it's very similar but much stronger. I'll post pictures of it too if this thing will let me.

jikelly · Jul 15, 2004

It looks like 71vert is going to get this mod sorted out before I even lift a wrench. I have a question for streetmod. How do you adjust the centerlink for bumbsteer? I am pretty thick headed so I would really benifit from an explanation.

71vert I still think the intrepid rack will be the one you'll want to use.

71vert-pga · Jul 15, 2004

Bumpsteer stuff

These sites (and many more like them) helped me a lot.

http://www.thedirtforum.com/bumpsteer.htm

http://www.ffcobra.com/FAQ/bumpsteer.html

http://www.woodwardsteering.com/rpi.htm#6

http://www.steeda.com/PR/Mustang/bumpsteer/bumpsteer.htm

http://www.rodandcustommagazine.com/techarticles/135_0401_ifs/

I seem to recall a really good write-up on bumpsteer and ackerman on a site for radio controlled cars not long ago but can't find it now.

71vert-pga · Jul 15, 2004

Post image please?

Have a photo with the modifications mapped out on it. If someone could post it for me send me a PM with a good email address. Thanks in advance!

Is anyone else having this problem?

jikelly · Jul 15, 2004

Are you still planing on cutting the front crossmember? I was just wondering if you thought it would be possible to mount the rack behind the crossmember somehow. If nobody else has contacted you about posting your image let me know and I can post the image on my website for you.

71vert-pga · Jul 15, 2004

Not a complete removal of the crossmember, just trimmed a little to make more room.

So anyway, no one has offered to post it yet. Tell me were to send it and I’ll get it to you. Thanks in advance!

BTW, I’m headed back to the machine shop in a few hours. Lyman is going to have a couple of Intrepid rack for me to see. I’ll take photos and measurements for you.

jikelly · Jul 15, 2004

71vert-pga said:
Not a complete removal of the crossmember, just trimmed a little to make more room.

So anyway, no one has offered to post it yet. Tell me were to send it and I’ll get it to you. Thanks in advance!

BTW, I’m headed back to the machine shop in a few hours. Lyman is going to have a couple of Intrepid rack for me to see. I’ll take photos and measurements for you.

That would be great. My email adress is jimmy.r.kelly@ttu.edu send me the pic and I'll figure out a way to get it posted for you.

Håkan · Jul 15, 2004

I have the r&p that I showed in another thread a while ago finished now:

Also made a webpage with some info about it here:

1965 Mustang Rack & Pinion

Just thought you guys might be interested.

J-car rack and pinion

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