Noisy differential and fuel additive questions

[83Pbass]

Sunny south Florida, temperature in the mid 40's running the TR down A1A doesn't get any better!!

A couple of questions for the collective:

I have a 65' live axle TR4A. Past month or so, car has developed a whine from the differential most notable in 4th gear. Checked gear oil level and it was very low. Added oil but still whining, have I damaged my differential? Can I continue to drive the car and just let it sing a bit? It appears rebuilt differentials run ~ $1,000 or is it just a matter of shimming it up? Realy do not want to go into the differential at this time.

Do you guys use a lead fuel additive I have been running Premium unleaded with no additive for about 3,000 miles

Thanks,

Jim

 

[shining_armor]

Address any leak and refill with synthetic gear lube. Personal preference is Amsoil 75W-140 Extreme Gear. Its GL5 but safe for GL4 applications. If it doesn't help you're out about $20.

Lead additive isn't a bad idea if you don't have hardened seats. Not likely 3,000 miles did significant damage.

Ernie

 

[TR3driver]

The synthetic lube is worth a try. IMO it won't solve the whine, but it may help the differential not fail any worse until you've saved your nickels & dimes for a rebuild. I use Valvoline Synpower 75W90 which, like the Amsoil, is GL5 but safe for the brass thrust washers. Unlike the Amsoil though, it's only about $8 @ Autozone.

OTOH I'm getting really tired of listening to mine whine, so I'm planning on rebuilding it myself (with 3.45 gears & LSD) sooner rather than later.

I've covered over 200,000 miles without a lead additive. Only problem I had was with a head that had hardened seats installed; so I replaced it with another head with the original seats still in it.

You'll know if you are having a problem, because one or more of the valves will be too tight when you adjust them. In my case, the seat was failing so fast that I had to readjust every few thousand miles or the engine wouldn't idle.

 

[Don Elliott]

Twice in the past 21 years, the differential started to whine. It just got worse and worse. The last time I was 400 miles from home but I made it. Both times the oil had been low. Each time, I took out the rear axle (1958 TR3A) and took it to a specialty diff shop to repair it. Both times they had to change the crown as well as the pinion gears. They changed the bearings and seals too. Each time cost me about $1000.00.

In 1990, I also re-built my 1991 cc TR3A engine. Then Canada announced no more leaded gas, so I ran it like that with no additives for 43,000 miles before putting in new inserts for the 4 exhaust valves + 8 new valves and 8 new guides.

The valve seats in the bare cast iron head were receding about 0.010" per month for the last 5 months. I was checking the valve gaps every 1000 miles and the gap was closing down to almost 0.002" per month. This told me it was time (May 2000) to do the inserts. Since then, I have had no issues and hardly find any need to re-gap the clearances since then (61,000 more miles).

 

[Geo Hahn]

I had excessive valve recession using unleaded in my TR4. Problem surfaced after a 5-hour 80 mph drive -- perhaps that sort of use aggravated or accelerated the recession. As Randall noted -- when I went to adjsut the valves the problem was obvious, had one exhaust valve I simply could not adjust to spec.

Now have harden seats in both TRs.

 

[TR3driver]

Each time, I took out the rear axle (1958 TR3A) and took it to a specialty diff shop to repair it. Both times they had to change the crown as well as the pinion gears.

The gears are a matched set and should always be replaced together.

One point I forgot to mention : If you do have a problem with VSR, the bit that erodes is the same bit that will be cut away anyway to install inserts. In other words, the cost to install hardened seats will be the same whether you do it now or wait until you have a problem.

IMO if the seats were recently resurfaced, then your chances of having a problem with VSR are higher. Being run on leaded fuel in the past appears to harden the surface of the seat enough that it may survive for a long time with unleaded. But resurfacing the seats removes the (thin) hardened layer.

 

[JerryVV]

Being run on leaded fuel in the past appears to harden the surface of the seat enough that it may survive for a long time with unleaded



Maybe that's why mine are lasting so long. The head has not been touched in maybe 40+ years. Compression is down a bit so I'm going to do a Valve Job over this winter and have the seats installed along with new valves. Some say why........because I want to!

 

[83Pbass]

Thanks Guys,

So if I have it straight:

OK to continue driving the car as long as I can tolerate the whining. Been married 25 yrs so......

I'll try a heavier synthetic gear oil.

Sounds like it would not hurt to use a lead fuel additive but probably OK either way.

One last question, can ya tell this is my first TR? With the cooler weather, the car runs really strong when cold and on choke. As the engine warms up and I disengage the choke, I seem to lose power. Carbs to lean ??

Thanks

 

[TR3driver]

IMO, most of the "lead replacement" additives are worthless. Probably won't hurt anything except your wallet, though. BMIHT ran some controlled tests back when the UK first got unleaded, and they said only 2 out of 11 or so tested products actually reduced VSR. Unfortunately, those two don't seem to be available in the US (Millers was one, I forget the other).

Losing power could be lean mixture, or just your letting the choke off too soon. The temperature shown on the gauge doesn't really reflect the temperature at the carbs. Another possibility is an ignition system that doesn't like being hot.

And of course there will always be a tiny amount of power drop, because the air going into the engine is not as dense once it's been warmed up.

 

[Don Elliott]

Quote from above "One last question, can ya tell this is my first TR? "

I'm still driving my first TR3A that I bought brand new over 53 years ago and I'm still learning a lot about it - and TRs in general.