[DeTomaso] Ferrari 308 steering rack - which one?

[Richard Barkley]

I received my new 308 rack from BUYAUTOPARTS.com. I ordered from their 
ebay posting and received it the next day using UPS standard shipping (I 
live ~100 mi away) 
http://www.ebay.com/itm/BRAND-NEW-MANUAL-STEERING-RACK-AND-PINION-GEAR-ASSEMBLY-FOR-FERRARI-DINO-308-GT4-/290640157982
This weekend I removed my original (rebuilt in 2002 with bushing and new 
lower pinion thrust bearing) to do a comparison.

Like others I've seen with the 80-70007 AN part number, mine has a black 
middle tube. There are no part numbers or markings of any kind on the 
rack. As noted on the PI forum, "It does seem a bit tight, there is 
certainly no slop. I'd expect it to be a little smoother." It seemed a 
little stiff to me, but when I compared it to my original rack, it was 
not much different. I measured the torque applied to the input shaft 
needed to turn it with no load. Using a digital luggage scale and a pair 
of vice grips I measured <.65 ft-lbs. My original rack measured about 
0.5 ft-lbs. It has about 120K miles on it and 15K since its rebuild. At 
the steering wheel I doubt if these differences would be noticed. What 
really matters I how much friction there is under load. I have no way to 
measure this. My guess is there is about 5% loss.

I noticed a variation (somewhat notchy) effort as I turned the input by 
hand. This was noticeable on both racks. The "vibration" it caused was 
really noticeable when moving the rack back and forth by push/pulling on 
the tie rods. On the new rack, it took about 15-20 lbs of force on the 
tie rod to move it. My old rack took 10-15 lbs. These forces seem 
consistent with the 17.45:1 ratio (seen on one spec sheet) and the input 
torque I measured.

I played with the adjustment screw to see if I could lower the friction. 
Backing it out didn't seem to reduce the forces but if you tightened it 
down you could lock things up. My guess is the it's purpose is to 
compensate for wear and to keep the dead zone to a minimum as things 
wear. I removed the two caps on the rack/pinion housing. The photo below 
shows the screw adjustment assembly. Notice that the lubricant is 
grease, not oil. The lower thrust bearing is under the other cap.

Finally, I was impressed with the quality of the rack's materials and 
workmanship. I'm sure it will last and work as well or better than the 
original.

Richard

To ski or not to ski, that is the question!
http://home.earthlink.net/~rlbpantera/


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