Delrin is ok, but I'm making mine out of something else.

Oddjob-

My set up costs are much less, unless you just feel like you need to spend the money.

 

Dave951M-

Care to clue us into this mystery material? Will they be streetable?

Thanks,
Max

 

I have not had delrin on MY car before. I have tried several weltmeister sets on my early car, and none lasted long. I was told both by weltmeister and paragon that the polyurethane stuff was not suitable for "track use", how dissapointing.

I can give feedback once I install them on the car (along with mo30 castor blocks). That said, I did not want to go metal for a few reasons. I'm weary of any wear (metal on metal@the subframe), as well as noise/harshness issues. I think delrin will end up being a great compromise. Also should resist oil damage, which was also a concern for me as something always seems to be leaking down there and I don't have the time or the money to keep throwing bushings at this thing. I feel that this could be a great solution for lots of people.

BTW, incase there was any misunderstanding, these bushings are for the late cars ONLY.
Ahmet
Ahmet

 

I run the red Weltmeister bushings on my 86 Turbo track car and I have had no issues at all with them. They required some creative grinding to fit well in the control arm, but I have numerous track days on them without an issue. I inspect them frequently, as you should with any component.

Welmeister does supply a warning with the product. They do not recommend them for track use. I was suprised to see this when I received the bushings, but discounted it as "CYA" for insurance purposes.

 

hey, if you and I are both posting on the same thread, then it really is "sh944's", right? lol

As for the delrin/other materials on streetable cars, I don't want to sound like a broken record here, but a little bit of rubber provides the right amount of "give" on the street, which will keep you from accelerated wear and or broken parts. You might ask Dmoffitt about this, as I believe he's experiencing this firsthand, running Chris Cervelli's old 951 chassis on the street.

As the other sh944 said... if you run delin on the street, you gotta check it often!

Regards,

 

I have run a number of bushings in my 84 944-spec car.

I replaced all the bushings with weltmeister blacks. Front and rear.

Everything worked fine until on the crossmember bushings on steel arms grenaded. I then replaced all the front black bushings with red ones.

I noticed that my castor block were ok and that the other side bushings were a little rounded out and cracked, but were holding. I ran some rubber ones as an back-up set and after on track session I noticed they had slid back and the arm was touchin the crossmember. This was the same for all steel arm 944's in spec group too.

Well the reds seemed ok for while and then I noticed one where the outer ring was ripped off and control arm was contracting the crossmember. I then turned to Skip & Jasaon at Paragon about the delrin bushings. I was able to make do for a few races on spare red bushing and even spare black ones. The red always got cut up.

I eventually got the delrin in stalled in the arm to crossmember joint and the have been flawless since. In fact I have forgotten about them they have worked so nicely. In my case metal bushing were not allowed per class rules.

I still run the weltmeister red castor blocks. The at racer's edge have not been able to come-up with good rear block due to wide varriation in part tolerances, but it seems the red welts are up to the task.

In the rear my black welts have been fine. I replaced the torsion bars (went from 28mm to 30mm) and inspected the rears and found them to be in great shape. They do tend to creak some. I never notice this on track, but have heard it clearly in the pits. I think on track I am too busy to listen for it as I have also heard then on in car video tapes often on warp-up or cool down laps.

 

A few clarification items:

- There are two grades of Weltmeister bushing material. The "old" black stuff was Poly-Graphite (Black in color). This is/was the stuff that broke down on the front of 944 because it was too brittle for that type of application. We, as well as most others, do not carry these bushings anymore.
- The rear Weltmeister Poly-Graphite torsion bar spring plate application is still an available part, and is of the same material. I've heard fitment issues with these, but the biggest complaint (me included) is the noise. They squeak. The fitment of any bushing, be it Poly or Delrin, in the torsion carrier spring plate is a swag. Model-to-model car-to-car manufacturing tolerances (where there was normally a molded-rubber piece) are vague. Most bushings need to be "shaped" to fit properly. Also, while the Poly bushing are more brittle, the application in the spring plate does not seem to break them down at any discernable rate. They just develop squeaks were Delrin does not normally.
- For a long time, the Delrin was either not available for the rear spring plate, or just one side was available. Now that BOTH the inner and outer spring plate bushings ARE available in Delrin, that's what we prefer to recommend. While it is not all that much harder that the Poly-Graphite, it is much more resilient (does not crack) and does not appear to produce squeaks (even without lube, as recommended). It is important to remember that you are replacing a rubber non-friction component with a harder component that will now see friction, and thus break down over time (not quickly, don't worry). There's a proverb about this somewhere, eh.
- The "problem" with any aftermarket material bushing in the front of the early steel-armed 944's is the shape of the area to work with verses the amount of load it has to deal with. The new RED Weltmeister bushing are Poly-impregnated rubber (the same type as used in most all other "performance" bushing kits from Energy Suspension, etc.) They are still relatively pliable, and are not the best material for that nature of use. They are not recommended for track both as the aforementioned CYA, but they also have proven to break down similar to the original rubber bushings when used in extreme (racing) conditions. Braking produces the greatest load on that area as the goal is to ultimately prevent toe-out. Simple up-and-down, rotational motion would likely not cause excessive wear. Another problem, though it could be corrected, is that the current RED Weltmeister bushing does not include a steel sleeve spacer to positively lock the crossmember at a fixed distance. As you torque down on the crossmember, the relatively soft bushing is squeezed. This is not ideal.
- The late (85.5+) cast aluminum arms have a more finite fitment in this area, and allow the bushing to be a bit more precise that will ultimately last longer. Regardless, the same assertion applies that they are not recommended for "racing" use.
- The new Delrin fitments for the front of the steel arms, and soon-to-come cast arms, are ideal for racing duty as the material is much more durable and they do make use of a steel sleeve to protect from slop and allow proper torquing. The only disadvantage is that they will produce a slightly harsher ride. For those track junkies out there, this is acceptable and even desirable.

The idea and product Ahmet is showing looks like a well designed piece. Good luck with it!

FWIW, I have been running the RED Weltmeister bushing on my track car for over a year now with no complaints other than the inherent design compromises. I will be running the new Delrin pieces this season since my car has retrofit steel arms. The rear caster bushing (for steel arms) will remain the RED Weltmeister type until the Delrin alternative is available - hope to see this one soon as well.

Further, Delrin is a polymer resin available in many different varieties. The white/opaque color is "natural". The "alternative" color is more brown/black. There should be no difference in the material based on color, though there are different formulations of Delrin. It is similar to Nylon, but is not a direct product or formulation of it. There are certainly other Nylon-like plastics out there for suspension component use where friction is a factor (lubricated, similar to Teflon), but they are cost prohibitive for this type of application - one such increasingly popular material is Nylatron (Nylon with molybdenum).

 

Thanks Skip and M758 for the excellent words of expierience. It looks like I'll be ordering the Delrin bushings for next season. I'll do them when I'm doing my wheel bearings. Anyone need a slightly used set of red welt bushings?

 

Skip hit the nail on head about the braking loads.

Ken, if you are just doing Autocross you are probably fine. In fact if you doing DE on street tires you will probably be fine. I my case I was RACING on R-tires. There was one spot on one track that I think caused all my problems. The g-loads under braking were quite intense ( 100mph to 60 mph) plus the slight cornering while I was doing this cause the problems becuase of the heavy loads on right front wheel. I the car it felt like it was standing the car on the right front wheel everytime.

That said I'd recommend delrin's for any steel arm 944 that see track use with R-tires. I feel the braking loads that can be sustained by R-tires require the tougher material.

 

Does the installation require the removal of the factory steel sleeve/outer piece that is now really stuck in there? It seem like this sleeve would make a good bearing surface, otherwise the delrin would be using the aluminum arm for the outer race, and that would wear pretty quickly. Are you including the inner sleeve shown in the pic, or is that taken from the center of the stock bushing?

 

Have a look at this picture of late model cast aluminum arm replacement bushings for reference:



You can see that the rubber is originally in contact with the aluminum - that is not a rotational point. The rotation as per original actually happens at the bolt-to-metal bushing surface. The replacement Delrin or other variety bushing would form a relatively tight fit to the arm itself, thus leaving the rotation point in the same place; where the bolt meets the what-would-have-to-be-included metal sleeve.

Here's a picture of the current adaptation for the steel arms - it would be the same idea, except different diameters:



Really, there may be several rotational/frictional surfaces from car to car (again with the tolerances we have to endure) but as with most things the friction will look for the least resistance - this is desirable and would abate wear where you don't want it most.

 

Good posts here.

Dave E, if that question was geared towards me, yes I will include a new sleeve as seen in the picture (as well as the lubricant, also in the picture).
Ahmet

 

Thanks for the advice. I'm going to try and get more into DE's this year. And since I have a set of R compounds for that, that's what I used and was planning to use on the track. My first and only track day was last year at Watkins Glen with a set of Kumho Victoracers.

They're on their way out though, and I need to replace them with some sort of autocross/DE compromise. Unless I get another set of wheels. Oh boy, this is how it starts isn't it?

Well, to keep it on topic, I think the Delrin is right for my purpose. As well the improved action will be a benefit on the autocross course. I'm in a very competitive region and need all the help I can get!

 

Skip and M758 gave more and better advise than I can offer.

My experience is somewhat limited as I have only had the bushings on my car for a few months. I used the delrin bushings to replace pretty well worn out stock rubber bushings. I cannot say whether the ride is more harsh as, again, my stock bushings were completely knackered, so not much to compare the ride to. I do not notice more noice, especially since the worn out bushings were allowing a whole lot of knocking anyway. I used the red bushings for the caster blocks.

This was the second to last round in my quest to get rid of all the front end knocks and rattles. Replacing the toasted Koni strut inserts is next.

 

Ahmet, what's going on with your bushings?

Dave Miller, what is the mystery material?