I'm currently restoring the rear suspension on my 75 1.8l and wanted to get other's suggestions regarding rear bushings.

My shafts are fine and I'm planning on re-using them.

I already have a set of bushings.

Mine are the "Daystar" polygraphite set that you can get from multiple vendors.

These are in AutoAtlanta packaging.

These puppies fit stupid loose in the arms...

I worry about squeaking...

I don't like straight poly bushings for the most part.

Would you use them?

What grease would you use on them?
Normal silicon grease for urethane bushings?

914Rubber has a rubber set that are reasonable. $ 44

PMB and Elephant racing have rubber sets that are far more costly. $92, $240

This car will be a mildly upgraded streetcar for enjoyment not competition.

I'm leaning toward the 914Rubber set...

What says the hive mind?

I'm just a little ahead of you. Have you already removed the old pivot shafts? Ours looked good until I got them out of the bushing. If searching for shafts, everyone I spoke to was carrying sold shafts except Restoration Design. While I'm sure the solid shafts are just fine, it seemed like unnecessary weight to me.
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If shooting for originality or street ride, you might want to go rubber for the bushing. The other compounds are reported to give a pretty harsh ride according to the vendors I spoke with.

Based on what I can gather, Precom is original 85 durometer and supplies Restoration Design, Porsche, Rebel Racing and Elephant Racing. I believe 914Rubber is the same spec, but perhaps from a different manufacturer.

For installation, I haven't seen anyone using grease. I've seem some dish soap used.

Plastic bushings squeak.
I have tried a few…they all squeak.

Now that rubber bushings exist again, I would use those hands down for a fun street car.

When racing…rubber works but bearings are the best choice.

Rich

Everything is apart and has been bead-blasted and painted.

My shafts are FLAWLESS compared to yours.

I commonly use "Energy Suspensions" silicon grease IF I'm installing urethane bushings.

A bunch of it and I will usually install grease zerks/drilled bushings to allow the addition of more silicon grease down the road because every single urethane bushing will need re-greasing far more often than you might think.

They still squeak like hell...

I don't prefer them.

I ended up winning an E-bay auction that had these Daystars in with a bunch of other stuff. I'm planning on selling them or throwing them away...

Installation of a rubber bushing requires soap or more commonly diesel fuel as an installation aid which should dry up and lock the bushing to both the shaft and the trailing arm housing.

If using rubber bushings, it's critical to have the suspension fully loaded before you lock the mounting hardware.

If you tighten with the suspension in full droop the new bushings will have a much shorter lifespan.

Thanks for the responses guys!

I've used a bunch of different rear bearing/bushing combos in the past: plastic, delrin, roller, all sucked. These are the best I've used and wholeheartedly endorse them.

https://www.rsrproducts.com/product-page/re...ear-bushing-set

Rubber bushings are fine for a street car to maintain stock performance. I went with the RSR thermoplastic inserts and never looked back.

Ever stop and wonder why 99.99% of automotive OEMs including the likes of McLaren, Porsche, Ferrari, Lamborghini use rubber bushings?

Hint: it’s not for cost reasons.

Those RSR bushings are interesting! I hadn't seen those before. A shaft in a tube.
Thanks for the link!

SuperHawk, I've been doing this a long time, yes I am fully aware why everyone uses rubber. Even with rubber many manufactures "tone" down their suspensions over time because the non-enthusiast owners demand it. The BMW M3 is a perfect example of this. AN E30 M3 (all rubber) is too much harshness for almost anyone and if you change anything it will beat you to death on the street. I have an E36 M3 These got toned down a bit to make them more user friendly and are the sweet spot in my book.
Put yellow billys on it and it's harsh, any urethane and it's harsh.
BMW heard their customers and the E46 M3 got toned down a BUNCH. This car benefits from suspension improvements as it was set up soft enough to be far more comfortable for thier average driver. All of those cars started life with rubber...

This 914 will be my father's final "sports car" and will be set up more for comfort.
He's an 83 year old multiple myeloma survivor and ALL additional padding has been removed frm his body. When he was healthy he weighed 180, now he weighs 130.

This is the main reason I'm not going Elephant poly bronze or (now!) RSR shaft in tube on this car...

Nice! do they actually ship the rears now? For years all they had up was a cad drawing on their site. I have the RSR fronts and love them. Picked up a set of elephant rears for my current project but havent installed them yet. If rebel has the rears now i may have to go that route.

I talked to Clint about two weeks ago. It’s hit or miss to get him on the phone but it’s the best way to verify what’s in stock.

A couple things to consider with ANY of the single piece plastic/poly bushings out there is that the factory designed the rear suspension to have all movement to be allowed though the deflection of the rubber. All the surfaces that the rubber bushing touches (the shafts, control arm, and mounting ears) are intended to be bound to the rubber bushing, they are not bearing surfaces.
All the single piece poly bushings turn these into friction surfaces and you wind up attempting to slide a bushing on a surface that was not designed to have anything sliding on it, so the performance winds up being very inconsistent, assuming you can even get them installed with proper gaps.

Elephant addresses this by supplying components to act as the friction surfaces, providing their own shafts and thrust washers, but single piece poly you are just grinding plastic on rough metal.


The 2nd issue to consider with solid bushings is alignment. With rubber a good portion of the fore/aft movement of the control arm is allowed via compression of the thrust area of the bushing, with solid bushings this isnt the case and you wind up having to get all the movement from flexing the control arm mounting ear on the chassis.

I'm listening.

Said differently . . . Rigid bushing increase loads on all your suspension bits and chassis mounting points . . . a lot. You wouldn’t believe how much higher the loads are. I’ve seen substantial changes in durability loads just going between different durometer rubber bushings and voided vs solid rubber bushings. Moving to urethane / poly bronze ratchets that up to another level. Move to spherical metal bushings and there would be enormous durability / fatigue issues .

Just because something is good on a track with a very controlled road surface for a race car doesn’t mean it it is “better” for a street car used in the real world.

And we haven’t even talked about the NVH degradation in road noise. Ninja touched on the ride comfort degradation. People’s tolerance for those degradations varies. Choose wisely.

I bought my 914 for spirited driving. My roads are very smooth, so I don't mind a little harsher ride. My drives vary from 1/2 to 1 hour drives. Maybe driving for longer periods I would have considered rubber bushings. My goal was to get the maximum handling out of the car. 19mm front Torsion bars, 22mm front sway bar, and turbo tie rods. 140 lb springs in the rear, and Bilsteins on all 4 corners. The car handles like it's on rails.

This is what I run on #41. 914-6 . I also run the front type from them as well. Super tight suspension and does not feel bad at all on the streets of Los Angeles.

Bob B


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Thats an excellent comment /explanation and what i‘ve always thought when i saw these simple hard poly / delrin bushings.
They work the wrong way, especially when you think about the alignment of the rear trailing arms.

BR

Benno

I went through the whole delrin bushings and the needle bearing bushings. And I went back to a set of Elephant rubber bushings.

The delrin bushings were harsher, and they stuck so the suspension didn't work freely. I eventually honed them out so they would move freely, but the ride was still harsh. At that time, there were no rubber bushings available for replacement.

I tried the needle bearing conversion on my big six. For street use it was terrible. It beat me up so bad just going over regular bumps in the road that I didn't want to drive the car.

When I saw that Elephant had new rubber bushings, I didn't hesitate. I bought them and put them in. The handling is not quite as good as with the needle bearings, but I can actually drive the car on the street now.

If you are racing, and looking for the last tenth of performance, then get the needle bearings. They will definitely improve your lap times over rubber bushings, and won't have the sticking issues of delrin bushings. But for street use, stick with the rubber bushings. Your back and kidneys will thank you in the long run.

Honestly, most folks wouldn’t be running enough power to realize any significant increases in performance.
Kind of like carbon fiber vs fiberglass, yes you can gain some improvement, but what you get for the dollar is at a significant cost.
So, if you plan to increase performance maybe worth doing this, but personally I’d put my money into increasing HP 1st.

I've the poly/bronze for a almost not street legal GT Tribute. I like them a lot, but the ride is harsh and direct. Thats what I wanted, but JamesM hit it n the head for most Drivers not racers. Best, Mark

I dont understand this comment, the rubber in the arms is intended to twist while bound to the shafts. Needles should provide free'r motion rotating around the shaft allowing the shocks to do thier job w/o any countering force? In theory I would imagine you could run softer compression & faster rebound shox's.

Bottom line: pro driver on rubber bushings will still be faster than your average weekend warrior / track hound on needle bearings / Delrin / Poly-Bronze.

Don’t kid yourselves.

Thanks for all the replies.

I've decided to try Mikey's rubber bushings.

I got a bunch of other stuff to order from them anyway.

On my other car, a 76 916 clone, I'll used either the Elephant poly bronze or maybe the RSR ones. I wasn't aware of those, and I like the perfect reproduction shafts better.

Thanks for the heads up yeahmag.

That decision will happen far down the road...

It has nothing to do with the compression or rebound of the shocks. It has to do with the transmitted impacts. The rubber bushings absorb some of the road impacts. The needle bearings transmit all of the impacts to the chassis. That results in a much harsher ride.

For me, that is an unacceptable situation for a car that is primarily driven on the street. I am not willing to sacrifice my kidneys on a day to day basis for a few tenths in the occasional autocross or track day.

I run Tangerine Racing bushings in the race car. They have a tube welded in the arm, delrin bushings, and a custom shaft. They are great. I have replaced the bushings once as they wore, but I think that was after 5ish years of lots of track time.

We just used the rubber Elephant kit on an original six and it was great. The new bushings, shafts, and tools worked perfect.