Little bump on startup.. but not u joint..
 

I've got a 99 Mazda 4x4 automatic with the 3.0. It's got this little bump when you start up. Kind of feels like a u joint needing replaced.. but I don't think it is. It won't do it in reverse plus if I start off forward on a slght incline I can actually be moving forward before the bump comes. It only comes after I begin accelerating a little harder. Feels like something finally breaks free. Think it's some part of the 4x4 system?

Also, second question... on my steering wheel, the buttons on the left, the cruise on and off do light up, but the other side, resume & accel don't. Should they?

thanks
stan

LOL, I was just about to post about my truck doing this same thing. I have a 98 4.0L 4x4 ranger that shudders for 1 sec when i first start accelerating. Since your having this happen too, maybe its just a ranger thing. IDK about the lights cause mine are busted.

yeah mine just started recently, when I left off the clutch it shutters for a sec then goes away. if I do it fast it doesn't, idk??

could be the slip yoke/the clutch is shuddering

but why would it be shuddering, the slip yoke just got regreased? it just kinda started, and I now have 3 different types of diff fluid in my ls rear because of a dumb shop so idk if maybe that is making the rear ls chatter alil because not the right proportion and friction modifier and the same gear lube you know.

if something is leaking onto your clutch and contaiminated it that will cause a shudder on moderate to hard acceleration

what would possibly be leaking onto my clutch lol its onmly got 60,000 miles on it and really the faster or quicker I take off it does it less, its just when I do normal or slow type release and apply power.

the slave cylinder...they are known for problems in the ranger

yeah but at 60,000 miles, id prolly havta kill someone. and wouldnt I be having other issues that would start to pop up?

A slave leak more then likley won't contaminate the clutch disc itself.

The lights on your cruise buttons do light up.

Have you checked the U joints

james here, just got a u joint for my 97 ranger but they look ok? no obvious wear. since the drive train knocking got progressively worse like a bad bearing? what shoud I check first as there are a list of things to look into including; center support bearing, clutch pilot bearing, companion flange, carrier bearing, pinon shaft seals, & bearings. Where do I begin? Desperately need to locate free schematic diagrams, where are they?

IDK if it's the clutch, because I are have the same problem but i've got the transmission and clutch checked out after i got the truck a year ago and the mechanic said it was fine. (it was doing it then)

you I think it kinda has to do with the awful driveshaft design that makes the clunking sound and kinda binds a tad, that puts alot of stress on the u joints especially if you have a manual which it then clunks even more than normal. So its just a bad design personally, and one day im going to have a driveshaft made to fix that.

yea probably. For me it shakes only when you accelerate from a stop, but not when i am already moving. So maybe it is just the drive shaft being jerked because it binds a little when u are stopped. I really have no idea why it does it, and i really don't care about it as long it doesn't cause any other problems.

I think mine is also my tires because they are cupped and worn awfully uneven, and I even noticed when I slow back down to 1 or 2 mps, even in neutral I can feel the little shutter. I just have to u joints replaced a few months ago so I could see them being bad already but maybe. After I get new rims and tires here in the next month or two, if it still does it, then I will have the u joints done AGAIN.

LOL good luck. hopefully it's the tires cause that would suck if u have to get u jouints already. haven't tried to do it in neutral yet. i'm gonna try it, i'll tell you tommorow if it does it or not. see ya

kk just let me know, I have a manual so its easier to just be in neutral than if you have an auto obviously. but whoever tried to change the u joints originally on my truck kinda hit the end ears with a hammer and put some marks on them. ever since then alot of shops including myself have had a hard time really getting the u joint on that end to work 100 perfect, and plus most shops nowadays aren't doing very good work for the money, its really sad.

yea I tried it out this morning in neuteral and it didn't do it, but have also heared a clunk when i put it in drive. I looked in my Hanes repair manual and it says both the shaking and and clunking can be worn out u joints, so that is most likely my problem. I don't know why i didn't think to look in the manual before now. For you it could be the u joints binding with the end ears since you can't get that end to work 100% maybe if you get new end ears or a new drive shaft and replace it would work.

yeah its prolly time for some u joints. like I said I still have problems with mine because of the previous owner. one day ill have one made to solve it all.