i was wondering if filling the holes around the bushings on the diff would strengthen/solidify them some and reduce drivelash. is this just completely stupid or a good idea?

 

On the ears? The one that usually flops around is the front mount when it decides its had enough for its lifetime and lets go.

If you weld the front mount, (like mine) expect to blow your subframe bushings within an oil change. (like I did) The force which once was absorbed by the front diff mount is transmitted to the subframe mounts and they make lots of noise within a couple weeks.

The whole purpose of all the bushings at the mounting points is to isolate vibration from the driveline and the road. Filling in the gaps in the rear diff mounts would probably make little to no difference other than potentially make your car rattle more than it already does.

 

FYI, Mazda Comp sells performance rear differential bushings that use a 40% stiffer rubber compound. If you're not a member of Mazda Comp, than you can get these same bushings from Corksport, but at a higher price. They aso have the front mount with the stiffer rubber compound.

I put these stiffer bushings into the recently modified rear end on my 90 GXL. I used the stock mount for the front of the rear end. The stiffer bushings transmit a little more vibration than the stock mounts. If I were to do it again, I would use the stock bushings at both front/rear mounting locations. I've never had a problem with front/rear bushings breaking.

Hot_Dog
90 RX7 GXL
02 RSX-S

 

i have a 91 gxl. i was just looking at reducing the driveline lash by tightening up everything. looked like an easy thing to fill in the holes in the bushings in the ears. thanks for the input guys.

 

You could remove the shocks too and weld the control arms in position to reduce rolling in a corner. But that would have very adverse effects on other aspects of the car. Same situation with welding pick-up points on the car that were designed to be flexible. Reducing the flex will usually increase response and feedback, but at the price of vibration and wear. Welding is extreme and should only be done on a drag car, and even then it will eat up parts. I have the stiffer front mount and it helped a bit at controlling the rear. Once the rear bushings are solid; they will prevent the whole rear subframe to act as it was designed. Without the movement in the differential the rest of the geometry will not work properly. I vote to just use stiffer bushings.

 

er, i never said i was going to weld. that would be bad. i was going the po' man's method of attempting to "firm" up the bushings by filling in gaps with silicone/equivalent. i know how the car will react to them being stiffened, i'm wondering if this will work as planned or not.

 

Urethan versions are available from victoria british, if you feel the stiffining is the way you want to go.

(but I do agree with most everyone else that it will make the cars ride harsher).

 

well thats expected. just like urethane bushings for the suspension

 

i also realized that everyone has given me information that i already know, said i already know, and am still saying i already know. yet know one has answered whether they think it will work as planned, or is just insanely stupid. i never said anything about welding or purchasing new bushings. i just asked about the silicone fill in.

 

Sorry, I assumed you were going to fill in the bushings with a weld. You never mentioned how you planned to fill them in.

Here is something you might not know: You're not very nice!

 

lol, sorry. its just frustrating that i ask a question and i have people telling me chassis dynamics. i'm trying to decide if filling these in will give the results i wanted or if it won't even show anything. or maybe doing so could develop problems that i didn't think of. i said silicone right after your post so you're off the hook. plus i'm not sure how i'd have filled the holes with weld w/o melting the rubber off. anyway, sorry about that.

 

 

werd. now does anyone have an answer?

 

From what I guess your saying now, is that you want to ghetto rig and squirt in some silicon rubber (like aquarium sealer or GE’s Silicon II) into the holes...

It wouldn't do a thing as silicon rubber has a lower density than the factory rubber, as well as you would have issues with getting the silicon to bond into the holes.

 

i was thinking more along the lines of shoegoo or a harder epoxy.

 

I still don't think it would make much if any difference

 

ok, thanks. i'll sav emy time then.

 

maybe try it with a couple of bolts first and see if that does anything

 

not following you?