I have a 700r4 an when I shift from 2500 from 1st to 2nd the rear have a clunk. It ride smooth when I drive normal . When I shift park to reverse or reverse to drive if have a slight clunk . I don't have a problem when going on a on ramp. My friend said u joints need replacing. What can it be .

 

Your transmission mount is bad. They cost on average $10 and are easy to replace.

 

would a Lakewood 24350 Polyurethane Transmission Mount be worth buying?

 

You might give the following link a peek before you purchase:

https://www.thirdgen.org/forums/tran...ison-pics.html

JamesC

 

Not to derail this post, but this is very similar to something I was about to ask.

I've had a lot done to my car in the past month, probably to much because now it's causing problems figuring out where what is coming from...

Anyway, I got a T56 swapped in, rebuilt the rear end with 28 spline parts and a detroit true trac, new 3.73 gears, and replaced the u-joints on the driveshaft.

At first I had a problem with whining but the mechanic reshimmed the gears and replaced the crush sleeve. I still have a whining noise but it's no where near as loud before and the mechanic is now claiming that it's in the gears and he wont be able to get rid of it because they are lined up right. That is problem one, is this true, are some gears just whiney? It's not a small whine, I can clearly hear it over road noise and when slowing down. It's quite annoying actually.

Anyway more importantly and in relation to this post, there is a strong vibration at 65 to 75 mph and also at slower speeds when getting up over 4k RPMs. It's back in the shop now for him to look at that. I was thinking the flywheel might be out of balance, but now I'm wondering if the transmission mounts might have something to do with it?

I used a spohn t56 crossmember with a driveshaft safety loop, but as for the transmission mounts themselves I'm not sure what was used. I didn't specifically buy any replacements so I'm guessing the stock ones are being used.

 

Some gear sets do whine, depending on the quality, and because of a higher gear ratio. As for your viberation, read James C. link, if a prothane or anything other than OEM was used on your tranny mount, you could be getting viberations from the mount. Usually a bad OEM mount will provide the "clunk" when shifting.