I know this is random, and u probably know this, but air pressure in the tires?

I could be way off here but it looks like your wedge may be in backwards. The axle looks like it is pointed up in the front rather than down.

I went out and took a picture of mine. The wedge on mine is set up so the front of the axle is pointed down.... the opposite of what I see in your picture. The narrow gap between the leaf spring mount plate and axle is towards the front of the car on my car... on your car the narrow gap is towards the back of the car.

Just an observation... maybe something to check.

Here is a pic of mine with the narrow gap towards the front of the car... which makes the front of the axle point down.
http://i1048.photobucket.com/albums/...ps4103fee4.jpg

^^^ It does look like it's the opposite of yours Dale

Didn't redrill holes just tapped the existing. Wheels mounted up fine.

I had paint marks on both so they are indexed the same.

Runout might be interesting thanks.

Damn I wish I had a drive-on ramp right now........or even wheel stands! :bang:

Reversing the wedges was the first thing I thought, went through my images to confirm earlier today and this is how it was.

http://photos.smugmug.com/photos/i-W...WkMLDSJ-XL.jpg

I'm not saying this is right but thats where we ended up when installing the trans with a drive on lift so I could determine the best angles given the setup.

What bothers me is I made three 1* changes and there was no noticeable change. :headscratch:

Realistically the biggest change from my baseline was the ring and pinion and new bearings.

I'll check with Roy who did the setup in the morning and see what he thinks.

Is the shim installed with the tapper towards the front of the car?? The yoke on the rear end should face down I'm thinking at least -3*..And the u joint is sitting all the way in the pocket (nice that you marked it)

No. The driveline is near parallel to the ground in this car. Engine/trans is 2.25* downward.

I've got the routine down now so I can try zero wedge and 2* & 4* opposite of what I have and see what happens.

Regretfull I don't have a convenient way to take accurate driveline measurements at this time.

I'm wondering if changing out the rear shackle bushings to urethane impacted the angles? Or if the shackles are too tight restricting movement. They're torqued to 10 ft lbs. ??? Travel felt OK, turn-in and cornering stability definitely improved.

Here's the info I used to set angles when I installed the T56:
http://www.iedls.com/asp/admin/getFi...&TID=28&FN=PDF
I used the example in Figure 5

I'm wondering if the urethane bushings I installed in the rear shackles at the same time are too tight and binding thus effecting the pinion angle. I torqued the uppers at 5 lbs, could get the torque wrench on the lowers so they're by feel. :headscratch:

Yes -- should have been is NOT down....

A driveline will feel like it's a rotational vibration -- kind of moving "around" the car...

Tires out of balance feel more like a "bouncing" vibration...

A bent wheel feels like a side to side vibration... or shaking side to side.


What we don't know is what kind of vibration you're feeling???

I know you've read these instructions/set up on driveshaft angles....


I've seen situation in FIG 7 -- many times.... and hope that you've loaded the rear axle and checked your driveshaft angle. I have a tool for that if you want me to bring it with me???

It's the same as it was before the gear and bushing change and it vibrates like a mother at 50-52.
Check......feels centered like the slight vibration that was present but magnified.

I jacked it up this morning but need taller jack stands to support the rear axle. Need to pick up a kid from school and grab taller jack stands then I'll confirm relations and angles best as possible with my little digital gauge. Then I'll loosen the shackles to snug and recheck angles. We'll see. :headscratch:

Engine trans -2.4*
Pinion +1.4*
Driveline -.6

2.4-.6 = -1.8
.6-1.4 = -.8
Uncancelled angle = 1.0

If the pinion goes up, that puts the driveline closer to 0 thus reducing the uncancelled angle..........Right? :headscratch:

None of Inlands examples show pinion down.....is there a reason?

Yes -- because engine trans are always DOWN.

Can you get the pinion angle up so it cancels??

Just running some rough numbers here, the vibration that was there occurred at 65 mph with a 3.31 ratio. With the new 3.73 ratio there is a vibration at about 52 mph. With a 275/40r18 tire, 65 mph is about 2700 shaft rpm with the 3.31. 2700 rpm of the shaft is about 45 hz. With the new 3.73 ratio, 52 mph is about 2440 rpm or about 40 hz. Might be the same vibration source that's now occurring lower in vehicle speed due to the ratio change. How well does the slip yoke fit in the trans. Any slop? U joints feel free to pivot?

Thinking about this ---- since the same issue was there - but got worse with the changes:


Major change was the improved bushings -- maybe stiffening the rear end as an assembly..... so just talking out loud now.... the pinion CLIMBS with force applied... maybe it used to (before new bushings) climb enough at speed to partly correct an out of angle driveshaft thus REDUCING the vibration (driveshaft working angles) and now it can't climb as much as it used to so is holding back and making the working angles out enough that it's increasing the vibration?

Yes, adding more wedge the front of the perch will rotate the nose up.
I had 5* up front at first I can add the 2* wedges I cut and see how it specs out.

My floor jack and those 1/2" u-bolts are kicking my butt! :lol:

Thanks for the math - much appreciated and the 65 mph is spot on. The intensity increase is alarming.

The trans, driveline, and u-joints have 3K 'relatively easy' miles on them. Ideally the driveline could be a 1/2" longer. Car in the air I can easily rotate the driveline by hand and don't feel any u-joint interference.

I you guys need me I'll be under the car doing shoulder and ab exercises. :D

I'd buy into that logic as the bushings made a noticeable effect on turn-in and cornering stability.

For laying on the floor and working under a car ---- 12 TON jack stands are a requirement....


Oh -- and a jack or a way to get the jack up enough -- to raise it 24"..... or near that. So sometimes guys have to go up -- set up the jack stands -- then put the jack on some boards (I don't like doing this but most jacks only go up 17 or 18") and get it up some more....


IS THE BALANCE PIECE THAT'S ALWAYS ADDED TO A DRIVELINE STILL IN PLACE??? Sometimes if they're not welded on well -- they'll break off.... it should be a small circular piece or maybe a square -- usually near one end. <writing all of the above incase someone else is reading and has issues they want to work out>

Balance plaque is in place and the location coincides with the runout on the dial indicator.

The 7* wedge was a slight improvement........-20% maybe. Just put it back up and stands to verify measurements.

Since stock 12 bolts are not centered, how about the cross-car angle on the U joints?

Well.........I added 7* wedge to it and it was a slight improvement but not near what could be considered close. The limiting factor in adding more was the pinion snubber was nearing 1.75" clearance at ride height....not good.

Dale called and we discussed the situation since our cars stances are within 1/4 inches of each other using the same trans, crossmember, rear end and springs. Pinion down appeared to be the only way to achieve the necessary range of adjustment and clearance.

I went extreme with 5* wedge and that put the pinion down 7.8 (on my baseline which is skewed but repeatable) did a little rough math and said no way it will but drove it anyway after checking rotation for clearances and binding. Not good at all.....babied it home. So I took another jump and went with 2* pinion down wedge and that was similar to the pinion up 7* wedge. Pulled back into the garage at 9 pm and threw it up on the stands again and did one more swap to a 1" straight block. Test drive finally produced some hope as the vibration was neutralized 60+% and started to fade away at 64 mph but I now have a decel vibe but that (if I'm correct) tells me I need to move the pinion up. Next week I'll start adding 1* increments. FWIW the last swap and 6 mile test drive was done in 70 minutes.

It's good enough for a Willows Taxi. :D

I'm flippin spent.....if any says crawling under cars, tossing jack stands, and pumping floor jacks, and torquing long u-bolts isn't exercise I'll pummel them.

Time to focus on packing and driving! :woot: :woot:

If it can make a beer run to WalMart --- it's good enough.... Oh yeah -- and get us to Casa Ramos and back tomorrow night.


I'll be at the 199 <our usual rendezvous> probably around 4 or 5 PM.... with saw... which you should plan on getting home tonight, if possible, rather than dragging that heavy little POS south and back, if that works for ya.

Norwood don't do the Springtuckey WallyMart lot.......that's similar to driving into downtown Tikrit!

He's really looking forward to chillin at Casa Ramos though.

Shoot me a text when you land at 199.

If its not the rear end it has to be the u-joint or driveshaft balance. :gitrdun:

PS - You were right...........again.

You're the best guesser I know.

:underchair:

Norwood
 

I hate to say it but I changed my lowering blocks several
times and also just lowered the front eyelets and never
installed any angled wedges... never had any vibration
before or after

I need to check to see where my pinon is pointing as it has
me wondering

I do agree that is hard work playing with those damn springs
and u-bolts.. I hope I am done with mine

Have fun driving the Lotus... the car issue will be waiting
when you get back

Panteracer Norcal Bob

Thanks Bob!

Thankfully I think I'm closing in on the sweet spot.

A 3 or 4 Link and a lift would have been waaaay too easy. :sieg:

Time you think you guys will be there tomorrow?

I'm in Coburg tonight -- Sieg is coming at 5:30AM --- we'll load his Camaro and be out on the road by 6AM --- figure 8 hour drive - puts us in there around 2PM

Sweet, see ya there!

:drive: :woot: :woot:

Drive safely you geezers.

:geezer:

When will we be blessed with your presence? :D

Saturday mornin... which to me is usually around 11:58 a.m. :D

That early :sieg:

You wouldn't do too well with our 5:30 am rendezvous tomorrow huh? :D

:happy23:

It's a LOT easier and rewarding to get up at the buttcrack for track related festivities. :unibrow:

Still fighting the driveline vibes issue!

Put the car on a drive on lift and checked angles.

Trans 2.2* down
Driveline 1.4* down
Pinion .6* down

According to this calculator I'm .15-.25* down on the pinion from 1 to 1 operating angles.

I double checked the u-joints and there's no noticeable play.

I finding it hard to believe .25* is causing a relatively noticeable vibe that comes in around 62 mph in 5th gear. (.80 OD)

I've been using .5" x 2.25" x 18 ga metal shims to add to the wedge until it's zero'd. One more adjustment and angle check and if that doesn't do it I'll take the driveline out and check it's balance.

The 3:73 gear has obviously compounded issues......IMO.

:bang: