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Is this is bad as I think?

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2033husky

Freshman Member
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I was backing out of driveway today & the car started to make thumping noise & didn't want to back up. It seems to ga forward ok but when I put it in reverse it makes a clumking thumping type of noise. It feels kind of like something is binding up. It had been driving great until this. To make matters worse I'm having my garage enlarged in the next week or so & have nowhere to work on it. What do you think. I really don't want to say what I think it maybe. 1971 tr6 with overdrive
Thanks
Jeff
 
Ah...Transmission? I would put money on the infamous cluster gear rear needle bearing. Reverse puts the most strain on that part of the transmission. I have actually driven my car (had to) with this problem. Would go forward, made a heck of a noise in reverse. A little later, it did it in first.

However, before going crazy, check the transmission mounts. Loose or broken ones can do the same thing.
 
Check the driveshaft and u-joints as well. Then, check the rear axle joints. Differential mounts too, before digging into transmission.

Not that Ray didn't hit it on the head, but let's try all of the other easy fixes first. Maybe you'll be lucky.
 
I was thinking transmisiion also but will check the easy stuff first. It has been a long time since I pulled a tr6 transmission & I hope its a bit longer. Where is the correct place to put jack stands under the rear of the car. Every time I do this I feel or know I am bending the car. Is this avoidable? I usually lift the car with a floor jack under the differential & put the stands in front of the trailing arms. Is the correct?
Thanks
Jeff
 
By any chance would your OD be engaged?
It can not handle reverse and makes noises like it is coming apart - because it is.
 
Jeff,

That spot is OK. Just make sure you are under the frame and not the arm.
 
Was your over drive engaged when you were driving in reverse, and do you have the A type overdrive. If so you may have caused damage to your overdrive and if your overdrive does not work anymore continuing to drive your car is causing all the broken parts to circulate through the oil that is shared with the rest of the transmission, don't ask me how I know. I am hoping this is not the case.
 
I'm not sure how it could happen in this case, but isn't there a failure mode where the overdrive roller clutch gets stuck? When this happens, the car cannot be reversed as the rollers bind up rather than slip. I can't describe how it happens, just that I've read many cautions about it.

I think it's a problem if the pressure is not dumped from the OD accumulator, like if lever that the solenoid moves got stuck. But wouldn't the pressure just bleed off naturally after a few minutes?
Jeff - can you physically check the operation of the OD solenoid and the lever it moves?

Jeff Fetner
'74 TR6 CF13816U
 
Jeff. all the full frame TRs flex when you lift them up. once you jack up one end the doors don't want to work right. This is normal. They did it when they were new. you won't hurt anything, just be careful of the door openings.
 
I thought that the J type OD would not engage in any gears except for third and fourth, as sort of a failsafe mechanism? Hence the solenoid and relay.

I'm not sure, so I'm asking. Well, I am sure that mine won't work in first or second, but I don't think that I've ever accidentally backed up with the OD engaged.

You can bet that I'll try not to now!!
 
How dumb am I? Yes the od was engaged. I flipped the lever & everything seems to be fine so far. Od seems to still work & backs up without binding & popping. Hopefully no damage to show up later as a result of this. Thanks a lot for the help.
Jeff
 
There's a 'dog clutch' or 'one way' clutch inside the OD that works with the planetary gears..it's the culprit that won't allow the car to reverse when in OD. An "A"-type is much more fragile than a "J"-type. The J-type will allow some slippage if you back-up when in OD which cuts down on broken parts. The A-type is not so forgiving.I'm not sure when Triumph installed an OD lock-out on their later cars...or if they ever DID install one. Let's hope you didn't break anything!
 
Glad the OD isn't still stuck in reverse, but it shouldn't engage in reverse regardless of the switch position. I'd make sure the solenoid isn't sticking in the "on" (up) position (electrically or physically).

Unfortunately the failsafe mechanism is the electrical circuit that provides a ground for the relay which powers the OD solenoid. It should give a ground only when 2, 3, or 4th gear is engaged. It's possible that the column switch (or some other short) is grounding it out. This would bypass the normal path and allow erratic (or constant) OD engagement. It's been awhile since I drove my OD TR4 though.

Maybe after you drive it some (forwards!) you could check the oil and mag plug for metal. The cluster gear rear needle bearing Ray referred to does have a habit of making metal.

Jeff
74 TR6 CF13816U
 
Check your OD switch. I've heard that a loose switch can cause a ground which will activate the OD and cause problems.
 
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