TR6 Clunking in rear [continued]

[pdplot]

With a friend's help, we checked out the rear suspension and differential mounts to find what was making the noise when hitting bumps. Here is our findings:
1. No cracked shock mount on tube shock conversion. Frame was fine.
2. Differential mounts looked fine.
3. Shock bolts tight.
4. Missing outer rubber boots on both sides.
5. Bottom part of shock - part that goes into mount and is bolted up - was bent almost 1/2 inch. We bent it back with a bar and socket but it would not straighten completely. After reassembly, he bounced the bumper while I felt around for the source of the noise - still present but not as loud. It seemed to be coming from that bent shock. We believe the piston was somehow cocked in the barrel of the shock and that was causing the noise. After checking the local auto parts stores - they had none in stock, we left the defective shock in place and I drove home.

Question 1. Has this happened to anyone before with a tube shock conversion? It may be that the different angle between the swing arm radius and the shock caused the shock part to bend.
Question 2. Did the installation of the Goodparts spacers aggravate the problem or cause it? The noise started after the spacers were installed.
Question 3. Perhaps the mounting bracket should be bent or realigned so that the angles coincide more closely.
Question 4. My friend has ordered the in-coil shock kit to replace his tube shock conversion. This would seem to cure the problem completely.
Question 5. If the problem was not a defective shock but was caused by the conversion, would it not be a waste of money and time to install a new KYB 343138 shock that would be subject to the same stresses? What would you do?
Any ideas or thoughts would be welcome for sure. Thanks.

 

[M_Pied_Lourd]

What type of tube shock conversion do you have? There are a couple of different types on the market.

Cheers
Tush

 

[pdplot]

TRF with KYB 343138 shocks. I believe the mount uses existing holes.

 

[M_Pied_Lourd]

Ok. I had the same conversion on my car.

I had no issues with the shocks bending. I was using the kyb shocks as well.

I was running good parts springs with good parts spacers as well.

I removed my conversion and went back to lever shocks with a heavier oil after I had a frame weld break that I believe was attributed to the use of the conversion without an angular brace. I would highly recommend that you install this brace if you continue with the conversion.

Cheers
Tush

 

[Tybalt]

I'm not a big fan of most of the tube shock/damper conversions that I've seen for the rear of the IRS Triumphs. They look like they either dump loads into areas that shouldn't have loads dumped into them such as the rear wheel well sheet metal or that they put increased torsional loads into the damper mounts on the frame where they bolt up. I think that you are better off running the lever dampers (either stock or uprated) than those types of tube conversions. The Revington conversion (what it sounds like your friend may have ordered) is a different story, but it's not just a bolt up affair. It requires that gussets and a top mount/reaction plate for the damper be welded to the upper rear spring pan along with modifications to the trailing arms for the lower mount brackets and the addition of an access hole for the damper adjustment screw.

I posted some stuff about my experience with the Revington conversion on pages 3 & 4 of the thread linked below:

https://www.britishcarforum.com/bcf/showthread.php?101497-TR6-aftermarket-rear-shocks/page3

Something else I probably should have mentioned related to "pulling" the hole for the damper adjustment access, don't use a high dollar carbide bit if you elect to "pull" the hole in a similar manner. Carbides while they last seeming forever for straight forward drilling are extremely brittle and "pulling" the hole like that will put enough of a side load on them that you'll snap it off in a heartbeat. I wouldn't even recommend using a HSS cobalt (high speed steel with some cobalt tossed into the mix) as while no where near as brittle as a carbide bit is still rather stiff and brittle. Just use your plain old everyday HSS cheapie bit. They are more flexible which gives you some breathing room for side loading it and if you do break, no big deal, those things are cheap, they practically give those things away!

 

[DanB]

Did you check the studs where the differential itself actually bolts to the frame? That is the weak point in the IRS.

 

[pdplot]

OK. Problem solved. I bought a new shock KYB 343138 for $17.92 plus $9 shipping from Rock Auto. It arrived in 3 days as promised. We had some problems removing the half shaft (or rather he did - I watched) - had to undo the u-joint- but when the new shock went on - voila. No more clunking. He also removed one of the two spring spacers hoping that would take some load off the shock and avoid bending the piston. We shall see.