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TR4/4A TR4 rear suspension


Freshman Member
Can anyone help me find a conversion kit bolt on not welded,to suit my TR4 any help would be most appreciated.


Great Pumpkin - R.I.P
More information might help; like what is it that you want to change and why.


Freshman Member
Hi Randall,ihave a very rough ride and a freind said it was because i dont have IRS,they suggested changing from leaver arm shox to upgrade to normal shox with a conversion kit!!


Jedi Knight
Hi there Jonty,
While I have not riden in a TR4A with the IRS, I did rebuild the rear suspension on my TR4 and must say I am quite pleased with the ride of my car. I picked up a set of new lever arm shocks off Ebay and a new set of leaf springs from The Roadster Factory along with new bushings. I went with stock bushings for the softer ride.

Others can hopefully comment on how much the IRS will improve the ride quality.

Andrew Mace

Staff member
Country flag
I never had either flavor of TR4, but I spent years with a TR3A and never felt the ride was all that bad. If that TR4 is overly bouncy, it's quite possible that going to all the trouble of converting to good tube shocks will help. It's equally likely that refilling the current lever shocks (which might simply be low on oil), or having them rebuilt or simply replacing them with new or rebuilt shocks will do the same!


Country flag
Are the suspension bushings AND rear damper shocks in top condition? When was the last time the shocks were rebuilt? Is the fluid topped off? Are they leaking?

Probably a good idea to make sure they are working properly before doing anything else Mate.


Great Pumpkin - R.I.P
There's nothing at all wrong with lever shocks; your friends are no doubt only familiar with the much softer ones fitted to cars with IRS. But the stock TR4 shocks will easily provide all the damping you need, if they are in good condition.

One way to test is to try to 'bounce' the car, by putting your weight rapidly on and off over each corner in turn. The suspension should not oscillate at all, only rise once and then immediately stop at it's normal height. If it rises a second time, there is a problem with the shocks (or links, etc.).

Usually a visual inspection will reveal bad bushings and so on; although you may need to disconnect the links temporarily to find if their joints are tight. The cylindrical end of each link is supposed to be bonded (not just a bushing) so the rubber has to deform as the suspension moves. Not unusual to find the bond broken.

Also check that the two bolts holding each shock to the frame are tight. They have a tendency to work loose, which can cause poor ride.

Most common cause of rough (as opposed to too bouncy) ride, IMO, is the leaf springs. Over time, they get rusty between the leaves and no longer work smoothly, which literally makes them act like a solid bar for small bumps (an effect known as stiction). Either new springs, or disassembling, cleaning and lubricating the old ones, will make a world of difference.

There are several types of tube shock conversion around; but they all suffer from a serious flaw. Because they must be located farther away from the frame mounting point, they put more force into the bracket, which will cause it to flex and eventually break. I don't recommend them.


Darth Vader
What Randall said is correct and I completely agree with what he recommends.


Luke Skywalker
Country flag
I'm lucky to own two TR4As, one with solid axle and one with IRS.

The IRS runs rougher than my solid axle.

I would not lean the slightest bit in the direction of a conversion kit or tube shocks.

I'd check the bushings, mountings, leaf spring operation, and lever shocks.

I'd also step aside and ask myself if it's the ride or the noise that is bothersome. Like Randall has indicated, I've actually had loose lever shocks maginify very minor issues.

Loose muffer fittings and other issues can also cause one to think the ride is terrible, when in reality it's the distractions from the ride causing a good part of the problem.

I'd say stick with your lever shocks, and strive to have the best riding TR4 around.
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