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Q: TH350 trans wear and 60' inconsistency
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DRR Trophy
Picture of Bad Nusz
posted
I run a TH350 transmission in my S10 drag truck. I had to get it overhauled half-way through the 2015 season, by a regular, non-racing transmission shop.
They put in some sort of heavy-duty friction parts, plus a TCI 36-element sprag.

It may be my imagination but it seems that my 60' times are not as consistent as they once were.

Could my transmission be worn out already? I probably make about 200 or so passes per season, with my 11.90 in the quarter and 7.50 in the eighth truck. Footbrake only.

I'm facing a three-week break from racing soon, and was thinking of pulling the transmission to have that same shop put it on their transmission dyno. But I just learned that their tranny dyno is broke down and will be for a few months yet.

It has about 8 1/2 seasons on it, so perhaps I've answered my own question, lol.

Thank you,
T.

This message has been edited. Last edited by: Bad Nusz,
 
Posts: 367 | Location: Sioux Falls, SD | Registered: March 17, 2018Reply With QuoteReport This Post
DRR Pro
Picture of Eman
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Time to buy the book and do it yourself. T350 isn't hard to build. Biggest wear is in the bushings and thrust washers. No real special tools required. You can make a stand or I've build them standing up on a 5 gal bucket with a flywheel on the bucket so the output shaft can pass through.
 
Posts: 1479 | Location: E TN | Registered: February 13, 2009Reply With QuoteReport This Post
DRR Pro
Picture of Goob
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quote:
Originally posted by Bad Nusz:
It may be my imagination but it seems that my 60' times are not as consistent as they once were.


To effect the 60' only, it narrows things down to tires (sidewalls), torque converter, and carb/tune, in my thoughts.

Check your incremental splits if you suspect trans wear or malfunctions down track, your 60' is most likely all done in low range.


"Despite the high cost of living, it remains popular."
Dave Cook
N375
 
Posts: 1703 | Location: Indy | Registered: November 21, 2008Reply With QuoteReport This Post
DRR Trophy
Picture of Bad Nusz
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quote:
Originally posted by Eman:
Time to buy the book and do it yourself. T350 isn't hard to build. Biggest wear is in the bushings and thrust washers. No real special tools required. You can make a stand or I've build them standing up on a 5 gal bucket with a flywheel on the bucket so the output shaft can pass through.

Thanks, Eman. I think I may have a copy of the book, plus there are gobs of YouTube videos on the subject online.
I have a complete TH350 trans that I got for free at a rummage sale; it might be good to work on that for a spare.
I have a 2,000 lb. engine stand and can probably fab up some sort of adapter for it.
The problem I have is that I don't have any sort of 'test mule' to test the newly built tranny.
A few of my racing buds were trained as pro mechanics, and they even send their race transmissions to tranny shops.

Thx again.
T.
 
Posts: 367 | Location: Sioux Falls, SD | Registered: March 17, 2018Reply With QuoteReport This Post
DRR Trophy
Picture of Bad Nusz
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quote:
Originally posted by Goob:
quote:
Originally posted by Bad Nusz:
It may be my imagination but it seems that my 60' times are not as consistent as they once were.


To effect the 60' only, it narrows things down to tires (sidewalls), torque converter, and carb/tune, in my thoughts.

Check your incremental splits if you suspect trans wear or malfunctions down track, your 60' is most likely all done in low range.


Thank you much, Goob.
You know, I'd never before paid much attention to the incremental splits, save for the 1,000' to 1/4 mi. split.

This weekend though I made a spreadsheet of all those incremental times and ran some numbers. I was astonished at what I'd learned.

For example, I made four passes on Saturday, and I figured out the extreme spreads from high to low for each point along the track.
From my best 60' time to my worst the difference was .08 second.
The extreme spread of my 60' to 330' split was .02 second.
For the 330' to 1/8 mi. it was .007 second.
For the 1/8 mi. to 1,000' mark the extreme spread of the split times was .01 second.
And the split times of the 1,000' to 1/4 mi. was no more than .008 second, from fastest to slowest.

I'm wondering about transmission temperature; I've traditionally had a hard time getting heat into the tranny.

Later on Sunday, as I was double-entered and was making time trials and elimination runs that were close together, the S10 settled down a lot and started to run much more consistently. I've seen this happen several times before, and am only now thinking that the trans was too cool to find it's 'happy place'.

Unfortunately my transmission temp gauge is not working, so that's a project for this week.

Lol, I found in my garage a 200-watt oil pan warmer and may try it out at the track to try to get my transmission warmed up faster to run consistently.

I'm also seriously considering a transmission cooler thermostat, set at 180 degrees or so.

FWIW, I've been running cheap, synthetic tranny fluid.

Thanks again
 
Posts: 367 | Location: Sioux Falls, SD | Registered: March 17, 2018Reply With QuoteReport This Post
DRR Sportsman
Picture of 329L
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As a transmission repair shop, i can tell you the WORST thing you could ever do is put a thermostat on a transmission cooler line. Normally they wont even open until transmission gets over 150+ degrees, also, when a transmission starts having issues, 90% of the time, the trash is flowing in the cooler circuit, and once trash gets into a thermostat, it will pack up and really over heat.


Jeremiah Hall
 
Posts: 712 | Location: Evansville, IN | Registered: February 24, 2010Reply With QuoteReport This Post
DRR Trophy
Picture of Bad Nusz
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quote:
Originally posted by 329L:
As a transmission repair shop, i can tell you the WORST thing you could ever do is put a thermostat on a transmission cooler line. Normally they wont even open until transmission gets over 150+ degrees, also, when a transmission starts having issues, 90% of the time, the trash is flowing in the cooler circuit, and once trash gets into a thermostat, it will pack up and really over heat.

Okay, thank you for that warning; I'll have to reconsider that idea.
Some others here run them I believe, but I didn't realize they could be that troublesome.
I thought too that some new cars use them even?

At any rate, my next move will be to re-install a torque converter cover on the transmission to hold in a little heat.
With my more modest performing combo and a lower stall converter, too much heat has never really been a problem for me.
Thx again.
 
Posts: 367 | Location: Sioux Falls, SD | Registered: March 17, 2018Reply With QuoteReport This Post



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