shimmy

[qac]

just p/u a 1980 tr7 spider addition . prior to this car im aware that some, only some tr cars had a shimmy at 50/55 mph and it go away at 60 miles hr. front end problem perhaps wheel balance all checked ok. prior owner changed the steering column . again I read that some tr have this condition . help any input on this demon shimmy .
thanks qac ................jerry

[trickyx12000]

its a clever in built system by triumph... its to check your speedo is reading correct if it at 70 or 40 mph.. your clock is reading incorrect.
they always do!
someone will give you a fix on here but it will come back!
the tr I had in 86 did it and the tr I have now dose it

[Hasbeen]

Do you have after market wheels?

If so are they a good tight fit on the hub?

The 7 has a hub centric wheel system. If the center of the wheel does not fit tightly on the hub, & you have typically tubular wheel nuts, no amount of OFF CAR balancing will stop your shimmy.

Having everything perfect, like wheels true, tyres round & free of side wall lumps etc will help, but only help.

With my 7s I could have everything perfect, & the steering wheel rock study at any speed, but remove & refit the wheel, even replacing the wheel on the same studs, & using the nuts on the same studs would result in a shimmy.

Only on car balancing would fix it, & try finding someone who still does that.

With the 8, stud centric wheels, with conical nuts have been fitted, replacing the hub centric system. I can change wheels around change nuts etc, just like a real normal car, without problems.

But who wants a car like that, except me of course.

Hasbeen

[nick]

There is more information than you can use on this topic on this forum. Try the search function and you can spend the next few hours learning everything there is to know about TR7 shimmy

[img][IMG]http://i615.photobucket.com/albums/tt234/nickmi/TR7%201975/Yellow.jpg[/img]
nick
'79 TR7 DHC
'76 TR7 FHC

[KFSullivan]

I'm having the exact problem on my '80 DHC. It's a very slight shimmy from 55-60 mph. Above or below this speed range it goes away.

I put the car on a hoist and checked out the front end and couldn't see anything obviously wrong. I guess I too will have to search the forum for past discussions.

1980 DHC Pagaent Blue

[FI Spyder]

While the mechanicals have to be right the biggest thing is the roundness and integrity of the tires, balancing can only do so much to fix a "bad" tire. This tire problem is not always visually apparent. I had the problem (violent shimmy at 55 mph that straightened out after 65) when I bought my car, new Kumho's fixed the problem. I've taken the wheels off several times, did a five wheel rotation and 16,000 miles later after, 4 emergency four wheel lock ups, the steering is still silky smooth.

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[kstrutt1]

They are very sensitive to shimmy, as said getting good quality tyres spot on helps, other items I have found which helped were poly bushes on the inboard end of the control arms and replacing the wheel bearings (even though there was no apparant Issue).

Flat spots on the tyres if they have been parked for a long time can also cause it, a high speed run to warm them up often cures this.

[FI Spyder]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by kstrutt1</i>

other items I have found which helped were poly bushes on the inboard end of the control arms and replacing the wheel bearings (even though there was no apparant Issue).
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Good point. Additional things I did between when I had it and when it disappeared forever was: replace ball joints and tie rod ends (They looked good but I had everything out and parts in stock so replaced them anyway.) I put hard black poly bushings on the front end. Did my own wheel alignment with string. New shocks and regular springs. Grease the rack. Replaced brake caliper piston seals as a matter of course. Now none of these caused the problem I believe, except the hard poly may have given it a bit of stability.

When you get to this stage, do it all, do it right.



- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[Hasbeen]

Obviously any slop in your front suspension will allow any small fault to become magnified by the time it gets to you at the steering wheel. One test is to hold the wheel rock hard, not allowing it to shimmy. If the whole car then shakes it indicates something like a bent road wheel, faulty tyre or shot wheel bearings, rather than balance.

Replacing any worn suspension parts will reduce the magnitude of the shimmy, as the extra friction between the road wheels & the steering wheel will absorb some & perhaps all of it.

This is like the steering dampener fitted to many cars when rack & pinion systems were first introduced. There are some old posts giving details of a couple fitted by some owners. The dampener from the 60s VW beetle is one that's suitable.

Modern cars with their power steering systems damp out all but a huge unbalance, which has allowed the industry to go to all off car balancing, much to our detriment. However if you have a shimmy at just under 100Km/H [60MPH], it is due to unbalance in your hub/wheel/disc rotor assembly.

This is why it is a rare occurrence in 7s with the original steel wheels, located by the studs, rather than the hub, or with the original alloy wheels, which locate properly on the hub.

If you have a high magnitude, lower frequency shimmy at around 75/80 Km/H just under 50MPH this is caused by wheel alignment, excessive toe in/out or castor is usually the culprit

Hasbeen

[qac]

thanks all to the input . I will have to go through all items as suggested. the car is a 1980 spider in supper condition yes even the original seats , (I might sell them )the 4 cyl is gone and its powered by a 4.3L 6 cyl Chev . looks like a nice job. the past owner knows nothing but did have a new steering rack installed ,I see new ball joints (2) like new tires , new struts ,factory alloy tr8 type rims and the steering tr8 wheel. . now what im doing??? well I have a 1980 tr7 4 cyl engine. it was sent to the usa after being rebuilt in the B/L FACTORY. YES THE FACTORY ,it has a gold label on it saying rebuilt in B/L .. IM thinking of converting it back to its original 4 cyl. I have lots of parts but I will need the clutch set up , it now has a th300 auto trans. I think this spider be better back to its history . anyway I just picked it up, so im still going through it .. any one want (so far)a good running 4.3 L Chev engine ???. again its in great shape in and out. thanks to all I be back again and what im going to do ..
this format is the best because of the people /owners who support it .. jerry qac

[trekcarbonboy]

I have the shimmy also and everything has been replaced except wheels and tires. I recently noticed the steering column making some rubbing noises on the firewall bushing (poly) so I sprayed it with a little lube. Now it didn't make the shimmy go away but it drastically reduced the severity. Apparently the dry bushing was just amplifying the shimmy.

Craig '75 2.0 FHC

[FI Spyder]

Unusual to see a Chevy V6 in as it is much larger physically than a same displacement Buick V-6. Be aware some Camaro's used the Buick V-6 and could be mistaken for a Chevy engine if they didn't know.

The TR8 steering wheel was standard on the Spider.

If you want an original car the Spider is the one to do it on.

Seems like a lot of work going back. I would keep it as is and buy another original Spider. We all need at least two.[:p]

Then you have one to drag the other cars at the lights and the original where you say to the draggers, "I've got a bowl of gold fish on the front seat" (American Motors ad from the 70's)[:p].


- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT