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-   -   Rack & Pinion adjustment (http://www.clubcobra.com/forums/backdraft-racing/145240-rack-pinion-adjustment.html)

SBSerpent 10-04-2021 10:03 PM

Rack & Pinion adjustment
 
Is there an adjustment on the R&P rack that can be made to eliminate some slack I have in the steering wheel? It's very small, but I can wiggle the steering wheel back and forth about 1/4" to 1/2" before seeing movement in the front wheels (this is when the car is parked). I see that there is some sort of adjustment (pre-load?) on the rack. Just not sure as to how to adjust.

t walgamuth 10-05-2021 02:50 AM

I have the same problem in my rack in my 39 Studebaker Coupe Express. It uses a T bird rack that has been rebuilt. My rack in my Cobra is the same rack but is not rebuilt and is perfect.

I tried adjusting the big preload screw but did not really impact it much. While tolerable in the much slower reacting truck it would be unacceptable in a Cobra.

Hotoxide 10-05-2021 10:30 AM

Get under the car and have a helper move the steering wheel. Is the rack moving in the mounts? Are there rubber bushings that may have deteriorated?

Dave and SNAKE65 - how old is the car?

SBSerpent 10-05-2021 11:50 AM

Quote:

Originally Posted by Hotoxide (Post 1497827)
Get under the car and have a helper move the steering wheel. Is the rack moving in the mounts? Are there rubber bushings that may have deteriorated?

Dave and SNAKE65 - how old is the car?

The rack is solidly attached to the mounts and the tie rod ends look good as well. It's a 2011 build with only 7500 miles on the odo and the car has been babied its entire life.

patrickt 10-05-2021 04:16 PM

Quote:

Originally Posted by SBSerpent (Post 1497830)
The rack is solidly attached to the mounts and the tie rod ends look good as well. It's a 2011 build with only 7500 miles on the odo and the car has been babied its entire life.

You can't rely on just looking at it. Put a dial indicator gauge on it like I did to measure mine. I had a bad bushing and this made it pretty obvious to spot and to measure improvement when I replaced it.



SBSerpent 10-05-2021 08:07 PM

All this input is greatly appreciated and I will take a closer look at the rack.

But, the question still remains as to how exactly is the preload adjusted? Remove the locking nut? Tighten the adjustment to_____? Back off by ____ turn after the adjustment nut bottoms out? Hits resistance? Replace locking nut.

t walgamuth 10-05-2021 08:19 PM

That is what I did but as stated above, it still has nearly an inch of free play.

SBSerpent 10-05-2021 09:29 PM

Quote:

Originally Posted by t walgamuth (Post 1497845)
That is what I did but as stated above, it still has nearly an inch of free play.

How much did you tighten the adjusting nut? When did you know when to stop? Did you tighten the nut until it bottomed out? Did you back off a little once it bottomed out? Did you do this adjustment with the front wheels raised off the ground?

t walgamuth 10-06-2021 05:18 AM

I tightened it until I felt bind then backed off a sixteenth of a turn or so. It works this way but there is still a slight bind and a free play on the steering wheel. I believe I'll have to buy a new rack to solve it. An inch of free play in a FF feels like half the distance to the barn.

I have a Tbird power rack which interchanges with the flaming river manual rack. With this setup the steering feel is equal to a good Miata which in my book is as good as it gets.

SBSerpent 10-06-2021 11:21 AM

Quote:

Originally Posted by t walgamuth (Post 1497857)
I tightened it until I felt bind then backed off a sixteenth of a turn or so. It works this way but there is still a slight bind and a free play on the steering wheel. I believe I'll have to buy a new rack to solve it. An inch of free play in a FF feels like half the distance to the barn.

I have a Tbird power rack which interchanges with the flaming river manual rack. With this setup the steering feel is equal to a good Miata which in my book is as good as it gets.


Is this adjustment made with the front wheels raised off the ground?

SBSerpent 10-06-2021 02:55 PM

After more sleuthing, I believe I have found the source of the problem. There is play in the universal joints in the steering arm, Not sure if this is normal but it is allowing for about a 1/4" play back at the steering wheel. The rack, tie rod ends, mounting hardware are all solid.

How much play, if any, should there be in the universal joints?

spdbrake 10-06-2021 04:51 PM

No play actually.

On the rack free play I had tried that route 1st with no help. The adjuster is simply pushes the back side of the rack into the steering pinion gear. The Spring under the cap does the work and getting it too tight can cause a bind. Also that bind really can't be felt with the wheels installed as the caster pulls the wheels left or right while jacked. A binding steering spooks me.
The BDR uses a flipped RHD MR2 rack.
https://toyota.epc-data.com/imgjp/B3/MCA933E.png

You probably should just replace the the steering shaft and joints with beefed up parts.
Shopping list is here. You most likely will not need the center Heim bearing I added to mine.
http://www.clubcobra.com/forums/back...s-upgrade.html

Further details are in this thread.
http://www.clubcobra.com/forums/back...g-upgrade.html

t walgamuth 10-06-2021 06:33 PM

Quote:

Originally Posted by SBSerpent (Post 1497866)
Is this adjustment made with the front wheels raised off the ground?

No.............

FredG 10-06-2021 08:20 PM

I am going through the same thing with my car. First, understand that the manual rack you have is junk. It comes from something like a Toyota or Mazda. It has no business being in a high performance car. A lot of the play comes from the fact that it is almost 4 turns lock to lock and that is ridiculous. The best thing to do is to bag the junk manual rack and convert it to a BMW Z3 power one. That will give you 2.6 turns lock to lock and the crisp response you are looking for. Experienced Backdraft dealers like Vintage can do this for you or you can try to do it yourself. I do believe there are some Backdraft owners on this forum who have done it themselves. I am working with Miller Speed, a Backdraft Dealer in California who has done a ton of these conversions and is putting a kit together for me to install myself.

spdbrake 10-06-2021 08:34 PM

Fred, If I remember right Grey65 is using a Z3 power rack as he autocrosses.

Your electric steering a no-go?

FredG 10-07-2021 07:00 AM

Rack
 
Yes. Kevin uses the Z3 rack. He suggested that to me a couple of years ago. Apparently it has become a popular upgrade and installation. Alistair Miller in California told me he is doing quite a few of them and so is Vintage in Connecticut. Putting in the Z3 rack is going to be my winter project. Alistair is going to put a kit together containing, rack, tie rod ends, pump and mounts. The only modifications needed are to the lower radiator hose and pipe to clear the belt. I bagged the electric steering a while ago. It was just a novelty. I felt like I was driving a Cadillac. There was no real feel of the road.


Quote:

Originally Posted by spdbrake (Post 1497875)
Fred, If I remember right Grey65 is using a Z3 power rack as he autocrosses.

Your electric steering a no-go?


spdbrake 10-07-2021 07:49 AM

Thanks for the update Fred,

Let us know how it progresses.

I had started a shopping list using KRC pump etc... about a year ago but switching from a Solid roller to Hyd, radiator, fans, seats, and others put me way off track on that project.
I'm moving yet once again here soon so am cooling my jets for awhile.

t walgamuth 10-07-2021 08:13 AM

I am using the power t bird rack. It came from Speedway motors. I autocross so needed the ability to turn quickly which the flaming river manual did not offer. I am a strong person but the manual rack just did not feel safe as it was so heavy to turn the car.

SBSerpent 10-07-2021 08:56 AM

I will have to reach out to Alistair being that his shop is only 90 minutes from me.

On a slightly different topic, can someone please provide step by step instructions as to how to replace the two bearings on the internal steering column? I have play up and down and side to side on the steering wheel. I did check the U-clamp that is behind the dash that holds the outer column and it is tight.

Also, what is the replacement p/n for the bearing?

spdbrake 10-07-2021 09:08 AM

Its the 1st part number listed in the 1st thread I linked. You'll need two bearings.

Remove the bottom bolt on the lower universal and pull the universal off the rack pinion spline.
Remove the two cross bolts that hold the BDR universal assy in the hollow smaller center column.
Remove the the universal assy from the hollow center column tube.
Loosen the two allen set screws that are in the large OD billet spacer. (the lower bearing is right behind it).
Slide the spacer and bearing out.
You can now pull the steering wheel and center tube out and access the upper bearing. (Outer support tube is not disturbed)


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