Updated TCP G-Bar triangulated 4-link...

a poly bushin will bind more sooner than the spherical bearing type will, but on most street cars this shouldn't be a problem as much as with a drag or road race car as a "typical" street car won't be put through it's paces like the others would, however if you're building a more canyon carver type car that will be pushed to the edge a lot more than a "typical" street car then you'd be better suited to use the spherical bearing type system. the sperical bearing one will probably be a little harsher and require more maintenance than the poly bushing type will. with the poly bushing one i'd imagine you'd just need to grease the bushings occassionally and that's about it as far as maintenance goes. the spherical bearing type would probably require more regular greasing and also probably require an occassional tear down of the joint to clean, inspect, lube and adjust the preload on it.

that's my take on it anyway.

Thanks, under what circumstances would you be causing bind ? Hard cornering while braking ? while accelerating ? hard launching ? straight line skid/braking ? And what could be the likely result ?
What I'm trying to get at is, would a bind issue be something an aggressive street driven car with this g bar (and I don't mean crazy) would be creating every time you mashed the pedal/ jam the brakes cornering or is it something that would maybe be an issue once in a blue moon under extreme circumstances that a street car would rarely if ever see.
What are the limitations ?

that's really hard for me to say. it really depends on how much body roll the car, the type of road (or track) you're on, car weight, weight transfer, etc and of course how hard you're pushing the car. Psydwaze would probably have a better answer than me on that one, i'm just trying to help the best i can and that one is probably just a little outside my realm there. i'm semi-worried about it on my car as well since i tend to drive the crap out of my cars but i figured since my car will rarely ever see any kind of track (only thing within a couple hundred miles is a dragstrip or two) and since west texas is really flat, the poly bushing steup will probably work just fine for 99% of the driving i do, now if i still lived in austin and was a lot closer to several different tracks and the terrain there is really and curvy i'd probably opt for the sphrical bearing type unit.....man i wish i still lived down there , if it wasn't so expensive and the wife was willing i'd move back there in a heartbeat just so i'd have some nice twisty roads to play on

Psydwaze, can you give your opinion on this whole bind thing or whatever else might be an issue for high hp street cars.

Psydwaze said:

... A rising spring rate is unavoidable when using rubber or poly bushings, because there is always some degree of binding...

Click to expand...

What I meant by this statement is that there will always be some degree of resistance from the bushings as the suspension moves. Take for example an lower control arm with poly bushings at each end. In order for the chassis to roll in relation to the rearend housing the bushings must deflect or give. Same thing with rubber bushings at the leaf springs and front control arm pivots or the strut rod bushings. They have to deform in order to allow movement. This is a bind so to speak since the control arm is not pivoting exactly on the bolt axis or if the bushing does not slip to allow movement against the inner and outer sleeves and must deform. Thats why you're supposed to have rubber bushing suspension components positioned at ride height before fully tightening the mounting bolts. You want the least amount of bind/resistance closest to the normal ride height position.

This isn't really a "problem", it's just how suspension bushings are supposed to work.

The g-Bar poly-bushing arms are fitted with grease zerks so that the bushings can pivot within their housings, making bushing shortcomings somewhat of a non-issue for moderate performance vehicles.


(Sorry for the giant picture. I haven't moved the mid-size image to the webserver.)


Mercomet,

500-600 hp and Saturday night drags: Make sure you read post #43. This may apply depending upon your tire selection and how aggressively you launch your car.

Sphercial bearings on the street: Personally I find this perfectly acceptable. I'll trade sharp handling for a cushy 1960's ride quality any day of the week.

I was just thinking about something. Couldn't one just replace one side of the upper link that has a poly bushing and put in a new sperical rod end on just one side? Would it be worth it? It seems like it would get you 1/2 the way there with much less expense. Perhaps it would take care of any binding issues. Just a thought and someone please let me know if that make sense or not. If it does I will make that change while I install my kit later in the year.

68EFIvert said:

I was just thinking about something. Couldn't one just replace one side of the upper link that has a poly bushing and put in a new sperical rod end on just one side? Would it be worth it? It seems like it would get you 1/2 the way there with much less expense. Perhaps it would take care of any binding issues. Just a thought and someone please let me know if that make sense or not. If it does I will make that change while I install my kit later in the year.

Click to expand...

Newby here from Oz - g'day to all.

I'd been searching for some info on the new TCP G-Bar set-up and came across this thread. The question above posed by 68EFIvert is exactly what I had in mind when I contacted TCP recently. Actually it was one of several questions I asked but the response I got was short and mono-syllabic, only addressing 2 of my 4 questions.

I would have thought that there would be no mechanical advantage in having a spherical bushing pivoting at both ends of the link particularly when a cost saving could be made by just having the one. In fact, I would have thought that a ride advantage could have been had by having the lower link with a poly bush at the chassis end and the pivot on the axle housing i.e. as in quieter. Please correct me if you think I'm talking out of my backside.

I'm looking to bolt/weld one up to a Currie crate rearend but am concerned that the centres between the upper link pivot brackets might be too narrow for the wider web of the crate 9". I've emailed Currie to get the dimensions but haven't had a reply as yet (in all fairness that was only on Friday) and TCP didn't get back to me with details on the weld bracket template thingy.

After seeing the pics posted by Reenmachine, I'm now hungry for one of these buggers!!!

Cheers, Mike B.

Unless the suspension was absolutely, perfectly designed, (in which case I still have doubts) you will still have either end of the rod connection mis-aligning with its original position. If the centres of the rods aren't aligned perpendicularly to their mounting holes at every point in their travel, they need some freedom to mis-align - hence the spherical bearings.

Now I understand where the idea of having one spherical bearing comes in, but you are still left with restrain at the end with a cylindrical bearing (poly bushings). So even with freedom on one end of each rod, if the suspension travel is such that the spherical end moves perpendicularly wrt the axis of movement of the poly bushing end, you are going to get binding.

Ok, I'm doing my best to follow that explanation with my limited knowledge of suspension systems. This being the case it seems I should avoid the poly bush type links and go with the spherical pivots as there is always going to be binding issues with the poly ends, right?

I found an exploded view of the poly bush links on the TCP site and it seems that the deflection totally relies on the 'give' in the poly bushing itself, rather than the tubing pivoting within the housing. I'm therefore assuming that the movement is going to be severely limited much like having poly bushings in your front strut rods instead of rubber for example. Am I on the right track here?

Mike B.