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Strange vibs

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Strange vibs
#1
  This topic is about my 1981 Triumph TR8
POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
This is a puzzler to me. First off i have not had my car on a lift so have not actually physically looked for anything amiss. My'81 factory TR8 has developed a vibration on neutral throttle only. Under heavy load or the slightest of load, no vibration. Coasting down hill against engine over-run, even lightly, no vibration. That fine point where there is neither engine working nor engine holding back is where the vibration comes on. Actually, in neutral or with clutch disengaged and revs at idle while letting gravity do it's thing is the conditions for vibration. Engine revs have nothing to do with it, likewise it is not a tire flat-spot or balance issue. I'm kind of thinking driveshaft?

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Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, Oregon, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1467713 by POW I'm kind of thinking driveshaft?

Sounds like.

Is it an original shaft, with the CV joint rather than U-joints? There are very few of those left alive any more. And they are not rebuildable. They tended to die prematurely as they were especially sensitive to dirt, and the rumor is the CV joints were not held to the necessary tolerances for smooth operation. Don't know if that last point is true, but it seems that most TR8s are no longer running the stock driveshaft.

The factory original installed them with the CV joint at the front, and a u-joint at the rear. Later they installed them the other way around to reduce complaints about vibration.

My car came already converted to a conventional drive shaft. I rebuilt it as a matter of course and it is back in the car. Thought about going back to an original driveshaft, but gave up on it as the installed one is doing just fine.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
In reply to # 1467756 by Darth V8R
In reply to # 1467713 by POW
I'm kind of thinking driveshaft?

Sounds like.
Vance


Thank's, I'll check this out. It is the original shaft and is installed with the CV joint at the front. I'm guessing it's possible to tell if the CV is bad by grabbing the shaft and looking for looseness. What's involved with a U-joint conversion?

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Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, Oregon, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1467806 by POW
In reply to # 1467756 by Darth V8R
In reply to # 1467713 by POW
I'm kind of thinking driveshaft?

Sounds like.
Vance


Thank's, I'll check this out. It is the original shaft and is installed with the CV joint at the front. I'm guessing it's possible to tell if the CV is bad by grabbing the shaft and looking for looseness. What's involved with a U-joint conversion?

Correct. Check both ends, as u-joints can fail too, although that is usually not what goes wrong on our wedges.

As to doing a conversion, find a drive shaft shop in your area, and take the car to them. They should fabricate one for you and install it for about $300.

I have not tried to see if anyone is making them for a do it yourself install. A web search is certainly worth a shot.

I suppose you could also try the factory solution of flipping the driveshaft and reinstalling it. It costs you nothing but a few minutes work.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

nick Avatar
nick nick m
Bend, OR, USA   USA
Any maintenace done prior to the start of the vibration?



nick

POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
In reply to # 1467993 by nick Any maintenace done prior to the start of the vibration?

No, not really. It came on gradually and is getting noticeably worse. Coasting with neutral throttle is not a condition that's used much. Usually for just a couple of seconds at a time in normal back-road driving. It would show up more with more highway driving. It's a rumble kind of feeling throughout the car and for sure it's something underneath. At first I was thinking tranny mount but I fear it is the driveshaft.

@ Darth V8R: Just realized My car has CV joints on both ends, no u-joint.

darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
Both TSI and The Wedge Shop sell u-joint drive shafts. I believe both require modification of the diff input flange, as apparently the bolt pattern isn't anything used anymore.



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

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POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
In reply to # 1468080 by darrellwalker Both TSI and The Wedge Shop sell u-joint drive shafts. I believe both require modification of the diff input flange, as apparently the bolt pattern isn't anything used anymore.

Actually I checked both Vicky B's and Rimmer Bros. Both have original CV type offered at $331 including ship from Victoria and $209 including shipping from Rimmer's. That's probably the most economical way to go. If the original lasted 36 yr's and 70 some thousand miles a replacement ought to outlive me. Maybe they're built better? Or only slightly worse! winking smiley

POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
I like to follow up on threads I've started. Seem's like the right thing to do is to let others who have helped know if their input was valid as well as valued. The vibration got worse so when RimmerBros had their 15% off sale on Triumph stuff I ordered a stock type new driveshaft. CV joints on both ends, fit perfectly, vibration gone. Just about $200.00 including shipment from England. I ordered it last Friday, 9/29 and it came to my door Wednesday 10/4. WOW! The old one had an obviously bad rear joint and to make matters worse the differential flange was loose. The flange nut could have literally been removed with a pair of needle nose pliers. LOCTITE® on the nut and a full 120 ft lb and all is now copacetic. Thanks, Pete

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