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Aisin 5-speed Manual rebuilder or upgrades?

25K views 42 replies 9 participants last post by  cammerjeff 
#1 ·
My issue is I believe the Synchro's are giving up on my stock Aisin AR-5 Transmission. My Car is a LS2 powered Mallet Conversion early 2006 Build (November 2005) so from what I have been reading it will have the early Synchro design. My problem is the car is Stock as it came from Mallet and I would like to keep it that way, so I don't want to replace the transmission, but just rebuild it with more durable parts.

Does anyone know of a rebuilder with experience with these transmissions? I am aware of the more durable carbon fiber synchro option that was used in the Hummer H3 version of the trans.

The car has about 23,000 miles on it, and the 2-3 shift is getting difficult unless I double clutch it, but that does not help acceleration. I did drain and replace the fluid with Royal Purple 70/90 full synthetic about a month ago. It has helped but not eliminated the problem.

I believe the Trans was having issues when I bought it, as the car would "jump" a little when you came to a complete stop, then placed the shifter into 1st gear. Now the other symtoms have arose.
 
#2 ·
Are you certain that you don't have a clutch problem? A jump going into first gear sounds like a partially engaged clutch, since something has to be turning to cause the jump. I have also noticed that shifts are a problem when I don't fully depress the clutch, and that would translate to your 2-3 problem.
 
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#3 ·
I have thought of that, but in the past if I had a clutch issue it would be in every gear change, there is no burned clutch smell that usually goes along with a clutch not disengaging fully. Also Double clutching never effected the shifting when it was a clutch issue in the past.

But this is my 1st Kappa so they may be different than the other cars I have owned.
 
#4 · (Edited)
Your description suggests a hydraulic problem. Rebleed the clutch and look for leaks or weeps. Inspect the MC. It may be letting go with the pedal depressed. The slave is not accessible until the engine or trans come out. In my Ls/Tremec conversion there is no access to most of the bell housing bolts; and a forward sliding pull of the engine trans package is necessary to expose them. I hope your Mallet swap allows you easier access.
 
#5 ·
The jump when engaging first at a stop is almost certainly caused by incomplete disengagement of the clutch, although it could be a galled pilot bushing. There is no way a synchro can create motion when the car isn't moving.

Unless you are losing fluid a hydraulic problem is most likely either the master cylinder or the clutch pedal return spring. A leaking master cylinder will normally allow the clutch to slowly engage while you hold the pedal down, but that is not absolute. A weak or broken pedal return spring will prevent a full charge of fluid in the master cylinder, resulting in incomplete release of the clutch. This recently happened to my RL.

The stock hydraulic system is self-bleeding, with no provision that I know of for any manual bleeding.
 
#6 ·
I will inspect the return spring when I get a chance, I may be over describing the "jump" it is more a feel in the shifter and the car does roll slightly when the shifter engages 1st gear. I have never had a manual trans car do that before, and I have been driving them for 30+ years.

I am not ruling out a clutch engagement issue. Just for complete info I did have all the fluids replaced this spring by my favorate ex Pontiac dealer and it did not effect the issue, it has grown gradually worse, and seems to be worse before the trans gets up to operating temp.

I have not seen a loss of Fluid to the brake system so I don't think there is a leak, I have not noticed the clutch slowly engaging with the pedal held down.

But I will check the return spring as soon as I can.

Thanks for the tips.
 
#9 ·
I just want to say that my car exhibits a slight roll forward when put into gear as well. I've always attributed it to the gears meshing and causing just a tiny bit of forward propulsion. It also just so happens that my synchros are nearly dead, so I await an answer to the initial question.
 
#12 ·
I believe we have the same symptoms, but if I get a chance Friday I will take the car to my buddies trans shop and get his opinion of what the issue is, he should at least be able to rule out a clutch disengagement issue. He has never worked on a Kappa of the Aisin transmissions so I don't know how much help he will be about internal trans issues. He mostly deals with newer automatic's & building T350 & T400's for drag racing and Higher HP street use.
 
#13 ·
#14 ·
Find a nice flat concrete pad that is as close to level as you can get (gas station filling areas are good). put it in gear with the clutch pushed in all the way - if it pulls forward at all you have clutch drag.

EDT, it doesn't matter what the gears are doing, without some clutch involvement it can't result in any motion to the car.

If it does move, then insufficient clutch travel is usually from hydraulic adjustment, air in the system etc. Or it may be in some failure mode.

This is why I hate cars with HTOBs. Instead of a 15 minute external slave change it means the engine coming out.....

I get into that argument all the time with the MG engine swapping guys. They usually use HTOBs as a matter of course and I tell them that every single component of a car WILL fail at some time or other, and it is just good planning to choose a fitment that minimizes the effort when, not if, that happens.

Sometimes you don't have much option; I haven't examined the tunnel area of a Kappa to see if there is room for an external slave.

Even when the HTOBs don't fail, they can be a real swine to bleed!
 
#15 ·
Agreed with all points.

There is no provision for bleeding the clutch hydraulics. The system is self-bleeding after (in my case after replacing master cylinder) five or six full pedal strokes.
 
#16 ·
Well I did take the car to my buddies shop, and another that he recommended and their opinion is that I do have a syncro issue, they both concluded that the clutch is fully disengaging and that the issue I have is internal to the transmission. But both shops do not have any special tools required ( if any ) and have never rebuilt one so they did not want to take on the job of rebuilding it.

So I guess I am back to my original question, does anyone have a suggestion on where I should send the trans for a rebuild/upgrade?
 
#17 ·
Have you tried a local shop that specializes in transmissions? You are talking about a synchro replacement, not rocket science. Any transmission shop worth half its salt should have no problems doing it, especially since its a common truck trans, based on another popular transsmisson. I did a quick google search of "transmission shop" and your town listed in your profile. I would give "Accurate Transmissions" a call. In the google reviews they look good, and several people have commented they have done transmissions on their race cars. Couldnt hurt to call, and tell em whats up and see what they have to say. Plus you will be supporting a local small shop, and thats always a plus!
 
#18 ·
Unfortunatly that is my buddies Transmission Shop, Sorry if I did not make that clear in my last post.

Unfortunatly he usually works on Automatic's and older Muncie or BW manual transmissions, He even does T-56's but aparantly he is not up for learning a not very common (in our area anyway) manual trans. I would be interested to know how many Colorado, Cannon, or H3's were actually built with the 5-speed manual. The other issue he has is my car has a LS2 V8 and he said he is leary to do it and have the same issue occur in a few thousand miles,

But thanks for the response, and the time it took to look the info up.
 
#20 ·
Like honestly, Ive thought about it, and rebuilding your transmission is probably not the way to go. You probably will run into synchro issues shortly again. Why dont you want to go to a t56? or a Getrag from a supra? or any other number of transmission options out there? Its probably going to cost you less in the long run, and you will end up with an extra gear and better ratios in addition to a stronger trans/clutch.
 
#21 ·
The T-56 is a proven alternative. I would not normally change to one, but if the alternative is having a rebuild done it may be worthwhile.

You might also look at a replacement AR5.

I still don't understand how a synchro can cause motion when engaging a gear at stand-still.
 
#22 ·
I still don't understand how a synchro can cause motion when engaging a gear at stand-still.
I found this on another forum that seems to explain it:

When you are off the clutch in neutral, the input shaft of the trasmission is spinning with the engine, while the output shaft is not, since it's connected to the road. The gears connect the input and output shaft together.

When you push the clutch in and shift into first, the synro has to match the speed of the input shaft (~800rpm) to the speed of the output shaft (0rpm). This can cause the car to lurch forward just a tiny bit, while the syncro slows the input shaft to 0rpm so the gear can fully engage. Since the syncro is connected to the gear, this will put just a tiny bit of torque through to the output shaft. The reason it doesn't happen again if you keep the clutch in, then go to neutral then back to first is because the input and output shaft are already matched.

Have none of you really noticed this? Go out and try it. Start your car, put it in neutral. Then let the clutch out, clutch back in and put it into first gear really fast. The car will lurch forward just a tiny bit. It's normal and isn't a problem.
 
#23 ·
Just saw an AR5 on Ebay for $800 used. I don't think that you will find a T-56 or any of the Tremec transmissions for anything close to this price. I'm a little surprised that the LS conversions stayed with the AR5 but I guess that it works even though I don't think that GM put this trans on any LS motors. You may find a good used T-56 but I have yet to see one under $2400.
 
#24 ·
right, but as far as I know.. the r154 supra transmission is a fairly simple swap with an LS motor... which is probably why it works with our AR5. Which also means, I would look and see if people are doing r154's behind LS motor (which I am fairly sure is a decently used swap option for LS powered anything). There are options but they are $$$. Fast, cheap, reliable - you only get to pick two.
 
#27 · (Edited)
LSX LS1 LS2 LS3 LS6 LS7 LS9 L98 Engine to 350Z 370Z VQ Transmission Compound Adapter Plate

with this adaptor you can use a 350z trans with your motor (there are other cheaper adaptors, but they require unique clutch solutions). That trans can be had for under 750 dollars used, and they are common to rebuild, and parts are available. So. Some options for you.

*edit* on another note.... if the LS motor can bolt to the AR5 transmission, then that means this adaptor could probably bolt the CD009 transmission to the LNF motor, opening up a six speed option to the rest of us.
 
#28 ·
Now you have me thinking, I found a Brand new in the box 350Z trans near me for $1000.00 asking price, that adaptor plate is $450 but having to saw off the stock cast on bell housing makes me nervious! I am sure I could do it but still. So figuring in a used 98-2002 F-body bellhousing, clutch, pressure plate, slave cylinder, driveshaft, X-member with mount, and what to do about the shifter. I could probably get it installed for around $3500.00 all in.

The new Tremec magnum 6-speed alone is around $3200.00 plus all the other parts would probably run close to $6000.00 all in. I may have to find a manual trans 350Z to test drive this weekend to see if I like the way the trans shifts. Hmmmmm
 
#29 ·
See now you are cookin with gas! If the trans is near you, maybe you could go take some measurements and see where the shifter location ends up compared to the AR5 trans, and get some detailed photos. I personally would probably try and find the cheapest trans possible, and then just rebuild it. Since the bell housing needs to be cut off anyway, getting a new one would be kind of a waste. Butttttttttttt on the same token the piece of mind with a brand new trans would be much better!
 
#30 ·
I may have figured out another option, I found the AR-5 Transmission is basically the same transmission that Toyota put in the Supra's and called a r154. There are a couple of companies that rebuild and upgrade r154's and advertise they can rebuild/upgrade your trans for $1300 plus shipping, plus the cost of any shaft, gear or case replacement required. They claim they can upgrade the r154 to withstand 500 lb ft or torque.

So if they will work on my AR-5 $1500 and no major modifications sound like a great deal to me. I will let you know what I find out.
 
#32 ·
Reread your 2nd post and yes you did, sorry I forgot. But I must of sorta remembered as I did start looking up r154 info. One of the rebuilders did get back to me and they said they could do it, but it would be " a little" extra for some different than normal parts. They did not explain how much or what parts. Good to know there is an option to upgrade the stock transmission.
 
#36 ·
John, that is a better description than I wrote of that symptom, it was present when I 1st bought the car, but has been getting progressively worse. Still if that was the only issue I was having I would not be concerned about it. I never thought about my driving style with not having my foot on the brake when going from neutral to 1st gear making much of a difference, but I can believe it does.

Choptop thanks for the link, but that price for a used transmission with unknown miles is probably about what I would pay for the other company to rebuild/upgrade mine, plus the shipping both ways. But as always I appreciate the effert involved.
 
#38 ·
Question: Sitting at idle you push in the clutch, select 1st gear, and lurch forward slightly. What happens if you then shift into neutral and back to first while holding the clutch in?
 
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