I searched the forum but only found threads about installing complete Jaguar IRS, which I'm not interested in. I'm curious if anyone has experience running 1961 - 1967 (corrected from 1971) Jaguar E-type rear coilovers (non-adjustable OEM style). At $160 loaded each from my parts houses, they seem like an economical and slick option since they are compact. The car is a 1926 Ford Model T roadster highboy that I'm building with period parts only available before 1968. I initially planned on running a single leaf spring behind on the rear axle to get the car low enough. However, I came across a 1967 XKE parked at the grocery store the other day, had a look at the rear suspension, and thought those coilovers were clean. Anyone have experience running them on a solid rear axle lightweight hot rod?
Jaguar use 4 on the rear of those cars. Guess you would need to know the rear weight of the car to know if these have enough spring.
I used a couple of Jag replacement Koni shocks on my old beater in my avatar years ago, they worked OK but were non adjustable so the shock mounts were made to have multiple adjustments and over that time the got weaker and I finally replaced them with QA-1 multi adjustable shocks, they have a knob that make them very soft to very firm. I wish these were available when I built the sedan, the ride is infinity better. HRP
Correct, Jag IRS uses one fore and aft of the control arms, but they are also designed for a sports car working on independent suspension whereas the T roadster is more of a straight-liner with a solid axle. I'm no suspension engineer, but I assume the geometry of the Jag IRS and its intended curvy road purpose dictates the need for four coilovers. Here's what I've found researching vehicle weights and using Q1's, Carrera's, and Speedway Motors' spring charts. All three charts verify each other's info: 1967 Jag coupe rear weight: 1,724 lbs. OEM spring length: 10" OEM spring rate: 250 - 280 lbs. depending on the source. Number of coilovers required: 4 1926/27 Model T highboy V8 roadster rear weight: 1,200 lbs. Spring length: 10" (to fit the Jag shock) Required spring rate: 225 lbs. Number of coilovers required: 2 From this information, two OEM 10" Jag coilovers should be more than what's needed for a T highboy V8 roadster. While the math pencils out, I'm curious to get some feedback from those who have used the coilovers on light (under 2,500 lb) hot rods.
Thanks for the details. A deuce Tudor comes in at around 1,400 lbs rear weight, so if they worked on your setup, maybe the 1,200 lbs. on the Model T won't wear them out or at least not as quickly? Do you remember what brand spring you used? Maybe some are better than others for the Jag. Did your car handle well with the Jag coilovers? Do you remember at what angle you had them set and at what location on the rear axle?
Jegs Steering & Suspension JEGS Single Adjustable Coil-Over Shocks View All JEGS Single Adjustable Coil-Over Shocks Single-Adjustable Coil-Over Shocks with Coil-Over Springs [10 in. 150 lb./in.] Part Number: 555-64986K2 ★★★★★ No rating value for 64986K2 Click image to zoom $371.96 More than 10 available Lowest Price Guarantee Single-Adjustable Coil-Over Shock Kit 10 in. 150 lb./in. Compressed Height: 10 1/8 in. Includes: (2) Single-Adjustable Coil-Over Shocks If the local parts store Jag shocks are $160. each it seem penny wise dollar foolish not to buy these. I wouldn't use a shock that is strictly for Jag on any of my builds unless it had a Jag rear in it. Pat
That 250# to 280# spring rate is what would be a concern in my opinion. I have progressive rate coilover springs on my T roadster that have more or less a "beginning rate" of 125# and the ride in it is a bit harsher than I'd like. Now, just for all of the facts, my T only weighs about 1400# TOTAL. The angle that a coilover is mounted at also plays a big part on the apparent or effective spring rate. There used to be a chart that gave examples in the angle effect on spring rate in Speedway's catalog, but just in a quick glance in the catalog at hand I didn't see it. Basically a spring mounted vertical will have the full spring rate but as spring/coilover is angled over more and more the effective rate becomes less and less. BTW....I'm talking spring rate (and shock dampening stiffness too) at the wheel. Some searching will likely find a chart to make what I am saying more clear. I hope this helps. Lynn
Here you go....found it right away. Other useful info too. https://www.onallcylinders.com/2017...spring-rate-correction-angle-mounted-springs/ Lynn
One other thing to remember is the Jag shocks don't come with springs; you're expected to re-use the existing ones. And if good ride quality is important, the OEM Boge shocks are best.
Thanks. Yes, I'm aware of the spring/shock angle effectiveness but appreciate you checking. That was actually a thought of mine to help take out some of the Jag's OEM stiffness by installing them leaned over a little more, maybe 12 or 15 degrees. With 1923tub's and your comments about the factory Jag springs being stiff, I might explore spring options since I can purchase the Jag shock separate. With so many modern coilovers available, I bet I could find a 10" spring with an i.d. and o.d. that will work with the Jag shock. Maybe start at 125 lbs. as go up as needed.
Interesting. The catalogues I've seen show the '61 - '71 Jag coilovers being the same with '72 + different. That photo explains the difference, but it's confusing on the transition year since it calls one style '61 - '68 and the other '68 - '87, unless they used both the 10" and 9" spring style in '68. Sticking with 1967 should clear up the confusion.
Thanks, Steve. Your comment about OEM Boge springs backs up what I've read on a few Jag forums. Ride quality isn't a concern for my build, but if I go with a factory spec spring rate, I'll keep my eye out for some OEM Boge if I can get them at a decent price knowing I'll be competing with vintage Jag builders.
I think your plan is fine. The trick will be to get the spring rate. As long as replacement springs are available and easy to swap, you are good shape. Look in junkyards, Jaguar bodies seem to rust out and kill the car long before the suspension is worn out. I have Jaguar IFS and IRS in my 52 GMC. Rides and drives great. The rear dual shocks are not too stiff, even unloaded. Sent from my SM-A102U using The H.A.M.B. mobile app
It's not rust, it's the Lucas wiring and/or lack of maintenance on the motors that kills 'em.... Then after they sit, then they rust out.... LOL I had a Jag monkey on my back for a while....
Spax has been making adjustable performance shocks in England since about 1960 , including parts for replacement on Jaguars. Look on UK ebay... usually plenty of vintage sets there. They still make the classic series as made in the 1960s. https://www.spaxperformance.com/classic-home/
Great lead. Spax's website is absolutely screwed in functionality no matter what browser I use, so I can't get to their catalogue/products pulled up. I'll call them if I go that route. I found their adjustable "classic XK" series on another website, however. Pricey, but an option. It looks like GAZ makes adjustables that looks pretty much identical to Spax but cheaper, so there's another option if the reviews pan out positively.
When I built my Austin 11 years ago a guy gave me a pair of Jaguar coilovers, so I set up my rear suspension to fit the length and used them. First ride in it I thought it was solid rear suspension, as it rode like a buckboard! I ordered a pair of QA1's and the correct springs, and fixed it. I tried finding lighter springs for the Jaguar coilovers, but they're a bastard size and nobody had anything but stock rate springs.
Any chance you still have the Jag springs/shocks to take measurements of the i.d. and o.d. of the spring or retainer?
I know you only want pre-'68 parts on your roadster so these probably won't fill the bill but, I grabbed a pair of coilovers off an '88 Subaru wagon at Pick-N-Pull for $9 each on half price day. Adapted them to my '27 roadster and they work great! IIRC, my research put them at 150psi. Granted, the car doesn't ride like a Cadillac but then it's a 1400 lb roadster! The ride is just about right.
I don't want to go on anymore about my statement other than Koni coil overs appeared in race cars and speed shops in 1958. Pat
I'm confused. My original question wasn't about whether coilovers exited by 1967 but about people's experience running 1961 - 1967 (corrected from 1971) Jaguar E-type coilovers in their light hot rods. Nothing I can find suggests anyone pre-1968 made fully adjustable (gas/spring) anodized aluminum coilovers that look remotely similar to the Jegs you posted. If you have a period photo or scan of a catalog that shows such a coilover by 1967, I'd appreciate seeing it for reference.
https://www.jalopyjournal.com/forum/threads/rear-coil-overs-on-my-27-are-too-stiff.656300/ Read this....
Thanks. Skimmed it and saved the thread for when I start dialing in weights and go to order the springs.
You can go a long way with a set of corner weight scales. Weigh all 4 corners, then sit the car on jack stands and disconnect the springs and then weigh the 4 corner wheels to get the unsprung weight. Then you can calculate how much weight the suspension actually supports. For a reasonably comfortable ride you want approx 5:1 weight to wheel rate ratio. So a car with 1000 lbs sprung rate in the rear [500 each side] will need a wheel rate of 100lbs/in The ^^^ would settle approx 5" when lowered off the jacks [with leaf springs] but with coils you preload or compress them at installation. The 1000lb estimate is a 3000 lb car with 55/45 front to rear bias. [1350 lbs rear] Deduct 350 lbs for the rear end /wheels/ suspension arms/ driveshaft etc. Suspension arms , shocks and driveshaft are 50/50 sprung to unsprung, so it is easier to simply disconnect the springs and weigh the wheels. spring stiffness can also be adjusted by altering the "motion ratio" Get it right....and the car will be nice to drive
The Jag IRS was used in the XKEs and period Sedans. The XKE was around 2500 lbs, the sedans 3900 lbs. All used 4 rear coil overs on each rear end, so I dont think 2 XKE shocks would be too stiff for your application. 2 Sedan shocks, yes. Might account for the different spring sizes. As Pat mentioned above, Koni adjustable shocks were period racing accessories. I had a 31 Chevy coupe with the adjustable Konis, but the PO mounted the top bushing at right angles to the bottom bushing which bent the rod - so I cant really tell you how they worked. Sorry, they are long gone. brg
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