drive line issue ?

[jwhit]

long story short
sbf 347 running t5 5speed with 8.8 rear end
i have noise that i thought was coming from transmission mainly when you were at speed above 40 and pushed in clutch to stop.sounded to me like bearings in tranny were worn almost like mainshaft rattling around
since i was running a used donor trans with unknown miles i decided to tear it down and replace all bearings and worn parts.to my surprise tranny looked good only issue was to much end play on counter shaft
so i went ahead and but in all new bearings and used shims to get end play as close to zero. after installing tranny back in i decided to go for test ride leaving top of tranny tunnel off and i still have the noise
but with tunnel off i can see what maybe issue.it looks like when i push in clutch mainly stopping i see driveshaft and yoke in trans wobbling and thats whats making the noise.if im under load its doesnt seem to be issue
but when you push in clutch i see it happen.since my rear end is 4 link i dont see anyway to change pinion angle but im not sure that is the problem any thoughts would be welcome

[RoadRacer]

So are you saying that you haven't set the pinion angle correctly? What are the driveline angles right now?

[jwhit]

i didnt check pinion angle since i dont see anyway to adjust

[NAZ]

Set the pinion & operating angles correctly. That may require procuring adjustable control arms.

[GoDadGo]

Adjustable Control Arm Link:

https://www.spohn.net/shop/Factory-Five-Racing-MK3-MK4-Roadster/

[jwhit]

check pinion angle based on my numbers i have 3 degree working angle at front and 3.7 degree working angle at rear
should be well in limits but the slip yoke seems wobbly in trans i had drive shaft built local and now thinking they may have gave me defective yoke
they wouldnt tell me what brand parts they use so i will order a spicer unit and see if thats the fix

[NAZ]

Assuming that the operating angles you stated are in the correct orientation, then based on your description of the vibration and when it occurs, here’s some things to consider as probable causes:
·
* Driveshaft out of balance.


· * Too much tail housing bushing clearance. Good luck finding a spec on what the wear limit on clearance should be. Referencing on old engineering manual on radial bearing design clearances for mixed film lubricated plain bearings (bushings) of 1.5” diameter running >600 RPM, expect to run between .002” and .005”. A typical slip yoke barrel diameter for your trans should be 1.497” diameter and the bushing I.D. should be ~1.500 +/- a couple thou so that would make the running clearance ~.003” - .005”. So, anything much over that and you may be running too much clearance and that can lead to vibration.


· * Not enough yoke spline engagement (read that as too little bearing support). Mixed opinions here but if you have more than an 1” of the barrel sticking out past the seal that may lead to excessive wear and vibration. Inland Empire Driveline Services, my go-to drive shaft builder, wants to see no more than 3/8” of clearance for removing the rear u-joint at the rear end. That’s tight but they build drive shafts for drag racers that see big RPMs under very high torque loads.


· * U-joints out of phase (manufacturing defect). I can only recall seeing this once but if the guy welding the yokes on the shaft tube indexes them incorrectly you will have out of phase vibration.


· * Excessive drive shaft runout. TIR should be no more than .010” within 2” of the weld and .015” mid-span. Less is better and more leads to vibration.


Good luck.

[jwhit]

i think its loose yoke in trans so i ordered a new spicer yoke and new bushing for tail shaft in hopes thats the issue .since i can shake yoke side to side in trans.i took drive shaft out and just did quick test fit of old yoke i had from mustang it seemed like a better fit
then one driveshaft builder used but i also found out my u joints are 1310 instead of 1330 not sure why he built my shaft using smaller joints then what ffr paper called for.i cant get any custermer service form the driveshaft builder almost tempted to
take to another driveshaft shop so they can check to see if balance is correct ,but i am not happy knowing i got the smaller u joints

[jwhit]

Assuming that the operating angles you stated are in the correct orientation, then based on your description of the vibration and when it occurs, here’s some things to consider as probable causes:
·
* Driveshaft out of balance.


· * Too much tail housing bushing clearance. Good luck finding a spec on what the wear limit on clearance should be. Referencing on old engineering manual on radial bearing design clearances for mixed film lubricated plain bearings (bushings) of 1.5” diameter running >600 RPM, expect to run between .002” and .005”. A typical slip yoke barrel diameter for your trans should be 1.497” diameter and the bushing I.D. should be ~1.500 +/- a couple thou so that would make the running clearance ~.003” - .005”. So, anything much over that and you may be running too much clearance and that can lead to vibration.


· * Not enough yoke spline engagement (read that as too little bearing support). Mixed opinions here but if you have more than an 1” of the barrel sticking out past the seal that may lead to excessive wear and vibration. Inland Empire Driveline Services, my go-to drive shaft builder, wants to see no more than 3/8” of clearance for removing the rear u-joint at the rear end. That’s tight but they build drive shafts for drag racers that see big RPMs under very high torque loads.


· * U-joints out of phase (manufacturing defect). I can only recall seeing this once but if the guy welding the yokes on the shaft tube indexes them incorrectly you will have out of phase vibration.


· * Excessive drive shaft runout. TIR should be no more than .010” within 2” of the weld and .015” mid-span. Less is better and more leads to vibration.


Good luck.

thanks for input

[NAZ]

i think its loose yoke in trans so i ordered a new spicer yoke and new bushing for tail shaft in hopes thats the issue .since i can shake yoke side to side in trans.i took drive shaft out and just did quick test fit of old yoke i had from mustang it seemed like a better fit
then one driveshaft builder used but i also found out my u joints are 1310 instead of 1330 not sure why he built my shaft using smaller joints then what ffr paper called for.i cant get any custermer service form the driveshaft builder almost tempted to
take to another driveshaft shop so they can check to see if balance is correct ,but i am not happy knowing i got the smaller u joints

Let us know how the corrective action you're planning comes out. It's not uncommon to get a vibration from too loose a fit between the yoke barrel and bushing.

As for the 1310 u-joints vs the 1320, if you spec'd 1320 and the builder gave you 1310 make him either fab a new drive shaft or credit you some reasonable amount for his mistake. If you didn't specify the u-joint size and type, that's just a lesson learned and you won't really notice once you get the drive shaft mounted in the car. The bottom line is that there is only 250 lb-ft difference in yield strength between the two and at 1,600 lb-ft the 1320 should be plenty strong enough for any engine you couple to a standard T-5 trans as they are not the 1st choice for big torque engines anyway.

[jwhit]

Let us know how the corrective action you're planning comes out. It's not uncommon to get a vibration from too loose a fit between the yoke barrel and bushing.

As for the 1310 u-joints vs the 1320, if you spec'd 1320 and the builder gave you 1310 make him either fab a new drive shaft or credit you some reasonable amount for his mistake. If you didn't specify the u-joint size and type, that's just a lesson learned and you won't really notice once you get the drive shaft mounted in the car. The bottom line is that there is only 250 lb-ft difference in yield strength between the two and at 1,600 lb-ft the 1320 should be plenty strong enough for any engine you couple to a standard T-5 trans as they are not the 1st choice for big torque engines anyway.

I will follow up when i get bushing and yoke replaced i got new bush in today and it seems super tight on yoke so the yoke maybe fine just bushing problem .also on the driveshaft builder i didnt tell him what to use but i did give him a copy of build sheet from ffr
which clearly states 1330 joints only response i got back was that 1310 stuff was more common and that i would never break it

[jwhit]

here is follow up
new yoke and new tail shaft bushing installed very little pay now . its was improvement