[Fot] Endurance TR6 at COTA

[Bob Kramer]

Pulled the diff tonight and got a couple of surprises. We were thinking outer hub bearing was making our noise but later assumed it was the diff since it eventually failed. Tonight I found two problems. 

The drivers side rear sway bar link broke off at the ball head. These are similar to the stock front TR6 links and it hid itself pretty well. 
I'm not sure when it happened since we had six drivers but no one complained about handling changing. 

Now the diff. It was welded at the spiders with a lot less welding than I've done in ones I've built, and not good penetration. The welds broke and the spiders started doing their thing. That's probably our noise. It looks to have shed chunks of weld and after a while the chunks started taking out teeth. I do not see the peeled away section of pinion gear I have seen in the past. It and the ring gear were chewed up. Smaller broken pieces allowed the diff to keep rolling. 

 I drove it into the garage tonight.

So these will be simple fixes, if building a another diff can be called simple. I think I'll build two!

The oil smelled like death, but I think that is a result of the failure not the cause. The finned cover will help in the future. 



Sent from my iPhone

> On Aug 7, 2016, at 8:52 AM, Greg Blake <gblake58tr3 at icloud.com> wrote:
> 
> Just a quick update. We were beaten by equipment at approximately 1:30 yesterday afternoon. Although certainly disappointed not to take the flag, we were all pretty proud of the old girl. She put in a solid 8 hours Friday and another 5.5 on Saturday. 
> 
> We were racing cars from the past two decades with a few exceptions. Out of 100+ cars, there was a pair of 60s mustangs, an Opel with a LS motor and us. Friday we finished 47th with 114 laps and yesterday 73 with 81 laps.  We were averaging 3:10s around the full F1 course. As a point of reference, the leaders were running consistent 2:50s. A certain pair of drivers on our team were clipping close to 2 minute laps and both swore they weren't pushing too hard, maybe.
> 
> We were running with 18 month old 200 tried wear tires that had been flat spotted at the last race. This became very noticeable at 100+ down the straights. We again limited RPMs to save the motor.  With a 3.7 rear end and no OD we were full speed about 1/2 into the straights.  This is where the leaders would pass us.
> 
> Some of you recall last summer we raced this car with WRL in the June Texas heat and had some issues with lower than desirable oil pressures and a diff that boiling its juice. 
> 
> For the engine side of things:  This time around we installed an oil cooler and used VR1 full synthetic. Oil pressure at full tilt was 90+ all weekend and 40-50 at idle at pit stops.  Problem solved. I am very impressed with synthetic motor oil. The oil still looks brand new after 13+ hours of racing. I know from past endurance races with Dino oil, it would be pitch black and stinky at this point. 
> 
> On the diff side (not so good):  after boiling the Dino based lubricant last summer, we opted to simply switch to synthetic. This seemed to be working on Friday as our diff catch can stayed dry. We had some terrible noises coming from the rear end on Friday that we thought were hub bearings going out.  The hub bearings are still suspect and will require attention. But our more serious problem was heat in the diff. The diff puked at about 1:30 and our day was done. 
> 
> Last summer Keith mention his solution was a diff cooler and I think we will be heading down that path for the next endurance race. Who knows, we may end up with a triumph that can go the distance, eventually. 
> 
> We were so close this time.
> 
> Sent from my iPhone
> 
>> On Aug 5, 2016, at 5:53 PM, Greg Blake <gblake58tr3 at icloud.com> wrote:
>> 
>> We finished the day strong. Only a brief stint in the garage to check some bearings. Other than that, ran all day long in the Texas heat. Right now 47th out 100+
>> 
>> Notice the only hood down in the pic?
>> 
>> 
>> 
>> <IMG_0793.JPG>
>> 
>> 
>> 
>> Sent from my iPhone
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