[TR] TR4A trailing arm shims

[McGaheyRx at aol.com]

Tony -
 
- I'd settle for bump stops and dishes  "not perfectly aligned" -  these 
are WAY off - but I'll try installing with  all with the  original shims back 
in place after I resolve the trailing arm/CV joint clearance  issue.
 
- I'm pretty sure this car has never had any frame or significant body  
damage and I think all the trailing arm shims are original to the car as  well.
 
- I've been working on the trailing arms with them mounted on the car but  
hanging almost straight down - with the car on a lift - makes test fitting 
the  axles and hubs pretty easy. 
Without the hub bolted onto the axle, there is enough play  in the splines 
to allow the CV joint to rotate thru a larger circle than it  would once 
bolted in place - making the interference appear worse than it would  be in 
use. I decided to use this as the test condition, so as to be assured of  
plenty of clearance in use.
 
- Originally, I did all my test fitting without a brake backing plate  
between the hub and the trailing arm - only to realize when I thought I was  
finished, that the presence of the brake backing plate draws the the CV joint  
into the tapered tunnel thru the trailing arm far enough to rub again.
 
- the hub mounting bolt circle on these trailing arms don't appear to be  
terribly far off, although I have noticed all the rubbing is on the front on  
each side.
 
- I have been removing material from the interior of that tunnel with 30  
grit sanding sleeves on a 3 inch diameter 1 inch deep sanding drum on an air  
drill. Silicon carbide sleeves for soft metals work really well without 
clogging  at all - unfortunately the reason the don't clog is that they abrade 
quickly -  so I won't be doing any more until i get more sanding sleeves in 
tomorrow.
 
Cheers,
Jack Mc
 
 
 
 
 
In a message dated 1/11/2015 11:08:34 P.M. Eastern Standard Time,  
spamiam at comcast.net writes:

Jack,  

My bump stop dishes do not perfectly align with the bump stops,  including 
all the original shims

My car has had no frame damage, and I  think the shims are all original to 
the car.  

I did/do have  trouble with clearance on the trailing arms.  On the first 
one, drivers  side (left), I had only a little interference and a little 
dremel carbide burr  grinding did the job

The other side was/is a bit of a problem.   The original installation of 
the 6 studs was a bit off.  You can see that  the bottom stud is well 
centered, but all the rest are slightly out of  position, the circle is pivoted on 
that bottom stud by a little bit to the  right.  This makes the left-most 2 
studs excessively close to the inside  edge (slight perforation of the inner 
thin wall when drilling for  keenserts)

And it further reduces clearance on the right side by maybe  0.060".  This 
means there is a LOT of interference.  I

I  thought I had everything just barely clearing on the bench.  I had the  
hub bolted very snugly and no palpable or audible interference was  present. 
 Mechanics blue showed no touching

So I installed the  axle and trailing arm which is a pain in the neck 
because the axle limits  downward excursion.  I got it all hooked up and all 
torqued except the  250ft-lb 1.25" nut.   As I then turned the axle, I could 
just barely  hear and feel some interference!  Then it went away, but if I 
shoved hard  on the hub, and twisted I could gets one real grinding.   So I took 
 off the TA again and I need  to hit it with  a real die grinder  tomorrow. 
 

I only need to remove a little more metal, but I will  put some tape on the 
highest parts,:  the clip and, oddly, the edge  closest to the wheel.  The 
tape will make sure I have enough clearance,  more than just a thousandth.  
I don't want to remove much metal, but  I  going to shoot for about 0.010 (3 
thicknesses of masking  tape?)

I will need to be removing some metal from nearly 180 degrees to  clear the 
clip, but only at the 3:00 position is it a significant amount.  

-Tony

Sent from my iPhone

On Jan 11, 2015, at 6:19 PM,  Jack Mc <McGaheyRx at aol.com> wrote:

> Tony - 
> 
>  I am also installing GoodParts CV jointed axles on a IRS TR4A at the 
moment  and I found the same thing - I think there were 5 shims behind every 
bracket,  plus a couple of non-original smaller shims that must have been 
added at some  point for alignment. I have remounted the trailing arms with no 
shims (for  now) thinking I'd let the alignment shop sort out how many should 
be where,  but I have noticed the bump stop dish on the trailing arm on one 
side no  longer lines up with the bump stop on the body. 
> I haven't looked into  that any further because I am distracted by a more 
immediate problem: 
>  The outer CV joint boot and boot clip are making contact with the 
trailing arm  - I've never had this problem on the many TR6s I've done this to - 
so I  measured and found the tunnel in the TR4A trailing to be smaller than 
any of  the TR6 trailing arms I have on hand - hard to quantify how much 
since these  tunnels taper, but looks like the TR4a trailing arm tunnels are a 
little over  0.1 inch smaller in internal diameter. Have you encountered 
this? 
> As  an aside, there are quite a few subtle differences between the TR4a 
trailing  arms and TR6 trailing arms - and the quality of casting looks 
better with the  TR4 trailing arms - the quality of casting got better during the 
TR6 model  run, but these TR4 arms make early TR6 trailing arms look crude 
by comparison.  
> 
> Cheers,
> Jack  Mc
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