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Rack and pinion in my ‘48 Plymouth


Scott Knecht

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On 2/7/2021 at 1:58 PM, scotty t said:

Yessir I am a mostly inactive member?. The pics shown earlier are indeed my 48 p15. Here’s what i remember about my set up: early cav rack and inner tie rod ends (94 and older),later cav (95 and up) outer with custom adapter sleeves, the steering arms were shortened, redrilled and tapered to 7*, actually the rack is listed as pontiac sunfire because manual steering wasn’t available  on the cavalier. The manual rack is shorter than the power version so the mounting brackets are unique to that application. My buddy and I did quite a bit of research regarding bumpsteer and we are confident that it will have a very minimal amount. When the car was mocked with most everything installed it steered nicely with the stock large diameter wheel. I believe I found a coupler for the rack to column joint through borgeson.

546C4B96-7622-4F99-91BA-5AACCF1D5586.jpeg

How much would you say that this swap cost you sir?

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On 2/24/2021 at 9:25 AM, Scott Knecht said:

Okay guys I pulled the trigger on the FatMan steering kit for my ‘48.  $324 total I guess is a small price to pay for not having to reinvent the wheel.  Lol

I’ll let y’all know what it’s about when it shows up.  

You know where I can find Fatman fabrications

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Hi David. Well all in all the steering swap cost me a tick over $700 total.  The biggest expense being the FatMan kit at $320.  A reman rack was $110 at Napa.  I think the rod ends and tie rods came in around $180. The bar stock for the steering arms was $20.  The bushing kit for the inner tie rod mounts was around $20. Also the tapered reamer I purchased on eBay was $70. Keep in mind these are all new prices.  If you have a yard to scour you would save a lot. You also always have the hidden cost of labor if you’re not doing it yourself.  

Here is the link to FatMan
 

 

 https://www.google.com/search?q=fatman+fabrications&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari#

Edited by Scott Knecht
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  • 1 month later...

I have been otherwise occupied so I just now am reading this thread. Very nice work and good detail on what was done.

 

My only comment, one I expressed in other threads some years back when looking into this is that the conversion using this rack may well be fine on the "lighter" cars, but not on the larger ones like my '47 Suburban.

 

In fact, when I contacted Uni-Steer and also Flaming River they both said they do not make any racks for cars over 3500 pounds.  There is a lesson in that.

 

I always worried that a caviler rack in the 5000 to 6000 pound loaded Desoto Suburban on a trip at 70 MPH may fail if I hit a big pot hole. The Uni-Steer and also Flaming River folks on the phone when pressed said that their custom units gears, the actual rack teeth may not take a hit on the larger cars without a failure. They are just not designed for the weight.

 

I suspect, but I do not know, that the same may be true with the caviler racks. The experience of racer-x is a warning shot on this.

 

I am not saying it would fail, but on the larger sedans, station wagons and limos like a Suburban, I suspect that the loading may be close to a danger zone. Something to think about.

 

James

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Thank you James! Yes it was a learning process but now looking back it’s really not that hard of a modification.  Just gotta pay attention to the details.  I do have to confess I sort of was wondering about weight however.  I mean a Cavalier is what? 2600lbs maybe? I’m guessing my Special Deluxe to be around 3800 but I don’t know for sure.

The car steers fantastic and the power assist makes it feel like the Plymouth weighs nothing.  So far so good here but in a Suburban it may be too light a unit.  

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  • 3 months later...

while the rack itself is NOT GM but that of TRW and also USED on the 4200 lb series of Chrysler LHS.  The inner bushings and such is the same both applications.  You got to keep in mind that these aftermarket companies has to default to the rating of the supplied donor part for liability purposes.  Take it from there.....to say there are no rack and pinion units for a vehicle over 3500 lbs is ludicrous. The Dodge Sprinter is the first to pop into my mind....not to mention the many trucks up to 3500  (Curb weight: 6,956 lbs. Maximum towing capacity: 34,110 lbs. Maximum payload: 4,440 lbs. Gross weight: 11,400 lbs)  

 

the light weight 6000lb car frame will fail first.  

Edited by Plymouthy Adams
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depends on the rate you take sharp curves or have to steer the car to maneuver into tight places....given the huge original steering wheels, worm drive and tire patch without the aid of PS the benefit of a R&P already screams major improvements...ad power steering and likely your kindergartener will be taking your car to school.  The rack and pinion in my 48 Plymouth business coupe is rated for over 6000 lbs. 

 

Edited by Plymouthy Adams
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On 2/4/2021 at 5:46 PM, Bob Riding said:

Here is my Olds rack. Does it look like the Cavalier? I assume the equal length arms are what we need for our Plymouths.

IMG_1592.jpeg

did you do the rack and pinion swap?

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  • 5 weeks later...

I was driving from Madison to Rockford for work early one morning in a friend's car. As I turned into the parking lot the car stopped like I had run into a brick wall!  I got out to look and discovered that the front wheels were splayed - the left pointing to the left and the right pointing to the right.  I looked underneath and saw that everything had come apart.  Luckily I was able to find the castlenut that had come off.  I got everything back together, worked for eight hours and headed back home.  What if that had all come

apart at 70 mph on the interstate?

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Castle Nuts are not to come off!  It's forbidden!  (The slots are for a cotter pin, to keep the nut from turning.  Maybe obvious. but someone missed something.  (Did I check the cotter pins on my last project? Ya, I'm sure I did.  Positive.)   

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  • 6 months later...
On 2/3/2021 at 4:29 AM, Scott Knecht said:

I’ve been in touch with Fatman Fabrications.   They do offer a kit expressly for the ‘46-‘48 Plymouth and counterparts.  
it includes the fabricated mounts to utilize the center steer rack from ‘82-‘94 Cavaliers.  It also includes tie rod sleeves to adapt the Cavalier inner rods to ‘04-‘05 Ford Explorer outer tie rod ends (purchased separately) which supposedly fit the Mopar steering arms. And of course it includes the u-joint necessary to attach the rack to the steering shaft, which I just frantically purchased from Rock Auto. (Insert sarcasm here) lol

the kit is $290 plus shipping. 
So as funds allow I may just purchase the kit to eliminate some guess work.  

Do you have  a part number? I can't find it on their site. Thanks

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the TRW rack in smaller GM cars with center links connecting rod...been years since this was really gone over in depth.  I searched my local files and found some of the install data but did not see the file where I had the bracket templates.  These could well be found, complete with the manner to located the brackets to prevent bump steer via searching this forum.    type in       +cavalier +rack    and you will get some 9 pages related to the subject.  Hope this will help you.

 

 

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Posted (edited)
On 8/3/2024 at 2:25 AM, hotrodbob said:

Do you have  a part number? I can't find it on their site. Thanks

I’m sorry I don’t.  I had to call them direct to order it. I do know they make up the kits as orders come in.  I don’t believe they stock them.  The Borgeson U-joint and custom made threaded adapters are the expensive parts.  Anyone could fab the brackets and honestly if I had to do it over again I would have to save $300. You can get the U-joint for about $60 and I’d just have a machine shop make the adapters.  They are 18mm left hand thread on the inner tie rod end and 14mm right hand thread on the outer rod end.  The total secret to no-bumpsteer is getting the inner tie rod pivots of the rack in line with the lower A-arm pivots.  Then fab up the brackets accordingly.  One note however I did have to make 1 and 3/8” shorter steering arms to work with the throw of the rack otherwise the car would not have a tight turning radius.  

IMG_5251.jpeg

Edited by Scott Knecht
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Getting ready to do the R&P conversion. Speedway Motors sells threaded tie rod tubing. Going that route to eliminate using the Cavalier inners and adapter.

The hard part is making or finding the C-shaped clamps to hold the rack in place.

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20 hours ago, Gramps46 said:

Getting ready to do the R&P conversion. Speedway Motors sells threaded tie rod tubing. Going that route to eliminate using the Cavalier inners and adapter.

The hard part is making or finding the C-shaped clamps to hold the rack in place.

That is a good idea and something I’d probably do the next time.  
As far the C-clamp they’re easily made from 1” x 1/8” steel available anywhere.  Got mine at Tractor supply.  Bend them with just enough clearance so the bolts cinch them snug to the rubber bushing and they’ll secure the rack perfectly.  IMG_5440.jpeg.c05b40c932baae677c2a747aa78fd059.jpeg

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