sciff5

iTrader: (1)

I dont know... I took the driveshaft out and had it checked and rebalanced and re-installed it and it made zero difference. I really wish it was that easy but at this point I've tried a lot of easy stuff and even some more involved stuff. I am kinda lost but I am going to measure the angle of the transmission and rear end in relation to the driveshaft to make sure they are equal and opposite and then I need to measure the total angle of the diveshaft. I just cant think of a perfectly flat surface on either the tranny or the rear end to use to measure the angles I need. Anyone have any ideas?

jfg455

iTrader: (5)

if you pull the drive shaft out then you can use the flats of the rear end yoke where the straps bolt on. Or if you are still using the RX rear you can go on the flat of the flange. the front you have to use the yoke and eye ball it or use another spare yoke and go across the ends of it.

sciff5

iTrader: (1)

I think I know what you meen after doing some reading I found out you can use a deep socket the same size as one of the 4 round ends of the u-joint spin the driveshaft till one of those 4 areas are pointing down then lay the gauge across the end of the deep socket and you should be able to get the angle.

Even better I actually learned a better way watching trucks or muscle car today on power block and they were working with a completly different car but to check and make sure the angles at either end of the driveshaft were equal but opposite they used a peice of filler rod (or you can use a coat hanger) and then bend the hanger to the angle along the bottom of the tranny and along the driveshaft, then once the coat hanger is the angle of the tranny/driveshaft, flip it around and see how well it matches the angle of the driveshaft/rear end. If its off, adjust as nessecary.

Its funny most of those shows on power block are crap but every once and a while something on there is really applicable to what your doing. This just happened to work out timing wise perfect.

sciff5

iTrader: (1)

Hey guys I wanted to create a new thread because I'm having such issues with a vibration that comes on at about 55-60 and I CANNOT get it to go away.

I figured the Wiring would bury me in this swap and it seems like the nuts/bolts mechanical issue is the thing burying me although I'm not out of the woods with the wiring either.


Heres the symtoms
Car drives well around town and vibration starts to become noticible around 40-45 and then peaks in violence at about 60-65. At this speed the vibration is what I would call low frequency vibration (my fuel cell which I unbolted and is hanging off a single bolt visible bounces up and down at this speed) that obviously increases in frequency as the car goes faster. The vibration is worse when I accelerate at all even ever so slightly. When I'm off the gas it does get better though. The vibration originates clearly from the rear of the car and you can feel it through the seat then as you move faster the vibration starts to be a higher frequency and moves through the floor boards and then throughout the car (even shakes the rearview mirror to the point you cant see whats behind you, like haveing a big subwoofer in the car for you audio guys) Car has delrin differential and rear subframe mounts which do transmit noticible gear whine noise into the car but I dont think its possible that a vibration like this could be transmitted just by the bushings.

So the vibration is deff speed related but is also tied to whether you accelerate or coast/decelerate.

What I've done so far
-Thought it was a bad U-joint so I pulled the driveshaft and brought it to get it checked out and balanced. They said the ujoints were fine but they rebalanced the driveshaft. Put the driveshaft back in, and made zero difference.

-Changed the tires just in case and had them balanced, No difference

-Swapped the halfshafts as excess play in the inner CVs can cause a vibration like a bad u joint. Made zero difference.

- Checked driveline angle today of tranny and rear diff in relation to the driveshaft.

Got my angle finder got the angle of the driveshaft, then zeroed it out and took the angle of the tranny (and verified it using the top of the intake manifold. The tranny was sloping down towards the back of the car 3 degrees in relation to the driveshaft. Then measured the angle of the rear end and what do you know its sloping up 4.5 degrees in relation to the driveshaft. So I felt better figuring alright they arent equal I know this can create driveline vibrations. Problem is the rear end is already as low as I can put it. I even put spacers between the rear subframe mount and the body to space the rear subframe down a bit and pull the nose of the differential down a bit, and I've already spaced the tranny down to the point where you can barely thread the nuts onto the bolts of the tranny mounts. So basically the tranny is already as low as it can go without modifying grannys trranny mount and the front of the rear diff is already as low as it can go. So I said well lets try something.

I couldent bring the car on the road today, because its been snowing like crazy. So I jacked the back end of the car and put it on jack stands with the wheels off the ground. I then unbolted the tranny mount all together and literally let the engine/tranny hang by the motor mounts. That gave me 4 degrees of downward slope (not an ideal situation by any meens and still doesnt equal the 4.5 degrees of upward slope of the rear end but closer) well I started up the car and got the wheels up to speed and the car vibrated like usual. Shut it down and then I jacked the tranny back up into place and re-bolted it to the tranny mounts (back where I had it originally) turned the car back on and brought it up to speed and again same ****. Vibration clearly coming from the rear. And the 1 degree difference in tranny angle didnt make **** difference.

Took the wheels off and did it again just to be sure it wasnt the wheels and it wasnt.

I know when the wheels are hanging the halfshafts are at odd angles and may cause a vibration in its self but like I said I couldent even get the car a foot down my driveway so I couldent bring it on the highway but the vibration on the jackstands happened at the same speed and in the same fashion as the original vibration.

So now I know the angles of the drivetrain arent perfect and I should fix them but I dont know how its physically possible, but even more interesting is the fact that I dont think the lion share of this vibration is because of the inequalities of the driveline angles. I think its something more rearward in the rear end/ half shafts wheels, In that area.

I know the rear end is offset a 3/4 of an inch or something to one side of the car (thats what grannys says anyway) so is there a left and right halfshafts because I havent checked them but they all look the same length to me.. Maybe if there was a right/left and I had em backwards or something... who knows I am just trying to come up with new ideas cause I'm fresh out.

Now that I'm done writing my college thesis here I'm gonna go to the bar and drink till I'm smart.

sciff5

iTrader: (1)

I'm gonna tear into it tomorrow. I am gonna disconnect the half shafts first see where that gets me. Then if that doesnt make any difference I'll disconnect the driveshaft from the rear end and pull it. Hell I didnt think I was gonna be pulling the rear end/suspension again but while its out I also might as well do the DTSS eliminator bushings.

sciff5

iTrader: (1)

Took the halfshafts off and it still vibrated... although wierdly not as much but still no where near acceptable. So the rest of the day was spent pulling the half shafts, pulling the exhaust. Tomorrow I need to get another jack and drop the rear subframe.. While the subframe is out I am gonna try and loosen up the toe adjusters (which are frozen in place) and get the DTSS eliminators installed.


Pics from today
Pulling the car appart





Driveshaft did have what looked like it might be some wear on the very tip of of the slip yolk






And finally my sentiments about the car and project cars in general
Its a love/hate relationship




Tomorrow hopefully I'll get the other diff in place and test it out but the girlfriend clipped a car with her 4 runner and took her side mirror off.. and now expects me to run to the junk yard and install a new one for her. I tried to tell her plenty of cars back in the day didnt come with a passenger side mirror so she should be fine.

sciff5

iTrader: (1)

Wow long day. Pulled the rear subframe/diff and noticed the rubber front diff mount was cracked. Good thing I pulled this diff or I would have had an issue anyway. I then took the spare diff filled her up as well as as actually cutting down the tube in the middle of the rear diff mounts. So that the rear diff mounts very close to the bottom of the car with only a thin peice of rubber isolating it. Which actually seems great. Then I actually mounted the cup that bolts up under the diff mount to hold it in place upside down which seems to be a perfect job at holding the diff in place. Seems like almost a solid mount but with just some rubber isolation. This pic should give you an idea of whats goin on.



In comparison Look at how thick the delrin mounts are. I HIGHLY HIGHLY suggest than anyone installing these shave them down A LOT. These were actually making my pinion angle even worse than stock.



And finally I spaced my pinion snubber down more. Now it looks nicely preloaded and should really help wheel hop



Finally I think I've achieved what I thought was impossible. I dropped the rear subframe mounts even further and with the rear of the diff sitting closer to the underside of the car. I bolted everything back in place and then took some quick measurements and was seeing approx 3 degrees of pinion angle :bowdown::bowdown::bowdown: I am so happy I cant belive I got it down to a reasonable angle. I am gonna bolt everything else back in place tomorrow and keeping fingers crossed it helps vibration. After trying a few different angles earlier today my driveline angle is at least part of the total vibration I'm dealing with.

sciff5

iTrader: (1)

Put the driveshaft back in and everything was shitty as usual.

Pulled the driveshaft right back out and brought it to the shop. He is gonna look at it again. Like I said there is some wear at the very tip of the slip yolk.. Only thing I can think of is the driveshaft is too short and is creating that vibration. I just thought of another thing. I should have run the engine without a driveshaft at all to make sure its not the tranny but I doubt it is anyway.

I'll let you guys know... I may need to get this driveshaft lengthened though

sciff5

iTrader: (1)

Also did some more bushings while the rear suspenion/rear end was out.

Got the rear steer eliminator bushings installed after about 4 hours.

The rx7s had a passive rear steer system that used a bushing that would flex under cornering to change rear toe. After 20 years though these bushings are like jello and the toe changes randomly going over bumps or under acceleration ect. The eliminators are delrin so they eliminate the system all together.

Hopefully it will stop the car from feeling like its moving side to side when going over bumps and help wheel hop some more.

Its a dirty time consuming job but I miss these simple jobs where I actually feel like I know what I'm doing.


Pulling the old bushing using a 5 ton jaw puller from the zone


EVerything appart.


Old bushing out, the center pushed out and then I had to cut the metal sleeve and then push that out, kinda a PITA like most bushing jobs.


New bushings installed

sciff5

iTrader: (1)

So after creating a new thread because my vibration issues were getting me so frustrated.

http://www.v8rx7forum.com/v8-rx7-tec...ious-help.html


I finally pulled the driveshaft and both sets of halfshafts and brought them to a local place, cape cod axle.

Man I'm getting good at taking this thing appart/ putting it back together.

I then took the spare c4 yoke and put it in the tranny and brought the car up to speed and thankfully I had no vibration so a bent output shaft or anything in the tranny is out of the picture as I thought but this was good reassurance.

Anyway after getting the same local driveshaft place recommended from several people I brought my half shafts and driveshaft to Cape Cod Axle. I didnt use them to balance my driveshaft because they dont do aluminum but they can check the work Rhode Island driveshaft did which seems to get mixed reviews.

He took a look at the used spicer slip yoke the last place put on and said man that thing looks beat I wouldent sell that to anyone. I took a closer look at it and it was pretty pitted. As you guys know I was having some trouble getting that yoke to slip into my tranny. That was also when the leak started. I told the guy at this place and he gave me a brand new spicer unit to see if it would slip in. I got back to the house and it slipped all the way in no problemo. So I know I wasnt bottoming out the tranny.. it was just that the splines on the old slip yoke were rusted pitted and creating friction. The guy at the shop also said that leak may be caused by the pitting on the outside of that old yoke may not allow the seal to create a seal because its not mating to smooth surface.

This guy said he would tear everything appart and rebuild the halfshafts if needed, check the cv joints check to see if the bars were straight (like I said one of the halfshafts was visibly wobbling even though there didnt seem to be any play in the cv joints.

He said he could also spin balance the entire driveshaft assembly together to make sure the rear flange of the driveshaft isnt out of balance or the ujoints are bad.

So basically I think if this doesnt find the problem I think I should cut my losses, cast this car off into the sunset in the ocean on a burning wooden raft to drive away the evil demons.

bambaboy

iTrader: (1)

Nice dude, keep me updated with the swap, nice job...

Red89GTA

sounds like you got hold of someone who knows what they're doing. Esp if there was no vibration w/o the d/s in, I'd say you have it narrowed down. Hope he finds that part 'x' was out of balance and replacment/repair will fix it post haste

sciff5

iTrader: (1)

Got an update from the place working on my driveshaft and halfshafts.

Hes gone through the driveshaft and found that it was NOT balanced at all. In the back of the driveshaft (where I felt the vibration) he needed to add not a little but a good bit of weight.

He doesnt weld aluminum so he epoxied the weight on. He said it should be fine and I know its a pretty common practice but still makes me nervous when this driveshaft is going to be spinning about 8000 rpm. He is also replacing the yoke with a brand new one.

I think the fact that the yoke rhode island driveshaft gave me is so pitted is why that seal is leaking. I the leak stops when I get the new yoke on there I'll know thats what it was. This still may not fix my issues but safe to say RHODE ISLAND DRIVESHAFT RIPPED ME OFF. They charged me 110$ and I got nothing but over a month of headache in return.


He also tore down the halfshafts but hasnet gone through them yet.

This is ****** expensive

Rhode island driveshaft charged me
$84 to balance the driveshaft (and didnt do it)
$25 for a used spicer 2-3-6081x slip yoke

Cape cod Axle is going to charge me
$75 to balance the driveshaft
$60 for a new spicer 2-3-6081x slip yoke
$75 x 2 to rebuild each half shaft.

I dont know about you guys but I am going to try this new driveshaft and halfshafts and if my vibration is gone afterwards I think I should ask for my money back from Rhode Island driveshaft.

x Wild Bill x

I agree, just read through the whole thing, nice job and sweet car. Where near the Cape do you live? I'm from Rochester and usually go to the car shows at Upper Cape, you ever go?

Hope the new drive line fixes your vibration

Capown

iTrader: (5)

FUQ me!! That was a long, funny, well detailed write up thanks!! I would take your receipts back to Rhode Island fuqers and say "show me the money!!"

NateLS1

iTrader: (4)

Keep your hopes up man! Your car is badass, dont let it get ya down lol. Think its gonna be ready for NED when it opens?

sciff5

iTrader: (1)

I might miss opening night but that might be a good thing cause I'm sure it'll be crazy the first night. We'll see if cape cod axle can finally get me straightened out

If not opening night it should deff be ready to go the next test and tune. I pulled the fuel cell and figured out I can fit it under the car (so I dont have to build a firewall between me and the cell) so I pulled my whole fuel system today and got my nhra approved battery box in the mail with the 2ga cable. So I'm gonna redo that. I'm also gonna put a fuel level sender in the fuel cell while its out of the car. I thought we had at least half a tank when we went on that drive dude there was like 8 ounces of gas left in the tank. Lol I am so lucky I made it home.

I have had to re-do things so many times though its crazy.

This is whats left to do before I go to the track

Puttin some brush on sound deadener on the floorboards while the fuel cell is out. Put on 2 coats today, lots more coats left.

Gonna drill the fuel cell tomorrow for the sender, mount the cell under the car, install the battery box, wire things back up and plumb the fuel lines. Gotta mount/wire an emergency shut off switch, gotta find a good switch to use as a clutch safety swith and wire that in, gotta adress that misfire (btw it went away on the ride home again after playing with that wire), and I need to adjust the hood pins to keep the hood down a little tighter, put the interior back together, and make sure the new yoke fixes the tranny leak/replace the seal if it doesnt.

Thanks again to Nate and your boss (if the older dude lookin under the car with us was him he seemed to know his stuff.)
I showed up at his work pretty much outta the blue and he really helped me out getting the car on a lift and thats how we figured out the halfshaft was wobbling. I gave you props on maxima.org too. If I can get things figured out I'll throw the drag radials on and swing by the dealership and we'll do some real runs at more than 10% throttle.

sciff5

iTrader: (1)

Today the skys opened and a ray of sunshine has decended from the heavens.. Not really it actually was was cold and rainy, but thats how it felt.

This is the weight the second shop added


After about a 6 hour day getting my electrical system and fuel system in place I put the driveshaft in and put some gas in her. Got her up to speed and shes positivly smooth as glass

I still need to make sure it doesnt vibrate on the highway, but there was a vibration with the driveshaft in before and now theres not. I got RIPPED. But I think I'll be ready for track opening

While I was down there I also got the car NHRA legal







I also wired the clutch safety switch in too.

If all stays good I will be running her at the track next week. Keeping fingers crossed

V8Rumble

iTrader: (9)

Dang man, after all you've been through, that's GOTTA feel good! Congrats!

sciff5

iTrader: (1)

Got the car out today with the newly balanced driveshaft/halfshafts and we can pretty much put an end to the vibration issue... almost. The car was smooth as glass. It was great. I got it on the highway and I didnt get a half mile before BANGG!

So I pull over, its dark. I look under the car and look to see if anything is going on. The car seems to be driving fine though and I cant see anything out of place. I drive the car right home and notice man.. this car is vibrating..wtf is goin on?

Then it clicked.. the ****** weight the guy had just epoxied on came off at only about 60mph (think of if it was 120) after only a half mile. Get the car up in the air and what do you know the weight is gone.

Lol 2 steps forward one back.. I'll drop the exhaust tomorrow and pull the driveshaft lol I cant even be mad at this point. I feel so much better at least knowing whats causing the vibration that the extra labor getting it repaired again doesnt even bother me that much.

Otherwise the car ran perfect. I have ZERO wheel HOP after my homemade hockey puck differential mounts and a ghetto thing I added.. I basically put a huge ratchet strap around the top of the front of the diff and then around the rear subframe. Its an 11000lb strap and doesnt really fit too well but I know between the strap and the pinion snubber theres no way I'm breaking the front diff mount. I might take the strap off but it seems to be working for me.