TR5/TR250 TR250/6 Rear Trailing Arm Bush Options

[glemon]

I just got back from an airport speed run in my TR250, we basically do a quarter mile drag turn around, and then do some slaloms and such on the way back.

Anyhow, middle of my second run the car gets pretty squirelly, I jack it up on site and notice considerable play (.5" or so) in the rear suspension passenger side inner trailing arm mount, so I am done for the day. Drive home slow and careful after making sure nothing seems to be about to break or fall off, and take it apart.

The rear poly bush has compressed enough to allow this movement, as in permanently distorted.

I didn't think they were supposed to do that.

I have a rear sway bar and I am thinking maybe the fulcrum effect of the bar pressure when I turned very hard did it. But I still didn't think they were supposed do that.

Anybody else had this problem?


Thinking of going to a hard rubber bush or maybe trying the poly again, not sure at this point. Are the rubbers hard to press in, don't really want to have to take the trailing arm all the way off (brake line) if I don't have to.

Oh yes, the good news, my one good first run was only half a second off that of a Sunbeam Tiger's best for the day (basically a very stock and original Tiger, I know I would have no chance against a modified Tiger), and way ahead of the MGBs and such, I am sure I could have shaved that much or more off in subsequent runs....

 

[tdskip]

I can't imagine that rubber would hold up better than poly.

Glad you upheld our honor!

 

[SkinnedKnuckles]

The rear poly bush has compressed enough to allow this movement, as in permanently distorted.

I didn't think they were supposed to do that.

Let them sit for a day or so - the deformation is not so permanent. When I switched over to Nylatron bushes on the trailing arms I was shocked at the deformation in the polyurethane bushes that were removed. The holes were oblong! I put them on on my bench and went on with the installation. A day or so later they looked like new. Are they supposed to do that? No - but they are plastic, not rubber, so in hindsight it's not unexpected. When I get around to the front end again I'm going with the nylatron instead of poly.

 

[Brosky]

That's one of the reasons that guys go to those. Just to prevent that from happening. I'll be curious to see some pictures when you get it apart.

 

[glemon]

Brent, where did you get the nylatron bushings?, and yes mine are oblong too.

As far as rubber, I assume it will compress easier than poly, but it would decompress as soon as the pressure is off, not over a period of time. Interesting on the compression going away over time, will check them later tonight or tommorrow.

 

[SkinnedKnuckles]

As always for stuff like this - Good Parts.

Yes - rubber will give and forgive, until it breaks down. Then there is a hollow. The plastic deforms under load, but still has a grab on the metal bushing. The deformation is the weight of the car on the bushes.

I did the front in polyurethane, too, about 15-16 years ago. There is no lost wobble, but I wonder about the plastic set. I'll get to it eventually.

 

[justin_mercier]

I've got both a poly set and a hard ruber set of rear trailing arm bushings, and i'm trying to decide which set to use when I re-install my trailing arms this next week with new adjustable camber trailing arm brackets. I'll be honest that it looks like the hard rubber ones are better made than the poly ones, but how long do hard rubber ones last?

 

[SkinnedKnuckles]

I'll be honest that it looks like the hard rubber ones are better made than the poly ones, but how long do hard rubber ones last?

I can't answer that one. Alot of so called "rubber" components these days aren't really a vulcanized rubber - they are a TPE - thermoplastic elastomer. Because it's cheaper. The TPE's have some really good & really bad properties - as in they can't stand up to heat as long as real rubber. Solvent (gasoline) resistance is another, but off topic. With all the topics on the poor quality of parts in general, I'd be careful on rubber ones.

 

[glemon]

Do the nylatron ride hard or make it more noisy?, found them on the Goodparts site, TS import list nylatron as "competition only" or something like that.

I have also read all polyurethane is not created equal, I notice you can also get "prothane" polyurethane, they are more exensive than most of the other polys but less than the nylatron, anyone have any experience with these?

 

[tdskip]

I have those Goodparts hard bushings in my TR6 and I haven't noticed them to be overly tough, spring and shocks will likely make a far bigger difference.

 

[swift6]

Harder bushings in the trailing arms won't really affect ride comfort/quality. The ultimate set up that some of the European fast road preparers are doing is to replace the bushing with a spherical bearing.

 

[DNK]

Shawn, one thing it does do , is put more force on the part. Correct?

 

[SkinnedKnuckles]

Same here. No extra squeaks. I also took a look at the site since it's been a while - didn't see any reference to "competition only".

 

[swift6]

Shawn, one thing it does do , is put more force on the part. Correct?

What part? Stiffer bushings resist the force applied more than the softer, which could lead to higher cornering speeds which could lead to more force, but the stiffer bushing itself shouldn't equate to higher forces, just higher resistance.

 

[DNK]

Won't a poly or Nylatron or even in this case solid bushing in the TA area provide less shock,if you may, than a rubber one on a very hard thump or pot hole?

 

[lbcs_r_fun]

Why not ask someone who races an IRS Triumph. I would think that something this basic was addressed long ago. How about Kastner's preparation manuals?

 

[tdskip]

I think everyone races solid axle cars.

 

[DNK]

What about 6's Tom

 

[lbcs_r_fun]

I think everyone races solid axle cars.

Group 44 raced a TR250 and TR6, which of course were IRS!

Group 44 TR250

I think Kas has a website with a forum. I am sure you could get some expert opinions there.

Good luck

T

 

[DNK]

Only cause I know what you meant the first time Tom