Rear Shocks

[MadRiver]

Howdy all. Just had the new tranny put in the TR-250, and man is he running great. However, on a recent drive, I started hearing a very slight clunking sound from the tail end every time I go over a bump. It clunks each time the car bounces, so if the car goes over a speedbump or a small ripple in the pavement, it will clunk as it goes over, and then as the tail end bumps up and down a couple of times, it will clunk each time. I jacked up the tail end, and everything looks tight, and I just had the u-joints checked out and everything lubed. I suspect the shocks -- I can't replicate the sound when I push on the tail end of the car when it's stationary, but it isn't very firm at all, and bounces a bit too much. Plus, I'm sure the shocks weren't serviced by any of the prior owners over the last twenty years.

Any thoughts on the foregoing, and any thoughts or tips on changing the rear shocks? I'm going to go with rebuilt lever shocks, rather than converting to tube.

Thanks as always!

 

[Brosky]

Are you sure that the noise isn't coming from the differential bushings? If you jacked the car, with the weight on the rear diff, you won't hear any noises.

 

[Guest]

[ QUOTE ]
I just had the u-joints checked out and everything lubed.

[/ QUOTE ]

Just curious (changed to tube shocks so I can't help you on the levers), just how did you lube your U-joints, especially the outer ones? Did you do it or have it done? Many shops will say they lubed the joints and not.



Bill

 

[DougF]

Make sure the shock mounting bolts aren't loose. They tend to back off a little and will make a clunking sound. While tightening the bolts, remove the filler screw on the top of the shock to check and fill the oil.
If those steps don't solve the problem, sometimes pulling the valve from the shock and replacing the o ring will revive it.
If you should have worn out shocks, you can either rebuild or look at a tubular conversion. I've converted and am happy with the upgrade. If the shock has a coating of oil on it and signs of oil leaking onto the frame, you are looking at new shocks.

 

[MadRiver]

Thanks for the suggestions, guys. I did have a shop do a lube job when they replaced the tranny, but I can't be sure.

As for the diff bushings, I'm not certain. I haven't been able to reproduce the sound when the car is on the ground and I give it some vigorous bounces. If it were the diff. bushings, would I be able to reproduce the sound easily?

Thanks as always!

 

[martx-5]

Check the differential mounts. They will clunk if they get loose or wear out. The shocks might also be loose. The bolts can come loose from the mount, or the rubber in the link to the A-Arm might be shot. Or it could be the rubber bushes where the link goes through the A-Arm.

Edit: Geez you guys are fast. I guess I type too slow. /ubbthreads/images/graemlins/hammer.gif

 

[John_Mc]

I'm sure you probably already checked this, but how is the rubber inside the ball joint of the shock absorber link? When I got my car, that rubber was shot, and eventually gave out leading to symptoms very similar to what you describe.

 

[Brosky]

Try to get the car on a lift where the rear axle assembly is hanging freely and the car is supported on the frame rails. You may have a better shot of inspecting the bushings and shock bolts, etc. in that condition. Make sure that the transmission mount bolts stayed tight as well.

Trust nothing, check everything twice.

 

[MadRiver]

[ QUOTE ]
I'm sure you probably already checked this, but how is the rubber inside the ball joint of the shock absorber link? When I got my car, that rubber was shot, and eventually gave out leading to symptoms very similar to what you describe.

[/ QUOTE ]

The shop actually replaced the rubber bumpers, as well as the rubber where the shocks link to the a-arms. The diff. mounts themselves look ok.

 

[Geo Hahn]

I'd certainly start by topping up the shock with oil... about 20W fork oil should be about right. That was all my TR3A (with similar symptoms) needed.

The fill plug is on the side near the top on a 4... on the top (I think) on a 6 -- don't know which on a 250.

 

[Tinster]

Holy Smokes!! A topic Tinster can actually address with
experienced knowledge.

First- Check the four bolts that hold the shocks to frame.
IMO- replace the outside bolts with new, longer bolts and
add locknuts. While you are replacing the bolts, check the fluid level in the shocks. Add 15W fork oil if low.
(see photo)

2. Now drive it and listen for the thunk when you shift from 1st to 2nd to 3rd. Got a thunk? Probably your right front
diff is broken.

3. No thunk on shifting? Pull a wheel and pull out a coil spring. Sometimes the top rubber mounting rings breaks or slides off.

4. Last resort on the suspension issues- replace the dreaded
trailing arms bushings!!

 

[Andrew Mace]

Tinster, I think you've nailed it, especially with your first point. I've experienced this in working on a friend's TR250, where even top-quality replacement shock bolts ultimately did not stay tight, which makes your suggestion of longer bolts and locknuts (i.e., nyloc) an excellent suggestion!

 

[Brosky]

Very good Tinster! Nice checklist. Sounds like you're well versed on those items. A lot more than me, but as mine gets older, my day will come.

 

[Tinster]

Here's a photo of a "crunching" coil spring.

 

[Tinster]

Here's the crunching coil spring

 

[MadRiver]

Finally had a chance to get Greenie on jacks and check out the rear shocks. I tested the bolts on the right rears shocks, and sure enough, one of them was slightly loose. I took the opportunity to replace the shock with a rebuilt unit, since I was back there anyway and the tail end always seemed to bounce more than it should. The entire operation took less than an hour from the time I got the tools out to the time everything was cleaned up and put away. Took Greenie for a nice long spin, and am pleased to announce that the offending noise from the tail end is gone! /ubbthreads/images/graemlins/grin.gif I'll check the left rear shock this weekend just to make sure it's behaving as well.

Thanks to everyone for your suggestions! /ubbthreads/images/graemlins/thumbsup.gif /ubbthreads/images/graemlins/england.gif

 

[Tomster]

I hate to state the obvious and I am not trying to be funny with the following:
Have you removed absolutly everything from your boot/trunk and taken it for a buzz?
Can you have someone stand near to or walk with the car as you go over a speed bump ? Maybe they will hear the sound and help to isolate the location.
Have you checked your entire exhaust system to see that it's not hopping or bumping?

 

[Camping57]

I had the same "clunking" sound in the back of my TR 3 and it turned out that I also had a loose shock bolt. I took the time to locktite all of the shock bolts and then really torque them down. Those short stubby 3/8 bolts don't like to stay tight very well under a shear load.

 

[MadRiver]

[ QUOTE ]
I hate to state the obvious and I am not trying to be funny with the following:
Have you removed absolutly everything from your boot/trunk and taken it for a buzz?
Can you have someone stand near to or walk with the car as you go over a speed bump ? Maybe they will hear the sound and help to isolate the location.
Have you checked your entire exhaust system to see that it's not hopping or bumping?

[/ QUOTE ]

Tomster: No worries stating the obvious! In fact, I think with car people, it never hurts to be reminded of the obvious -- we often get very wrapped up in the possible technical problems that we miss the simple things. I learned this in my teens thusly: As I've written before, my father is a professional restorer. Shows at Pebble Beach, all that stuff. One year, we're at a show with a 1936 AC (great grand-daddy of the Cobra, actually), and we can't get the thing to start. Crank, crank, crank, but it won't start. We check the carbs. We check the fuel pump. We check the plugs, wires, everything. Still won't fire up. As we toil, more and more car people wander over and start to offer suggestions. There are now at least five highly skilled mechanics standing around this thing, and we can't figure it out. Then, the owner of the inn where we were staying -- who is not a car guy at all -- wanders over, looks at the negative battery lead and says "Isn't that thing supposed to be connected to the battery?" The lead had shaken off. We put it back on, tightened the bolt, and the car fired up. The lesson: look for the simple stuff first! /ubbthreads/images/graemlins/grin.gif

Sooo, yes, I absolutely agree with your suggestion and you can never state the obvious too often! When I first heard the noise, everything came out of the trunk, I tightened the bolt holding the spare tire, and drove around a neighborhood with gentle speedbumps for about 1/2 hour to figure out where it was coming from.

The good news is that now that the bolts are good and snug, the noise is gone! Yay! /ubbthreads/images/graemlins/thumbsup.gif

 

[Andrew Mace]

[ QUOTE ]
The lesson: look for the simple stuff first! /ubbthreads/images/graemlins/grin.gif

[/ QUOTE ]AMEN!

Years ago, I went to look at an early Herald convertible advertised in the local paper. The seller was having some difficulty getting it to run right; naturally, I offered to help. After about 15 minutes of struggling with minor adjustments to the dual SUs, etc., etc., I finally stared at the plug wires...and realized that #2 and #3 had been swapped accidentally! Quick fix, and all was well.

I'm not sure which one of us was more embarrassed.... /ubbthreads/images/graemlins/blush.gif