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4T65e-HD main drive chains slipping. by mental floss
Started on: 12-24-2014 12:45 AM
Replies: 8 (675 views)
Last post by: Fieroking on 01-07-2015 02:20 AM
mental floss
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Report this Post12-24-2014 12:45 AM Click Here to See the Profile for mental flossSend a Private Message to mental flossEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have a question about replacing the main drive chains/gears in the trans. This is a complete GM car w/3800SC for a swap, but it had this drive chain condition when purchased. The chains slip so badly that you can't test the performance of the engine at all. Going up a hill, if you don't feather the gas, it will jump teeth with ease. So, if just the drive chains/drive gears are replaced, does that mean there are still metal shavings floating through the entire transmission via the fluid where bits of gear have been ground off? Anyone have experience with this issue and had success from the trans without a full rebuild? The car needs to be mobile until next year when there's enough time for the engine/trans removal and swap.
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Report this Post12-24-2014 09:14 PM Click Here to See the Profile for virtuetoviceSend a Private Message to virtuetoviceEdit/Delete MessageReply w/QuoteDirect Link to This Post
You sure the teeth are jumping? Misfires on the engine can cause a very similar feeling.
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mental floss
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Report this Post12-24-2014 09:18 PM Click Here to See the Profile for mental flossSend a Private Message to mental flossEdit/Delete MessageReply w/QuoteDirect Link to This Post
Positive. Very easy to tell the difference. I really can't imagine someone could confuse the two. IMO, a person would have to have the HVAC blower on full with the stereo at top volume to confuse the two. EDIT: On second thought, that wouldn't work either. The process of not moving while the engine and tach are revved to the red line should indicate the difference.

[This message has been edited by mental floss (edited 12-24-2014).]

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Fieroking
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Report this Post12-25-2014 01:48 AM Click Here to See the Profile for FierokingClick Here to visit Fieroking's HomePageClick Here to Email FierokingSend a Private Message to FierokingEdit/Delete MessageReply w/QuoteDirect Link to This Post
While I doubt that the chains are jumping teeth. If you are having slipping issues you should do a complete rebuild of the trans to make sure all the metal is cleaned out

JoevSokol

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85 SE Daily driver with a 3.4 DOHC OBD II
88 Formula/GT 4.9 Allante Intake (My Baby)
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mental floss
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Report this Post12-25-2014 08:56 AM Click Here to See the Profile for mental flossSend a Private Message to mental flossEdit/Delete MessageReply w/QuoteDirect Link to This Post
Does anybody have any experience with a site for these GM transaxles? Maybe a dedicated GM site might have someone with the knowledge?

ETA: For those who don't know the issues of the 4t65e-HD issues in their host cars, the chain is a known weak point.

http://www.grandprixforums....n-or-7-8-quot-single

http://www.wbodystore.com/t...ch-drive-chain-.html
 
quote
What's better than 2 chains moving all the weight of your vehicle? One chain moving all the weight of your vehicle! Conventional wisdom says two is better than one but not when it comes to transmission drive chains. The dual stock chain setup is inherantly weak and uses a staggered gear to engage one link while the link next to it is disengaging. GM says this makes your transmission quieter. The fix is to switch over to a 7/8ths inch wide single chain setup. These setups are significantly stronger than stock, with both reliably holding over 300whp, much more than the stock chain is capable of.

[This message has been edited by mental floss (edited 12-25-2014).]

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Report this Post12-25-2014 11:21 AM Click Here to See the Profile for lateFormulaSend a Private Message to lateFormulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Are you certain it is the drive chain and might not be failure of one or more of the clutch packs in the trans? Either way you'll be in for a full rebuild, or just try to find a low mileage unit out of a salvage yard and replace it.

Merry Christmas everybody!

[This message has been edited by lateFormula (edited 12-25-2014).]

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mental floss
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Report this Post12-25-2014 12:45 PM Click Here to See the Profile for mental flossSend a Private Message to mental flossEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks. Merry Christmas. But that does not answer the questions asked. Full rebuild is the default to repairing a faulty transmission, as is replacement...which isn't the question. So...returning to the big picture and goal of this thread, the goal is to determine the health of the engine and to keep the car mobile, which can't currently be done. Now it's only mobile. Doing so without spending $1000 to $1500 on a trans that won't be used in the swap that I mentioned in the OP is the goal. The engine can't be tested in boosting phase presently. And it makes little sense to just take a gamble and build a complete Fiero swap based on this untested engine especially when it will be mated to an F23 trans and not an automatic transmission. Thus spending $1000 to $1500 to rebuild an unused transmission is not a practice in sensibility, but I am on a Fiero site so maybe I'm being unrealistic. Perhaps the engine loses oil pressure when warmed up? Maybe it smokes when warmed up? Maybe it consumes copious amounts of oil, or even anti-freeze? These are some of the goals of this exercise.

However, since trans diagnosis seems to be of greater interest currently, I'll add that I trust the diagnosis of the mechanic who owned/sold the car and am not arrogant enough to dispute him. The person he got it from brought it to him because he thought it was a CV shaft/coupling getting worse, since it sounds similar. When he got the actual diagnosis from the mechanic , he traded the car to him due to cost of a rebuild which would be more than the worth of an ugly car that he commutes in for 80 miles per day. The mechanic , who became the owner of the car determined that the car has lost half it's factory GM paint, which is common to white GM cars of this vintage, observed that it also has an aging interior and knows that there is no profit to be made from repairing/replacing a trans in a car needing a complete paint job, that won't sell for $1000 when fixed so he sold it for $650 (his determined investment/plus diagnostic cost) to someone who might want the engine for a project. Hopefully this will satisfactorily convince those curious of the health of the transmission that enough information has been offered so that advice can be given on how to proceed in getting to a point where the health of the engine can be determined?

After more creative word phrasing in search engines today, I believe I have gotten as far as I can get on the internet by confirming that yes the stock chain/gears are weak and prone to stretching when abused and can be replaced, but flushing the old trans can expose other problems that weren't apparent before the flush. It's a case by case basis whether it will be a successful temporary fix. I was hoping to hear from someone here who has experience, but I located some discussion about it on a GP site amongst guys who have had chain failures with modded/somewhat raced GPs. I'm going to give it a try and see if I can get the engine into boost for a period of driven time.

Merry Christmas all.
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mental floss
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Report this Post12-25-2014 01:15 PM Click Here to See the Profile for mental flossSend a Private Message to mental flossEdit/Delete MessageReply w/QuoteDirect Link to This Post
BTW, there was a '97 Bonnie SSEi in a junkyard with the trans partially disassembled which I further pulled down far enough to view the main drive chains and gears. The outer chain was extremely stretched as compared to the inner chain which rides right beside it on the same drive gears. I also noted that the 4th gear(?) shaft spines were almost completely worn off of this trans. Once they're worn down there is no more 4th gear, I read. Later versions had the hardened part that didn't wear like this. Think that was 2002 when they upgraded.
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Report this Post01-07-2015 02:20 AM Click Here to See the Profile for FierokingClick Here to visit Fieroking's HomePageClick Here to Email FierokingSend a Private Message to FierokingEdit/Delete MessageReply w/QuoteDirect Link to This Post
After rereading your post I'll try and answer your question. Yes you can just replace the chain set. I would recommend that you replace the filter and check to see how much metal there is in the pan. If there in not a lot of metal then you should be OK for the time you need the trans to work for you.

Hope this helps. Also I might have a spare chain set if you need one.

Joe Sokol

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88 Formula/GT 4.9 Allante Intake (My Baby)
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