t18a96 turbo jet

[sub22b]

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hey guys sorry for the late pics bit here is one of the problems. The thrust washer if thats what you want to call has big grooves and is worn down so the shaft and comp wheel moves forward and rubs on comp housing.

[racket]

Hi

That "thrust washer" in the pic is the "unloaded" part of the thrust bearing unit , the thrust bearing is the one on the backside of the backplate to the comp housing.

The other piece in the pic is the rotating oil slinger whose front face is generally forced against the thrust bearing on the back of the compressor part of the turbo .

If you have grooves in the face of the rotating steel component then the actual thrust bearing will be severely worn , an overhaul kit will put things right

Could you please post a pic of the thrust washer .

Cheers
John

[sub22b]

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Is this the item in question?  Now if it is how do i remove it from the comp backing plate?

[racket]

Hi

Yep , thats your actual thrust bearing , its riveted to the backplate because generally once the thrust bearing is worn badly theres other damage to the cast iron backplate casting making it unserviceable , so you need to replace it as well .

Anders and I both use similar bearings, but have the thrust bearing fitted to the rear of our comp diffuser wall , I use 3 screws to hold mine in place , also we use the upgraded 6 pad version rather than your 3 pad one for more thrust bearing capability which helps when running our higher comp pressures ( P2) .

Axial clearance on the thrust bearing is between 0.003 - 0.010", quite a bit of endfloat .

Cheers
John

[sub22b]

Hi john i have had a look at the steel comp backing plate and there is no damage. Do you think i will be able to remove the thrust washer and refit the new one wit with rivets? Or screws? And i take it there are three rivets one between each pad?




Cheers nick

[racket]

Hi Nick

Yep , try and remove the 3 rivets .

But before you do that , could you let me know what was the endfloat in the assembly , the 3 pads have wear/grooves , but they aren't really badly worn down , certainly not as bad as some I've seen.

Was the comp wheel scraping the inside of the front cover ??

More info please .

Cheers
John

[sub22b]

Hi john unfortunately I don't have the gear to test the end float. The comp wheel was just touching the comp housing but only when the combustor pressure was higher than idle pressure at idle there was no issue with clearance. I will talk to the company I am getting the rebuild kit from and see if it comes with the thrust washer before I remove the rivets just incase they can not supply one.


cheers Nick

[racket]

Hi Nick

OK , that makes sense , once theres pressure being built the air loads on the rear side of the comp wheel force it forward against its shroud.

Theres a good chance the kit will not contain the thrust bearing as its a part of the backplate , but it should be possible to order just the thrust bearing separate to the overhaul kit.

Also check with them if the later model 6 pad thrust bearing fits as it has a great load capacity .

Cheers
John

[sub22b]

Hi john i got the thrust washer out and fitted the new one had to drill three new holes for the rivets as i could not drill out the origional ones. But it is all back together and is ready for the first run this weekend.


cheers Nick

[racket]

Hi Nick

Good one , all the best for the test run :-)

Cheers
John

[sub22b]

Hi guys test runs went well it runs better than it ever did. Now with my gokart idea i may need to make things smaller. Would there be any way i could make the combustion chamber smaller??

[smithy1]

Hi Nick,
Why make it smaller for a kart.....why not have a huge one like mine:



Cheers,
Smithy.

[racket]

Hi Nick

With a 4.5" inducer - 15.9 sq inches of inlet , we need ~3 times that for the flametube cross section , so ~47.7 sq ins or ~7.9 inch ID , and as your comp wheel is a very large 81 Trim ( 4.5 /5" wheel ) its not going to be a high pressure wheel so you need to have the full 3 times area to keep air speeds low enough in the primary zone .

The outer can could be made a tad smaller but I wouldn't be going below ~10 inches so as to allow a reasonable flow area around the flametube , you'll be shifting a lot of CFM of air so good aerodynamic flow passageways are a must.

Better to have a generously proportioned flametube that will produce good combustion than a compact one that could give nothing but problems .

Cheers
John

[sub22b]

Hi guys cheers for the info. i have double checked my combustion chamber size after a few mods its 280mm in diameter and 530mm in length it is actually a old air compressor tank chopped up so the whole engine has a fair bit of weight to it so im worried a gokart may not be able to handle it. how much thrust would u estimate this engine putting out.


cheers Nick

[racket]

Hi Nick

As you'll probably be limited to 30 psi P2 as a maximum , the outer can could be relatively thin , 1.6mm - 1/16" sheet will hold the pressure .

Your 530 mm length is OK .

Smithies GT6041 combustor is pretty heavy duty and along with the very heavy turbo its a sizeable weight hanging off the kart , but it survives .

Cheers
John