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Thread: Rear shock mounting plate

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    Senior Member mt10flyer's Avatar
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    Rear shock mounting plate

    I have had a rear-end clunk (on the car) which I now believe is caused by the holes on the rear shock mounting plate having become worn over time. This allows the entire shock and mounting bolts to move with respect to the plate. The clunk is the bolts wearing the holes on the mounting plate even larger (I think). I was going to try acres sleeves as a solution.

    https://avstop.com/ac/apgeneral/repa...agedholes.html

    Seem reasonable?
    David
    My hovercraft is full of eels.
    1959 TR3 SN42940

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    Great Pumpkin TR3driver's Avatar
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    Re: Rear shock mounting plate

    Seems like that would work OK for the shock; but not the relatively thin mount.

    After looking them over (and having the same trouble myself), I've come to the conclusion that the shocks cannot be located only by the fit of the bolts in the respective holes; and must be clamped tightly enough to be held from moving at all by friction. I believe there was always some side clearance between the bolts and holes (otherwise the bolts would have had ground shanks and be very hard to install, like dowel pins). If the shock is allowed to move through that small distance, it will eventually wear the bolt and so on. So it must be clamped firmly. Using "Stover" nuts (aka deformed thread conical top) seems to help a lot. I also use Grade 8 bolts and torque to more like 45 ftlb than the factory-recommended 30.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Senior Member mt10flyer's Avatar
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    Re: Rear shock mounting plate

    Stover nuts. Great idea. I'll try that first. Thanks.
    My hovercraft is full of eels.
    1959 TR3 SN42940

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    Jedi Knight TRMark's Avatar
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    Re: Rear shock mounting plate

    Had the same problem years ago, the shock mounts were very badly warn on my tr4. I ended up welding around the edge of the mounting hole and then resizing with a die grinder to zero clearance for the bolt. I clamped a piece of copper plate to the back side of the hole to keep the weld more towards the front (hope that makes sense). You will still have to grind the weld smooth on the surface. I used a socket (Allen) head bolt, tight fitting thick washer and a steel locking nut, not a nylock. The tight fitting washer was ground a bit on the edge to fit tightly to the shock casting. I used a socket bolt because a regular bolt was to close to the shock casting to fit a drive socket. Still tighten the buggers up every spring along with my regular maintenance. I can't remember for sure, but if the bolt fit loose in the shock body I may have used a metric for an incremental size.
    ex spec5 Mark

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    Great Pumpkin TR3driver's Avatar
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    Re: Rear shock mounting plate

    Quote Originally Posted by TRMark View Post
    tight fitting thick washer
    Oh yeah, forgot to mention that. Ordinary SAE flat washers won't fit, the shock body is too close to the bore for the bolt. In the past, I've ground down the outside edge of a 3/8" washer so it will fit into the space. This time around, though, I opened up the center hole of some 5/16 "setup" washers (which are hardened, extra-thick washers normally used for holding objects to be machined) so they fit snugly over the 3/8" bolts. The outside diameter was a perfect fit against the shock body. The washers may not be essential, but I could see where the aluminum shock body was deforming under the edge of the nut, which could allow the joint to loosen even with the nut locked to the bolt.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Jedi Warrior 6TTR3A's Avatar
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    Re: Rear shock mounting plate

    I also suffered with the "clunks" in my 3A. Passenger side, rear. I attacked the shock with Stover nuts (didn't know they had a name) and "TORX" head bolts. No help. Hard to re-create a clunk while up on blocks in the garage, but I gave it a try. AND FOUND IT !!! (see photo) The rear apron assembly has a corner piece just behind the spring eye to accommodate a frame mounting bolt. It had ruptured (probably rust) but I never noticed it during my frame off some 20 years ago. The bright area around the corner area is several coats of paint after my friend TIG welded it back together.
    Frank
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    Yoda Geo Hahn's Avatar
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    Re: Rear shock mounting plate

    FWIW - I'm using Stover nuts and allen-head bolts (possibly called cap screws) as that let's me tighten the bolts more & more easily.

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    Great Pumpkin TR3driver's Avatar
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    Re: Rear shock mounting plate

    Interesting. I wonder if that area changed at TS60,000. I don't recall there being anything that close to the spring eye. And since I just changed the shackle on the driver's side last week, I probably would have noticed.

    I'm also somewhat curious how people are tightening allen-head bolts (aka socket head cap screws), as on my car there is very little clearance between the head of the front mounting bolt and the body. No way to change the bolt without either removing the body or cutting a hole in it. Do the later bodies perhaps have a plug to allow access to that bolt?

    It's a little tricky to reach in there with an open-end wrench, but not enough so to make me want to take the body loose or cut holes!
    (Come to think of it, I reached for a tappet wrench last time, it might be harder with a shorter wrench.)
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Jedi Warrior 6TTR3A's Avatar
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    Re: Rear shock mounting plate

    Randall, By "just behind" I meant about 7 inches. Also, I guess I need to take a course in "tool & hardware identification" I didn't know that my thin wall open end wrenches (3/16") were considered tappet wrenches & deformed thread nuts were called Stover.
    Frank

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    Re: Rear shock mounting plate

    Quote Originally Posted by TR3driver View Post
    ...I'm also somewhat curious how people are tightening allen-head bolts (aka socket head cap screws), as on my car there is very little clearance between the head of the front mounting bolt and the body. No way to change the bolt without either removing the body or cutting a hole in it. Do the later bodies perhaps have a plug to allow access to that bolt?
    Mine (TS47905) has an access hole for the forward mounting bolt, but... the body is off center about a 1/4" so I can sneak a wrench in on the passenger side but on the driver's side the access hole would be needed if it was lined up with the nut. But it's not -- the hole is about 3/8" inch too far forward to be of use there. So, in fact, I only have allen head bolts on 3 out of 4 positions, for the other I am stuck with the old bolt until I figure something out.

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    Great Pumpkin TR3driver's Avatar
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    Re: Rear shock mounting plate

    I think you can be forgiven for not knowing what a tappet wrench is, Frank. I've never actually adjusted a tappet with one, it's just something that comes in handy from time to time. In addition to being thinner (3/16 instead of 1/4), they are quite a bit longer than the usual open-end wrench. I measured just for fun, and my 1/2-9/16 tappet wrench is almost 10" tip to tip, while the same size open end is only 6" tip to tip.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Re: Rear shock mounting plate

    Quote Originally Posted by TR3driver View Post
    I think you can be forgiven for not knowing what a tappet wrench is, Frank. .
    Yeah, even I know what a tappet wrench is, it's the wrench you tap on things with when you can't find your hammer.

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    Jedi Knight mgedit's Avatar
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    Re: Rear shock mounting plate

    Interesting thread. Waiting for my rebuilt distributor from Jeff at Advanced Distributors, but my next job was to find why I was getting a clunk at rear when I hit a bump. Seems to be from right rear. Sounds like shock mount might be possible area to check. Shocks currently mounted with nylocs I believe. So at minimum it sounds like those should be changed to these stover nuts (new to me those). Anything else that I might check to address clunk? Cheers, Mike
    Webmaster Ottawa Valley Triumph Club (www.ovtc.net)
    1956 TR3 - TS11537 (www.triumphowners.com/to-car/tr3-9/)

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    Jedi Knight mgedit's Avatar
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    Re: Rear shock mounting plate

    While looking up information on Stover nuts found this link. Looks like might be useful for shock mounting. Not sure of cost or availability or whether enough room to use. Anyone familiar with these? Might they work? Cheers, Mike

    https://youtu.be/mgwmuZuJ02I
    Webmaster Ottawa Valley Triumph Club (www.ovtc.net)
    1956 TR3 - TS11537 (www.triumphowners.com/to-car/tr3-9/)

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    Great Pumpkin TR3driver's Avatar
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    Re: Rear shock mounting plate

    They might, but I don't believe that video at all. They had to have not been installing them tight to begin with. The whole point of proper bolted joint design is that you need enough compression (aka preload) to prevent movement under any conditions that will be seen. That little drill motor just can't be producing that much vibration, to stretch that big a bolt enough to let the nut work loose. I smell a marketing gimmick.

    No doubt there are cheaper sources; but I just bought a box of 100 nuts (likely a lifetime supply), currently $15 from MMC https://www.mcmaster.com/?m=true#92501a430/=rtmusp I originally bought them for the driveshaft flanges (which always seemed to work loose on my previous TR3A, probably because the driveshaft was out of balance), but discovered they work well on shocks too.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Re: Rear shock mounting plate

    Hi all. Very interesting topic. But as I read it I find I have a more fundamental question. Which way do the shock mounting bolts fit? I have a 1957 TR3 and a 1959 TR3A, and the direction of the mounting bolts is different in each car. On one car the mounting bolts face towards the inside of the car - thru shock, thru mounting plate, with nut on inside of car against plate. On the other car the mounting bolts face outwards - thru mounting plate, then shock, with nut against shock body. Which direction is correct - or does it matter? Chuck

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    Senior Member mt10flyer's Avatar
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    Re: Rear shock mounting plate

    On mine (1959 TR3) the bolt is on the inside and the nuts on the outside. I doubt the bolts have ever been removed. There is an access hole to the passenger compartment which does not align with the top bolt (as I remember). No way to remove the bolt without a hack saw, which will be tons of fun. Upon replacement, with high strength nuts and bolts (and likely the Nord-Lock washers) the nuts will be on the inside.
    My hovercraft is full of eels.
    1959 TR3 SN42940

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    Great Pumpkin TR3driver's Avatar
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    Re: Rear shock mounting plate

    I believe the factory installation was with the bolt heads on the inside and the nuts against the shocks. Installing a nut into that narrow gap between the shock mount and the body would be extremely frustrating; much more difficult IMO than sticking a wrench in there blind to grab the bolt head.

    UNTITLED.JPG
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Jedi Hopeful
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    Re: Rear shock mounting plate

    I have a related question about the horizontal mounting plate under the spring where the shock lever is attached. While under the car adjusting the end float I thought I might just check the 4 nyloc nuts securing the U-bolts to the plate. They weren't really "that" tight so I thought it best to see if there was a torque spec for them. Sure enough, the nuts on the "clip" (U-bolt) securing the "road spring to rear axle" take 28-30 lb/ft.

    My question has to do with the best technique for torquing these nuts. Given the architecture of the U-bolt it seems that it might be a bit tricky to get both sides snugged down evenly without putting undue stress on the "U" on the top. Any suggestions on a good approach to tightening these nuts evenly to the correct torque?

    Rick...

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    Great Pumpkin TR3driver's Avatar
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    Re: Rear shock mounting plate

    Quote Originally Posted by RC64 View Post
    My question has to do with the best technique for torquing these nuts. Given the architecture of the U-bolt it seems that it might be a bit tricky to get both sides snugged down evenly without putting undue stress on the "U" on the top. Any suggestions on a good approach to tightening these nuts evenly to the correct torque?
    .
    I just run them up in stages, working corner to corner and keeping the plate more or less flat to the spring. Don't even use a torque wrench, just guess at it. No problems so far.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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