1980 Cj5 Suspension Advice

Gents,

A little background:
I'm tearing down my 80 CJ5 (Id like to bore out its 6 cyl engine a bit) since I have a lot of stuff I didnt like about the POs "handy work." Ive already completely rewired it but l also need to replace the transmission and drive shafts so I figured why not do it all myself and get it right. The jeep had a T176 mated to a Dana 300 and what looks to be a pretty standard ~3" skyjack lift over what I'm guessing are the stock leaf springs. I got a crazy deal on a T18 transmission that needs a top plate that I think should fit right up to the existing Dana 300.

The Questions:
What would you recommend for a 4-6" suspension lift? I'd really like to get some better articulation and a wider offset out of the current axles and wheels. I need to measure the tires but for now I'm guessing ~30s (seem a tad bigger than the stock 225/75R15 though). And If I recall correctly I've been told that the tires he chose are crap so a future upgrade would be good once the tread is down. Not sure I'm a leaf spring fan, but is a coil conversion even possible in an 80 if I just weld on new brackets and add some control arms? My searches have only shown pre-80s CJs but it seems like a total PITA.

I'm in no rush to get it done so if it makes sense I'll consider it. Also wondering if I should leave the stock clutch or change it while it's all easily accessible. Finally...drive shaft recommendations? I tossed the old ones.

The jeep would just be for light jaunts to the beach, maybe some basic trail drives, and driving close to home, but I dont want to underdo it either. Overkill is underrated and moderation is for cowards.

Pics and more info in a bit when I get home.

Thanks for playing.

Jon

 

I uploaded some files for reference. I should probably start a new thread for this but in the meantime since I mentioned the T18...can someone confirm that this is the right T18 for my jeep?

The tires are 31x10.50R15LT Definity Dakota M/Ts. I'd probably like to keep them for now and just max the offset. Maybe bigger on the next set if they won't rub.

 

The tag says it's a t18 and it looks like one. If you're looking to make power, over boring an engine is the least effective way to do it.

 

Suggesting something else, specifically?

And about the transmission...from my reading I've learned that some T18s wont fit, but I believe they're pre-79 models with aluminum cases and more shaft splines. That's why I wanted confirmation before I prep, paint, and mount it.

 

4.0 head (or whole engine) swap is probably the best bang for your buck performance wise.

 

I'll check it out but tbh it was probably a stupid idea to mess with the engine right now anyway. Only brought it up because my neighbor mentioned it. Enough to do already and it runs well. Seems like a head swap would be quite a project in itself.

 

If you haven't done so already, I suggest you spend some time reading through Novak's web site regarding your T18 swap for your particular application. It should help you understand what is involved. May help you decide about your clutch too.

 

I've read it, thanks. That's where I got that bit of info. on the older models. Definitely a good reference, though. Dont recall the clutch being mentioned...

 

Looks like an early T-18 with the early reverse shifter ............the input shaft looks like a 6.5" stick-out which is good......but you should check how many teeth are on the input shaft gear inside that meshes with the counter shaft below........17 teeth for a 6:32 gear low gear........also inspect that large sliding gear in the back which is 1st & Reverse that also meshes with the counter shaft below........since 1st and reverse are non syncro that's where gear wear and damage to gears happens the most...........

4-6 inches of lift is allot.......for those small tires and if you go that way with leaf springs the steering will also need to be addressed........and ride quality will also suffer.........Low is better off road and long as you have clearance for tires...................linking the front and rear for coil overs can be done ..........but it's no easy task.

 

Good advice on the transmission. I would like to leave some room for bigger wheels and tires later, without it being ridiculous for these 30's.

If youve got any good resources on how to do the coil over swap, please share. I know very little about suspensions. I'm up for it, but I'll need to do some homework. For example I dont understand what you mean by linking the front and rear? I thought the idea was independent suspension for each tire and you link the via the axles with whatever steering components are needed.

The bigger lift and larger offset are why I wanted to do away with the leaf springs, in addition to getting rid of some weight and clutter under the vehicle.

 

The bigger tires obviously need more room and the only way you get that to a certain extent is to have wider axles..........spacers to gain axle tread width should only be used when you have ran out of options..............Linking simply means your attaching points from the frame to the axle.............front end due to space , a motor and a offset driveshaft usually has a 3-link suspension.........in the rear due to a centered drive line a 4 link suspension is normal...........independent 4 wheel suspension is not the norm for most off road Jeep type vehicles , but can be done.......most off road vehicles still have solid axles.......with suspension points similar as the leave springs.........the benefit on the coil overs is room , weight and the ability for infinite tuning for ride...............

if your leaning that way........you will need a lot of hands on knowledge and experience nearby...........and not getting it over the internet.

 

Makes more sense now. I have a roommate who is a mechanic and a few shops nearby should I run into anything unexpected. Welding isn't a problem. I'll try to get a better feel for it and go from there. Still lots to do before I have to commit to any one thing. Rather stay away from new axles. Maybe I'll see what I can get away with using these axles and go from there, since that will be the limiting factor.

 

I did some talking with a few dudes and priced some things out. It's still possible (maybe even a hybrid setup) but we should definitely talk leaf spring suspensions. I've narrowed it down a bit to 15" or 17" wheels and like a 10" wide tire with a very negative offset and a hub spacer. Maybe around a 33" tire should do nicely to widen the base a bit and lower the CG on the small CJ frame I'm thinking. Thoughts on this? Any recommendations for maybe a progressive spring set up for my needs? Good brands, etc.?

 

Here's my feeling on your desires for a new suspension. The standard lift for a CJ5 to clear 33x12.5.15 is around 3 inches. Lots of folks use a 2.5" spring and slightly longer shackles. Its also common to put in an additional 1" body lift. Just looking at your objective for the Jeep, 4-6" is not necessary, unless you're going for looks. You"ll then have to deal with drive line angles and steering issues. I've done a custom spring over suspension for about 6", but it was for a mostly off road jeep and required lots of corrections. Here's my suggestion: Its relatively easy to convert to YJ leaf springs on an 80' CJ5. That will give you lots of options for a spring kit. I bet you could find around a 3.5" kit that would work out great. It will ride nice, articulate well and be a simple install. FWIW, another important upgrade for your jeep would be a rear axle upgrade. Either a Dana 44 or 1 piece shafts for your AMC model 20.

 

Good stuff thanks I'll check that out.

Might leave the axle for later until I can find a good deal in a scrap yard on a D44 or maybe a Ford 8.8.

 

The two main problems with the AMC 20 in these Jeeps is the separable hub (weak axle shafts), and weak housing tubes. Many owners have upgraded their axles with 1-piece aftermarket axle shafts, and some reinforcing (a truss typically). I expect there is lots of info about this on the internet. The gears are plenty strong; the ring gear of a Corporate axle is larger than a Dana 44. In the meanwhile, make sure those axle nuts are tight, and check them - they have some unreal torque spec. Looked it up - "250 min." I interpret this as run it up to 250, and then turn it however much more you need to put the key in.

 

Damn. It's ironic because the truss would fit well with the coil overs, but even a hybrid setup would be expensive and just put them in front. I see what yall mean with the wheel spacer now though. Plus I just found out the T18 to Dana 300 adapter costs ~$550 Good thing I got the transmission so cheap. After the top plate, shifters and adapter and doing the work myself I might end up saving a couple hundred bucks all said and done. Looks like I'll need to put that towards the axle. New(ish) disk brakes sound like a good idea anyway.

Didnt find much on the clutch, besides the stocker will work but because of the hydraulic clutch link I'm installing I might want a new pressure plate that plays nice.

 

Regarding the clutch, I recall the 258 and 304 run the same 10.5" combo. The 360 and 401 got an 11" Borg&Beck package, which will bolt in to the 304s. The 258 should accept the same parts; you can look at the flywheel for the larger diameter bolt circle. IIRC the export 258 J20s got the 11" clutch too. That said, I'm not sure you need (or want) a heavy 11" clutch for a lightweight vehicle like a CJ, even with more power.

If you want more power, the cheapest and easiest route is to swap in the 4.0L HO engine with its excellent Mopar/Bosch multiport fuel injection. Take the 258 crank and put it in the 4.0L block and you'll have a 4.6L stroker. There's a forum devoted to these engines - Jeep Strokers - Homepage

 

You read my mind! Novak recommends changing the pressure plate when you upgrade to the hydraulic link. So I'll keep it stock but make that $120 change since itll be open. If I understand correctly I can also use the same T176 bellhousing if I drill out a new hole. That should set her up nice and then I'll measure for the YJ lift from there. I think the adapter will set the rear wheels back further, which should be fine. I can cut the fenders a bit and still keep the relatively same look.

I'm rebuilding the T176 transmission with Novaks kit since I already had it. Hopefully I can sell that and throw it in to the money pit

 

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