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

[bnickel]

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.

 

[mercomet]

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 ?

 

[bnickel]

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

 

[mercomet]

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

 

[Psydwaze]

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

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.

 

[68EFIvert]

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.

 

[Aussie Mike]

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.

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.

 

[Route666]

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.

 

[Aussie Mike]

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.

 

[reenmachine]

You shouldn't necessarily interpret the fact that many suspension systems require bushings to deflect as a flaw.

In some applications it's not appropriate because it doesn't allow completely unrestrained motion.

In some applications spherical-end systems aren't appropriate because ride quality can suffer.

There's a concept that very many people fail to understand and it's called compromise. A system like the g-Bar provides much-improved handling without totally sacrificing ride quality.

If you're not routinely in situations where you are striving to minimize lap times then the bushings won't be a detriment to you. Moreover, if you drive your car on the street for fun and enjoyment then you'll appreciate them.

 

[reenmachine]

I'm about halfway through the install on a customer's car and should have some pics to post tomorrow. Everything has gone really smoothly so far, and the instructions are excellent.

The stock steel fuel line had to be tweaked a bit to clear the driver's side frame bracket, but that was no big deal.

The only "gotcha" I foresee is that I think the driver's side upper bracket on the axle housing is going to cover the hole for the vent fitting/brake line "tee". Best case, I can relocate it a bit and just bend the lines a little, worst case I have to make some new lines.

 

[68EFIvert]

Reen I would love to hear how many hours it takes to install the kit. I want to decide if I should pay to have it done or just bring the axle in to a welder to have them weld the tabs on. I don't trust my welding on suspension parts. That is when I buy the kit that is. Thanks for the info and review.

 

[reenmachine]

The only "gotcha" I foresee is that I think the driver's side upper bracket on the axle housing is going to cover the hole for the vent fitting/brake line "tee". Best case, I can relocate it a bit and just bend the lines a little, worst case I have to make some new lines.

OK -- I'm done and the above was the only little wrinkle. Everything else went smoothly and came out the way it was supposed to.

The driver's side upper bracket did indeed weld right over the threaded hole on the axle housing for the vent fitting, which also holds down the "tee" for the rear brake lines. I made a new hole (threads are 7/16"-20) clocked about 20° towards the front. With a little creative line bending I was able to relocate the brake lines without ever cracking them open. Not the super-slickest solution, but on this everyday driver it got the job done without having to bill the customer anything extra.

In the future I'll just vent the housing somewhere else and make custom brake lines.

 

[68EFIvert]

How is the exhaust routed on your customers car?

 

[reenmachine]

Something else came up that could have turned into an issue, but the fix was pretty easy and TCP will include it in the kit probably by the time you read this.

As you probably know, the axle tubes on a 65-66 taper down significantly towards the ends. The kit didn't take this into account, so the U-bolts were too big and you couldn't use smaller ones as the main brackets wouldn't fit them.

The fix is to weld "hats" on the tapered section to size it up. You're welding on the housing anyway, and so it only takes another couple of minutes. No big deal.

Here's how the housing comes out:

 

[reenmachine]

How is the exhaust routed on your customers car?

2-1/4" exhaust through a GT valance. At first blush it looks like a good exhaust shop will be able to get the pipes up and over. I'll post more pics of that are in a minute.

 

[reenmachine]

Here's what the system looks like installed:

 

[reenmachine]

Here's the room the exhaust has to go through. Like I said, it looks like 2-1/4" pipes will be able to find their way through here OK. Granted these photos are with the suspension at full droop -- I'll get pics with the car on the ground once I've driven it and it's all settled in.

I've got to run but I'll post my general overview and impressions of the whole installation later tonight.

 

[bnickel]

it looks like you wouldn't even need to weld the "hats" on the diff tubes if you didn't want to. the u-bolts should hold it tight and the leaf spring pad will keep the diff from moving anyway but i'd still at least want to tack them on just to be safe.

i can't wait to get mine for the cougar. know anyone looking for a 69 GT coupe?

 

[Aussie Mike]

There's a concept that very many people fail to understand and it's called compromise. A system like the g-Bar provides much-improved handling without totally sacrificing ride quality.

If you're not routinely in situations where you are striving to minimize lap times then the bushings won't be a detriment to you. Moreover, if you drive your car on the street for fun and enjoyment then you'll appreciate them.

That is aptly put Reen. I look forward to reading your review on the finished install. Thanks for taking the time.

Mike B.
Perth - West Oz!