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Author Topic: Transmission Life Expectancy
rmgroth Series Champ
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What kind of life are most of you getting out of transmissions?

I put a new Drago trans in my car this spring, in my freshly built '99. During the Putnam 3 hour Enduro with NASA this past Friday I lost 3rd gear, it held together and I finished the race in 4th gear, but there are definitely some pieces floating around inside. At the time of failure it had approximately 44 hours on it. It's never been shifted hard/without clutch or abused as far as my standard of "abused", and has had regular fluid changes with MTL every 12 hours.

I guess my question is this typical failure? I am headed to Atlanta for the 8 hour enduro in 7 weeks and need to get it fixed!

Thanks

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Ryan Groth
#52 SM
NASA Midwest Series Director

Keith in WA Verified Driver Made Donation to Website
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I'm told by the local SM gurus that about one season is all if you're driving it hard. 44 hrs doesn't sound too bad. Baby it shifting and it will last longer but you'll watch the pointy end getting farther and farther away.

I put a low milage used 99 trans in my car this season. Now it sounds like scratching a needle across a record every time I shift to 3rd.

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Keith Novak
(Will work for tires)

davew Verified Driver Made Donation to Website
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Transmissions are TOTALLY driver controlled, with rare exception of a parts failure.

Most failures are 3rd gear. 4th sometimes on tracks that use 5th gear.

The issue is improper down shifting. Heel/toe rev matching helps. But the biggest cause of blowed up gears is early downshifts.

A gear tooth is shaped like this /l, with one side almost verticle and the other side angled. Under load the force is applied to the vericle side of the tooth. This is the strong side.

When you down shift too early, the rear wheels actually drive the engine. This puts force on the angled side or weak side. The teeth actually climb up the "ramp" and put the force on the tip of the tooth. Which is even weaker. Do this too many times and the tooth breaks.

I coach all my drivers to: brake, wait, wait wait, wait, downshift-turn. Thsi saves a lot of gearboxes
DAve

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Dave Lewis
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Year : 1991
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quote:
Originally posted by davew:
Transmissions are TOTALLY driver controlled, with rare exception of a parts failure.

Most failures are 3rd gear. 4th sometimes on tracks that use 5th gear.

The issue is improper down shifting. Heel/toe rev matching helps. But the biggest cause of blowed up gears is early downshifts.

A gear tooth is shaped like this /l, with one side almost verticle and the other side angled. Under load the force is applied to the vericle side of the tooth. This is the strong side.

When you down shift too early, the rear wheels actually drive the engine. This puts force on the angled side or weak side. The teeth actually climb up the "ramp" and put the force on the tip of the tooth. Which is even weaker. Do this too many times and the tooth breaks.

I coach all my drivers to: brake, wait, wait wait, wait, downshift-turn. Thsi saves a lot of gearboxes
DAve

That man knows what he is talking about.

Shop Teacher
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Region: SF Nor Cal
Car #: #39
Year : 1990
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I have built many of these transmissions and I have NEVER seen a broken gear. Most of the time its a broken Blocker Ring or shift fork. They are not hard to rebuild, but most of the time I find that the bushing at the bottom of the shifter gets worn and they shift sloppy. Replace the bushing really helps them shift smoother. Part #0398-17-462A. Shifting with a soft touch helps them get into gear easier. Try not to force the shifter.
AL

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Al Angulo
Auto Instructor
Ford Senior Master Tech
ASE Master Tech

Qik Nip Verified Driver Made Donation to Website Series Champ
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If it's a transmission in a certain red 1990 with white stripes, (driven by me), the average life expectancy seems to be about one season! For other (spelled gifted) drivers, they seem to last forever. But it can't be me can it?
Rick

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Fortune Cookie Racing SM 60
Directions for use: Race, Rumple, Repair ... Repeat!

Motor City Hamilton
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Not trying to jinx myself, but I'm at 3 seasons on mine now and still super smooth. Need to pull the crate motor this winter after three seasons, so probably a good time to have the trans looked at as well?

Qik Nip Verified Driver Made Donation to Website Series Champ
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quote:
Originally posted by Motor City Hamilton:
Not trying to jinx myself, but I'm at 3 seasons on mine now and still super smooth. Need to pull the crate motor this winter after three seasons, so probably a good time to have the trans looked at as well?

Maybe because your legs are so damn long, you use more clutch than we "normal" sized drivers?
Rick
P.S. Where'd you go yesterday? I looked back and you were in P4 and then when I looked again you waz gone!

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Fortune Cookie Racing SM 60
Directions for use: Race, Rumple, Repair ... Repeat!

davew Verified Driver Made Donation to Website
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Al, I can send you a box of broken gears with your next order!!!!!!

I have had drivers who would destroy a trans in 1/2 a season. Others go 3-4 years. That is why I said it is driver controlled.

Dave

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Advanced Autosports, The Midwests leader in Spec Miata Service, Parts and Rentals
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www.advanced-autosports.com

Motor City Hamilton
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quote:
Originally posted by Qik Nip:
quote:
Originally posted by Motor City Hamilton:
Not trying to jinx myself, but I'm at 3 seasons on mine now and still super smooth. Need to pull the crate motor this winter after three seasons, so probably a good time to have the trans looked at as well?

Maybe because your legs are so damn long, you use more clutch than we "normal" sized drivers?
Rick
P.S. Where'd you go yesterday? I looked back and you were in P4 and then when I looked again you waz gone!

I made the pass into 4th, then got some help making the corner over Madness. Brian just touched my back bumper at the crest of the hill. Did a couple of loops, saved it and got back on track to stay in 6th. Brian stopped by my pits right after to apologize. The way it should be. He drove right to my pit spot and manned up to the mistake. We shook hands and will race each other close again all next season. Class guy, in my opinion.

joe v
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What Dave said X 2

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Be Ready! "To Win the race" before you load the car.

Qik Nip Verified Driver Made Donation to Website Series Champ
Loose Member '09 & '10 Great Lakes Regional Points Champion

Region: Cincinnati Great Lakes
Car #: 60
Year : 1990
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quote:
Originally posted by Motor City Hamilton:
quote:
Originally posted by Qik Nip:
quote:
Originally posted by Motor City Hamilton:
Not trying to jinx myself, but I'm at 3 seasons on mine now and still super smooth. Need to pull the crate motor this winter after three seasons, so probably a good time to have the trans looked at as well?

Maybe because your legs are so damn long, you use more clutch than we "normal" sized drivers?
Rick
P.S. Where'd you go yesterday? I looked back and you were in P4 and then when I looked again you waz gone!

I made the pass into 4th, then got some help making the corner over Madness. Brian just touched my back bumper at the crest of the hill. Did a couple of loops, saved it and got back on track to stay in 6th. Brian stopped by my pits right after to apologize. The way it should be. He drove right to my pit spot and manned up to the mistake. We shook hands and will race each other close again all next season. Class guy, in my opinion.
That he is. Sorry your guys made contact.
Rick

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Fortune Cookie Racing SM 60
Directions for use: Race, Rumple, Repair ... Repeat!

Scott Zetterstrom Verified Driver
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Year : 1990
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I'm ending my third season with this tranny and I think the previous owner put 2 years on it before that. It is just now showing problems.

I have a question for any gurus. Do you see layshaft bearing issues or thrust bearing issues on these trannies?

Thanks,

Scott

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#13 SSM
ME Solutions LLC
Windsor Customs Racing
PBC Automotive

Chris Windsor Verified Driver Made Donation to Website Series Champ
windsorcustoms.com

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Bearings usually have no issues

And What Dave said +1

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2011 Season schedule coming soon
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CP Verified Driver
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Are there any special tools required to take a trans apart to replace the 3rd gear shift fork (my spare is "ker-chunking" on downshifts into 3rd)? Somebody mentioned a long gear puller for one of the seals in there. This may become a winter project.

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-Cy
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Rt1 AutoMile - Norwood, MA
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Your fork may be bad, but it is the syncro that is "ker-chunking"

Several special tools required

--------------------
Advanced Autosports, The Midwests leader in Spec Miata Service, Parts and Rentals
608-313-1230
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www.advanced-autosports.com

   

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