Transmissions and DrivetrainNeed help with your trans? Problems with your axle?
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How much horsepower can a stock 700r4 tranny take? I have a 55k miles '86 IROC with a 305 TPI. I'm going to bump up the horsepower in this engine, but I don't want to overdue it and have to start rebuilding/replacing the tranny. Sorry if this has been posted before. I didn't find it in a search, either that or I'm doing it wrong.
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id like to know the answer to this also but i think they can handle about 300 wheel hp without any problems, and one of the best upgrades to do to a 700r4 is to buy a corvette servo for it, they're awesome.
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-1989 Camaro with a 305 TPI, soon to be 6.0L LSx. -1985 Camaro with a 350 TPI, probably gonna stay that way. At least until I'm done with the other one...
Transmissions are primarily rated with regards to engine torque. According to this chart the 700R4 is rated @ 350 lb/ft.
Sounds about right, thats where mine gave up the fight...I was running low 15 second passes and it bit the bullet. I recommend you start getting ready to put in a new one if your planning on 15.5 or better. Sorry just the way it is. Believe me I wish it wasnt so.
I've heard it said that you can shear the input drum off just trying to do a burnout with the stock transmission on a stock 305.
FWIW, that chart is referencing the 4L-60E, not the 700R4. While I am aware that they are "technically" the same transmission, the 4L-60E weighs 40lbs more than a 700R4. I'd be willing to bet that the parts on the inside are just a tad more durable than the 700R4 based on weight difference.
If you look at the chart again you will see that the 700R4/4L60 is covered with the 4L60E being a separate entry. Granted, they do list the same torque numbers for both. I also wouldn't say that that list is necessarily the official numbers from GM, but it's all I could come up with...
As for the breaking behind a stock 305, I'm sure that can and has happened. But, also, there are the people that have gotten away with running significantly higher than the rated input through them and been fine.
I dunno, I mean if you wanna be safe then, yeah, you should probably build up your 700 if you are going to be running anything decently above stock power levels or driving it hard on a regular basis. But, I'd definitely be one of the people that would just run it 'till it breaks and then fix it to be better than before. That's provided when it does break it doesn't do so in a spectacular fashion and explode everything...
If you look at the chart again you will see that the 700R4/4L60 is covered with the 4L60E being a separate entry. Granted, they do list the same torque numbers for both. I also wouldn't say that that list is necessarily the official numbers from GM, but it's all I could come up with...
Thanks for that, missed that part.
I also got some editing to do, the weight number I listed was for the 4L-80E. But in case anyone is curious, a fully operational 4L-60E with Converter weighs 176lbs.
If you keep the 305 and beef it up, stock tranny and rear end will be fine. If you go performance 350 or 383 you will have to consider upgrading. Kind of a grey area for stock auto and rear end when you get into 350-400 HP range. I am planning to upgrade both on my car with also a stronger 350. I feel a coupe of grand for the drivetrain is worth it. I don't want to be out somewhere and have either break with who knows what kind of damage to car. With the power you are compteplating I would upgrade both as best you can.
From what i've been reading they can handle 300 HP at flywheel as mentioned above. Dana at Pro-built sells upgrade kits for these auto's that can make them withstand over 600 HP. They cost about $600 but include parts to upgrade pretty much everything in the tranny. Figure about double that or $1,200 for the kit and somebody to install. http://www.700r4l60e.com/store/home.php?cat=19
If you increase power significantly you also have to start looking at the stock rear end. You can upgrade the stock 7.6" rear end with better components to withstand about 400 HP. Higher HP than this and the rear end size becomes a problem due to house twisting. As mentioned above, the tourqe kills more than higher HP. Cost to upgrade parts seems to be around $1,000 and looks like something you can install to save $$. More power than that and you need to swap rearend which will cost at least $2,000 for a new one that doesn't include installation. Below are some good links on beefing up rear end. http://z28boy.cz28.com/mods-rearend.htm http://www.ws6transam.org/10bolt.html http://www.thirdgen.org/beefinguprear
my stock 700r4 took a dump on me back when i had my stock l98 with just a catback... you need to get these 700r4s built if you have any decent motor... they are a wonderful automatics once built up... the corvette servo gives you abit firmer 1 to 2 shift and reduces slippage... its a good mod for a 700r4 and can be done with the tranny in the car
Does the servo increase line pressure as low rpms? I have heard that a corvette servo will keep it from down shifting from 4th to 3rd, or maybe 3rd to 2nd.
im not sure about the line pressure you need to ask some of the tranny people bout that...if you have a ten bolt then i doubt it unless you baby it......
the servo does not increase line pressure, it increases clamping force on the bands etc. the vette servo has a larger apply area which means it has more surface to clamp, so it basically just clamps better and harder. does not affect the 4-3 downshift, thats the 3-4 upshift valve, stock is set to about 50% pedal pushed down before it will shift itself out of 4th and into 3rd. B&M and TCI make new valves that can increase that to 3/4 or 75% so u can hold 4th at 3/4 throttle for higher cruizing speeds. all downshifts are controlled by the valve body, and thats where the upshift valves are located.
line pressure is all controlled by the valve body, the boost valves and low reverse boost valves will increase line pressure but so will a shift kit. the 2 should be matched for optimum performance. increased line pressure will make the trans shift harder. boost valves and a good trans go shift kit will increase the stock pressure of about 150-175 psi to about 250-300psi being MAX. too much pressure can hurt the trans. which is why u should get a matched kit from DANA. dont mess with other shift kits, B&M, TCI etc only increase line pressure where transgo increases the pressure but reroutes the fluid in the valve body etc, which results in better harder shifts but actually fixes some of the issues in the trans
just rebuilt it, in stock form the 700 is only rated to like 300-350ftlbs. the 700r4 weak links are the stock servo(go with corvette, or billets if u get serious) sun shell is weak up untill 89 where GM learned they would sheer off at the teeth and then they started hardening them, 3-4 clutch pack, shifts are weak (transgo shift kit will help alot) and other things should be addressed. give dana at probuilt a call and he will hook u up
i just rebuilt mine to handle 675+hp
new clutches, 3-4 clutch pack 9clutch borg warners hi energy clutches instead of 6 like stock, billet servos 35% larger than corvette, and 50% larger than stock 4th gear servo, mega boost valve and low reverse boost valve, the best transgo shift kit level 2 i think right before full manual racing one(level 2 does a full valve body reconfiguration and allows me to hold any gear untill any RPM and allows me to upshift or downshift whenever), all heavy duty springs inside allows 7,800 rpm shifts, new 10vain pump, HD sleeve reinforcement, THE BEAST reaction sun shell (most beefy sun shell ever and strongest, even more than the 89 and newer hardened ones) all the other is small stuff. also running a 2900 stall and deep pan with a 24,000GVW external trans cooler.... and thats how i roll baby
An Ls2 in your car with a stock rear will wipe it out pretty fast. depends wat rear u have too. a 9bolt is stronger than the 10bolt. but your rear should be rebuilt if its still stock, an upgraded eaton posi, hardened moser 28spline axles etc and support girdle will help ALOT! and upgraded rear will be able to handle the LS2 and can handle about 400rwhp. stock ones can wipe out at 250rwhp
Last edited by customblackbird; 08-12-2009 at 01:36 PM.
That was quite an essay. My 86 has the stock r4 and seems to be in good working order. When under stress (WOT), the 1-2 shift seems to slide bump just a tad.. I have noticed this with other r4's pre 87. I thought about going to a corvette servo to help this issue.
how many miles are on it? i would think you would need a rebuild. and yours might not have the external Valve body/accumulator. believe they came out in 87. there are a bunch of things that should be upgraded bc yours isnt and 87 or newer trans.
You prob need a complete rebuild. you can go cheap if you want and get a kit for less than 200$ and then spend another 20$ on the vette servo, 30-40$ on the boost valves and get a shift kit. id say you would be good for 350hp with that and those upgrades.
i wouldnt just throw a vette servo on it. but if you wanna see how it would help you could try it. and i would do a shift kit. slipping trans most ppl throw in a shift kit to help as a quick fix. but this will sumtimes just buy them some time. if you go the vette servo i would do the shift kit as well and see if it helps
The IROC has 95000 on it. It could very well use an upgrade due to the year. It does shift quite well though for the vintage of r4's. My tranny shop guy gave it a clean bill if health.
ha some tranny guy worked for AMCCO or watev that cr@p tranmission place is. said that the 700r4 cant handle more than 400hp and the only upgrade he does is the supieror shift kit and its better than transgo and thats all they need to handle massive amounts of power lol... it took all my strength just not to snap his neck. this guy builds all kinds of tranmissions and here i am only built 2 700s and i kno more than him scaryyyy stuff
I wouldn't subscribe to big chain tranny outfits either. The guy I know is a one horse operation, and has a good reputation. He advised me not to get a rebuild yet.
The EcoDYME
