Because of the gear ratio or because of durability? 
Towing with a modified LT1
Thread Starter
Joined: May 2011
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From: Conshohocken, PA
Towing with a modified LT1 I'm looking for those who have first hand experience towing with a modded LT1. This mainly applies to b-bodies and swapped trucks as I'll need to pull around 5k or more (weight of trailer + camaro) occasionally.
For those who don't know, the towing capacity of the LT1 b-bodies with tow package is 5k with the only real differences between the base models being a clutch fan, suspension, larger radiator, better gearing and posi. The d-body Fleetwood has a capacity of 7k but that could be attributed to more curb weight and slightly longer wheelbase.
My Roadmaster will be doing the hauling. It currently has Monroe SS shocks, Vogtland springs, 3.73 gears, Yukon posi, full bolt-ons, and T56 swap. I'd be adding air helper springs, 4.30 gears, shorter Impala SS wheels/tires (with proper load rating), and a real oil cooler to help out. Trailer will definitely have brakes/load leveler and I'll be driving like grandma the whole time.
Car made 295/351 rwhp/rwtq without ever opening the valve covers but it's time for more. I got a smokin deal on some LE1 (or 1.5) heads and wimpy cc304 cam. I needed to keep duration down and LSA wide being that cam surge due to increased overlap would be unacceptable in a tow rig. The loss of low end associated with larger cams should be negated by improved head flow... at least I hope. There's a 15 degree difference in overlap between the 304 and stock b-body cam which shouldn't be too much.
The big question I have now is regarding compression. Has anyone ever run a CR 11:1 and towed before? Lloyd said a compression bump wouldn't hurt and I'm assuming this is if I keep the timing soft and run 93. I don't see myself going under 10.4:1 being that these LE1s are aluminum and getting closer to 11:1 would mean much tighter quench -- help with detonation. I'm looking for real world experience though.
For those who don't know, the towing capacity of the LT1 b-bodies with tow package is 5k with the only real differences between the base models being a clutch fan, suspension, larger radiator, better gearing and posi. The d-body Fleetwood has a capacity of 7k but that could be attributed to more curb weight and slightly longer wheelbase.
My Roadmaster will be doing the hauling. It currently has Monroe SS shocks, Vogtland springs, 3.73 gears, Yukon posi, full bolt-ons, and T56 swap. I'd be adding air helper springs, 4.30 gears, shorter Impala SS wheels/tires (with proper load rating), and a real oil cooler to help out. Trailer will definitely have brakes/load leveler and I'll be driving like grandma the whole time.
Car made 295/351 rwhp/rwtq without ever opening the valve covers but it's time for more. I got a smokin deal on some LE1 (or 1.5) heads and wimpy cc304 cam. I needed to keep duration down and LSA wide being that cam surge due to increased overlap would be unacceptable in a tow rig. The loss of low end associated with larger cams should be negated by improved head flow... at least I hope. There's a 15 degree difference in overlap between the 304 and stock b-body cam which shouldn't be too much.
The big question I have now is regarding compression. Has anyone ever run a CR 11:1 and towed before? Lloyd said a compression bump wouldn't hurt and I'm assuming this is if I keep the timing soft and run 93. I don't see myself going under 10.4:1 being that these LE1s are aluminum and getting closer to 11:1 would mean much tighter quench -- help with detonation. I'm looking for real world experience though.
I'd be more concerned with the t56, a stop light, and a hill. You don't have a granny gear to fall back on, or a hand brake. You will NEED to get a good trailer brake controller with the manual hold feature for the brakes, that way you can have 1 hand holding the trailer brakes on so you don't roll back and the other on the steering wheel. 4.30s will help, but 1st gear in a t56 with 4.30s wouldn't hold a candle to a real granny gear.
I'd get a monster radiator and a 160 stat and keep it very cool and go for 11:1 and 93, just to grab as much low end as possible.
I'd get a monster radiator and a 160 stat and keep it very cool and go for 11:1 and 93, just to grab as much low end as possible.
A tundra will tow a space shuttle.
Watching your timing and coolant temps, don't try and barrel up hills. Make sure you get a inertia tow control vs time based one and as pointed out make sure it has a oh **** button. If it starts to ping, back off the tune.
I know its been done, but say a 3400lb fbod and a 5k rating, thats a 1600lb trailer... does such a thing exist?
Watching your timing and coolant temps, don't try and barrel up hills. Make sure you get a inertia tow control vs time based one and as pointed out make sure it has a oh **** button. If it starts to ping, back off the tune.
I know its been done, but say a 3400lb fbod and a 5k rating, thats a 1600lb trailer... does such a thing exist?
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OP
might want to talk to Lloyd about what is often referred to as a "RV cam". One that is all about low end TQ.
The Crane 227 was a low end TQ cam, that could be a option but I would think Lloyd could cut even a better grind specific to your set up
4:30's will help as I found 3:73 in a B-body with T56 somewhat sluggish off the line so pulling a trailer with 3:73 would really suck
on the start from a hill thing. Yeah a trailer brake controller could be used but using that hand to activate it + shifting & steering....might want to consider a line lock with the button on the shift **** (Hurst makes one).
Your clutch may take some abuse for this but so will your brakes. Run a full face organic disc vs some ceramic puc type disc
might want to talk to Lloyd about what is often referred to as a "RV cam". One that is all about low end TQ.
The Crane 227 was a low end TQ cam, that could be a option but I would think Lloyd could cut even a better grind specific to your set up
4:30's will help as I found 3:73 in a B-body with T56 somewhat sluggish off the line so pulling a trailer with 3:73 would really suck
on the start from a hill thing. Yeah a trailer brake controller could be used but using that hand to activate it + shifting & steering....might want to consider a line lock with the button on the shift **** (Hurst makes one).
Your clutch may take some abuse for this but so will your brakes. Run a full face organic disc vs some ceramic puc type disc
Thread Starter
Joined: May 2011
Posts: 1,241
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From: Conshohocken, PA
So a 27" tire, 2.66 first gear in the T56, and rolling at 10 mph means these engine speeds.
3.73 = 1235 rpm (ew)
4.30 = 1423 rpm
4.56 = 1509rpm (best, but tiny pinion gear)
I looked up the specs for a 90s C1500 with the NV3500 5-spd. 1593 rpm @ 10 mph. Truck should pull 6k easily.
I would be towing the car to the track occasionally and a ~2.5hr road trip (with a break in the middle) twice a year. Terrain is pretty flat where I'm going and there shouldn't be many hill starts, if any. I can hop on the highway 5 minutes from my house and get wherever I need to go pretty easily.
I will also look into figuring out the brake controller.
They make aluminum car haulers... pricey but weigh ~1400. Have no idea what the Camaro weighs right now but I would like to pull more out of it. Might be able to get away with a steel/wood floor car hauler. Not too worried about going over 5k though, people have towed B-bodies with their B-bodies before.
It has a stock style organic clutch that's practically brand new. Unsure about what to go with to avoid chatter.
I talked to Lloyd a while back about this and the custom grinds he had weren't all that different from what I was looking at. I was looking at the Crane 227, ZZ4, cc304, LPE 211/219, etc. I eventually settled for the cc304 because I got it for stupid cheap. I also believe it has the least overlap of the entire group @ -13. Specs are 210/220 .533/.544 114 LSA. I also wanted to keep the lobes pretty lazy for more longevity in the valvetrain.
The 3.73s were put in way back when the car was A4 and I agree, they are way too long. I don't make it into 6th as much as I'd like. It's between 4.30 and 4.56.
3.73 = 1235 rpm (ew)
4.30 = 1423 rpm
4.56 = 1509rpm (best, but tiny pinion gear)
I looked up the specs for a 90s C1500 with the NV3500 5-spd. 1593 rpm @ 10 mph. Truck should pull 6k easily.
I will also look into figuring out the brake controller.
It has a stock style organic clutch that's practically brand new. Unsure about what to go with to avoid chatter.
might want to talk to Lloyd about what is often referred to as a "RV cam". One that is all about low end TQ.
The Crane 227 was a low end TQ cam, that could be a option but I would think Lloyd could cut even a better grind specific to your set up
4:30's will help as I found 3:73 in a B-body with T56 somewhat sluggish off the line so pulling a trailer with 3:73 would really suck
The Crane 227 was a low end TQ cam, that could be a option but I would think Lloyd could cut even a better grind specific to your set up
4:30's will help as I found 3:73 in a B-body with T56 somewhat sluggish off the line so pulling a trailer with 3:73 would really suck
The 3.73s were put in way back when the car was A4 and I agree, they are way too long. I don't make it into 6th as much as I'd like. It's between 4.30 and 4.56.
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I assume the tow vehicle is disc/drum brakes. Towing what will be likely closer to 6k LBs the front disc are going to be hard pressed to deal with ...lets say urgent stop if needed on their own. Having a trailer with electric brakes and a brake controller, IMHO, would be advised.
I wired one up on my truck, got it from e-trailer.com. You can buy the controller, wire, circuit breakers etc from them. Several youtube videos to watch also
If you want to keep ABS and buy a ABS compliant gear set there is a guy on the Impala SS forum, Bob Shirley, who makes the reluctor gears. IDK anyone running the 4:30's but many run 4:56 in the B-body with T-56. I would think either would be fine
I wired one up on my truck, got it from e-trailer.com. You can buy the controller, wire, circuit breakers etc from them. Several youtube videos to watch also
If you want to keep ABS and buy a ABS compliant gear set there is a guy on the Impala SS forum, Bob Shirley, who makes the reluctor gears. IDK anyone running the 4:30's but many run 4:56 in the B-body with T-56. I would think either would be fine
Thread Starter
Joined: May 2011
Posts: 1,241
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From: Conshohocken, PA
Pick-em-up trucks! A real tow rig would be ideal but I have too many hoopties right now. My beater is a 4.3 Blazer that can barely haul itself around so there's no way I'm using that.
Yes, the boat has disc/drum and trailer brakes are a must regardless. I will look into getting a controller wiring everything up when it comes time to install the class 3 hitch.
Car doesn't have ABS currently with the 3.73s but I wouldn't mind having it back assuming the reluctors don't cost a small fortune. How much weaker are the 4.56s? I'd imagine the pinion is really small but not much different than 4.30s. Car gets flogged a lot on the street and might see the track a handful of times. Maybe a diff cover will help.
Yes, the boat has disc/drum and trailer brakes are a must regardless. I will look into getting a controller wiring everything up when it comes time to install the class 3 hitch.
Car doesn't have ABS currently with the 3.73s but I wouldn't mind having it back assuming the reluctors don't cost a small fortune. How much weaker are the 4.56s? I'd imagine the pinion is really small but not much different than 4.30s. Car gets flogged a lot on the street and might see the track a handful of times. Maybe a diff cover will help.
You don't need to worry about having a free hand to shift, as soon as the clutch is out you can take the hand off the trailer brake and your fine. The nv3500 is a bad example, it was NOT made for towing, more for fuel economy, which is why they wouldn't put it behind the 5.3, only the 4.8 in gmt800s. In gmt400s, behind a 350 they got torn apart. If you wanted to toe with a stick you had to jump up to a nv4500 in a 3/4 ton. You'll be nearly 10,000 lbs combined with the trailer and heavy b body loaded up for the track, and the tall t56 would be better with 4.56s.
Meh, motor will be just fine. It's the rest of the car that you need to pay attention to. That multilink will probably be good and squishy, but if you're just pulling another car on an open deck I'm not seeing it as being life threatening to you or those around you. If it's tuned properly, it doesn't matter what compression ratio you have.
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IMHO on a heavy B-body T56 car I would & do run one as they have pre-load bolts for the main bearing caps of the diff.
I have had my 4:10's in since 2005 and can't remember what the reluctor gear I bought from Shirley was then. IIRC is was something like $75-$100
Yeah the lower the gear ratio the smaller the pinion gear and larger ring gear. In a 8.5" 10 bolt I don't think the 4:xx gear ratios are to vulnerable to breaking like some 7.5" rear ends may have had. I don't see the OP doing 5k RPM clutch dumps towing the trailer
I have had my 4:10's in since 2005 and can't remember what the reluctor gear I bought from Shirley was then. IIRC is was something like $75-$100
Yeah the lower the gear ratio the smaller the pinion gear and larger ring gear. In a 8.5" 10 bolt I don't think the 4:xx gear ratios are to vulnerable to breaking like some 7.5" rear ends may have had. I don't see the OP doing 5k RPM clutch dumps towing the trailer
Catmaigne, with all the thought you've already put into this endeavour, you're going to be just fine. Get those 4.56's in there, make sure your cooling system is operating to stock specs, repair any worn suspension parts/bushings, get a brake controller, and that's ALL. No upgrades whatsoever needed for that drivetrain. Trust me, I've abused stock configuration GM 8.5" rearends (including all the way up to 5.57 gears) in both the Impala and trucks far more than you ever will.
Since you stated the terrain will be fairly flat, I don't see you having clutch issues.
Since you stated the terrain will be fairly flat, I don't see you having clutch issues.