Topic: Subframe Bushings

[JoshRiess]

Looking forward to this conversation, keep it going and please post your findings !
Thanks
                                                          JOSH

[Greenbird76]

Hey Greenbird, where are the SFCs welded? To the floor pans or cross-braces? I'm using the same Mastercraft tires as you and I like them, too. I got my rear suspension (GT) from PTFB, and I like it a lot. Dave's been good to work with.

One more quick question: Are these guys in Charter Oaks really flogging their cars, or is this something that's seen overtime?

I am afraid of getting extra drivetrain vibration. Very afraid. I'd have serious remorse if I could feel excessive vibration just revving the car in park. That just doesn't seem consistent of the characteristics of a good road car... I thought I was sure what I was going to do now I'm just confused again.

Have you seen this Not A TA?

http://www.youtube.com/watch?v=NcCwHBhd8Jw&feature=player_embedded
Here is a video of a installation of Hotchkis SFCs on a 2nd gen camaro, but they installed poly bushings which I will not do.  solids only.  This video  Illustrates the process to a tee.  Protourings are very similar and install the same way.  the cool thing about Hotchkis, Protourings GEN V and others is that you do not have to cut the floor as you do when installing Comp. Engineering SFCs. 

The driveline vibration is not bad at all.  Just slightly noticible.  I would not worry.  It is not like we are restoring Olds 98s or Cadillacs LOL

Charter Oak members do not beat on their cars as far as I know.  If that is what you were implying by using the word "flogging".  I did not understand that question.

[rpguitarrepair]

Well, I know what you mean about these being unrefined cars, I just don't want to make it where I hate driving it 500 miles on a Power Tour.

Thanks for the info Greenbird. I'm going to call Dave at PTFB and aggravate him awhile, haha. And also to reward your automotive and linguistic intuition, I'm going to share my word of the day:
flog
transitive verb
1 a : to beat with or as if with a rod or whip
   b : to criticize harshly
 
2: to force or urge into action : drive

[Grand73Am]

Poly is fine in compression but I'm not a fan of it for parts that rotate like A arm bushings.

Notice that NOT A TA mentioned that he's not a fan of poly control arm bushings. I've used them before and don't like them either, and always use original type MOOG rubber control arm bushings instead. Control arm bushings are meant to twist, which is something that poly can't do.

One of the problems I experienced with poly a-arm bushings is they can loosen up and wallow out from the looseness. To avoid that, you must make sure the control arm bushing nuts are tightened to the proper torque specs. Most people tighten them to what "feels" tight enough, but it's usually not tight enough, and they loosen. So the torque is something to double-check if you used the poly bushings. And check it periodically. Of course, when you install poly bushings, you also have to be sure to coat them liberally with the special poly bushing grease that's super sticky so it will stay on the bushings over the long term and not squeak. And for those who don't already know, the control arm bushing nuts should only be tightened with the car's weight settled on the suspension, like it's sitting with tires on the ground. 

I'll also be watching this thread with interest, since when some of you get your SFC's installed with your choice of body mounts, it'll be great to get your impressions of the results in terms of ride harshness, vibration, noise, and handling. 

[rpguitarrepair]

Good word, Steve.

I'm taking my subframe out tomorrow and I'll have everything in my lap. What is the proper torque spec for the a-arm bushing nuts? I'd like to recheck them, even though I think I 'bout threw out my rotator-cuff the first time around, lol.

[Grand73Am]

Here you go Randy. Uppers 55 lb/ft, Lowers 90 lb/ft. It's in the front suspension torque specs in the service manual if you forget.

[Greenbird76]

Poly is fine in compression but I'm not a fan of it for parts that rotate like A arm bushings.

Notice that NOT A TA mentioned that he's not a fan of poly control arm bushings. I've used them before and don't like them either, and always use original type MOOG rubber control arm bushings instead. Control arm bushings are meant to twist, which is something that poly can't do.

One of the problems I experienced with poly a-arm bushings is they can loosen up and wallow out from the looseness. To avoid that, you must make sure the control arm bushing nuts are tightened to the proper torque specs. Most people tighten them to what "feels" tight enough, but it's usually not tight enough, and they loosen. So the torque is something to double-check if you used the poly bushings. And check it periodically. Of course, when you install poly bushings, you also have to be sure to coat them liberally with the special poly bushing grease that's super sticky so it will stay on the bushings over the long term and not squeak. And for those who don't already know, the control arm bushing nuts should only be tightened with the car's weight settled on the suspension, like it's sitting with tires on the ground. 

I'll also be watching this thread with interest, since when some of you get your SFC's installed with your choice of body mounts, it'll be great to get your impressions of the results in terms of ride harshness, vibration, noise, and handling. 

I agree.  I have found that that unless a grease gusset is installed, that thick lithium grease will eventually wash out and an annoying squeek will occur when poly bushings are used on control arm bushings or other friction creating suspension parts .  This is why I installed OEM rubber control arm bushings.  The only non static suspension component I have poly bushings on are the sway bars and so far everthing is great.  I will say this though.  when my frame does flex with the poly body bushings I currently have installed, there is a slight squeak.  Not annoying and very mild, but it is there. I also have rechecked my torque for my sway bars and did have to retorque the bolts on the rear bar. 

[NOT A TA]

Everything in this post is JUST MY OPINION.

Everything below the frame needs to work together as a system of matched components to achieve the desires of the owner. Of course there's always compromises that have to be made based on the budget and different types of use the car might get. No two cars are the same and neither are the expectations of their owners. Just installing different tires or even raising/lowering the air pressure can make a difference. Add 10 PSI and you'll really notice more noise, drop 10 PSI and the car quiets right down. You may have seen races on TV and heard of the race teams raising and lowering tire pressures by as little as 1/2 lb to make the car handle differently.

I had the opportunity recently to switch back and forth between my car and a stock restored 73 TA. They drove like they were totally different model cars. I've made mods to my car slowly over 20 years and become accustomed to each change and although I've driven a bunch of other mildly modified TAs I was really amazed at the difference when driving mine, then stock, then mine. Each little thing changes the car and the combined changes can make a 2nd gen feel and drive like a different car.

Many of the 2nd gens being restored now were driven into the ground (or way beyond the useful life of rubber body mounts anyway). Their owners at the time probably didn't even know the body mounts were shot and the body and subframe were wobbling around on just 4 bolts with the radiator support hanging from the front fenders rather than being supported by the core support mounts to the subframe. The caged nuts in the frame and bolts take quite a load when the stock mounts are worn out and just the bolts are trying to hold the subframe square with the body during high stress such as off camber driveways, hard braking, acceleration etc. The mounts normally spread the load to the frame itself but as the mounts decomposed they do nothing but space the body/subframe and slide around the wobbling bolt. This is why the unrestored cars feel like a bowl of Jello as the body and subframe wiggle/bounce around on the worn mounts. Metal fatigue may be part of the cause of many nuts snapping free inside the frame when combined with the additional torque needed to loosen bolts with rusty threads.

I have not actually witnessed any cases of "ovalizing" caused by bolt in subframe connectors used in conjunction with poly body mounts on an installation I could be reasonably sure was done correctly.  So if any of you have heard or actually witnessed this I would first question the installation of both as well as the condition of the caged nuts prior to the connector/mounts installation. At least 19 times out of 20 when I ask anyone what they torqued the bolts to in applications such as this I get a deer in the headlights look with the reply. "I tightened them real good." My next question is "With what? And was the car on the ground or jack stands?"  The reply is usually a 1/2" ratchet/socket and the car was on jackstands so they were being safe. Any of you who've done this know it's pretty hard to tighten them to the correct torque with a normal length ratchet and the full weight of the vehicle should be on the wheels (frame off restos are different)



I would not use polyurethane or polygraphite for anything that rotates much such as A arms.  The cost/labor vs. benefit ratio isn't good compared with the alternatives of stock rubber or solid aluminum/Delrin. Stock rubber is cheap, easy to install, and dampens which makes stock or entry level components seem like they are better than they are at isolating NVH. Polyurethane transfers vibrations more and is likely to squeak eventually. Polygraphite is promoted as being self lubricated to reduce the squeaking problem. The release of the antisqueak graphite impregnated in the poly requires wear of the bushings as far as I know so they have to wear to lube themselves creating the "wallowing"wear discussed in another post above. The aluminum/Delrin bushings like Global West Del-A-Lums are a solid type and while they allow nice smooth articulation of the rotating parts they will transfer NVH if the rest of the components aren't that great. The springs/shocks and wheel/tire combos will affect the vibrations that might be transfered through the solid A arm bushings .

The current popular thinking is that solid body mounts should get used with subframe connectors whether they are bolt in or weld in. When I did mine many years ago solids weren't used much on street cars. Prior to that bolt in connectors were used on many cars with stock rubber mounts (perhaps that's where the ovalizing concerns started?). The problems with elongated bolt holes is rare and I believe some damage may have been done when the original body mounts were used till there was little left. These cars are now 30-40 years old and may have been driven a long time with worn mounts which placed tremendous stress on the bolts/nuts and frame section where the nuts are allowing more flex of the frame metal itself. Along with possible poor installation I can see how the bolt holes can become a problem. This is compounded by the additional G forces capable with modern tires.  I'd bet my street legal DOT R tires are better than some of the best race slicks available when my 70 was built. Even a new Radial TA can place more stress on components than the tires that came stock in the 70's due to modern chemistry.

As for engine/drive train vibration the same kind of thinking applies. Worn out engine and trans mount rubber allows everything to bounce around allowing vibration to be felt. New rubber mounts offer the most dampening, poly next with more vibrations felt in the car and solid mounting shakes the car.

So, the trick is to purchase and properly install components that will work together to create the ride and handling that the owner wants. This INCLUDES wheels and tires which have not been discussed in this thread. The wheel diameter and weight along with the tires used have a big affect on NVH as well as braking, acceleration, and handling.

[Grand73Am]

Great post. Thanks! 

[72blackbird]

John pretty much hit the nail on the head with his description of running solid subframe bushings- in a nutshell it may be too harsh for T/A and Firebird owners used to rubber bushings and rubber mounts. I too replaced the stock rubber subframe mounts over 20 years ago with solid body mounts and polygraphite suspension bushings, so what I'm used to is definitely not the same as what a more stock T/A or Firebird owner would be accustomed to. The plus side is that it makes the car handle more responsively and stiffens the chassis noticeably over stock, even without SFC's and the PTFB engine bay braces.

I'm planning to make major upgrades in the suspension department very soon- 18" wheels/tires, SFC's and engine bay braces, as well as new springs and shocks. It will be interesting to see how much stiffer and harsher my 72 Bird will ride, since with the current suspension my Bird has a kidney-busting ride even with the old 15" 60 series BFG's and H-O Racing springs.

Geno

[oldskoolubr]

OK I am back to MY Own Thread!   WHAT THE HELL IS NVH?  LOL No Seriously?!
I talked to Dave(PTFB), and like everyone else said he is a very helpful and informative guy!

He explained to me that the Solid are definitely the way to go with the SFCs!
I will more than likely be going with the Tubular control arms as well.  He explained to me that with the technology of newer tires as opposed to what originally came on these cars, the adjustability would make better use of the them.  It never even crossed my mind?
I will be running 15" snowflakes and either 17" or 18" customs with LoPros so this was a huge help.  I am going to go with the rubber bushings but the Poly Ball joint Boots should be ok right?
So to sum it up:
If you aren't using the SFCs then Rubber or Poly(Body Bushings) is fine and most the issues arise out of the orignal bushings being SO Damn Old!
If You are doing the SFCs then it is definitely recommended you use the Solid Bushings.
Also TORQUE everything!  Will go a long way in taking advantage of the mods or upgrades and longevity of your parts!

If I missed anything PLEASE chime in!

 You guys have given me LOT of knowledge Thank you, and I hope it is helpful to the others that are following along!

[Grand73Am]

I wondered what NVH was too, but after reading a little further realized that it must mean Noise, Vibration, Harshness. A good way to abbreviate those.

[oldskoolubr]

[NOT A TA]

Kinda funny thing happened today after posting in this thread last night.

I met with a customer I'm building a 69 Camaro for I'll be starting work on this week. It's a rescue pulled from a shop that didn't get work done in a timely manner. Sitting in the pile of parts he'd already bought was a set of Poly bushings next to a set of subframe connectors! So I thought of this thread ahahaha. Anyway, I told him to get a set of solids to use with the frame connectors and sell the poly bushings. So if any of you want to firm up the body to sub without installing frame connectors let me know and I'll get a price and part # from him. I believe they will fit 67-75 F bodies.

Oldskool I envy you, wish I had a set of Dave's tubular arms. The additional caster and - camber possible with them makes them one of, if not the best , A arm sets available for 2nd gen traditional spring/shock type setups available now. I'm still using stockers I put Del-A-Lums in many years ago.

[oldskoolubr]

Ya the only bad thing is is I will have to remove the Poly bushings out of them and put the Moog Rubber ones.  But still cheaper buying that way bcuz of the break in price.  No Envy needed, yours is driveable mine is mostly in my garage and office!    I am almost tempted to leave out the SFCs but I know I will be sorry in the long run!