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Thread: towing using a repu
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MAZDAMARK
Hauling
Posts: 139
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posted June 17, 2008 10:41 AM |
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Towing Using a REPU
I was considering buying a trailer a few months back, and I searched the site for some info on towing, but didn't find much. It made me a bit wary, but I went ahead and bought a trailer anyway. To make a long story short, the REPU tows just fine.
While reading this, please keep in mind I have what is possibly the worst setup repu for towing. My truck has a 12a, an RX7 tranny and a 3.91 rear from a B series pickup. Gets decent mileage, but torque is nowhere to be found. I swapped out my tokicos in the rear for some coil-over shocks I bought on ebay, but that's about it.
I picked up a 16' tandem axle flatbed trailer with a ramp and trailer brakes. The guy I bought it from thought I was crazy, as the trailer with the tongue is a few feet longer then the REPU. I thought about buying a smaller trailer, but I knew I wanted the ability to tow a car, so I figured, best to go with the larger trailer and worry about what to do if the poo wouldn't handle the weight later.
I was moving, so I started light, just furniture and boxes. Truck did fine. I didn't even hook up the trailer brakes. I took progressively heavier loads and the truck did great. 65 on the highway, had no problem stopping etc. Probably took a half dozen loads about 50 miles one way over the course of a week or 2. Towed most of the way in 4th, occasionally using 3rd to get revs for the hills and 5th going downhill.
Then I worked up to towing my FB, which is in pieces at the moment. Truck still towed well, but stopping became a little more difficult. I hooked up the trailer brakes and tried towing my '90 vert. Stopping was much better with the trailer brakes, but the added weight of the vert (~3000) plus the trailer (which is around 1500) started to be a bit much for the 12a. Used 4th on the flats and going down hill for the braking affect and 3rd quite a bit more. Ran the truck from 55-65 on the highway. Even with the 3.91 rear, the 12a did just fine, but I had to keep the revs up. I plan on swapping in the 13B out of my -SE this winter, which would be a much better towing setup, imo.
Now, I live in Texas, so I'm not sure I would want to tow a car through the rockies or anything. But with a set of trailerbrakes, and maybe upgrading the fronts to a performance pad, (I believe Porterfield R4S pads for the RX4 will fit the REPU, yes?) the rockies should be doable --especially with a stock 13B-4.65 rear truck.
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94 RX7
89 RX7 GTUs
85 GSLSE
88 323 GTX
1975 REPU
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MAZDAMARK
Hauling
Posts: 139
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posted June 17, 2008 10:50 AM |
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Hey, anyone know why it says "towing a REPU" on the main page when it says "Towing with a REPU" when you open the post? Should say "Towing With..." on the main page. That's a big difference in meaning...
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MAZDAMARK
Hauling
Posts: 139
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posted June 17, 2008 10:55 AM |
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Hmm I changed it to Towing Using a REPU and that seemed to take.... Weird.
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94 RX7
89 RX7 GTUs
85 GSLSE
88 323 GTX
1975 REPU
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Brad
Rotorhead
Posts: 1672
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posted June 17, 2008 05:24 PM |
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towing with REPU
In the research I've done on towing with the REPU, everyone's towed on flat ground or what could described as a hill. No mountains. Several things to consider. Even though the REPU brakes did fine with the 2nd gen, keep in mind it has non vented fronts and non vented, non finned rears. So they'll heat up. Once they overheat you'll have no braking until they cool. I HAVE OVERHEATED REPU BRAKES DOING A CANYON RUN with the Miata club, the front pads smoked and progressively lost bite. Porterfield R4S all 4 corners.
I wouldn't consider towing down a mountain w/o 12" vented front rotors.
REPU has enough frame stiffening but the tires are underrated for the job. The more air and stiffer sidewall your tire has = more load capacity. Not enough room for big tires in the wheel wells IMO. Those Leaf springs can carry a lot of weight.
The wheelbase is okay but longer = better. You also want your tow vehicle to weigh more than the entire load you're towing. Otherwise under braking or cornering, the load will push your tow vehicle around.
Torque. Rotormotor not known for it. Houston, we have a problem. You don't want to be chugging 15mph in the slow lane up the rockies.
Gearing. 462 and a TORSEN will really help here. The ribcase I hope is up to it but definately install a tranny cooler, tranny filter, and fluid pump. But gearing will not make up for not enough torque.
I've towed my 81 rx7 with a V6 Amigo many times over The Grapevine (Calif.) and up to the Mojave desert ( long uphill tow with a few steep elevation changes). 214ft lbs of torque and shorter wheelbase than REPU. BUT, better brakes, weighs more, more tire and torque.
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-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge
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sparky
Redlining
Posts: 299
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posted June 17, 2008 09:20 PM |
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Saw a torsen on ebay yesterday. I think its at 200 bucks.
I love my torsen. Can't wait for BIG power someday.
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MAZDAMARK
Hauling
Posts: 139
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posted June 18, 2008 03:45 PM |
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I agree with most of the things you're saying, Brad. I'm not saying the REPU will tow as well as a Ram 3500 dually or anything. But the truck tows very, very well for what it is. I can't think of any other small pickup that would do as well.
Brakes: I totally agree with you on the brakes. That's why I ordered my trailer with trailer brakes. It made a huge difference in both stopping power and overall handling. If you're going to tow a load, I feel it is a must for the REPU. However, with trailer brakes, porterfields and responsible driving, you should be able to tackle some pretty steep stuff. Especially if most of the driving is on interstates where the grades are gradual.
Now, I disagree with your statement that the tow vehicle should weigh more than the load. Yes, a tow vehicle handles much better when that is the case, but it is not necessary. Case in point, the Ram 3500 weighs 5900 pounds, but is rated to tow 16,200!
Now again, you need to be smart about it. You need adequate tongue weight, a properly balanced load, etc. And again, responsible driving.
I somewhat disagree with you on the tires issue. Bigger tires are obviously nice, however the tires on my truck are rated for 1600 pounds each. That's 6400 pounds. You could almost put an FC in the bed of the truck and not go over the load ratings.
I totally agree with you on the tranny cooler, for extended tows especially. I swapped my fluid out in my truck before and after my move, to be on the safe side, as I do not have a cooler.
I mostly agree with you on the torque. Though gearing makes a huge difference, imo. The rotary can run at 5k+ all day long if the cooling, oil systems etc, are set up for it. The guys who convert Mazda rotaries for airplane use run a 5000+ rpm cruise. That means higher rpms in climbs and at takeoff. The only time a rotary airplane spends below that rpm would be descent and landings. Most are seeing 1500 to 2000 hour TBOs, on those engines IIRC. I figure if they're doing that to the motor in a single engine plane in the air, I shouldn’t (and didn’t) have a problem revving out my truck a bit to make up for the lack of torque.
Not sure I agree with you on the Torsen, either. Torsens are rotten on loose or slippery surfaces. Ever drive a Torsen in the snow? It acts pretty much like an open diff if there is not enough traction to spin up those worm gears. That’s why Torsen makes the Torsen III diff. It’s a hybrid clutch/worm transfer diff. They use it in the military hummers and some other off-road vehicles. It’s uber nice and uber$$$. There’s a guy over on the 323 GTX forum that is an engineer for JTEKT Torsen. He did a great writeup for us on the different torsen versions, what applications they meet and how they work. Let me see if I can find it. IMO. a clutch type diff or a locker would be best for towing…
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94 RX7
89 RX7 GTUs
85 GSLSE
88 323 GTX
1975 REPU
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MAZDAMARK
Hauling
Posts: 139
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posted June 18, 2008 04:09 PM |
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To add to what is said above, while the REPU is not an ideal tow vehicle, it is a very capable platform. I bought my REPU because I wanted a truck to do truck stuff with, but not a truck that drove, well like a truck. I've owned or had in my family a couple F150s, a tacoma 4wd, and a B4000 4wd over the years and they all universally sucked when it came to driving fun. (on the road, at least)
It’s cool that Mazda put together such a capable and fun to drive platform all those years ago…
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94 RX7
89 RX7 GTUs
85 GSLSE
88 323 GTX
1975 REPU
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Hunter
Hauling
Posts: 178
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posted June 18, 2008 06:02 PM |
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REPU in the mountains
IMHO I think the REPU does not do as well as it should in the mountains because it is jetted too rich even at sea level. The thin air in the mountains just make this bad situation even worse ... on top of the "less dense air" problem. If possible make the main jets smaller before heading up over the pass ....
just my two cents.
Bruce Toski
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bliffle
Revvin Up
Posts: 95
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posted July 28, 2008 10:02 AM |
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Gee, now I'm REALLY sorry I sold my Very Nice 74REPU, since I'm thinking of getting a small travel trailer. My 74 had a pretty new 13B that ran fine and strong, and everything else seemed good over the 4 years I had it.
I can see that the brakes would have to be upgraded, though. And I suppose the trailer would also require brakes. I don't know how I'd hookup a transmission cooler, which might be necessary, but I suppose others have done it already.
I wonder what size travel trailer I could successfully tow with a properly prepared REPU (13B, improved brakes, improved tires/rims, cooler, etc.)?
I only weighed my 74 once, when I picked up some garden stone, and I thought it was 3400 lbs empty.
Anyone have experience pulling a TT?
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BadAssRX-7
1st Gear
Posts: 49
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posted January 15, 2009 03:20 PM |
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2 things, 1 a comment 1 a question.
Comment, with my RUSTY 74 i have hualed in the bed a hell of a load. I had 25 4x4x8 p.t. posts and i had 30 80 lbs bags of quikcreet(sp?). oh it was fun the guys at home depot thought i was nuts. i only had a 7 mile drive on roads with 35 mph limits. the ass was plenty low and the front was high but it handled it great. i bit touchy when you were 45 or so but hey the front end is up in the air. Im running a 6port 13b with dellorto 48mm DHLA r.b. header back to im not to sure who or what. it had plenty of power.
ok now the question. what are you using to tow? a bumper mounted ball or a reciver hitch deal? I have looked all over the web and in stores and NOBODY lists a repu, 1600 or courior with a hitch kit. I have no rear bumper so this was the way i planed to do it.... just incase i needed to hual a towdolly or a wire trailer with a few bikes on it. I guess im gonna have to make a reciver hitch.
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83 limited edition rx7...T2 SWAP ON HOLD, 89 vert d.d., 74 rusted repu with 6port & Dellorto, 05 ZZR600
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Brad
Rotorhead
Posts: 1672
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posted January 16, 2009 01:19 PM |
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Craig had uhaul make a hitch for him back in the day. It had to be fabbed, no plug and play. Take it to uhaul.
Airlift sells rear air shocks that you can fill up with up to 250psi of air. They help level the load and stiffen the rear suspension too. That really helped out when I moved a bedroom set from norcal to socal. Just check the air pressure at every fillup. Then drop them to 40psi for softer normal day 2 day driving.
quote:
2 things, 1 a comment 1 a question.
Comment, with my RUSTY 74 i have hualed in the bed a hell of a load. I had 25 4x4x8 p.t. posts and i had 30 80 lbs bags of quikcreet(sp?). oh it was fun the guys at home depot thought i was nuts. i only had a 7 mile drive on roads with 35 mph limits. the ass was plenty low and the front was high but it handled it great. i bit touchy when you were 45 or so but hey the front end is up in the air. Im running a 6port 13b with dellorto 48mm DHLA r.b. header back to im not to sure who or what. it had plenty of power.
ok now the question. what are you using to tow? a bumper mounted ball or a reciver hitch deal? I have looked all over the web and in stores and NOBODY lists a repu, 1600 or courior with a hitch kit. I have no rear bumper so this was the way i planed to do it.... just incase i needed to hual a towdolly or a wire trailer with a few bikes on it. I guess im gonna have to make a reciver hitch.
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-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge
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MAZDAMARK
Hauling
Posts: 139
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posted January 21, 2009 10:52 AM |
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Custom hitch on my truck, too.
Brad: That air setup sounds really nice. FWIW, I run Tokicos on my truck, but before I bought my trailer, I found a set of Monroe rears with helper springs. They were like $30 on ebay, but I haven't seen them since. Truck definitely rides stiff with them on, though. That's where a nice air setup would be nice -full adjustability.
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94 RX7
89 RX7 GTUs
85 GSLSE
88 323 GTX
1975 REPU
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Brad
Rotorhead
Posts: 1672
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posted January 21, 2009 12:39 PM |
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Yes. The shocks with integrated springs are stiff and bouncey when the bed is uloaded. Which is why the adjustability of air shocks is fantastic.
Gabriel sells the best air shocks.
Monroe sells second best.
I stand corrected on AirLift. The don't sell air shocks for REPU. They sell the real deal air SPRING that goes inbetween the frame and the axle. Brackets have to be bolted to frame and some sort of axle attachment. Lot of work.
You can also try http://www.supersprings.com/productguide.asp but would have to figure out which one fits. Perhaps an 80's Nissan would be close.
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-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge
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Klaus45
Redlining
On two wheels
Posts: 218
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posted January 22, 2009 10:07 AM |
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RE: Hitch
The blue truck I sold Neal had the most heavy-duty, well-made (rectangular cross-section)'custom' bumper + hitch receiver setup I've ever come across... if he still has it, it might be a good example to replicate, or use as a 'blueprint', perhaps for a slightly lighter-weight version(?)
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Crit
Revvin Up
Finally REPUing
Posts: 90
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posted May 15, 2009 12:44 PM |
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I just picked up a 77, and was thinking the same thing about a receiver hitch. Neal, do you still have that receiver that you could perhaps measure up and snap a few pics?
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BadAssRX-7
1st Gear
Posts: 49
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posted July 12, 2009 04:58 AM |
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well I have been lookin and looking for a hitch that will work. and i think wally world has it its like 135$ and fits jeeps, dodge, ford, mazda, chevy cars trucks vans its adjustable width and drop(hitch drop from frame) and the spacing to be flush with the bumpper or to miss the stock spare.
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83 limited edition rx7...T2 SWAP ON HOLD, 89 vert d.d., 74 rusted repu with 6port & Dellorto, 05 ZZR600
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