TR4/4A tr4a irs clunking rear end on fast acceleration

[Richard_Brown]

First time for this car to really be on the road for over 15 years, most everything has been rebuilt but I am not sure of the rear end, I hear the rear splined axels can bind if not kept lubricated with grease .
Anyone have any other ideas?
It only happens from very slow speed and a quick take off when the rear end squats down a bit.

 

[mallard]

It could be any number of problems, Differential mounts are broke, diff mounting tabs are broke, u joints,a arm bushings, differential mount bushings, dry splines, loose shocks, rusted and weak frame, loose bolts, shock links, It's time to jack up the car and take a look. Are you a member of the local Triumph club? You should be able to get lost of help from them. I'm sure somebody will chime in with a few more things I missed. Just this weekend I was trying to solve a similar problem. I removed the axles, and a arms and found no problems. I need to road test the car to see if anything has changed, next weekend.

 

[hondo402000]

thats what they call the TR Twitch, when the splines lock up on a hard acceleration, especially when you go around a corner, then you let off the gas, the splines unlock and the back end shifts sideways, there could be a noise associated with it.

Hondo

 

[Richard_Brown]

lol@twitch I have some lithium waterproof grease, I will get some going.

 

[Adrio]

I had that happen on my TR4A IRS and it stumped me for a while. Turned out to be the mounitng bolts for the lever shocks. Just tightened them up and the problem was solved. The thing that made it hard to figure out is that when the car is up in the air the arm of the lever shock is against the stop and that allows the road spring to hold everything tight. So on block in the air nothing "seems" loose when in fact it is (at least on my car it was).

 

[rlich8]

Richard,

I feel your pain. I am still chasing clunks in the rear end of my TR4A IRS. Why Triumph chose to put an IRS system on such a weak, cheaply built car is beyond me. The solid axle version is much preferred. Nonetheless, I love my 4A and am choosing to R&R everything necessary until it's perfect.

Lots and lots of stuff to check. The obvious ones first:

-Differential mounts (check for cracks or stress - best way to do this is with the differential OUT)
-Differential mount bushings
-U-Joints (most common is input to the differential but check ALL, there are 6 - yikes!)
-Slip yokes/slip joints/half shafts
-Wire wheel splines

The less obvious ones:
-Semi-trailing arm mount bolts
-Semi-trailing arm bushings
-Shock mounting bolts
-Rear wheel hubs
-Ring & pinion inside differential (this one is a real PITA to replace if it's bad)
-Shock link

The cars were clunking after a couple of years of use. It's not gotten any better over time.

Best of luck as this could be a gremlin.

Royal

 

[glemon]

I was getting the same thing, a real head scratcher as I has had it all apart, replaced all u-joints and bushings, checked all mounting poiints and brackets.

I was afraid it was the differential or the diff mounts cracked after install, but I have ust checked the sway bar mount, my addco bar mounts to the in the hole under the spring on the trailing arm, they supply large washers to sandwich around the holes. The top washer is really not big enough, and I found that it had become skewed and slipped through the hole, allowing the mount to move, I got a pair of slightly larger washers, and at least on the the test drive this morning no more clunk.

If you don't have a rear bar this couldn't be your problem, but just another example of check everything as there are lots of possibilities back there.

 

[poolboy]

I am still chasing clunks in the rear end of my TR4A IRS. Why Triumph chose to put an IRS system on such a weak, cheaply built car is beyond me.

Royal

Just imagine that. Here it is about 55 years after the car was built and it's still able to be driven...not bad for weak cheaply built car.