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TR4A Lever shocks

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Does anyone have any idea how long lever shocks (TR4A) may last before requiring rebuild or replacement? If they don't leak, can they be assumed to be ok? TR4A solid axle is a very stiff riding car and it is difficult to tell how much dampening the shocks provide. Many thanks for any comments.

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Hi Richard,

 

About four minutes on average! ;)

 

Realistically, I found they were never as long lasting as straight shock absorbers, which is why I upgraded to straight shocks using one of the kits (I don't remember which one). The other thing you need to consider is whether the lever arm shocks will be available at reasonable prices longer term. There are very few vehicles using them.

 

I would never assume they are OK. As with most modern shock absorbers, they rely on a damper moving through a viscous fluid. The fluid can become aerated causing variable response, The damper can become jammed, the various bypass valves can become clogged or jammed, the shock will alter completely if it is even slightly dented and so on.

 

Unless you have a powerful desire to keep this level of originality, I would buy the upgrade and go with Spax variable rate dampers. That way you can tune them to get the response best suited to your requirements.

 

TT

 

Does anyone have any idea how long lever shocks (TR4A) may last before requiring rebuild or replacement? If they don't leak, can they be assumed to be ok? TR4A solid axle is a very stiff riding car and it is difficult to tell how much dampening the shocks provide. Many thanks for any comments.

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Does anyone have any idea how long lever shocks (TR4A) may last before requiring rebuild or replacement? If they don't leak, can they be assumed to be ok? TR4A solid axle is a very stiff riding car and it is difficult to tell how much dampening the shocks provide. Many thanks for any comments.

The only way to tell their condition is take them off and see how much effort it takes to move them through their arc of movement. You will soon tell if they arent doing a lot!

TR 4a with the solid axle doesnt have the luxury of the availability of tube shock conversions. I have uprated lever arms on mine and I have found the repro rear springs to be too soft for my liking (only one type available and no uprated ones) so I have 4 extra spring clamps fitted to each rear spring to stiffen the whole lot up and with Spax adjustables up pretty hard on the front it now goes round corners on rails.

Stuart

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Hi Richard

 

We've got the solid rear axle set up with uprated lever arms, uprated springs (165lb leaf springs I think)? and the rear anti roll bar as per the Revington TR integrated road/rally package.

 

Absolutely superb. Just came first in class at the Ilkley rally with some quick test times (when I went the right way!).

 

Sideways drifting, full power on tarmac and rough ground, very balanced. You can see some photos on Tonylarge.net under rally and then the ILKLEY RUN icon. We're car 82 the red TR4.

 

Doesnt really show movement too well but on any corner you can just throw thye car in and it is so poised, little bit of oversteer, gives you bucket fulls of confidence and not a harsh suspension. Feels softer than standard in many ways.

 

Although a lot of forum members swear by tyres nearer the original spec. I wouldnt change the Vredestein 195/65/15 for anything. Probably helps with the suspension package.

 

Cheers

 

Darren

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Hi Richard

 

We've got the solid rear axle set up with uprated lever arms, uprated springs (165lb leaf springs I think)? and the rear anti roll bar as per the Revington TR integrated road/rally package.

 

Absolutely superb. Just came first in class at the Ilkley rally with some quick test times (when I went the right way!).

 

Sideways drifting, full power on tarmac and rough ground, very balanced. You can see some photos on Tonylarge.net under rally and then the ILKLEY RUN icon. We're car 82 the red TR4.

 

Doesnt really show movement too well but on any corner you can just throw thye car in and it is so poised, little bit of oversteer, gives you bucket fulls of confidence and not a harsh suspension. Feels softer than standard in many ways.

 

Although a lot of forum members swear by tyres nearer the original spec. I wouldnt change the Vredestein 195/65/15 for anything. Probably helps with the suspension package.

 

Cheers

 

Darren

 

Darren,

 

Thanks for the reply. I, too, have upgraded my 4A with new rear springs, poly bushings, and both front and rear stabilizer bars but I still feel a slight yaw to the left on rapid throttle reduction or power on upshifts. The yaw has been significantly reduced and the only thing left to change are the lever shocks. Mine are the original from the factory, circa 1966 and although they don't leak, it is difficult to tell what's going on inside. I get a pretty rough ride over undulating pavement and hence, I'm going to go ahead and install new shocks. This yaw or twitch has been a real mystery to all who have driven and worked on the car. Hopefully, new lever shocks will solve the issue.

 

Regards,

 

richard

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Darren,

 

Thanks for the reply. I, too, have upgraded my 4A with new rear springs, poly bushings, and both front and rear stabilizer bars but I still feel a slight yaw to the left on rapid throttle reduction or power on upshifts. The yaw has been significantly reduced and the only thing left to change are the lever shocks. Mine are the original from the factory, circa 1966 and although they don't leak, it is difficult to tell what's going on inside. I get a pretty rough ride over undulating pavement and hence, I'm going to go ahead and install new shocks. This yaw or twitch has been a real mystery to all who have driven and worked on the car. Hopefully, new lever shocks will solve the issue.

 

Regards,

 

richard

If your shocks are original then no wonder you are having problems as they probably went past there best quite a few years ago! :blink: A new pair of uprated ones will make a world of difference.

Stuart.

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On 5/1/2009 at 11:03 AM, Richard said:

 

Darren,

 

Thanks for the reply. I, too, have upgraded my 4A with new rear springs, poly bushings, and both front and rear stabilizer bars but I still feel a slight yaw to the left on rapid throttle reduction or power on upshifts. The yaw has been significantly reduced and the only thing left to change are the lever shocks. Mine are the original from the factory, circa 1966 and although they don't leak, it is difficult to tell what's going on inside. I get a pretty rough ride over undulating pavement and hence, I'm going to go ahead and install new shocks. This yaw or twitch has been a real mystery to all who have driven and worked on the car. Hopefully, new lever shocks will solve the issue.

 

Regards,

 

richard

Sorry to resurrect on an old thread, but my TR4A SRA exhibits quite a bit of yaw or torque steer, pulling to the right on acceleration and then shifting back to the left when I let off. I acquired this car only recently and the past history is a bit unknown. The previous owner was not the "mechanical" type.

I tightened the spring u-bolts but that made no difference. There is no discernible play in the spring shackles. On investigating the lever shock I found that the one on the right was nearly empty of fluid and topping it up helped a lot but did not eliminate the problem entirely.

If the original poster is still about (Richard) I'd like to hear if replacing the lever shocks cured the problem.  I am wondering if being very low on shock fluid for who knows how long has knackered the valving.

Edited by Andy303

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11 hours ago, Andy303 said:

 

Sorry to resurrect on an old thread, but my TR4A SRA exhibits quite a bit of yaw or torque steer, pulling to the right on acceleration and then shifting back to the left when I let off. I acquired this car only recently and the past history is a bit unknown. The previous owner was not the "mechanical" type.

I tightened the spring u-bolts but that made no difference. There is no discernible play in the spring shackles. On investigating the lever shock I found that the one on the right was nearly empty of fluid and topping it up helped a lot but did not eliminate the problem entirely.

If the original poster is still about (Richard) I'd like to hear if replacing the lever shocks cured the problem.  I am wondering if being very low on shock fluid for who knows how long has knackered the valving.

I would get your shocks rebuilt by  Stevson 

I would also replace the spring eye bushes and replace the rear shackle bushes with polybushes as well. I have a solid axle 4a and its very stable at high speed and can be thrown through bends with lots of confidence as I know where its going to go. I would also check your front shocks and bushes too.

Stuart.

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12 hours ago, Andy303 said:

 

Sorry to resurrect on an old thread, but my TR4A SRA exhibits quite a bit of yaw or torque steer, pulling to the right on acceleration and then shifting back to the left when I let off. I acquired this car only recently and the past history is a bit unknown. The previous owner was not the "mechanical" type.

 

This behaviour on my 4A ceased after I shimmed the rear suspension on both sides  to zero toe in.

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Thanks for the replies. I think rebuilt dampers are indeed indicated. Here in the States Apple Hydraulics offer uprated rebuilt units at a reasonable price:

https://www.applehydraulicsonline.com/collections/triumph/products/triumph-tr4a-tr250-tr6-rear-armstrong-lever-shock-absorber-yours-rebuilt

Regarding toe-in or toe-out, this Is not easily adjustable on a solid rear axle TR4, but I think that the weak shock definitely contributes a geometry change under acceleration. Kas Ksatner’s competition manual recommended the installation of some very sturdy torque or radius rods to control windup of the axle. Unmodified street cars don’t need these of course, but in studying the damper arrangement of the TR4 versus the solid axle TR4A there are some striking differences.  

On the TR4 the lever shock was mounted in front of the axle with the lever arm parallel with the leaf spring. This was a common setup for live axle cars and I think that arrangement acts as a radius rod to help keep the axle aligned and works well for street use.

On the TR4A Solid Rear Axle they adapted the IRS chassis to work with a live axle, modified the rear leaf spring design with more arc necessitating a spacer block, and more importantly, used the same damper and damper mount as the IRS system, with the damper located perpendicular to leaf spring. The damper is located behind the axle and the link is attached to the spacer block. The damper arm no longer works as a radius arm; instead I believe that in this arrangement the two dampers work together as a sort of Watts linkage to maintain axle alignment. However if either of the dampers is weak the axle geometry will change in undesirable ways. I think it is therefore vital that the TR4A SRA have matched dampers, and as Stuart suggests, to improve the shackle bushings. I think the Racetorations rear axle location kit may be the ticket: http://www.racetorations.co.uk/triumphs-c56/tr2-c3/tr2-chassis-suspension-and-steering-c76/racetorations-rear-axle-spring-location-kit-p241 that in

 

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1 hour ago, Andy303 said:

You cant use the essential part of that kit (the large location washers) on a solid axle car as the front spring eye is in a bracket from the chassis in a different way as opposed to off a pin out from the chassis.

My earlier reply is what you need to do.

Stuart.

Edited by stuart

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Stuart:

Many thanks for pointing that out, you saved me some needless expense.

Andy

 

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On 4/25/2009 at 11:20 PM, Richard said:

Does anyone have any idea how long lever shocks (TR4A) may last before requiring rebuild or replacement? 

Several decades!

Pete

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I had that "torque steer" effect on my TR3 many years ago, it was caused by the locating pip (bolt) on the leaf spring moving back & forth in the hole which is in the bracket below the  axle. The hole had become worn into a slot. each time I accelerated, the axle would slightly move on one side thus causing a change in direction !

Fixed with a bit of welding.

Bob.

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There is no reason why lever arm dampers should not last as long as telescopic dampers. Many cars have been fit with them in the past with litte problem. They also have the advantage that they can be topped up with oil. This was a common service practice back in the 50s and 60s.

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Stuart,

Rimmer Brothers list a tube shock conversion for “Model - TR4A Rigid Axle” (RW3077), but the kit listing says, 

“Not suitable for North American Spec TR4A vehicles (where damper is fitted at 90 degrees to the spring).”

Did US market live axle cars use different lever shocks than UK spec live axle cars?

Jim

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AFAIK there is indeed no tube shock conversion for the TR4A solid rear axle (SRA). All TR4As use the same Armstrong lever damper mounted exactly the same on the rear bridge piece, which does indeed put the unit 90 degrees to the leaf spring. The IRS set up uses a different shock link which bolts to straight into the semi-trailing arm and which lends itself to a fitting a telescopic damper. The SRA damper links are turned 90 degrees at the bottom, but otherwise are attached like all of the live rear axle cars.

BTW I would not use a telescopic damper in place of the stock Armstrong unit on the IRS cars, if I had one. The lever arm incorporates a stop that corresponds to a rubber shock bumper attached to the body so that when the suspension bottoms out the shock is absorbed by the body and not the damper mounting.

141464.jpg

s-l640.jpg

TRI-031_2.jpg

Edited by Andy303
add Moss schematic

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13 hours ago, Andy303 said:

AFAIK there is indeed no tube shock conversion for the TR4A solid rear axle (SRA). All TR4As use the same Armstrong lever damper mounted exactly the same on the rear bridge piece, which does indeed put the unit 90 degrees to the leaf spring. The IRS set up uses a different shock link which bolts to straight into the semi-trailing arm and which lends itself to a fitting a telescopic damper. The SRA damper links are turned 90 degrees at the bottom, but otherwise are attached like all of the live rear axle cars.

BTW I would not use a telescopic damper in place of the stock Armstrong unit on the IRS cars, if I had one. The lever arm incorporates a stop that corresponds to a rubber shock bumper attached to the body so that when the suspension bottoms out the shock is absorbed by the body and not the damper mounting.

141464.jpg

s-l640.jpg

TRI-031_2.jpg

What he said! Also there were no UK market live axle 4a they were N. American market only. Though there are quite a few back here now including mine that came from up state New York

Stuart.

Edited by stuart

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