New Clunk in Reverse

[gerviswaddell]

Well the car is all back together now, and everything went pretty smoothly (clutch/CV/Tie rod assemblies/ball joints) But now I have a clunk.
The clunk occurs mainly when in reverse, say if you dump the clutch, or even if you give it some gas in reverse, I can make the clunk repeat by dabbing the gas (this produces a dull thud, the more abrupt the shot of gas , the sharper the sound). It feels like it is coming from the transmission tunnel.

This same clunk can be heard when I punch it in first gear, but happens much less often. Also, there is no clunk when I apply the brakes (possibly ruling out the suspension/steering parts as the source ?) As the Tie rods and ball joints are new, I am thinking that they are not the problem either.

Now here is where it gets interesting: The new (reman) passenger side Axle has a peculiar problem, the cylindrical metal casing which wraps the 3 pronged portion of the inboard CV joint ( it is pressed on just after the first major flange on the cv, nearest to the differential, and continues to where the boot is fastened) has some play in it. I can spin it roughly five degrees either way, then there is resistance. The dead cv's which I have lying around dont act this way.

Next, there is the issue of the transfer case/diff. When I took this one off of the car in the first place, the two bolts which hold on the stiffening plate (passengers side) broke off. So i was forced to drill them out. Problem is, I broke a cobalt drill bit off inside one of the holes ( i know so stupid) so I am now running one bolt where there were once two (the bolt is also smaller than the original). So how much 'stiffening' does this plate actually do ( I still have the one on the drivers side attached properly) and could this be the cause of my clunk while in reverse? The last time I gave it a dab of gas in 1st I also heard a relatively crisp and loud snapping sound...worried and confused (but the car drove fine after that, and My one bolt on the stiffening plate is also intact)

My apologies for the long winded question, but I wanted to be descriptive.

thanks again folks!

GW

[Petros]

the clunk sounds more like a drive shaft issue. Check the center mount (it is supported by a rubber mount that is flexible, sometimes the rubber breaks down so it can clunk), and the u-joints. Also if any of the rear suspension mounts, especially the trailing arm links, are worn or sloppy, it will cause the front of the diff to move up or down when you put in forward/revers because it allow the axle to rotates, and can cause a clunk.

The main stress of the trans/engine assembly is taking by the bell housing and bell housing bolts, the 2wd version of this car does not have the side stiffeners at all, so I doubt you have any issues there. I find these side plates a nuisance every time I need to pull the engine or the trans, I kind of question if they add much stiffness anyway. I am a bit curious at what the engineering department was thinking when they added these massively strong side plates to the assembly in the 4wd version, and if it was really necessary. I mean, how much torque would it take to make these cast iron reinforcements necessary? And if so why were they not necessary on the 2wd version (which has the same hp engine)?

If you are going to turn your mighty Tercel4wd into a baja off road racer, or put it into extreme off road use, it would be a good idea to do a permanent repair of the side plates. But you will likely ever miss the missing bolt if you treat your car somewhat normal, with only occasional abuse.

[gerviswaddell]

Petros,

Thanks for your reply, I am unsure about any pre existing problem with the centre mount (on the driveshaft), and I am awaiting a replacement for the trans mount itself, Its just that there was no clunk prior to taking everything apart. Im glad to hear that the stiffening plates arent as important as I had feared, somewhat of a relief (I do treat my car quite normally, just like to take it in the snow!) Any take on the axle issue? is this 'looseness' of the sleeve worth taking everything apart again?

Also, would the driveshaft still be as much of an issue even if the car was in 2wd the whole time? and why would this only be happening while in reverse?

thanks again,

GW

[Petros]

could be rear trans mount causing it. does the shift lever move much when you get the clunk?

The sleeve is only there as a dust sheild, and to hold in the grease in the CV joints. If the sleeve does not ooze grease, I would ignore it. Otherwise you need to return the axle assembly, can not have it losing grease, the joint will fail in short order.

[gerviswaddell]

Good to hear about the cv sleeve, I haven't noticed anything funny with the shift lever moving...I will check tomorrow, I am thinking of isolating the problem by removing the prop shaft, (but that will be a pain), So I will remove the stiffening plate, and be sure that my bell housing is well tightened to the block while im at it. One thing at at time, one thing at a time...I will find this clunk!

[Highlander]

Noises can migrate from their point of origin, unless you can hear it in the same place with the window open and your head out the window, I wouldn't be so sure that its coming from the tranny tunnel (just my humble opinion). I would check the sway bar bushings where they meet the control arm- it took me a while to figure it out for myself on one of my '85s. The large flange on the sway bar should not touch the control arm, and there shouldn't be a shiny spot on the control arm around there either (classic sign).

[gerviswaddell]

Think I got it, after all of that worry, one of the trans mount bolts was caught on some debris (inside the threads) so there was an 1/8th inch gap between the body of the car and the mount on the right side, Im quite sure this was causing the clunk...we will see this afternoon, im just reading about how to lean out my fuel air mixture.

thanks again,