308 steering rack bushing replacement

Not sure if anyone else has had this issue, but my steering wheel had some play. Checked all suspension links, and found nothing. Disassembled steering rack, and found nothing. Then, I looked at the steering rack bushings. The short story is the bushings were the problem. The longer story is,.. what an "interesting" design. First off, why are the mounts rubber? Every other manual steering car I have owned has a rigid mount between the rack and car frame. The other question, is why do the metal sleeves inside the rubber bushings have a 9mm hole when the bolt is 8mm diameter? I suppose if everything is really tight, the 8mm verses 9mm might not be and issue, but it just doesn’t seem right to me.

So, I thought about buying OEM replacements, but, one I didn't want to wait. The weather is so nice in Maryland now, second, I thought I could do better. So here is a picture of the old and new bushings, and a print if anyone else has an interest. Material cost was around $10 for 12” long X 1 1/8" dia. black acetal rod. Took less than an hour to make the first 4. I think a real machine shop could make 8 in less than an hour.

All of the steering play is gone, and the steering feels great. There is no extra vibration transmitted to the steering wheel. In fact, there is less. This might sound counter-intuitive, but I think the rubber in the rack mount was allowing the rack to bounce left and right when either wheel hit a bump.

I would highly recommend this change if you are changing the bushings. Just to clarify, I no longer use the metal sleeve that runs inside the rubber.

Attached pictures show: old and new bushings, bushing print(tolerance is +/-.02”), installed rack and bushings.
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Chris, very nicely done! Looks like you nailed the dimensions very precisely.

I believe rubber is sometimes used to lessen the feedback going up through the rack and column to the wheel and hands. Not everyone wants to feel every pebble the tires are feeling.

What made you choose acetal? Seems like an excellent choice to me given its properties. Easy to machine on the lathe. Given its hardness I would agree, no need for a sleeve.

 

I picked acetal mostly for the reason you gave. Easy to machine. It was also easy to get overnight from MSC. And, I wanted a little give. I could have used aluminum, but the bushings go into a cast feature on the rack mount, so the surface is not perfect. I thought the acetal would "flow" into the rough casting better.

I'm sure someone could use other materials with success.

Your comment about feeling every flaw in the road, is what I would have thought too, but it really doesn't feel that way, and I'm running 17" Ronal wheels. Honest.

I was so happy with the result. Sometimes I put some new part in, and I feel like I wasted my time and money, because I can't feel a difference. Not this time.

 

Oh yeah, found it on my car and after cleaning everything up, mentioned it to some fellow owners and found the same thing on their cars. I can only speculate but I believe CamGears (makers of the rack) probably recommended the rubber mount. This same rack was used in many other cars of the period and prior to the 308, notably the Pantera. In the Pantera it is rigid mounted... downfall is that chuckholes and bumps beat the internal bushing on the passenger side of the rack into pieces. Having the rack "shock" mounted may help reduce this failure pattern. But, I still had the same failure in my 308. If you want to see the whole fix process, feel free to look:

http://www.flickr.com/photos/moseley_ferrari/sets/72157602899521527/

I've followed Brian Keegan all over the country as my parts guy. I believe it was while he was at Rutlands that I found this problem and he was able to source direct replacements for me in Poly. Note: these do have the same dimensions as stock so you do use the steel sleeve. I think this is a good idea as it limits crush on the poly. Probably not needed on the acetal. Oh, these poly bushings also work on the A/C mounts.

Rick
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Where might one find a set of these poly bushings?

 

Track Keegan down at FerrParts. I may have gotten the last couple on the planet to mount my A/C compressor.... but he was working with someone to have more made.

Rick

 

If I'm not mistaken, these bushings are also used on the front anti-roll bar drop links of many various Ferrari models (Drop link bushing P/N: 108244 or A/C support P/N: 107335).

John Haller of Seattle (I believe his F'Chat name is "jh355" ?) has/had rack rebuild kits and includes these cone-shaped bushings. I think the rubber he used was of a harder durometer and thus, gave more precise steering feel.

 

When we rebuilt the steering rack on my GT4 with a the quick ratio set-up, it was installed with solid mounts as well. World of difference and absolutely no vibration or negative effects.

It is a good modification.

 

It would seem strange that Ferrari would have not done this the best way but I have to say I agree. The same Cam Gears racks were used on Lotus cars of the era and solidly mounted.

I can't think of any justification for rubber mounting the rack. Rack height is critical to avoid bump steer and having it move about in rubber mounts isn't exactly going to help with this!

 

The 308 was designed to be a fairly high end GT and along with that concept you get AC, nice leather seats and sound deadening/rubber mounting of various components.

In a race car, no problem, just bolt it solid.

I too would like to source the red poly bushings not only for the rack but the AC next time i do a major, these would be cool to refresh the ac mounts, (maybe the compressor would appreciate it and make the car a bit cooler).

One can always hope.

If anyone sources those bushings, or manufacturers them let me know.

thanks,
chris

 

I hade a couple sets of the hard (acetal) bushings made to try & cure my steering wheel shake. Didn't cure the problem & they gave way too much vibration & road feel for me. Anyone need a set let me know.
Bill

 

Well I'm confused...

Some say the new hard rack bushings reduced vibration and some say that new hard bushings increased vibration.

This makes my hair hurt!

 

I think it comes down to preference. The hard mounts transmit more "feel". Some like that, some don't.

In my case, I always found the 308 steering to be vague at the start of a steering input. Once loaded up in the corner it was fine, but just off center it just didn't feel good. What causes this sensation is the steering rack moving relative to its mounting point. When an input is first applied, the rubber squishes and the rack moves. Once it moved as far as it can everything firms up and feels fine.

Installing solid bushings eliminates this problem. It will also result in a bit more road feel transmitted to the wheel. Although subjective, I would peg it at about a 25% increase. I don't find it offensive at all and actually prefer the additional feed back. However, for those that are used to modern cars with power steering it may feel disconcerting.

 

If you have something causing vibration like a bent wheel, bad bearing, defective tires, flat spots on tires from lockup, etc. I can see how the hard mounts would make it worse. However I still believe that a non-problem car isn't going to feel much different with new rubber ones or hard acetal. Maybe I'm just not sensitive enough.

 

Do you still have them Bill? I'd be interested! PM sent..

 

Great points, Andy!

A couple of other things to consider when stiffening (the rack mounts) with these bushings...

-The Ferrari is much heavier than the Lotus's of that era.
-The stiffer you go, the more vibration that's transmitted into the rack.
-The rack's failure rate will increase, due to internal wear.
-The TRW/Cam Gears racks are grossly under engineered and not exactly robust to begin with.
-In the event of a side impact to a wheel, all of the impact load is now absorbed by the rack, versus some degree of bushing "give." In a race car, who cares? On a street car, you make the call.

Race versus street; this is always a balancing act. The red or black hard poly bushings were made by an F-Chatter years back who has abandoned that business. I purchased all of his inventory several years back and have been slowly selling it off. Currently, I have one set left that I may sell to a gent who contacting me recently. There are no more...and I'm not sure if the (recent) demand warrants another production run. The Acetal bushing is interesting although for safety reasons, I would have retained the metal collar.

Best,
David

 

Thank you

 

You're welcome, Matt. Don't get me wrong, there are benefits, but it's just not a free lunch, as potentially advertised.

 

Don't use hair-bushings...you might actually hurt your hair.


BTW, selection would generally be application specific (road or track or both) or a matter of choice and affordability. Some prefer OEM because of originality.

However, replacement is much better than fostering contiued deterioration.

When I did my front suspension, WRT the steering rack, all looked good; I only replaced the tie rod ends because it was convenient. My rack has no mount play, minimal to no wheel rotation play and no longitudinal play, so mine should be good for another 2K. However, since I like to refurb stuff, in the next couple of years, I will rebuild the rack with new bushes as well. Since I'm not a track-goer, I'll likely use OEM or a newer material designed as OEM.

For those replacing the rack mount bushings, I would emphasize at least a full inspection from rack to wheel. Check u-joints, splines/bolts, mounts and...the "partridge in the pear tree."

This is because any system requiring any parts for replacement usually has more replacements than planned that need doing.

 

Good points. I think a more rapid failure of the right side bushing (the internal one) is probably the most likely negative impact. When I went through my rack I made a bronze one, so hopefully that will be better than the plastic. I will certainly report back if I encounter any issues, but at only a couple thousand miles per year to will likely be a very long time before anything crops up.

 

I appreciate it, as I think long about consequences when making decisions about parts, fluids, etc. for this car.

 

Restoring an old thread...

Over the last several months, my steering has become somewhat imprecise or sloppy, especially over uneven surfaces. I've checked everything and the only item I suspect are these bushings.

Does anyone have a current source for the poly bushings?

 

I suggest you go with the brass one. It will last longer. P.I. Motorsport.

 

How old and in what condition are your tyres?
I had the same issue with my car and thought it was the steering rack.The Pirelli tyres had about 65% tread on them but were over 5 yrs old.They gave me the steering symptoms you described.
I put on a fresh set of tyres and the transformation was incredible.
The guy that owned the store told me that Pirelli tyres tend to wear bad.
Just a thought..

 

Very interesting...the steering doesn't seem loose, just a little sloppy. My tires are in roughly the condition you describe (including age). I'm going to put the car on the lift tomorrow and check the bushings and then move on to the tires. Appreciate the insight!