SWB spring plate bushings

[shbop]

Yeah Yeah, I know: plenty of posts on this topic. I thought I'd read them all, but I might have missed the one that can answer my question. I ordered the replacement bushings for my origonal plates. 66' 911 When I compare what I got, part #901-333-195-00 and part # 644 333 131 00; they're not even close to the same size, in width or thickness, as what I cut off. I've double checked the part numbers. Could someone please tell me what I'm missing. I hate that , "you should have ordered the Welmeisters in the first place feeling" Thanks in advance for any help. The bushing in the photo is the 644 333 number

[Evans, Marv]

Wow,
That new bushing doesn't even look anything like the bushing you need. Try calling PP to ask them. Did you run your part number in the catalog search to see if it's correct? I've got a couple of sets setting around & they don't look like that one.

[shbop]

Thanks for the reply Marv. I did check the part number. I'm thinking that somehow maybe the wrong part got put in the bag, but I got two of them the same. ??

[Evans, Marv]

I would have to agree with you. I can't really identify what the bushing you picture is for. They should have sent two bushings, one for each side of course. Lots of people here have been happy with the Neatrix bushings. I put polybronze on my car, but I would consider Neatrix good also, & they aren't expensive.

[ttweed]

Jon-

I did not think that Porsche supplied replacement bushings for the springplates--I always understood that you had to buy entire replacement springplate sets, which come with the new bushings vulcanized onto the pivot points, but checking the PP catalog with your given part numbers shows a description of "Inner (and Outer) Spring Plate Bushing (2 per car, sold per each), 911/912 (1965-67) Brand: Genuine Porsche" here. It looks like you ordered the right parts, so if all 4 bushings are the same size, somebody screwed up your order. The inner and outer springplate bushings are two different sizes in the early SWB cars. The inner bushing is not as thick, and has a smaller OD but a larger ID. The pic you posted looks like the inner bushing next to a springplate outer bushing.

There was a revision to the springplates for the 1967 911S, but all the '65 and '66 cars should have the smaller, thinner inner bushing w/ a larger ID than the outer. Here are some pics of the Welmeister (red) early SWB bushings next to some later Neatrix bushings.







The differences are hopefully obvious from the pics. I tried to show the difference in ID of the inner bushings in the third pic. The first two show the difference in thickness and OD.

The revision to the springplates happened first on the '67 911S and then was phased in on all the tubs later in '67, I believe. All the '68 SWB cars had the later bushing/springplate setup, AFAIK. The changes involved a deeper "cup" in the tub that receives the inner bushing, and a smaller diameter inner pivot "stub" on the springplate. These same dimensions were carried over to the LWB cars in '69.

I have an extra set of the Weltmeister early bushings if that would help you out of your quandary.

HTH,
TT

[shbop]

Tom, Thank you very much! Your explanation helps a lot. I guess I first need to back-up a little bit. I acquired a set of early spring plates, as well as another set of early front-end parts. I thought I would make things easier, ha ha ha, by preparing the ones I got for installation. So, I bead-blasted the rear plates and began to remove the rubber. At some point, I paused and grabbed one of the bushings I had received to compare it, and Voila. You were correct. The bushing shown was for the inside.So if I understand what your saying, I will actually need to remove the ones from my car to insure the correct size bushing? Second point is that: they made two different sizes for the SWB cars? Boy, now I've got a real headache. I was tempted just to order the Welmeister plates with bushings attached, but now I question whether or not they would work. If I understand correctly, your saying that in 67', with the S model, they changed to the larger diameter? Do you know if Weltmeister made plates for both diameters?

Now I think I remember reading a post that you were involved with, discussing this point. I wasn't sure what you guys were referring to, as I couldn't understand that Porsche would have made two different diameters iin such a short time.

Tom, I've sent a pm.

[ttweed]

Originally posted by shbop
So if I understand what your saying, I will actually need to remove the ones from my car to insure the correct size bushing?

Yes, when you get your springplates off, I think you will find that you have the smaller, shallower "cup" in your '66 tub. This will work fine with the Weltmeister adjustable springplates, as that early SWB configuration is what they were designed to fit. They only made one size SWB springplate, but they can be made to work with the later, larger version by using the larger, later plastic bushing on the inside, or the Elephant polybronze one (sized for Weltmeister springplate.) The "stub" or inside pivot pin for the springplate bushing is shorter than it could be, to fully engage the ID of the bushing, but there is plenty of bearing surface to support the bushing adequately. It can't move laterally at all, as it is bolted in place by the springplate cover.

That is what I did on my '68 Normal (non S) when I found that it had the larger inside bushings. I had ordered the SWB Elephant kit from Chuck for the smaller size SWB bushings (he turns them down on a lathe to fit) and then discovered the '68 had the larger bushings. I had to return the inside bushings and have him send me the bigger ones.

Unfortunately, if you bought a set of '67S or '68 springplates, they will not work on your car if you have the shallow bushing cups, without shortening the inside pivot pin. You would be better off using your original ones and rebushing them, or just buying the Weltmeister adj. plates.

Now I think I remember reading a post that you were involved with, discussing this point. I wasn't sure what you guys were referring to, as I couldn't understand that Porsche would have made two different diameters iin such a short time.

That was probably the thread about drumming up interest in the WEVO SPS for the SWB cars. That mid-year production change in '67 is one of the complications for Hayden to develop such a product. There will have to be accomodation for both sizes of inside bushings for the entire '65-68 SWB production.

TT

[Grady Clay]

Guys,

Here is from my ’65-’68 parts manual:

This plate is dated 6/66.
“
"
© Dr. Ing. h.c. F. Porsche K.G.



These parts pages below are dated 6/67 and 11/67.

#24 901.333.013.02 “Radius arm rear.”
L&R same, ely 911 with removable gummi

#26 644.333.131.00 “Rubber bushing fir
radius arm hub (inner) – up to model ‘A’.”

#27 901.333.195.00 “Rubber bushing fir
radius arm hub (outer) – up to model ‘A’.”

#53 901.333.003.00 “Rear axle radius rod
with rubber bearing. Type 911 from chassis
number 307325 on.”


Let’s document what parts fit the A-series arm
when you cut off the rubber piece (if any).

Best,
Grady

[shbop]

Thank you Tom and Grady! I got a start on taking it apart today, but with the kids on a long weekend, time was limited. I'll resume work on it next week. Thanks again for the help. Never a dull moment with these cars!

[shbop]

Here's a picture of the culprit. Looks like 40 years have taken their toll. I'm going to try and photo this job so the next guy has a reference. Hopefully by Wednesday I'll have the plates out and identify which ones are in there. Thanks again for the help with this project.

[ttweed]

Jon-

Here is the page from the factory repair manual in the Supplements section that specifies the change to the rear radius arms:



I don't know how legible this scan is going to be when I post it, so I will repeat the key text here. The first springplates with the bushings vulcanized in place were as follows:

Type 911S - from Chassis #305101S (which is the very first production S, according to the charts I have seen, although there is one reported in the S Registry database with a 303066S serial number, which if it is real would have to be a prototype, maybe?)

Type 911 - from Chassis # 307325 (which is 1967 production, but I don't know how late in the year--possibly just before Christmas?)

Type 912 - from Chassis # 354938 (Also 1967 production, about 1/2 way thru the run.)

If your chassis has an earlier serial number, the chances are it has the early, removeable/replaceable bushings that are a different size, as shown in Grady's parts book pic above.

Note that it says the "seats in the transverse support tube were enlarged to accomodate the new radius arms" and the newer ones cannot be used in earlier cars. The seats are what I was calling "cups" in my previous posts.

Good luck and let us know how it goes. It is obvious from your pic that your bushings are very deformed and need to be replaced, one way or the other.

TT

[ttweed]

Just so you don't feel bad, here is a pic of my original '68 springplates before I replaced them. Ya think they needed it?



TT

[shbop]

Well I managed to get a head start. Found a couple of surprises. My bushings were not attached to the plate. One came off with the outer cap, and the other remained in the tube until I pulled it out. Turns out the plates I got before were for a LWB because when I compared them, the one from my car was quite a bit shorter.
I feel fortunate that everything came apart so well. No rust. The rear TB measures 23mm and appears in good shape. Still covered with a layer of grease. Is it odd to find that the bushings were not attached to the plate? Does it indicate a previous replacement? I certainly appreciate all the advise here. I'm flying way above my net at the moment, and any observations or comments are welcomed! Tom thanks for that info.

[Grady Clay]

Your VIN is correct to have the separate rubber bearings.

I’m sure glad you didn’t do a lot of work on the ’69 and later LWB spring plates. Clean and inspect. Someone needs them.

Now for some scare.

Put a fresh bag in your vacuum cleaner and use a 4’ piece of ½” EMT to extend your tip. Vacuum the rust out of the bottom of the torsion bar tube. Measure how much.

See if you can find a bristle bottle brush you can use to clean the ID of the torsion bar tube. You also want a smaller one to clean the splines. You can pop the outside cap off the spring plates and clean those splines. Use solvent for all this – not water.

Be sure to NOT nick the paint/coating on the torsion bars. That will give a site for a crack to start. Test fit your torsion bars in the splines, both inner and outer. If they need much force, keep cleaning and working. With WD-40 they should be a nice tight slip fit.

While the torsion bars are out, drill a 13 mm hole in the bottom of each side of the torsion bar tube. That is directly under the middle of each torsion bar. You can’t safely do this when the torsion bars are installed. Carefully de-burr each hole, particularly on the inside (yes, there is a tool for that).

Now comes the decision of how to coat the inside of the torsion bar tube to prevent rust. I painted my two new drain holes. I coated the inside with several layers of Tectyl with hair dryer heat and a day between applications. Just before installing the torsion bars I cleaned the inner splines (inner and outer) and greased them.

Each time I have been there I have repeated the process. It still looks like new after 38 years.

The torsion bars need to be coated with a thick layer of grease. It is hard to not scrape the grease off during installation and angle adjustment so be careful.


For those who have their tub apart in this area, there is a Factory reinforcement that should be installed. These two steel brackets connect the torsion bar tube (just forward and inboard of the trailing arm mounts) to the end of the tunnel. This is best done by also gaining access through the rear seat bottoms.

This transfers the suspension forces, torsion bar reaction, engine & transmission weight and reaction forces, etc. additionally to the tunnel and pan. Without this all the forces are transferred down the torsion bar tube (bending and twisting) to the side frame. This is the primary reason (combined with rust) for torsion bar tube failures.

I have posted on this before. I’ll see if I can find the links.


See if you can borrow a bore-scope that will fit in the threaded pieces in the chassis. It would be useful to know the extent of rust inside the chassis at that very important place. In any event, some rust protection is useful – even WD-40 is better than nothing.

Be sure and clean to metal around the threaded pieces. Inspect it carefully. That is a common place to find a crack – usually between the weld and the chassis sheet metal.

Use antisieze on the new bolts when they go in the chassis.

More pictures please.

Best,
Grady

[shbop]

Grady, As always, thank you very much. I went ahead and pulled the trailing arms. Glad I did, as the bushings in those simply pushed out with my finger. Left behind was the outer shell. It gave me a chance to clean the arms up and re-paint as well as re-bush. I'm using por-15. I have limited experience with it, except I know it doesn't like ultra violet light. I figured underneath it would be o k. The 13mm holes you spoke of-- those are simply for drains?? Is por-15 ok for inside the tube? Somehow I'm thinking it might be to thick of a surface. By the way Grady, thanks for the parts id. Just like Tom was talking about. I imagine I'm lucky to have this style for my first attempt! Perhaps a little easier to deal with. More pics tomorrow!

[911ctS]

Grady has some real good tips.

Just for reference, I recently got back from the vintage historics at Laguna Seca and found 28 out of 28 911's present to be running Teflon or PTFE suspension bushings in the front and rear. This included 911 ST's 911 R's 934's 934.5's. Team mechanics told us that they have them custom fit (turned on a lathe) to each of their suspension arms and they work superb. Since all the arms have slight variations these components are more effective in a custom one off manner but are really worth the effort according to the teams. So going to the local machine shop and having some bushings made is always an option, i guess as long as its not too expensive.

Ruf also used Teflon bushings in the Yellowbird

Rubber is good too! just wanted to share the info.

[shbop]

Thanks for the input. If I was able to race the car, I might try another option, but where I live racing is out. I am considering the Weltmeister route.
I got the right side banana re-painted (por-15) and re-bushed. The old ones are on the ground beside the arm. They easily pushed-out under finger pressure, leaving the outer shell inside. Can't imagine how much better the car will feel after all this. So far the parts removed have been beyond worn-out.

[Grady Clay]

Jon,

The 13mm holes you spoke of-- those are simply for drains??
Yes, Porsche started having them in ’72.

Is por-15 ok for inside the tube? Somehow I'm thinking it might be to thick of a surface.
No, I’m concerned that it might get in the splines and the torsion bars will never again go in or out.

The Tectyl is easily removable with standard solvent so if you get some in the splines, no big deal.

Looks like good progress.

Best,
Grady

[shbop]

Update. I now have both banana arms re-painted and re-bushed. I was fortunate not to find rust in the torsion bar tube. Slight surface rust only. Drain holes have been drilled in the bottom of the tube on both sides. Funny how the work grows with each project. I didn't plan on detailing all the parts, but once apart I couldn't resist. I've discovered brake trouble, frozen piston, but I guess that's another project all together. Finding a replacement caliper hasn't been easy. It seems that A-1 Cardone are all I can find. I don't really want to do a brake mod here, but we'll see how it goes. Just waiting for the outer bushings. Should be here any day.

[Grady Clay]

Jon,

While you are there … A very useful mod is to dent the torsion tube and reverse the bolts for the trailing arms. You can shorten the bolt and use a thinner pattern metric loc-nut. This allows you to remove the trailing arms with the transmission in place.

Best,
Grady