Triumph Repair: TR7 4 Speed synchro hub measurement Photo, thick oil, gear oil

Question

Synchro hub measuremen   QUESTION: Howard,

  Here's the photo I forgot to attach to my last question.

  Thanks,

  Steve.

ANSWER: Hi Steve,
The books quote 19 to 27 lb to shift the hub but I never tested one other than to hand move them and never found any that had weak springs in the hub. What we often found was the end play was often excessive due to ware on the bushings and thrust washers. We also had to examine very closely the teeth of the splines of the hub and gears as they would get beveled and thus walk out under hard acceleration and even a few on decel. This was usually due to a dragging clutch and/or a driver who didn't use correct shifting practices. Read my tech tip on how to make a straight stick transmission last. http://mg-tri-jag.net/tech4.htm

Howard

---------- FOLLOW-UP ----------

QUESTION: Howard,

   All the splines look brand new, but I just discovered both brass synchro rings for 3rd/4th are broken.  When I get this thing back together - do you have any opinion on the best oil to use ?  Is there any break in period & appropriate oil like after an engine is rebuilt, would you recommend synthetic ?
  
   Thanks,

   Steve.

Answer
Hi Steve,
Before BLM, we used engine oil in all the British car gearboxes and when BLM came into power they advised all the dealerships to use gear oil. Within a couple of weeks after we did that, the cars were lined up in our doorway every day complaining about gear clash when shifting and especially in the morning. We switched back to engine oil and just never told BLM.

The syncro operates by the teeth in the ring grabs traction on the cone of the gear to get the hub and the gear spinning at the same speed. With the thick gear oil the thick oil gets trapped between the teeth and holds the teeth off for a split second when shifting and allows the gear to spin inside of the hub which causes the gear clash.

In the early 70s Dodge also had the same problem with some of their gearboxes and they change the gear oil for ATF.

I have never tried the synthetic oil in a gearbox so I can't advise you on that. I did have a customer put STP oil treatment in his gearbox once and the syncros didn't work at all. We drained and flushed it several times before we got them to work again.

Howard