Vibrations fixed. 951.

[Kelly]

After putting my 951 back into service recently I discovered an error I had made many years ago, aka 14 years ago. The car hadn't run balance belts since 2003 and that was when I made the error. In Apr 2017 I put the balance belts back on and found the engine had excessive vibrations. A check showed the gears were 1 notch off correct alignment but fixing that didn't fix he problem. For a while I thought the issue might be the Torque tube, but I've checked that and its fine. A revisit and closer inspection of the Balance shafts revealed I'd put the upper drive gear on 180 Degrees out of phase. The tell was the fact that the "0" on the gear face appeared in the square window, not in the round window. Doh!  All sorted now but what a long time from error to discovery.

FWIW the lower balance shaft gear is installed correctly when the zero appears in the square window.

Now I'm looking forwards to a much smoother track day next time out, just waiting on parts to rebuild the TT now.

 

 

[Jason E]

Great job.  I'm excited re your TT rebuild.  Bring on the details please when you crack in.  Absolutely can't wait to hear about those bearings.

[Pauly]

When you rebuild the TT. save your self a headache and use the super bearings.

http://www.blackseard.com/site/index.php?option=com_content&view=article&id=6&Itemid=9

I did the whole pull the cases apart and use FAG 6006ZR c4 bearings with "derlin" bushes. I think 2 of the bearings moved on installation and wore the bearing out and wore the bushings out allowing the whole shaft to move. 

The 2nd time i bought SNR bearings
SNR 6006 FT150ZZ.
Max recommended Temp: 150°c
Max recommended RPM: 11000rpm

Which are a lot more expensive and durable. We used a different plastic, forgot what but it worked until one unit had moved in the installation and this time the plastic bush pulled itself out of the bearing causing the worst vibration i've ever felt. 

The 3rd time we reused the SNR bearings as they where perfect still. made out own housings, much wider. that is still in the car now. When we where making them, i realised i should be using bigger bearings so i could make thicker inner bushings to hold the TT. Which i then realised that's exactly what the blacksea bearings are. bigger sized bearings & wider. 

[Kelly]

Wow Pauly what a hassle you had! When I was researching my TT rebuild options I came across the superbesrings and liked the design better than anything else I'd seen. Have been discussing a few things with Constantine and placed the order a week or so ago. I'm expecting delivery of the superbearings in the next few days. So hopefully I'll be putting the car back together next weekend.

[Kelly]

The prospects  for fewer vibrations are getting closer. These superbearings  are pleasingly meaty, an the thought of taking up the play between the shifter and shift tube with the only944 needle bearing shifter is one I am looking forwards too. I will be honest though and put it out there that there wasn't much play to begin with as my shifter had been rebuilt a while back and the SSK had already snugged things up nicely. So I am wondering if the combination will feel too tight if that is possible. I guess I'll know in a couple of weeks.

 

[Jason E]

Hello again Kelly,

I just watched a couple of your brief youtube videos on knocking your bearings out of your TT -well done.  I was interested to see the pilot bearing video you did as well as it showed a bit of minor wear on the spline.  I have just acquired a donor 1988 turbo TT that I can install into my S2 & get rid of the problematic split seam TT.  I was interested as the donor TT is in good condition but has a similar amount of wear on the spline which was worrying me slightly.  A knowledgeable mate who is going to help me rebuild the TT looked at the photos of the wear on the spline & declared it within specs & not a problem.  It makes me feel good that yours seems to have a similar amount of wear & you are going ahead with your rebuild.  I sent off an email today to Constantine at Black Sea re the super bearings to get an idea of freight & suitable bearings for my job.  I look forward to seeing more of your build info.

cheers,

Jason  

[Kelly]

Hi Jason,  I started the bearing extraction with a threaded rod draw through, but the rod became damaged after a while as the nut threads deteriorated. So I knocked the bearings part way and then completed the final distance using a threaded rod draw through after I cut the rod behind the damaged threads. I posted pics and a breakdown on Rennlist here https://rennlist.com/forums/944-turbo-and-turbo-s-forum/992145-torque-tube-rebuild-pics-video.html

Good job on locating a non split TT. I expect that'll serve as a much better basis for your rebuild.

Next on my to do list is cleaning the TT and prepping it for the new bearings. Time is running a bit short as I hope to be back on track on the 9th and I've got a few other things chewing up my time.