• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

thrust washer material

Share this page

71tr

71tr

Jedi Warrior
Offline
Okay we all know of the trials and tribulations of the TR6 engine thrust washer design. My understanding is that these thrust washers are made of bronze over steel. I have seen an aftermarket product of solid brass which I've always thought was a good bearing surface. Any thoughts on this?

Now lets go to the gearbox. I'm in the midst of rebuilding my gearbox and pulled the countershaft thrust washers yesterday. The rear washer was in good shape, the front washer has seen a lot of wear. I'd like to replace this but the TRF glovebox catalog states that while original gearbox thrust washers were bronze over steel new aftermarket washers are solid brass and could damage your gearbox. Does anyone have thoughts or experience regarding bronze/steel vs brass thrust washers for both the engine and gearbox applications?
 
I installed a 0.098-inch thick Scott Helms' thrust washer at the rear over 8,000 miles ago. I reused my old rear TW at the front. My crank endfloat is unchanged from the install spec (0.005 inches). The TW material is a special bronze alloy that was extensively researched by Scott and it does not feature cladding that is the weak point in the OEM design.
 
As far as use of bronze as a TW material in a gearbox, all I know is that GL3/GL4 gear oil is incompatible with 'brassy' metals (the oil will eventually dissolve the copper component of brass). Perhaps that is the basis for TRF's concern over solid brass TWs. A steel TW that is clad with brass is subject to the same concern, but at least you'll have a steel substrate that will remain.
 
My understanding (I could be wrong) is that GL4 is compatible with bronze and GL5 (the current commonly available stuff) isn't. However, for an engine thrust washer, this wouldn't be a concern.
 
You are correct Eric, and my post is backwards. If you use 'modern' gear lubricants in your gearbox, you need to be concerned about corrosive attack on bronze.
 
Yes, that is correct. GL4 good, GL5 bad in the gearbox. The Scott Helms bronze (not brass) thrust washer replacement is what I had in mind for my engine rebuild as well. Maybe I can convince Scott to make a bronze gearbox thrust washer as well?
 
Brass is considerably softer than Bronze. Bronze has much better load, lubrication, heat & deflection characteristics as well.

I'm not sure what would be better in the trany,as I have never rebuilt one (yet).

I have used the standard Crankshaft thrust washers with flawless performance over many tough miles. The key here is to set your end play tighter than spec, as low as .003 & not more than .005. the more the crank can slide back & forth , the faster it can wear the washer. .003 clearance still leaves room for lubrication. If you have abnormal TW wear look for imperfections on the mateing surfaces.
 
TRboost, you are correct, setting of endfloat is crucial. Interesting observation with the gearbox forward (larger) thrustwasher. Not only is the wear side (toward gears) worn but also the backside (steel) is worn. Turns out the original builder or last rebuilder of this box used an awl or other sharp object to roughen-up the aluminum face of the gearbox to raise it's surface undoubtedly to reduce endfloat. I have read of this technique. In reality while reducing the endfloat the thrustwasher spins against this aluminum porcupine which eats away at the steel backing. Talk about being caught between a rock and a hard place.
 
Back
Top